Special Report on Sea Level Rise

by Judith Curry

I have now completed my assessment of sea level rise and climate change.

The complete report can be downloaded here [Special Report- Sea Level Rise].

My preliminary compilation of information was provided in the 7 part Climate Etc. series Sea level rise acceleration (or not).

This report reflects 18 months of work on this topic. Why have I devoted so much time to the sea level rise issue? First, I regard sea level rise to be the most consequential potential impact of predicted global warming. Second, there is a great deal of public confusion about the issue, including decision makers. Third, a number of CFAN’s clients have queried me about a range of specific concerns that they have regarding sea level rise (and I have been doing consulting on this topic).

Why do I think an independent assessment of the sea level rise issue by yours truly is needed, given the plethora of international and national assessment reports? My clients are concerned about the alarmist predictions they have encountered. I have seen various ‘experts’ make public statements projecting 21st century sea level to be as high as 9 m [30 feet]. My clients are looking for someone that they trust to provide an objective assessment that focuses on their issues of concern.

I am not a published expert on sea level rise, although I have published some relevant papers in oceanography and the climate dynamics of the polar regions. What I bring to this assessment is a broader perspective on the issues of climate dynamics, climate modeling and uncertainty than most of the community working on the sea level rise issue. In any event, it is arguably useful for a knowledgeable person outside of the publishing sea level community to provide an independent assessment.

The process that I used in preparing this Report was to:

  • read in detail the relevant international and national assessment reports,
  • conduct an extensive literature survey of recent publications (twitter has been invaluable for this),
  • post my initial chapters on the blog for comments and references that I might have missed, and
  • elicit comments on a draft of the report from several different clients regarding readability and needed clarifications.

My report provides a different way of framing the sea level rise issue and of interpreting the evidence, in a way that I don’t think is inconsistent with the evidence in  the mainstream sea level rise assessments.

While on the plane last week headed for Thanksgiving travel, I received an email from Roger Caizza, informing me that a draft was available for review of the IPCC Special Report on Ocean and Cryosphere in a Changing Climate. Since I am a registered reviewer with U.S. Global Change Research Program, I signed up to review this Report. I did a quick read of chapters 3 and 4 over the weekend, and I saw nothing in this Report that made me feel uncomfortable about my own Report. Later next week, I will do a more careful read and submit comments. I will obviously not make any public comments on the IPCC draft, other than to say I was fairly impressed with what I read.

A few comments are in order regarding my impressions of the sea level and cryosphere communities. I know very few of these individuals personally (and then in only the most casual way). I have to say that I am quite impressed overall with this community. They have made a massive amount of progress since the IPCC AR5, particularly in understanding the ice sheets. They ‘get’ the importance of natural internal variability, deep uncertainty and worst-case scenarios. That said, the way all this gets portrayed in the media does not provide a balanced perspective or one that is useful for decision makers.

Report summary

The overall report is 80 pages long, with 7 pages of that being the reference list. The focus of the report is on the 21st century, with one Chapter specific to U.S. coastal sea level rise.

Here is the text of the introduction, minus the references and footnotes.

The alarm over sea level rise

The public discourse on the threat of sea level rise is typified by these dire statements from climate scientists:

“That’s the big thing – sea-level rise – the planet could become ungovernable.” – Dr. James Hansen, former Director, NASA GISS

“We’re talking about literally giving up on our coastal cities of the world and moving inland.” – Dr. Michael Mann, Penn State 

 The alarm over sea level rise is not so much about the 7-8 inches or so that global sea level has risen since 1900. Rather, it is about projections of 21st century sea level rise from human-caused global warming.

This Report refers extensively to the Assessment Reports prepared by the Intergovernmental Panel on Climate Change (IPCC), since these Reports are used to guide policies developed by the UN Framework Convention on Climate Change, including the 2015 Paris Agreement.

According to the IPCC, the projected 21st century sea level rise depends on the amount of greenhouse gas emissions. The likely range of projected sea level rise by the end of the 21st century is from 0.26 to 0.82 m [10 to 32 inches], depending on the emissions scenario.

The primary concern over future sea level rise is related to the potential collapse of the West Antarctic Ice Sheet, which could cause global mean sea level to rise substantially above the IPCC’s likely range in the 21st century. The IPCC AR5 has medium confidence that this additional contribution from the West Antarctic ice sheet would not exceed several tenths of a meter [less than a foot] of sea level rise during the 21st century.

Subsequent to the 2013 IPCC AR5, there has been a focus on the possible worst-case scenario for global sea level rise. Estimates of the maximum possible global sea level rise by the end of the 21st century range from 1.6 to 3 meters [5-10 feet], and even higher. These extreme values of possible sea level rise are regarded as extremely unlikely or so unlikely that we cannot even assign a probability. Nevertheless, these extreme, barely possible values of sea level rise are now becoming anchored as outcomes that are driving local adaptation plans [link].

Is the alarm over sea level rise a ‘false alarm,’ or not? The following four issues frame this report:

  1. Whether recent global sea level rise is unusual in context of the historical and geological record.
  2. The extent to which recent global sea level rise is caused by human-caused global warming, relative to natural causes of global sea level rise.
  3. The extent to which local sea level rise is influenced by the global sea level rise, relative to local vertical land motion and land use practices.
  4. Projections of sea level rise (global and local) for the 21st century, from all causes.

This Report critically evaluates the assessment and conclusions from the IPCC and other recent assessment reports regarding sea level rise, and includes an assessment of recent research and the knowledge frontiers. The IPCC and other assessment reports have been framed around assessing support for the hypothesis of human-caused climate change. As a result, natural processes of climate variability have been relatively neglected in these assessments. Arguments are presented here supporting the important and even dominant role that natural processes play in global and regional sea level variations and change.

Understanding and predicting sea level rise is a vibrant and active area of research. The challenges and uncertainties are well recognized by international scientific community, as formulated by the World Climate Research Programme (WCRP) Grand Challenge on Regional Sea Level Change and Coastal Impacts.

Conclusions

Here are my conclusions:

Mean global sea level has risen at a slow creep for more than 150 years; since 1900, global mean sea level has risen about 7-8 inches. The implications of the highest values of projected sea-level rise under future climate change scenarios are profound, with far reaching socioeconomic and environmental implications. However, these projections are regarded as deeply uncertain and the highest of these projections strain credulity.

The IPCC and other assessment reports are framed around providing support for the hypothesis of human-caused climate change. As a result, natural processes of climate variability have been relatively neglected in these assessments. Arguments have been presented here supporting the important and even dominant role that natural processes play in global and regional sea level variations and change.

With regards to the four issues raised in the Introduction:

  1. Is the recent sea level rise (since 1993) of magnitude 3 mm/year unusual?

No, although this conclusion is conditional on the quality of the global sea level data. The available evidence shows the following:

  • Sea level was apparently higher than present at the time of the Holocene Climate Optimum (~ 5000 years ago), at least in some regions.
  • Tide gauges show that sea levels began to rise during the 19th century, after several centuries associated with cooling and sea level decline. Tide gauges also show that rates of global mean sea level rise between 1920 and 1950 were comparable to recent rates.
  • Recent research has concluded that there is no consistent or compelling evidence that recent rates of sea level rise are abnormal in the context of the historical records back to the 19th century that are available across Europe.
  1. Has recent global sea level rise been caused by human-caused global warming?

 Identifying a potential human fingerprint on recent sea level rise is confounded by the large magnitude of natural internal variability associated with ocean circulation patterns. There is not yet convincing evidence of a fingerprint on sea level rise associated with human-caused global warming:

  • The slow emergence of fossil fuel emissions prior to 1950 did not contribute significantly to sea level rise observed in the 19th and early 20th centuries.
  • The recent acceleration in mean global sea level rise (since 1995) is caused by mass loss from Greenland that appears to have been larger during the 1930’s, with both periods associated with the warm phase of the Atlantic Multidecadal Oscillation.
  1. To what extent is local sea level rise influenced by global sea level rise?

In many of the most vulnerable coastal locations, the dominant causes of local sea level rise are natural oceanic and geologic processes and land use practices. Land use and engineering in the major coastal cities have brought on many of the worst problems, notably landfilling in coastal wetland areas and groundwater extraction.

  1. How much will sea level rise in the 21st century?

Local sea level in many regions will continue to rise in the 21st century – independent of global climate change.

Emissions scenario choice exerts a great deal of influence on predicted sea level rise after 2050. If RCP8.5 is rejected as an extremely unlikely or impossible scenario, then the appropriate range of sea level rise scenarios to consider for 2100 is 0.2–1.6 m. Values exceeding 2 feet are increasingly weakly justified. Values exceeding 1.6 m require a cascade of extremely unlikely to impossible events, the joint likelihood of which is arguably impossible.

Further, these values of sea level rise are contingent on the climate models predicting the correct amount of temperature increase. There are numerous reasons to think that the climate models are predicting too much warming for the 21st century, and hence the more extreme values of sea level rise (above 1 m) are arguably too high.

Kopp et al. (2017) state:

“The breadth of published projections, as well as of remaining structural uncertainties, highlight the fact that future sea-level rise remains an arena of deep uncertainty.”

Climate-related decisions involve incomplete information from a fast-moving and irreducibly uncertain science. The challenges of understanding the causes of sea level rise and projecting future climate change and sea level rise are well-recognized by the international community of climate and sea level researchers, as summarized in the World Climate Research Programme (WCRP) Grand Challenges. The WCRP Grand Challenge on Sea Level Rise states:

“Despite considerable progress during the last decade, major gaps remain in our understanding of past and contemporary sea level change and their causes. These uncertainties arise from limitations in our current conceptual understanding of relevant physical processes, deficiencies in our observing and monitoring systems, and inaccuracies in statistical and numerical modelling approaches to simulate or forecast sea level.”

“A significant part of this large uncertainty arises from inappropriate (or sometimes missing) model representations of some physical processes that affect sea level and needs to be reduced for more accurate sea level projections.”

“Improved sea level predictions/projections, particularly over the next decades, are critically dependent on understanding observed natural variability, accurately reproducing it in models, and mapping its future behavior under climate change.”

Publication

I’m publishing this through my company Climate Forecast Applications Network (CFAN) as a Special Report. I regard the currently posted version to be final, although I will correct any errors that are spotted.

I considered publishing this in some other venue, but it wasn’t obvious as to where/how I might publish this, and I didn’t want to wrestle with copyright issues. Plus I wanted to make sure this is publicly available, and hope that it will reach a wide audience.

I encourage you to read the entire report. I look forward to your comments, and would like to thank you again for comments on the original Sea level rise (acceleration or not) blog posts.

