Hurricanes & climate change: recent U.S. landfalling hurricanes

by Judith Curry

An assessment of whether any of the impacts of recent  U.S. landfalling hurricanes were exacerbated by global warming.

6. Attribution: Recent U.S. landfalling hurricanes

During the past decade, the following continental U.S. landfalling hurricanes rank in the top 5 historical hurricanes in terms of damage:

  • Hurricane Harvey (2017)
  • Hurricane Sandy (2012)
  • Hurricane Irma (2017)

Hurricane Michael ranks in the top 5 strongest continental U.S. landfalling hurricanes (Table 6.1).

Table 6.1 Strongest U.S. landfalling hurricanes. Source:Scientists have argued (in journal publications and media interviews) that at least some aspect of each of these storms was made worse by human-caused global warming: track, intensity, size, rainfall. Here we assess the arguments for claiming a contribution from global warming for each of these four impactful storms.

6.1 Detection and attribution of extreme weather events

Given the challenges to actually detecting a change in extreme weather events owing to the large impact of natural variability, the detection step is often skipped and attribution arguments are made, independent of detection. There are two general types of extreme event attribution methods that do not rely on detection: physical reasoning and fraction of attributable risk (NCA4, 2017),

The fraction of attributable risk approach examines whether the odds of occurrence of a type of extreme event have changed. A conditional approach employs a climate model to estimate the probability of occurrence of a weather or climate event within two climate states: one state with anthropogenic influence and the other state without anthropogenic influence (pre-industrial conditions). The “Fraction of Attributable Risk” framework examines whether the odds of some threshold event occurring have been increased due to manmade climate change.

Participants at the 2012 Workshop on Attribution of Climate-related Events at Oxford University questioned whether extreme event attribution was possible at all, given the inadequacies of the current generation of climate models (Nature, 2012):

“One critic argued that, given the insufficient observational data and the coarse and mathematically far-from-perfect climate models used to generate attribution claims, they are unjustifiably speculative, basically unverifiable and better not made at all.”

Given the inadequacies of climate models particularly for simulating tropical cyclones, attribution arguments related to individual hurricanes typically rely on the physical reasoning approach. The physical reasoning approach, often referred to as the conditional or ingredients-based approach, looks for changes in occurrence of atmospheric circulation and weather patterns relevant to the extreme event, or considers the impact of certain environmental changes (for example, greater atmospheric moisture) on the character of an extreme event.

6.2 Hurricane Sandy

Hurricane Sandy made landfall on 10/22/12 near Atlantic City, NJ. Hurricane Sandy’s most substantial impact was a storm surge. The highest measured storm surge from Sandy was 9.4 feet (at The Battery)[2]. The argument is that human-caused global warming worsened the storm surge because of sea level rise.

Curry (2018a) summarized sea level rise at The Battery. Sea level has risen 11 inches over the past century (Figure 6.1), with almost half of this sea level rise caused by subsidence (sinking of the land). Kemp et al. (2017) found that relative sea level in New York City rose by ~1.70 meters [5.5 feet] since ~575 A.D. A recent acceleration in sea level rise between 2000 and 2014 has been attributed to an increase in the Atlantic Multidecadal Oscillation and southward migration of the Gulf Stream North Wall Index. The extent to which manmade warming is accelerating sea level rise remains disputed (as summarized by Curry, 2018a).

When Hurricane Sandy made landfall on the mid-Atlantic coast, it was no longer classified as a tropical cyclone, but its maximum wind speed at landfall was equivalent to a Category 1 hurricane. As a result of its transition from a tropical cyclone, Sandy became a hybrid storm, which greatly increased its horizontal size.

Figure 6.1. Tide gauge measurements at The Battery, New York, obtained from NOAA (downloaded 8/2/18)..

The 2017 U.S. Climate Change Special Report (NCA4, 2017) evaluated published analyses seeking to attribute aspects related to Hurricane Sandy to human-caused global warming: e.g. sea surface temperatures, atmospheric temperatures, atmospheric moisture, and hurricane size. The analysis concluded:

“In summary, while there is agreement that sea level rise alone has caused greater storm surge risk in the New York City area, there is low confidence on whether a number of other important determinants of storm surge climate risk, such as the frequency, size, or intensity of Sandy-like storms in the New York region, have increased or decreased due to anthropogenic warming to date.”

6.3 Hurricane Harvey 

Hurricane Harvey made landfall in southern Texas on August 24, 2017 as a Category 4 hurricane. The primary damage from Harvey occurred after the storm had been downgraded to a tropical storm and stalled near the coastline, dropping torrential and unprecedented amounts of rainfall over Texas.

As summarized by Landsea (2017), observations indicate a maximum amount of rainfall of about 60 inches just east of Houston, with