Conflicts of interest statement

I imagine that the first reaction to this Report from the activist wing will be to question my ‘motives.’ Well my motives are the same that they have always been: sound, evidence-based science and helping decision makers make effective use of that science.

From CE’s About page:

Funding disclosure:  Funding sources for my research  have included NSF, NASA, NOAA, DOD and DOE. Recent government contracts for CFAN include a DOE contract to develop extended range regional wind power forecasts, a DOD contract to predict extreme events associated with climate variability/change having implications for regional stability, and a NOAA contract to improve sub seasonal forecasting. CFAN contracts with private sector and other non-governmental organizations include energy and power companies, reinsurance companies, financial companies, other weather service providers, NGOs, development banks and government agencies.

Specifically with regards to the issue of sea level rise, CFAN’s clients are in the insurance, energy and public sectors.  As a matter of company policy, CFAN does not name its clients.

If anyone thinks that I can be bought or otherwise influenced, they should think harder. Many have tried, none have succeeded.

168 responses to “Special Report on Sea Level Rise

  1. Reblogged this on Quaerere Propter Vērum and commented:
    Money quote: “Local sea level in many regions will continue to rise in the 21st century – independent of global climate change.”

    So, start preparing for this eventuality now (if appropriate), independent of the blame game attached to “cause.” Don’t wait until the last minute to make adjustments to where you might live (again, if appropriate). The choice is yours to make.

    Another well-researched special report by Dr. Curry. Thank you.

  2. Thanks Judith, very interesting and extremely useful.

  3. Linking Greenland’s ice loss to only the AMO is dangerously narrow. It may well be linked to global temperatures, and the latest rise is several times larger than that in the 1930’s and likely to continue upwards through 2100, regardless of the AMO oscillations, which has implications for the melt rate of Greenland. Under the scenario that Greenland responds to global warming (with its Arctic amplification), its melt rate will continue to grow. Since 1990 the growth rate from Greenland+Antarctica fits an exponential with a doubling time near 10 years. CO2 levels above 400 ppm have not been experienced by Greenland’s ice sheet before, so it may be at a tipping point that eventually results in complete melting. A continuation of the 10-year doubling time would lead to 3-4 meters between now and 2100.

    • Jim D “CO2 levels above 400 ppm have not been experienced by Greenland’s ice sheet before”

      CO2 levels are thought to be pretty consistent world wide and ice core data shows that levels have been above the 400 ppm levels, so I don’t know how you come up with this statement.

      • When do you think CO2 levels were last above 400 ppm? Let alone 500-700 ppm we may have by 2100.

      • JimD. Is this the kind of tipping point you are thinking of. Based on the article, stuff is going to hit the fan in only a year. Well, to be fair, 1 year, 1 month and 2 days. Do you think we should warn Tony what is to befall his beloved Great Britain in a little over a year?

        I’m sure many believed this article when written in 2004. Now it’s almost 2020. And what do we have? Just more dopey predictions that will be falsified in a few decades.

        After seeing how many times their predecessors have been wrong, it seems the Doom Mongering Class would shut their mouths for awhile.

        If you keep the predictions to 2100, there won’t be anyone left to give you grief.

  4. Will provide comments after studying the report.

  5. The second to the last paragraph on page 9 should read “The IPCC AR5 WGI (2013) provided the following summary statements:”
    instead of “The IPCC AR5 WGI (2013) provided the follow summary statements:”

  6. Pingback: Judith Curry: Special Report on Sea Level Rise - The Global Warming Policy Forum (GWPF)The Global Warming Policy Forum (GWPF)

  7. 1. Typo: Reference to “Figure 4.1” in paragraph 3.1 should be to Figure 3.1.
    2. Figure 3.2, second panel (Grinsted). The portion of the graph beyond ~2006 should be noted as a projection. Or deleted if you want to focus solely on reconstructions, as described in your caption.
    3. Also in figure 3.2, the x-axis scales of the two graphs aren’t quite registered. Close though.

  8. Outstanding report. Seems comprehensive and very readable.

    Thank you for highlighting the level of uncertainty referenced by several authors. Also, thank you for discussing the geothermal activity aspect not only under the Ice Sheets but also the paper estimating its impact on the oceans temperatures. That was a first for me to see that kind of analysis.

    Given the growing interest in geothermal activity and its effect on the Ice Sheets and the ocean heating, I’m sure the IPCC will be addressing the issue of attribution just as Wunsch(2018) did.

    And finally, thank you for such an extensive list of citations. My book marks list just got bigger. Much reading ahead.

    • I too am very appreciative seeing more attention devoted to geothermal activity. That this kind of analysis in the past seems to have been relegated to out-of-sight-out-of-mind, presumably because of the difficulty to research inaccessible, remote regions of deep oceans/ice sheets; it’s rationale for doubting the legacy of models in itself IMO.

      • Heretofore it’s been in the realm of only “cranks”. Given the names associated with this recent research and that Judith references it in her report, it’s gained the imprimatur to discuss in mixed company. To ignore it much longer would be cause for misfeasance.

  9. Alarming scenarios are clearly off, but even medium scenarios are generally too high according to my projections (including the modest acceleration observed so far). IPCC RCP4.5, NOAA middle scenarios, and the Horton survey average of high and low scenarios are all too high.

    The difference will become very clear by 2025-30. The “Stadium wave” hypothesis and the extrapolation of the 60-yr oscillation in sea level change both agree that we are entering a period of a couple of decades of slow increase.

    Just to agree with us, NASA shows that from October 16, 2015 to June 14, 2018 the increase has been of 2.6 mm, or 0.98 mm/yr.

    If I am interpreting correctly the “Stadium wave” hypothesis, we are moving from a high sea-level rise rate (~3.9 mm/yr) to a low sea-level rise rate (~2.0 mm/yr). If it comes to pass, let’s see how they can explain it.

    • @Javier “If it comes to pass, let’s see how they can explain it.”

      Expect the already well rehearsed explanation: “Even though we were wrong we were right.”

      You may think this manoeuvre is invalid because it is breaking the rules, but that is to assume their rules and yours are the same.

  10. Very clearly stated. I am looking forward to digging into the full report.

  11. “We’re talking about literally giving up on our coastal cities of the world and moving inland.” – Dr. Michael Mann, Penn State

    Good example of Mann’s inhumanity to man and the snarl logic of Leftist insanity. “Imagine your life without abundant, reliable, affordable electricity and transportation fuels,” says Paul Driessen (Holding Greenpeace accountable). “Imagine living under conditions endured by impoverished, malnourished, diseased Indians and Africans whose life expectancy is 49 to 59 years.”

    • under that formula, I’m sure the alarmists would be quite comfortable with seeing quotes in the newspapers along the lines of:
      “if Progressive “action on global warming” happens, we’re talking about literally giving up on modernity and democracy and returning to a time when people cooked over wood fires, washed their clothes in the bathtub, and bowed to unelected dictators.”

  12. My house is at 27′ above sea level and a half mile from the Gulf of Mexico. Been here for 40 years and nothing happening down here on Florida’s west coast. And when you here of a hurricane hitting somewhere in the gulf at hide tide to scare people, keep in mind that from Brownsville, Tx. to Naples, Fl., nowhere is there more than 14″ between high and low tide. You’ll never hear that on the news. Dr. Franks, past Hurricane center & still on the air in Houston. taught me that. Him and John Coleman never played the climate game.

  13. Some confirmation of the upper bound: More than 1.2 m ( globaly) is extremely unlikely says the report from the UK, written by Tasmin Edwards: https://blogs.plos.org/models/too-early-to-say-whether-the-white-cliffs-of-antarctica-are-unstable/ .
    The “catastrophic” upper bound was generated former with some papers about the disintegration of Antarctic ice, which were not anymore considered. It was going too far…

    • thanks for spotting this!

      • Judith, my pleasure and as you wrote:” post my initial chapters on the blog for comments and references that I might have missed” … this is the right way for improvements IMO.

    • She has no scientific basis to claim poorly understood dynamic collapses are extremely unlikely.

      • The issue is that the driver for the dynamic collapse is RCP8.5, which is borderline impossible

      • JCH “She has no scientific basis to claim poorly understood dynamic collapses are extremely unlikely.”
        Harsh.
        More to the point is that we have no evidence that dynamic collapses are a frequent and common occurrence.
        Small scale dynamic collapses are known but I believe you are referring to her comment.
        ”The primary concern over future sea level rise is related to the potential collapse of the West Antarctic Ice Sheet, which could cause global mean sea level to rise substantially above the IPCC’s likely range in the 21st century. The IPCC AR5 has medium confidence that this additional contribution from the West Antarctic ice sheet would not exceed several tenths of a meter [less than a foot] of sea level rise during the 21st century.”

        I point out that said shelf has been there over known volcanoes for many millennia without bothering about collapsing hence logically [also known as scientifically] such collapses are inherently extremely unlikely.
        Arguing for the mere sake of arguing is poor form.
        In fact your argument bears a strong resemblance to that of your adversary’s chaos theory and sudden unexpected shifts.
        If you wish to continue denigrating Judy’s two bob I feel you are obliged to apologise to the chiefio for all those times you said he was wrong but now choose to use his very argument.

      • It’s fracture mechanics. Dynamic collapse. An ice sheet is a structure. It was not designed by a structural engineer. You think you know it is highly likely that a structure designed by nobody can withstand unknown forces. Brilliant bet.

      • “It’s fracture mechanics. Dynamic collapse. An ice sheet is a structure. It was not designed by a structural engineer. You think you know it is highly likely that a structure designed by nobody can withstand unknown forces. Brilliant bet”
        Look, first of all a diamond is a structure designed by nobody as well.
        The fact is that being designed by nature is not, repeat not a valid reason.
        Secondly unknown forces is a cop out of an argument as well.
        What do you plan to use? Ninja turtles riding a very large meteor would be included in your definition but it is not a realistic argument either.

        ” the WAIS contains just under 10% of this, or 2.2 million km3. The weight of the ice has caused the underlying rock to sink by between 0.5 and 1 kilometre in a process known as isostatic depression”
        We are discussing global warming as cause. The same global warming that melted the glaciers 20-1000 times bigger than this in the last ice age.
        The pitiful, slow rate of melt will take thousands of years to melt the ice even a little bit less.
        Not a little 1 km long 300 meter high bit of ice shelf. Calving glaciers do this all the time but they have a sea to fall into, not land all around.
        Give it up on this point and concentrate on the real ones you might win.

      • ‘borderline impossible”
        I think she meant impossible.
        Either way what she has just written sinks your third comment.
        She has every scientific basis.

      • stay tuned for tomorrow’s post, will clarify borderline impossible etc

      • Craig Remillard

        Catastrophic effects are almost by definition poorly understood and rare. Can you add any nuance to this point?

      • The driver as Judith intimated is the background state of the globally coupled Earth system. But even if the emission scenarios have any validity they feed into theoretically impossible opportunistic ensembles. Someone quoted the TAR on the impossibility of predicting future climate – although I’m not sure they quite grasped the point being made.

        But the ice itself is much more a materials than a structural problem. With boundary conditions including ocean and atmospheric temperature and isostatic rebound. Abrupt change in the background Earth system state cause the dynamic changes in Antarctic ice – not a structural collapse.


        http://www.antarcticglaciers.org/glacial-geology/antarctic-ice-sheet/icesheet_evolution/

        The Earth system is so complex – with – inter alia – stadium waves and anti-phase polar synchronous chaos that only data matters

        see – ‘Synchronization of polar climate variability over the last ice age: in search of simple rules at the heart of climate’s complexity” – http://www.ajsonline.org/content/312/4/417.short

        Data is hard to come by but it shows abrupt change at every scale – one of the simple rules at the heart of climate chaos.

      • Thx for reminding me of Rial, I will try to incorporate this

      • Two quick points. Wunsch ‘s figures are easy to explain and well documented. 0.09W/m^2 is the effect of the 47TW of internal heat of formation and radioactive decay of Thorium and Uranium released by conduction. Also what makes the healthy >300mSv pa radioactive Monazite sands of Guarpari and Kerala, etc.

        But not considered significant in the climate models as it is VERY steady hence not a cause of change. But note the scale is at predicted AGW level.

        So, at the risk of boring, I suggest the internal heat released as magma intrusion and extrusion under the oceans is 4 times this, and significantly variable, at AGW level. This variability of significant quantity is supported by many papers in the Volcanology and Geophysics field, but the effect on climate has not been attempted, until I did as referenced above, as far as my research has turned up. The approach includes considering gravitational and other stress effects on the lithsophere (see Io) and how heat balance is affected by the planet’s necessarilly very different response to varying internal and external heat load. A bit too joined up for many. AS far as the basic topic, The physical quantity must be significant in changing sea levels.

      • JCH,

        This seems to be a common issue with sea level rise. How do you quantify probability and communicate probabilities when you have some aspects which are well understood (e.g. thermal expansion, glaciers to some extent) and some aspects which are very poorly understood but could ultimately be large enough to dominate the overall total.

        The AR5 approach was to take estimates of the reasonably well understood aspects, calculate 5-95% ranges but then report those calculations as only a likely range, meaning 17-83% range. That allowed for a substantial chance of the rise lying above the stated range. They then stated a rough quantification of how much larger it could get than that range – “several tenths of a meter”.

        The Met Office report has a different and quite confusing approach. They are referring to their range as likely but also reporting it as a 5-95% range. But then they say:

        The UKCP18 interpretation of the projection ranges presented in this report is that there may be a greater than 10% chance that the real-world response lies outside these ranges and that this likelihood cannot be accurately quantified.

        In other words, they haven’t placed a meaningful probabilistic constraint on the upper bound at all. I suspect that will be lost on quite a few people though.

      • stay tuned for tomorrow’s post, i am suggesting a new way to deal with this

      • Pure genius. Let’s ignore the evidence and just go with the science of linear ice melt.

      • JCH “Let’s ignore the evidence and just go with the science of linear ice melt.”
        Yet you also said.
        “You think you know it is highly likely that a structure designed by nobody can withstand unknown forces.“
        Evidence is the opposite of unknown forces. So you choose to totally ignore the need for evidence in your catastrophying.

      • paulski0 |. “JCH,This seems to be a common issue with sea level rise. How do you quantify probability and communicate probabilities when you have a catastrophe to spin and no evidence to provide”
        One answer is to walk around in a sack carrying a big sign to scare everyone.

      • paulski0 You forget SLR can be higher or lower than expected.
        “The AR5 approach was to take estimates of the reasonably well understood aspects, calculate 5-95% ranges but then report those calculations as only a likely range, meaning 17-83% range. That allowed for a substantial chance of the rise lying above OR BELOW the stated range. They then stated a rough quantification of how much larger OR SMALLER it could get than that range – “several tenths of a meter”.
        In other words, they haven’t placed a meaningful probabilistic constraint on the upper bound OR LOWER bound at all.”

      • “The Met Office report has a different and quite confusing approach. They are referring to their range as likely but also reporting it as a 5-95% range. But then they say:
        The UKCP18 interpretation of the projection ranges presented in this report is that there may be a greater than 10% chance that the real-world response lies outside these ranges and that this likelihood cannot be accurately quantified.”
        Well 10% by definition lies outside the 5-95% range by definition. If they felt more does or could lie outside it then they are not the real 5-95% ranges anyway and should not have been published as such. The chance in the prediction is fixed. The chance of the prediction is not.

      • Angech

        You forget SLR can be higher or lower than expected.

        That is how they’ve phrased things in the reports for the sake of simplicity. However, the reality is that there is no evidence whatsoever to suggest sea level rise could be significantly below the modeled 5% bound. Whereas there is abundant evidence to suggest it could be much higher than the 95% bound. So it is correct to focus solely on the space above the upper bound.

        And there is a simple physical reason for this: entropy. The space beyond the modeled 5-95% range is all about ice sheets. You can have catastrophic collapse of unstable ice sheets. You can’t have an ice sheet catastrophically put itself together again.

  14. There has been some discussion of sea level rise on the UK Telegraph’s website, I’ve posted links to this blog and the paper, together with the paper’s conclusions. The paper is an injection of sanity to an often hysterical “debate.”

  15. Thanks for the new analysis.
    As I see it sea level changes are mostly a technological and engineering challenge and humans are good at dealing with slow incremental changes. I do not consider sea level changes a threat to the global biosphere.

    In the medium to long term it’s what is IN the water that will be much more problematic than if the ocean levels rise (or fall). The chemistry of the oceans is changing much faster than the level.
    https://earthobservatory.nasa.gov/images/92786/a-broad-view-of-flooding-in-the-carolinas
    https://www.nola.com/environment/2018/11/coast-guard-orders-taylor-energy-to-stop-14-year-oil-leak.html
    “The site may have released 150 million gallons of oil over the past 14 years. That would make the total release on par with the estimated 168 million gallons spilled during the BP oil oil disaster in 2010.”

  16. Im sure the IPCC report will mention the most outlandish sea level rise predictions as could/would/might/possible etc etc

  17. Page 67 section 6.7 first paragraph second to last sentence syste should be system.

  18. Dr. Curry ==> There is one graphic that troubles me — or gives me a problem — Figure 4.2 . from Chen et al. 2017 . The I-bars indicating adjusted and un-adjusted sea level to me are impossible to tell apart when they start converging on the right hand side. I know that is how it is in the original — I have used it in an essay and had the same complaint with myself — but the graphic loses one of its intended messages when it is not possible to discern between the two. I may fuss with it from the original paper and see if I can alter the colors or something. If I can improve it, I will email you a copy.

  19. Have now read the entire report. Very comprehensive. Glad you brought in the latest closure research, because it triangulates a bound on observations.
    A suggestion concerning the various historical tide gauge papers. None sample the same subset of available long record gauges. In fact, some authors wrote subsequent papers that did not even reuse their previous paper sample—by a lot. Given the importance of local VLM to each gauge, shifting the sample creates another methodological uncertainty that you might want to note.
    A second suggestion also illustrating the gauge sampling /ocean dynamics problem. You might want to note Woeppelmann’s 2014 paper ‘Evidence of differential sea level rise between hemispheres’ The ‘observed’ finding is improbable from first bathtub principles. The ‘found’ hemispheric rate delta of ~ 2mm/ yr (IIRC) would cause a lot of sloshing from north to south. More likely just sample bias, as there are many fewer long record tide gauges in the southern hemisphere so VLM is less likely to wash out of the sample.

  20. Judith, in The Netherlands we are scared by the collapse of the West Antarctic Ice Sheet this century. Did you investigate the boundary conditions for such a collapse?

  21. David L. Hagen (HagenDL)

    Excellent scientifically justifiable perspective.
    Minor suggestions:
    Re: “2100 is 0.2–1.6 m. Values exceeding 2 feet are increasingly weakly justified. Values exceeding 1.6 m…”
    When mixing SI and US, recommend showing both. e.g.
    “2100 is 0.2–1.6 m (8″-63″). Values exceeding 0.2 m (2 ft) are increasingly weakly justified. Values exceeding 1.6 m (5 ft)…”
    Similarly “3 mm/yr (1.2″/decade)”
    (There is also controversy over the 2 vs 3 mm/yr regarding land rebound from glacial melting.)

  22. “According to the IPCC, the projected 21st century sea level rise depends on the amount of greenhouse gas emissions.”
    There are now several sources showing that the assumed human cause of recent atmospheric CO2 content is invalid.
    See Harde 2017 and his censored response to Kohler 2017 at
    https://hhgpc0.wixsite.com/harde-2017-censored. For further discussion of Harde’s first principals analysis and the errors in Kohler see https://edberry.com/blog/climate-physics/agw-hypothesis/what-is-really-behind-the-increase-in-atmospheric-co2/.
    A mention of this work would not be inappropriate in your report as it further underscores the uncertainties involved.

  23. Coastal geomorphology and its evolution depends on local geological sedimentary platforms and igneous shields and sediment supply. Where there are sand flats, mangroves, salt flats or saltmarsh – accretion involves the transport of fine sediment onto coastlines by wave action in periods between storms. It can be washed away in storms. In estuaries floods can scour out channels and erode banks. Between storms asymmetric tidal flows carry fine sediment upstream restoring – and building – the platform. Streams on sedimentary platforms migrate – a result of helical flow steams – if we let them. Responses to these processes are embedded in the adaptive management practices of modern coastal and fluvial engineering.

    “Here we present an integrated global modelling approach that considers both the ability of coastal wetlands to build up vertically by sediment accretion, and the accommodation space, namely, the vertical and lateral space available for fine sediments to accumulate and be colonized by wetland vegetation. We use this approach to assess global-scale changes in coastal wetland area in response to global sea-level rise and anthropogenic coastal occupation during the twenty-first century. On the basis of our simulations, we find that, globally, rather than losses, wetland gains of up to 60 per cent of the current area are possible…” https://www.nature.com/articles/s41586-018-0476-5

    see also – https://www.eurekalert.org/pub_releases/2018-09/viom-cww092018.php

    Blue carbon is an Australian initiative that was announced in Paris in 2015 – it joins the French 4 per 1000 soil carbon initiative as the bits of COP21 that aren’t a charade.

    http://www.environment.gov.au/climate-change/government/international/blue-carbon

  24. You might find my humble 2 year effort to quantify the global geothermal heating effect of interest. If you want some up to date numbers on this, test this back of the envelope paper with skeptical scientific method, and please tell me why it is wrong in substance? Crude but deterministic, no models were forced in its making, so hard to deny on the basic physics. I hope I have addressed the criticism that these are the opinions of freaks with no data. Suck on this, as real scientists say.

    Roughly 7×10^21 Joules pa currently from 5×10^12 Tonnes of magma pa. 3 times the internal energy by conduction. A lot more than geologist’s “consensus” of the total sub aerial magma budget, which i calculate would not even fill the 75,00Km’ish of spreading gaps between divergent tectonic plates every year, leaving troublesome leaks in the planet. Please check my the arithmetic.

    My revision is also supportable on the data from these same geologists – a dichotomy of the few hundred times scale! So prove me wrong on th oether data and its extension. My answer needs there to be around 100,000 sub aerial volcanoes, assuming the data from Scott White that showed 10 times the emissions from ocean floor volcanoes, which is supported by the practical physics of 1/10 the pipe length and roughly the same pressure differential on the continents and the oceans (20KBar’ish on the input end dominates!). I have attempted to explain all this in the paper supporting my assessment. A deterministic step beyond qualitative opinions. I hope it has merit.

    https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3259379

    This heat is neither as insignificant nor as invariate as atmospheric models assert. The magma levels I estimate can physically raise the oceans by the amount in question by simple displacement, as well as warm the oceans at a level comparable with the heat effect climate models attribute to CO2. No models or CO2 are required to explain change if the magma did it. Obviously it is the effects that are discounted and the gains assigned to the preferred parameters in the partial IPCC models by their programmers that such an assessment questions the validity of.

    This paper is not peer reviewed, but is accepted work in progress on SSRN. I need to find an honest Journal that will not reject because it is not supportive of the “atmospheric CO2 dominates climate” “consensus”, and allows holistic science tobe considered across the atmosphere, lithosphere, oceans and planetary orbits (atmosphericists don’t like holistic approaches, they aren’t paid to prove anything elsewhere so assume passive status for the global oceans, volcanoes, anything inconvenient gets assigned “low forcing” or not significantly variable status. I suggest this is a mistake, in terms of the both the actual global equilibrium setting, and its variability within the ice age cycle range, that water vapour related controls acting in the atmosphere totally dominate, including any tiny perturbation from CO2. I would really like someone to tell me what is wrong with the basic physics here.

    I wonder what Feynman would have said about atmoshericist consensus climate science? Almost certainly that if their are demonstrable exceptions, it is wrong, or that the proposition of climate change from CO2 variation is too vague to prove or disprove, as the IPCC admit of their models, in their own publications.

    “The climate system is a coupled non-linear chaotic system, and therefore the long-term prediction of future climate states is not possible.” Source IPCC https://www.ipcc.ch/ipccreports/tar/wg1/501.htm

    Does nobody read that bit? No money or headlines in it? I hypothesise the crustal movements did it, with magma, under the ocean, unseen, on the simple physics. To a significant extent TBD. Deterministc scientific criticism is very welcome. No statistical models please. There are references to the data sources and I believe all my points of investigation that survived scrutiny were validated by independently published papers. All except the quantification of global magma budgets. But I have no mentor on this, so may be wrong somewhere. Can anyone improve on this?

  25. Pingback: Sea-Level Rise | Transterrestrial Musings

  26. typo:
    Figure 4.5 Profile through the Antarctic ice sheet (A) Bellinshausen Sea

  27. Tide gauges also show that rates of global mean sea level rise between 1920 and 1950 were comparable to recent rates.
    BINGO!
    A quick trip through the PSMSL finds several long running tide gauges
    that show exactly that (-:

    • And, land ice was melting much faster then than currently. This implies there was larger forcing then than recently (because of large heat absorption of heat to melt ice). I expect that sea surface temps stayed low and kept steric rise down?

  28. Thank you, Judith. Well done.

    Regards,
    Bob

  29. Great analysis! Found an error on page 49; you have written “very likely range (5-95%) is 0.2 – 1.0 m [7.9 to 5 feet]”
    Clearly the 1.0 m is wrong or the 5 feet is.

  30. According to the IPCC, the projected 21st century sea level rise depends on the amount of greenhouse gas emissions.

    Such never-adequately-established attribution is typical of the bald conjectures made by those who are not among the mere handful of oceanographers in the world truly qualified to discourse upon the subject. Prognostications by all others should be dismissed out of hand. Public agencies and others should become concerned only if SIO decides to sell off its lower campus in La Jolla at a no-reserve auction. Even then, there will be scientifically savvy bidders.

    • “Fingerprinting” the complex responses of measured geophysical variables, especially SLR, to presumed “forcings” is virtually impossible without the rigorous methods of system analysis. Alas, “climate science” is largely ignorant of these well-founded analytic techniques, relying blindly upon simple linear regression for the purpose. This, in effect, imposes the simplistic assumption of a static linear gain upon the input-output relationship, instead of a far-more-general convolution of input with an impulse-response function that is not restricted to being a delta function. To make matters worse, even the regression results are often misinterpreted, as the above links show. That is what makes many “fingerprinting” claims of “climate science” pathetically specious.

  31. Judith,

    Why do you believe this:

    First, I regard sea level rise to be the most consequential potential impact of predicted global warming.

    This is not consistent with the projections from the FUND3.9 IAM, or with Anthoff et al, (2010) The economic impact of substantial sea-level rise https://link.springer.com/article/10.1007%2Fs11027-010-9220-7.

    Julia FUND3.9 projects the economic impacts of 3C global warming from 2000-2100 (at 3.14 C GMST increase relative to 2000), by impact sector, to be:
    Agriculture 0.13%
    Health 0.05%
    Storms -0.01%
    Sea Level -0.01%
    Ecosystems -0.11%
    Water -0.13%
    Energy -1.09%
    Total -1.17%
    Excl. Energy -0.07%

    According to this, the economic impact of sea level rise by 2100 is negligible.

  32. Re: “According to the IPCC, the projected 21st century sea level rise depends on the amount of greenhouse gas emissions.”

    Their claim is deeply anti-scientific, because we’ve done the experiment, and we’ve seen the result: GHG emissions and levels have no detectable effect on the rate of sea-level rise.

    Honolulu has one of the very best long measurement records of sea-level in the Pacific. It’s a near-ideal measurement location, too: in the midst of the Pacific, on an “old” tectonically stable island, with very little vertical land motion, and a very typical trend. The only thing atypical about the Honolulu sea-level measurement record is its unusually high quality: 113 years of continuous data, without even a single month missing. Here’s the graph (in blue), juxtaposed with CO2 (in green):

    (Here’s the interactive version.)

    All the best-quality, long, sea-level measurement records show the same lack of significant acceleration, for ninety years or more.

    http://sealevel.info/MSL_global_thumbnails5.html

    Anyone who looks at graphs like those, yet still insists that the rate of sea-level rise depends on greenhouse gas emissions or levels, is rejecting science, itself.

    • Many of the longest measurement records seem to show a very slight acceleration, by at most 1.5 mm/yr, sometime between the mid-1800s and about 1930, but little or no additional acceleration during the subsequent large rise in GHG levels over the last 2/3 century.

      Between 1850 and 1930 CO2 levels rose less than 8%. That was accompanied by a slight but measurable acceleration in sea-level rise, in some places. The acceleration was most apparent at Brest, France (PSMSL gauge #1), where the sea-level trend was flat (+0.0 mm/yr) in the 1800s, but +1.5 mm/yr (6″/century) since then. At Brest, the “knee” in the graph was around 1900:

      The slight (+ 1.5 mm/yr) acceleration at Brest over a century ago obviously does not support the notion that CO2 drives sea-level rise; since 1930 CO2 levels have risen another 32%, and that 4× greater increase in CO2 forcing was accompanied by no measurable acceleration in sea-level rise.

      Here’re the interactive versions of the graphs for Brest, France…

      19th century (1807 to Dec. 1899), zero SLR:
      http://www.sealevel.info/MSL_graph.php?id=1&datasource=psmsl&c_date=1800/1-1899/12&boxcar=1&boxwidth=3

      20th-21st century 1.5 mm/yr: http://www.sealevel.info/MSL_graph.php?id=1&datasource=psmsl&c_date=1900/1-2017/12&boxcar=1&boxwidth=3

      Satellite era (1993-present), +1.99 ±1.57 mm/year:
      http://www.sealevel.info/MSL_graph.php?id=1&datasource=psmsl&c_date=1993/1-2017/12&boxcar=1&boxwidth=3

      Is that a slight acceleration? Only if you ignore the enormous confidence intervals!

      At Brest, the “knee” in the graph was circa 1900. At San Francisco the knee was later.

      1854-1930, +0.51 ±0.40 mm/year:
      http://sealevel.info/MSL_graph.php?id=San+Francisco&boxcar=1&boxwidth=3&c_date=1850/1-1929/12

      1930-present, +1.95 ±0.31 mm/year
      http://sealevel.info/MSL_graph.php?id=San+Francisco&boxcar=1&boxwidth=3&c_date=1930/1-2017/12

      Satellite era (1993-present), +1.69 ±2.15 mm/year:
      http://sealevel.info/MSL_graph.php?id=San+Francisco&boxcar=1&boxwidth=3&c_date=1993/1-2017/12

      Is that a slight deceleration? Only if you ignore the enormous confidence intervals!

      At The Battery (New York City), SLR is inflated by a lot of subsidence (perhaps because Battery Park is built on fill dirt). The knee was later, and the slight acceleration was even slighter:

      1856-1930, +2.29 ±0.27 mm/year:
      http://www.sealevel.info/MSL_graph.php?id=Battery&boxcar=1&boxwidth=3&datasource=noaa&c_date=1850/1-1929/12

      Since 1930, +3.08 ±0.20 mm/yr:
      http://www.sealevel.info/MSL_graph.php?id=Battery&boxcar=1&boxwidth=3&c_date=1930/1-2018/3&datasource=noaa

      Satellite era (1993-present), +3.63 ±1.40 mm/year:
      http://www.sealevel.info/MSL_graph.php?id=Battery&boxcar=1&boxwidth=3&c_date=1993/1-2018/3&datasource=noaa

      Is that a slight acceleration? Only if you ignore the enormous confidence intervals.

      Arguments that fossil fuel use must be curbed to reduce sea-level rise are based on superstition, not science.

      • BTW, Brest shows the most striking “acceleration” of any of the long sea-level measurement records that I’ve looked at (although it occurred more than a century ago). Ignoring the confidence intervals, the difference between a quadratic projection of that acceleration (calculated from the full 210 year measurement record at Brest) and a linear projection (calculated from the measurements since 1900 at Brest) would amount to a grand total of five inches by 2100. (To see the projections for sea-level in year 2100, click on the links, and then hover your mouse cursor over the right-hand end of the red or orange trend projection line.)

        Not feet, inches.

        And that’s for a site with a much larger than typical measured “acceleration.”

        Most of the other very long, high-quality measurement records saw even less acceleration, even in the 1800s. E.g., at Wismar, Germany, the difference between a linear projection to 2100 (using data since 1900) and a quadratic projection to 2100 (using the full record, i.e., data since 1948) is just 1.1 inch.

      • DaveBurton: E.g., at Wismar, Germany, the difference between a linear projection to 2100 (using data since 1900) and a quadratic projection to 2100 (using the full record, i.e., data since 1948) is just 1.1 inch.

        Thank you for that informative series of posts.

      • dave
        nobody thinks c02 alone drives sea level.

        Its like this

        ALL the forcings drive temperature
        Temperature drives SLR with a Lag.

      • “With a Lag,” Steve? What possible mechanism can you imagine that would cause a forty year “lag” before warmer temperatures affect sea-level trends?

        CO2 levels have increased every year since precise measurements began, 59 consecutive years, totaling a 29% increase in level. From ice cores we can tell that the increase has been monotonic since about 1950, and the rate of forcing increase has been barely more than linear for about forty years:

        Temperatures have been rising, too, with fits and starts, for about forty years. Yet there still has been no acceleration in the rate of sea-level rise.

        Steve, forty years is a very long “lag,” don’t you think?

        In fact, there’s no plausible mechanism for such a lag. The lack of effect on sea-level from GHGs and global warming is not due to a “lag.”

        Rather, a warming climate has effects which both increase and decrease sea-level trends, and, it seems that (at least when there’s no Laurentide ice sheet to melt!) those processes roughly balance each other.

        The only effects that many climate alarmists seem to be aware of are those which increase sea-level, like ice melting, sublimation, thermal expansion, and glacier calving. But the most important process which affects ice sheet mass is none of those things. It is snowfall.

        A warming climate increases snow accumulation on ice sheets and glaciers — and thus decreases sea-level — in two ways:

        1. Most obviously, warmer air holds more moisture. Every 1°C of warming increases the amount of moisture which the atmosphere can hold by about 7%.

        When temperatures are very low snowfall is greatly reduced, because the frigid air carries very little moisture; it is said to be “too cold to snow (much).” The heaviest snowfalls usually occur when temperatures are only modestly below freezing.

        2. Decreased polar sea ice coverage (Arctic, North Atlantic, and Southern Ocean) increases water evaporation, which increases “lake/ocean-effect snowfall” (LOES) downwind. Some of that snow falls on the ice sheets and glaciers, increasing ice accumulation, and offsetting meltwater losses. Other snow falls on land, snowpack.

        Snowfall is, by far, the most important factor in ice sheet & glacier mass fluxes. Increased snowfall is the main reason that, for the second glaciological year in a row, the Greenland Ice Sheet (which usually loses ice) apparently had no net loss of ice.

        Yet in eighty pages of fine print, which you can read here…
        https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter13_FINAL.pdf
        …the IPCC’s AR5 authors never even mentioned lake/ocean-effect snowfall, and its effect on ice sheet & glacier mass balance, and sea-level. It appears that they had never heard of it.

        That amazes me. Any competent meteorologist could have told them all about lake/ocean-effect snowfall. It’s the reason Buffalo, New York famously gets so much snow. But the IPCC’s sea-level authors seem to have been unaware of it.

        In both Greenland and Antarctica, snowfall is the most important factor affecting ice sheet mass balance, greater in magnitude than melting, sublimation, or iceberg calving. In fact, in Antarctica, snowfall accumulation is approximately equal to the sum of those other three factors.

        Multiple studies have found that snowfall accumulation in Antarctica has been increasing.[1][2][3][4]

        The magnitude of ice accretion from snowfall on ice sheets was illustrated by the amazing story of *Glacier Girl.* She’s a Lockheed P-38 Lightning which was extracted in pieces from beneath 268 feet(!) of accumulated ice and snow (mostly ice), fifty years after she made an emergency landing on the Greenland Ice Sheet.

        That’s more than 5 feet of ice per year, which is equivalent to more than seventy (70) feet of annual snowfall, which had piled up on top of the airplane! That snow represents evaporated water, mostly removed from the Arctic and North Atlantic Oceans, which then fell as ocean-effect snow on the Greenland Ice Sheet.

        We know that some of the effects of global warming increase sea-level, and others decrease it. Forty years of experience tell us that those factors roughly cancel each other, meaning that there’s no reason to expect significantly accelerated sea-level rise from mankind’s GHG emissions.

      • A lag? SM wants the uninitiated to slurp that up so he has an excuse for why SLR isn’t doing what the troop of failed predictors have been saying for decades. Just like everything else, they make up stuff ad hoc, on the fly Excuses. I can’t wait until the Arctic Sea Ice Extent recovers and see how imaginative they become once yet another prediction goes paws up.

      • Typo correction:

        I wrote: “at Wismar, Germany, the difference between a linear projection to 2100 (using data since 1900) and a quadratic projection to 2100 (using the full record, i.e., data since 1948) is just 1.1 inch.”

        I intended: “at Wismar, Germany, the difference between a linear projection to 2100 (using data since 1900) and a quadratic projection to 2100 (using the full record, i.e., data since 1848) is just 1.1 inch.”

        The exceptionally long and high-quality sea-level measurement record at Wismar began in July, 1848, not 1948.

        http://www.sealevel.info/MSL_graph.php?id=120-022&quadratic=1&lin_ci=0&boxcar=1&boxwidth=3&g_date=1840/1-2099/12

    • Might not the erratic increase of sea level with time be a reflection of an increase in the rate of ocean-plate mantle convection and the consequential exothermic release of heat via the process of mantle serpentinization. The year to year variation would relate to random processes in the global sea floor spreading environment.

  33. Is there a standard level we can use, or being entertained, such as GPS of an Atlantic and a Pacific basin which is fairly reliable? Need both I believe because of different levels??
    We have the satellites and can measure average height daily, yes?

    • The satellite altimetry measurements of sea-level are very rough, angech. They are much lower quality than the coastal (tide-gauge) measurements.

      Aviso’s satellite altimetry sea level data, notes, and graph (and new version, old version, and criticism of their dramatic revisions to the ENVISAT data [alt] [2]).

      Univ. of Colorado Sea Level Research Group, Aviso and NOAA all have groups working on sea-level measurement by satellite altimetry.

      Even though the satellite measurements show no significant acceleration in sea-level rise, changes in how the satellite data is processed and adjusted have substantially increased the amount of sea-level rise which U. Colorado reports. There are many different factors [2] which can affect reported trends, but which are difficult to ascertain with certainty, and are subject to substantial and often mysterious corrections.

      To see how malleable the satellite altimetry data is, consider this well-known paper, which sought to explain away an apparent declining trend in the rate of sea-level rise measured by satellite altimetry. They managed to massage the data until that embarrassing decline had almost entirely disappeared. (Does that remind you of anything?)

      Here are two pairs of graphs from the paper, each with “before” and “after” versions, showing how they “corrected” the work of 5 (five!) different satellite altimetry analysis groups, to almost completely eliminate the decline, which all five groups had measured:

      This article & comments at WUWT have a good discussion of how adjustments have increased rate of sea-level rise reportedly “measured” by satellite altimetry. (h/t Steve Case [here & here])

      Another example illustrating the malleability of the satellite altimetry data is a widely-hyped 2018 paper by U. Colorado’s Dr. Steve Nerem et al, which claimed to have discovered “acceleration” in the satellite altimetry measurement record of sea-level — by reducing the rate of measured sea-level rise in 20 year-old Topex-Poseidon data, thereby making more recent measurements appear to have accelerated, by comparison.

      From Frank Lansner and Jo Nova comes an enlightening but disturbing article about suspicious adjustments to sea-level measurement data from satellite altimetry.

      >Unfortunately, measurement of sea-level by satellite altimetry is fundamentally unreliable. Physicist Willie Soon explains the problems starting at 17:37 in this very informative hour-long lecture.

      To address some of these problems, in 2011 NASA proposed (and re-proposed in 2014 / 2015) a new satellite mission called the Geodetic Reference Antenna in SPace (GRASP). The proposal is discussed here, and its implications for measuring sea-level are discussed here. The Europeans are apparently considering a similar mission (E-GRASP).

  34. Yes, Angech! Try ODN Newlyn, GB, near Cornwall, the “Datum” for the British isles and CGPS validated – Tectonic Subsidence = 0.7mm/yr. Sea-Level Rise? 1.8mm/yr. Net rise? 1.1mm/yr. – and for the Pacific, Prince Rupert, BC. CN which is basically tectonically inert and also CGPS validated Tectonic Subsidence = 0.07mm/yr. Sea-Level Rise? 1.17mm/yr. Net rise? 1.1mm/

  35. The science of sea level changes is complicated and calls for deep knowledge in a number of fields. It is sad to see that people still think that there are short-cuts and that an outsider can contribute with anything significant; summarizing some data maybe yes – advancing the science of sea level change certainly not.
    best wishes
    Nils-Axel Mörner

    • One of the biggest issues in sea level rise science is synthesizing and assessing the evidence, in short, how to think about thinking. This requires a different skill set than conducting fundamental research on a particular topic. I am not conducting new research in the field, rather my contribution is to re-frame how we think about the problem.

      With regard to ‘outsiders’, to me the word is meaningless in the context of science, with one of the norms of science being ‘universalism’. I have seen so-called outsiders make major published contributions to climate science. These outsiders are academics from other fields, as well as non-academics who have invested the time to spin up expertise.

      • There was a similar comment on twitter. Someone replied characterizing this as the ‘myopic view of individual researchers’, I thought that was very well stated. Researchers can be pretty myopic about their own specialty, which is why the assessment from outsiders is useful.

      • Given what I know about his work and his apparent view of SLR I was a little surprised by the tone of his comment. Or maybe I misinterpreted what his views have been on SLR. I thought one of your messages echoed his, that SLR is complicated.

        I think extremely so. The stream of emerging facts coming out annually speaks to that.

      • It’s about ‘turf’, I’m playing on others turf, they don’t like it. I’m not writing for other climate scientists, but rather for the public, particularly for decision makers grappling with the sea level rise issue.

        I didn’t reference any of morner’s papers. They didn’t seem to add anything to my overall arguments, and I thought my case would be stronger if I didn’t rely on authors that are vocally dismissive of AGW.

      • I have seen so-called outsiders make major published contributions to climate science. These outsiders are academics from other fields, as well as non-academics who have invested the time to spin up expertise.

        The nominal success of “spun-up expertise” is prima facie evidence of the dismally primitive state of “climate science.” Far from being an endorsement of the perspectives of “outsiders” on highly complex issues, it should be taken as a caveat by those primarily interested in scientific validity. The facile resort to academic “turf” sociology is indicative of other interests.

      • Judith, that is exactly the skill I needed as an economic policy adviser. Many economists deal with a very small area of expertise. By contrast, I had a very broad purview of drivers of economic growth as well as advising on many specific issues or proposals in a wide range of fields (including CAGW from 1988-89). I couldn’t be across the finest scientific, engineering, etc of everything which crossed my desk, but I had the capacity to draw out the essence of the issue and its ramifications, and to present and compare various options in response. My skills were sufficient that I was often the only non-specialist invited to meetings, seminar etc on a variety of topics, e.g. economic modelling, R&D and innovation, and various science issues. As an outsider, I often brought a fresh perspective and insights which the specialists in an area had not seen. There are some prominent in public life in Australia who insist that we must accept the “proven science” on global warming and the dangers it poses, and give them highest priority without challenge. This is, of course, nonsense: even if all aspects of the warmist version were completely true, any policies relating to it must be developed in a world of many pressing issues, limited resources and conflicting views on the importance of particular issues. It is essential that people such as yourself, and many others posting here, should be ready to examine and challenge areas beyond their immediate expertise.

        And, of course, having expertise in a particular field of climate science does not per se give you the right or capacity to determine energy policy etc. Some proposals in Australia would see the bulk of our farming and resources industries closed down, with huge ramifications. To what purpose? How do you trade off reduced warming against massive loss of livelihood? We can’t leave it to Morner and co.

    • nilsaxelmorner: an outsider can contribute with anything significant; summarizing some data maybe yes

      Was the paper a good summary? Any noteworthy omissions? Useful for policy makers and voters? It did not claim to be “advancing” the science.

    • I wasn’t going to comment on this to me disappointing comment, but the subcomment thread lately changed my mind. Tribalism and aour grapes are unbecoming ANY ‘scientist’. Yet we see it everywhere, in all disciplines. I caught it as a ‘supercapacitance outsider’ (and horrors, just a JD/MBA, not a PhD scientist) despite having derived a rigorous mathematical equation, proving experimentally (cour different ways) that conventional effective surface ‘science’ was just wrong, and then usingnthe insights to produce experimentally fundamentally better materials. I assumed this was because the Helmholtz double layer capacitance community is VERY small.
      Nope, seems a general law of human expertise nature. Tribalism.

  36. This may be too insignificant, but…
    In section 2.1, you write, “Melting of sea ice has no impact on sea level
    – water or ice that is already floating does not change the sea level by melting/freezing.”
    This is almost true; there is a minor increase in sea level when sea ice melts, as sea ice is less salty than ocean water (and hence the melted sea ice is less dense than the surrounding ocean), see Jenkins and Holland 2007. Shepherd et al. 2010 estimated about 0.05 mm/yr change in global sea level due to loss of sea ice. [There might be a more recent value; this is not a topic which I follow.]

    • yes sea ice has already rejected most of its salinity, so when it melts it is slightly less dense than sea water.

    • Harold, floating ice, regardless of its density, will not cause any water level rise upon melting. When something is floating it’s about displacement, not density.

      I’m sure you already knew this and just had a hiccup. You are a true climate master IMO. Dr. Curry is alright too.

      • Ron, I disagree. Yes, Archimedes’ principle is about displacement, but density has a part to play as well. Let’s take an example, positing that seawater has density 1025 kg/m3, and that the ice has expelled all of its salinity — that is, it is purely fresh water. Let’s add enough ice to displace 1 m3 of seawater. Given the seawater density, that means that the mass of ice is 1025 kg. When it melts, that fresh ice water, at density 1000 kg/m3, will take up 1.025 m3. That’s slightly more than the 1 m3 of displaced seawater, so the water level must increase.

        The paper by Jenkins and Holland, cited above, has a more thorough and nuanced explanation, including temperature and salinity effects.

      • Harold, sorry I am late to reply here. You wrote: “When it melts, that fresh ice water, at density 1000 kg/m3, will take up 1.025 m3.”

        Why is ice that is less dense relative to the sea water, which is why it is floating, going to stay less dense once it melts? It will gain density both by melting and ionizing the sea salt (contraction volume in each). The later process would potentially expand volume beyond the Archimedes principle if it lowered the density of the sea. But diluting the ocean I thought could be neglected. Perhaps that is what Professor Kay R. Brower is postulated.

      • I followed your link to the cited paper and they are indeed talking about freshening the ocean. Here is Dr. Brower’s lab experiment that inspired them: https://nsidc.org/news/newsroom/20050801_floatingice.html

        I think they are underestimating the ocean’s volume in comparison to he volume of their beaker. The ocean will not be freshened so easily. Though their paper looks very impressive, I would have an experiment with different size beakers of sea water and then plot an extrapolation to simulate a beaker the size of a building. I predict their effect will evaporate.

      • Ron, you’re quite correct that the melted ice, although it starts out fresh, will increase in salinity and become denser. The quantity of salts being constant, as the melted ice gains salinity, the salinity of seawater reduces and it becomes correspondingly less dense. As the fresh water diffuses, the amount of freshening reduces, but there is a greater amount of seawater affected, so (the argument goes) to first order the change in volume remains.

        Your experiment would indeed be interesting.

      • The photos on that NSIDC web page, credited to “Professor Kay R. Brower, of the New Mexico Institute of Technology, Socorro,” appear to be a hoax. Eyeballing the two pictures, it appears that roughly the entire volume of the ice above the waterline has added to the water level, which would be impossible even with a fully-saturated salt solution. I suspect that the ice in her photo is resting on the bottom of the beaker (invalidating the result):

        http://www.sealevel.info/sea_ice/

        It is true that when floating ice melts it reduces the salinity, and thus the density, of the seawater, causing a very slight (negligible) increase in sea-level. But don’t forget that it’s a strictly local effect. Gravity balances mass, not volume, so the effect on sea-level is limited to the part of the ocean in which the salinity is affected. The meltwater has no effect at all on sea levels beyond the area of ocean into which the meltwater actually flows/mixes.

    • A billion tonnes of ice will displace a billion tonnes of seawater – and float because it is less dense. As water it is the same billion tonnes – displacing the same billion tonnes of water.

      • But after the ice melts, a billion tonnes of fresh water (low salinity) occupies slightly more volume than the billion tonnes of displaced seawater. Please see the paper by Jenkins and Holland, cited above, for an explanation of the change in volume as the melt mixes with the surrounding water, including temperature and salinity effects.

      • You would have to explain why temperature is relevant – because it isn’t constant. And while the volume of a less saline mix is greater – that’s not something you are going to pick in a flask – and in the wild it is variable too. Whatever fresh water enters the oceans an equal amount is lost in evaporation.

      • HaroldW wrote, “a billion tonnes of fresh water (low salinity) occupies slightly more volume than the billion tonnes of displaced seawater”

        The difference is above the “surrounding waterline” — in other word, the difference is how much the fresher water “sticks up above” the surrounding saltier water.

        It’s easier to see when it’s ice:

      • The ice berg melteth,
        some of it evaporateth.

  37. Pingback: Sea Level and Climate Change–Judith Curry | NOT A LOT OF PEOPLE KNOW THAT

  38. Thanks for the paper Judith. Thanks to your review I now find Wunsch has determined a short term figure in the decimal W/m^2 for warming from direct ocean heating, which is interesting as it is relatively close to my own macro level long term effort at global quantification of this effect and suggests that the effect is real at this level, and must be variable with variable seismic activity in the thin and fractured oceanic crust which is in constant movement. The West Antarctic ice sheet site has some 130 or so volcanoes, more that the previously largest collection in Central Africa, I read. Of these, 90 new volcanoes were discovered recently by the University of Edinburgh, as you were probably aware. I worked out that 100 normal surface volcanoes on a continental crust would produce enough heat to melt 1 Gigatonne of ice pa, which may have some relevance to our problem, as Feynman said, although this is small as regards total antarctic ice its effect on a local cantilevered ice mass projected from a continent and stressed by tidal action is obvious. Obviously that average heating rate is unlikely and it will have peaks and troughs over only 100 volcanoes or so, as well as natural variation in global seismic activity through changing crustal stresses. So magmatic heat will affect the likelihood of the ice shelfs detaching and glaciers flowing faster, in unpredictable ways. We don’t know, but the control of the “West Antarctic Anomaly” is dominantly volcanic, not likely to be significantly affected by warming from a predicted 1W/m^2 effect of human AGW from CO2, if real. I suppose I could calculate the heat effect of 1W/m^2 at the West Antarctic surface and compare it to the average heat from 100 volcanoes. But I don’t have time and also believe I already know the answer. Will check later.

    PS Sorry for typos earlier. My first genuine Apple keyboard is hopeless and the post production editing facilities on WordPress a tad hopeless, or I lack competence in them.

    • While your at it Brian check out the heat balance related to exothermic mantle serpentinization!!

      • What? I nearly forgot the latent heat of crystalisation of magma in my paper, that is about 40% of the heat deposited in oceans by magma, but not as big an error as I thought when I first went “AAAARGGGHHH!”. Also it made the hypothesis more likely, as did finding out that oceanic volcanoes must have around ten times the magma output of continental surface volcanoes, and actually do. the 20Kbar starting prssure (10-30KBar) has something to do with an insensitivity to trivial ocean deep pressures.

    • APOLOGIES: On a relook I find I miscalculated myself, and based my West Antarctic heating estimate on flow rates calculated before the X10 factor of undersea volcanoes was “discovered” using basic physics and Scott White et al data. I just covered another envelope and find 100 undersea volcanoes can deliver 7×10^18 Joules pa to the seafloor on average, or 7×10^17 Joules pa on continental crust. So enough to melt 20Gigatonnes of ice pa in the oceans and 2 Gigatonnes pa on land. Usefully more than the last calculation. A bit more than 1Gigatonne wherever. If anyone cares to check, that would be great.Any ideas how much heat to break the cantilevered ice shelf as it is worked constantly by tides? Why wouldn’t it break off, given the glaciers keep pusjing it out to the circular Antarctic current , over the volcanic line of fire? PS my estimate of the CO2 contribution to this compared to an annual local heat burden of 7 EJoules pa would be would be “insignificant”.

    • Follow up. Did a quick check on the Wunsch figure. It is is for internal heat only, heat conducted to the surface through the crust and oceans, which is roughly 50TW. This converts directly to 0.1W/m^2. This reportedly comes half from heat of formation and the other half the long half life decay of Uranium and Thorium isotopes in the interior rocks that appear in the magma and make those nice immune system boosting radioactive Monazite sands to take a cure in. NOTE: Magma delivers much more internal heat than this to the sea floor

      As described elsewhere I calculate the sub aerial magma budget transports roughly 4 times as much heat to the surface directly, and suggest total internal heat reaching the oceans currently is roughly 0.5W/m^2, which can vary significantly on multiple timescales, from daily to 100Ka due to different cyclic stresses that are all observed to cause variation in volcanic activity on the thin oceanic crust.

      • William Church

        Brian – oceanic basalts are formed as a result of the loss of pressure involved in the convective uplift of hot mantle (lherzolite). The heat released to the surface from the cooling of mid-oceanic basalt is however only one component of the convective process. A second component involves the exothermic hydration reaction of mantle material with cells of downward convecting sea water. Could you please address this!!

  39. Stockholm has sea level measurements since 1774.
    Google Stockholm sea level and an english 3-page info appears.
    No visible acceleration since 1890, and a “hiatus” 1950-1975.

    • You probably mean the sea level corrected for the land uplift. Here’s the sea level at Stockholm as measured by the tide gauge:

      It’s the longest record in the world and the linear trend for the entire period (1774-2018) is -3.74 mm/year. You’re right, there is no AGW ‘fingerprint’

  40. Good post. I liked the summary. The target is…
    Not other climate scientists. Voters.

  41. Pingback: Special Report on Sea Level Rise – Climate Collections

  42. Here’s a better picture. It shows WAIS stabilizing mechanisms with ice mass loss. The key is ‘Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability’. http://science.sciencemag.org/content/360/6395/1335


    ‘Diagram showing how ice melt and bedrock uplift could prevent ice sheet collapse. On both sides, A indicates the initial position of the grounding line. On the right, dashed lines represent the initial positions of the land, ice and sea level; B indicates the position of the grounding line when the reduction in gravitational attraction between ice sheet and ocean is considered and C shows the location of the grounding line when both land uplift and the reduction in gravitational attraction between ice sheet and ocean are considered. Source: Barletta et al. (2018)’

    They attribute it to lower bedrock viscosity than anticipated – but I wouldn’t take that as gospel. Mind – the mechanisms for ice sheet collapse are dubious as well.

  43. Judith Curry, thank you for this essay. I hope that it enjoys a wide readership.

  44. Thank you for your reasoned approach Dr. Curry, and your work in developing this excellent analysis of an area rife for misinformation — the fact is that the measuring of GMSL by satellite altimetry is only in it’s “juvenile phase”; and just like in other aspects of life — for anyone making assumptions based on a juvenile’s understanding of a complex issue, they are bound to be disappointed!

  45. Pingback: Special Report on Sea Level Rise « How to s..t on humans

  46. heat flux from the interior – approximately equal amounts radiogenis and the heat of planetary formation – is some 47 TW. From the sun some 174,000 TW.


    https://www.solid-earth.net/1/5/2010/

    So if you want to ‘discuss’ this nonsense – start with some facts.

    • Right – very small relative to insolation for TOA concerns.

      However, in the context of the post, some glacial discharges are thought to result from basal melt. Heat transfer through ice is very slow, so heat can accumulate beneath the ice from interior fluxes, enough to lubricate and prompt discharge. I hadn’t seen these estimates for Greenland and Antarctica before, so thanx for that. I note for Greenland and Antarctica, flux is greater than average. Do you know why?

      • I always like physical mechanisms – so yes basal melting is one. The isostatic rebound study suggests that Antarctic ice mass loss is 10% greater than thought.

        Geology – but the specifics?

  47. Here is an ABC Catalyst story that includes the fact that sea levels on Australia’s east coast were 1.5 metres higher just 4,000 years ago, or at the end of the Holocene climate optimum.
    This seems to show up in many studies around the world, both in the NH and SH and many Eemian studies refer to this much warmer inter-glacial with sea levels many metres higher than today’s levels. ( approx 130,000 to 118,000 YBP)
    See down page at link for late Hol optimum Sea Level reference or 4,000 YBP.
    http://www.abc.net.au/catalyst/stories/2278381.htm

  48. There certainly doesn’t seem to be much CAGW to be found in the long Greenland instrumental record. The Vinther et al 2006 Greenland study ( note Jones and Briffa listed as co authors) use instrumental data from the late 18th century until the then present day. ( 2000)

    Certainly doesn’t seem to be much CAGW there either if you look at their Table 8 of the study. Anyway what will happen when the AMO changes back to the cool phase or has that started in 2015 as some scientists have asked recently? Here’s the link. So Dr Judith or Ristvan etc what do you make of this very long Greenland instrumental record and the decade by decade table 8? I can’t find any post 1950 warming that seems to point to any scary CAGW, but perhaps I’m missing something?
    https://crudata.uea.ac.uk/cru/data/greenland/vintheretal2006.pdf

  49. The BAS Turner et al 2016 study also found no warming on the Antarctic peninsula over the past 18 years.
    This was supposed top be one of the fastest warming areas according to Gore’s AIT book and Sci-fiction flick.
    And any number of studies have found little warming in Antarctica for a very long time and even PAGES 2 k found the 1,000+ year warming of Antarctica from the year 145 AD to be much warmer than today.
    Here’s the BAS Turner study link.

    https://www.nature.com/articles/nature18645

  50. I have not heard an explanation of the 250 meters (800 feet) of new ice at the top of the Votok ice core over the last 18,000 years with the high rise in CO2 in the last about 12,000 years.

  51. This doesn’t even consider the increased retention of water on land as precipitation increases, biosphere growth accelerates, soil water retention increases, and aquifers replenish. ;)

  52. Over at WUWT
    “Slow-motion collisions of tectonic plates under the ocean drag about three times more water down into the deep Earth than previously believed, according to a seismic study that spans the Mariana Trench.

    The observations from the deepest ocean trench in the world have important implications for the global water cycle, researchers say.

    “People knew that subduction zones could bring down water, but they didn’t know how much water,” says Chen Cai, who recently completed his doctoral studies at Washington University in St. Louis and is first author of the paper, which appears in Nature.

    “This research shows that subduction zones move far more water into Earth’s deep interior—many miles below the surface—than previously thought,”

  53. Here is a thorough analysis of Australian SLR by Ken Stewart and his summary.

    https://kenskingdom.wordpress.com/2018/10/22/why-are-australian-sea-levels-rising/#comments

    Conclusion:

    “Across all tide gauges of the Australian Baseline Sea Level Monitoring Project, a significant proportion of sea level rise since 1990 is due to circulation changes associated with the El Nino- Southern Oscillation. The effect is much greater in the north and west, where sea level rise is highest, but also is evident in the south-east.

    Sydney’s long term record tells us that sea level has been rising at an average rate of about 1 mm per year. There have been short periods of rapid increase and a long plateau of very small or zero trend in the second half of last century. As Australia is geologically stable, it is likely that a similar pattern occurred all around the coast.

    This gradual sea level rise is consistent with oceanic warming since the Little Ice Age, with fluctuations resulting from ENSO changes.

    There is no sign of any unusual acceleration in Australian tide gauge data. In 100 years from now sea level could be expected to be 100 mm to 200 mm higher. A sea level rise of 5 to 10 times this amount is purely speculative and not based on empirical data, but instead is based on the worst case scenario of computer models.”

  54. Geoff Sherrington

    Hi Judith,
    Thank you for this timely and relevant review. Nothing I write below is disparaging of you.
    It remains indisputable that it is dangerous science to assume that we can contemplate near-surface ocean properties like ocean level change, when so little is known about the deep oceans that comprise the lower 50% of ocean volume. It is dangerous to assume that the snapshots of the ocean/global system that we have taken in the last 100 years or so, will continue to represent our best knowledge and science in the next 100 years as we gain more knowledge of these ocean deeps. There are hints of this lately, for example, as people seem to understand that there is little known about sea floor volcanism and water mass and heat balances in subduction. The little we know suggests the possibility of effects of that can be large enough to change the narrative.
    As a minimum, I suggest a strong caveat in future scientific papers about lack of deep ocean data.
    With sea level change, what we are discussing here is a lot of noise of little interest and maybe a tiny signal that is of interest. These changes of millimetres per year are minuscule. The last 20 years has seen some separation of signal from noise as factors like isostatic adjustment are better measured by satellite geodesy and raw ocean level measurements are made more understandable. However, noise is noise and no great harm can be foreseen from its effects as we now know them, for they are small. As is the signal, with its uncertainty unresolved.
    Calamitous events like the collapse of part of Antarctica’s ice should be evaluated, but with caution. So should be the heat flow from ocean floor to ocean over a wider measurement term. We need to question – not just to question, but to deride – the asymmetry assumption that everything that can happen will make the effects of ocean level rise worse for humans. We do not even know if today, or over the last century, the Antarctic is accumulating land ice or losing it, so we cannot state that we should fear the future.
    We need to caution calamitous conclusions when we cannot yet state the magnitude of the alleged effects linking air temperatures to atmospheric carbon dioxide, or vice versa, the said climate sensitivity; and when we cannot state the ocean level rise that would happen from an air temperature increase of 1 degree C – not with acceptable, useful certainty.
    Play down tiny signal and the tiny noise, for their effects are harmless. Study calamity, but assure people that calamity can be equally disregarded, because change is slow and mitigation is easy.
    ……………………….
    Recall, if you will, your last flight on a modern airliner. In those engines there are compressor blades, beautifully sculptured from exotic materials. Each one is a tribute to masterful design flowing from a host of people with specialist inputs. Each blade costs a lot, but then it does a lot. It has a high benefit:cost ratio. Sure, one can break, but one does so rarely. Overwhelmingly, each blade is a benefit to society in ways that can vividly be seen. People like them more than they fear them.
    Contrast this with the way that society looks at ocean level change. We have no benefit:cost studies worth a fig. Citizens are groomed to be fearful of it for improbable reasons. We have a field of scientific and social sciences acolytes complementing and complimenting each other without advancing human knowledge greatly. Nothing useful has so far been produced, especially not a useful and beautiful benefit like a turbine blade.
    I would be putting my money on the private enterprise advances of the aircraft industry before I’d give a passing glance at the government funded, bureaucratic mess that is called climate science, the outstanding example of paid underachievement.
    Geoff.

  55. Judith: Skimmed your report with interest. Your earlier posts left few surprises in the report.

    Some of your clients may be interested in managing the uncertainty in SLR. Your report doesn’t tell us that we shoud have plenty of unambiguous warning before “catastrophic” rates of SLR arrive. Right now, SLR is about 1 inch/decade. If one assumes a quadratic model one needs a constant acceleration of 1 inch/decade/decade to reach 36 inches of SLR by the end of the decade. If society wishes to prevent 36 inches of SLR driven by rising GHGs by the end of the century, one needs make substantial changes in emissions ASAP. However, if your clients merely want to stay out of the path of danger or sensibly adapt to danger, they may be comfortable conducting business as usual for a couple of decades and waiting to see if SLR really reaches 2 inches/decade in the 2020’s and 3 inches/decade in the 2030’s. If our greatest fears are realized, there will still be up to a half-century to adapt or to get out of the way. If I were advising a coastal city today, I would tell them to prepare for 6 inches of SLR in the next few decades and wait a decade or two to decide whether to do anything about the possibility that SLR might be higher than the IPCC’s central estimate.

    This leads to the question of how quickly we can detect that global SLR has risen from 1 inch/decade to 2 inches/decade with either tide gauges or satellite altimetry. Based on at least one paper I read (but have lost track of), given the innate variability we have observed so far, unambiguously (95% ci) detecting a doubling of the trend could take more than decade with satellite altimetry and is probably impossible with tide gauges. So a “wait-and-see” strategy isn’t quite as simple as it sounds. However, one doesn’t need to have 95% certainty to act, only to publish.

    Why use a quadratic model? Well, if we are worried about the possibility of SLR of 1 m or more, that process is going to dwarf natural variability such as the AMO. In a Taylor series expansion, a quadratic term comes next. When your data is only slightly non-linear, there appears to be only one pragmatic non-linear option. A quadratic model could easily break down in the late 2000’s, but it will have served its purpose reasonably well.

  56. The Kench et al 2018 study found that Coral islands have expanded in area over the last 40 years.
    Of course the young Charles Darwin came to this conclusion more than 150 years ago. Yet Gore still doesn’t understand it.

    https://www.nature.com/articles/s41467-018-02954-1

  57. Because of the thermal inertia of the oceans there is a varying lag between the solar activity Millennial Turning Point at about 1991 and the varying climate metrics. The temperature peak is about 2003/4 – lag is about 12years. The arctic sea ice volume minimum was in 2012 +/- lag = 21years. Possible sea level Millennial Turning Point – Oct 2015 lag = 24 years +/- (see https://climate.nasa.gov/vital-signs/sea-level/) Since Oct 2015 sea level has risen at a rate of only 8.3cms/century. It will likely begin to fall within the next 4 or 5 years. For the details see data, discussion, and forecasts in Figs3,4,5,10,11,and 12 in the links below.
    See the Energy and Environment paper
    The coming cooling: usefully accurate climate forecasting for policy makers.
    http://journals.sagepub.com/doi/full/10.1177/0958305X16686488
    and an earlier accessible blog version at
    http://climatesense-norpag.blogspot.com/2017/02/the-coming-cooling-usefully-accurate_17.html See also the discussion with Professor William Happer at
    http://climatesense-norpag.blogspot.com/2018/02/exchange-with-professor-happer-princeton.html
    The establishment’s dangerous global warming meme, the associated IPCC series of reports ,the entire UNFCCC circus, the recent hysterical IPCC SR1.5 proposals and Nordhaus’ recent Nobel prize are founded on two basic errors in scientific judgement. First – the sample size is too small. Most IPCC model studies retrofit from the present back for only 100 – 150 years when the currently most important climate controlling, largest amplitude, solar activity cycle is millennial. This means that all climate model temperature outcomes are too hot and likely fall outside of the real future world. (See Kahneman -. Thinking Fast and Slow p 118) Second – the models make the fundamental scientific error of forecasting straight ahead beyond the Millennial Turning Point (MTP) and peak in solar activity which was reached in 1991.These errors are compounded by confirmation bias and academic consensus group think. Sea level will likely fall until about 2650. See also
    http://climatesense-norpag.blogspot.com/2018/10/the-millennial-turning-point-solar.html

    • Thanks for these links. At some point i need to spend more time wrapping my head around these issues. If you are interested in doing a guest post here on millenium turning point for solar, that would be most welcome.

    • The ocean has thermal inertia but it also has turbulent momentum.

      “We introduce a simple variational principle for coherent material vortices in two-dimensional turbulence. Vortex boundaries are sought as closed stationary curves of the averaged Lagrangian strain. Solutions to this problem turn out to be mathematically equivalent to photon spheres around black holes in cosmology. The fluidic photon spheres satisfy explicit differential equations whose outermost limit cycles are optimal Lagrangian vortex boundaries. As an application, we uncover super-coherent material eddies in the South Atlantic, which yield specific Lagrangian transport estimates for Agulhas rings.” https://arxiv.org/abs/1308.2352

      You can see it in action.

      https://earth.nullschool.net/#current/ocean/primary/waves/overlay=significant_wave_height/equirectangular/loc=-102.917,-56.667

      And turbulence is 3 dimensional. Surface heat variability appears to translate readily to the deeps.

      The wiggles are solar variability due to orbital eccentricity.

      This ENSO proxy is especially telling – 30 to 40 year regimes adding up to millennial variability. The next regime is due in a 2018-2028 window. More salt in a Law Dome ice core is La Nina.


      https://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00003.1

      It is related to SAM and NAM in the gyre hypothesis – e.g. https://www.mdpi.com/2225-1154/3/4/833/htm

      And those to solar variability.

      “However, variability in ultraviolet solar irradiance has been linked to changes in surface pressure that resemble the Arctic and North Atlantic Oscillations (AO/NAO)8,9,10 and studies of both the 11-year solar cycle11,12 and centennial timescales13 suggest the potential for larger regional effects. The mechanism for these changes is via a stratospheric pathway, a so-called ‘top-down’ mechanism, and involves altered heating of the stratosphere by solar ultraviolet irradiance. Anomalous temperatures in the region of the tropical stratopause give rise to changes in the subtropical stratospheric winds, in geostrophic balance with the modified equator-to-pole temperature gradient. This signal then propagates poleward and downward and is amplified by altered planetary wave activity8 before being communicated throughout the depth of the troposphere in the Pacific and Atlantic basins14. ” https://www.nature.com/articles/ncomms8535

      But to claim it all turned on a dime in Oct 2015 is – well – fanciful.

  58. If you understand the laws of water as it cools then you understand that the water around the poles is between 32’F to 39’F at the upper few meters and 39’F from that layer to the sea floor. That means all the ice exposed to water below the top layer is losing heat to the ice it contacts and then fights to reach the surface. The new Ice Age began 18,000 years ago and the Ice Melting stage of the last Ice Age began about 78,000 years ago. So for 78,000 years the the bottom of the ice shelf has been attacked by the 39’F water while for the last 18,000 years the top of the ice shelf has accumulated as much as 800′. Until the weight of the new ice began breaking off the ice bergs the ocean level was dropping. As the icebergs melted the new ice was put back into the ocean, thus slowing down the dropping of the oceans.

  59. Anyone else having trouble downloading the report – link seems broken.

  60. Pingback: Judith Curry On Sea Level Rise – Motus Mentis

  61. Re: “My report provides a different way of framing the sea level rise issue and of interpreting the evidence, in a way that I don’t think is inconsistent with the evidence in the mainstream sea level rise assessments.
    […]
    There is not yet convincing evidence of a fingerprint on sea level rise associated with human-caused global warming”

    That’s not going to work, since your claim on anthropogenic attribution conflicts with the evidence in mainstream sea level rise assessments. This has been explained before, with citations to the relevant literature:

    https://judithcurry.com/2018/01/16/sea-level-rise-acceleration-or-not-part-i-introduction/#comment-864643
    https://judithcurry.com/2018/01/16/sea-level-rise-acceleration-or-not-part-i-introduction/#comment-864645

    To summarize this again:
    The rate of sea level rise varies with warming, with sea level rise accelerating with warming. This is because warming melts land ice and causes thermal expansion. Post-1960s warming is primarily anthropogenic, so concurrent sea level rise acceleration is predominately anthropogenic.

    Some relevant papers on this, from the first link posted above:

    “Internal variability versus anthropogenic forcing on sea level and its components”
    “The rate of sea-level rise”
    “Quantifying anthropogenic and natural contributions to thermosteric sea level rise”
    “Detection and attribution of global mean thermosteric sea level change”
    “Long-term sea level trends: Natural or anthropogenic?”
    “Anthropogenic forcing dominates sea level rise since 1850”
    “Anthropogenic forcing dominates global mean sea-level rise since 1970”
    “Detecting anthropogenic footprints in sea level rise”
    “Model estimates of sea-level change due to anthropogenic impacts on terrestrial water storage”

    Re: “The slow emergence of fossil fuel emissions prior to 1950 did not contribute significantly to sea level rise observed in the 19th and early 20th centuries.”

    It’s the rate of warming that’s relevant, not the rate of CO2 emissions. The rate of CO2 emissions is not the same as the rate of CO2-induced warming, nor is it the same as the rate of total warming.

    Re: “The recent acceleration in mean global sea level rise (since 1995) is caused by mass loss from Greenland that appears to have been larger during the 1930’s, with both periods associated with the warm phase of the Atlantic Multidecadal Oscillation.”

    As has been explained ad nauseum: you can’t rebut anthropogenic attribution by claiming there were larger natural changes in the past. Otherwise, every murderer could go free by claiming there were lots of deaths by natural causes in the past. Instead, you need to look at specific aspects of that death (ex: the presence of fingerprints) to see what caused the death.

    Similarly, you need to look at specific aspects of post-1960s warming to see what caused the warming. Those aspects (or “fingerprints”) point to increased greenhouses as the primary cause of the warming (ex: cooling of the stratosphere, mesosphere, and thermosphere). Other scientists have explained this to you before. For instance:

    “Comment on “Climate science and the uncertainty monster” JA Curry and PJ Webster”

    And there are plenty of studies showing that AMO’s contribution to post-1960s global warming is less than that of humans and increased greenhouse gases. For instance:

    “Causes of irregularities in trends of global mean surface temperature since the late 19th century”
    “Application of regularised optimal fingerprinting to attribution. Part II: application to global near-surface temperature”
    “Contribution of Atlantic and Pacific multidecadal variability to twentieth-century temperature changes”
    “The Atlanto-Pacific multidecade oscillation and its imprint on the global temperature record”
    “A new estimate of the average earth surface land temperature spanning 1753 to 2011”
    “Atlantic and Pacific multidecadal oscillations and Northern Hemisphere temperatures”
    “On forced temperature changes, internal variability, and the AMO”
    “Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years”
    “Evidence for external forcing on 20th-century climate from combined ocean-atmosphere warming patterns”

  62. Pingback: Energy And Environmental Newsletter – December 3rd 2018 | PA Pundits - International

  63. Pingback: Who You Gonna Believe? A Scientist? | PA Pundits - International

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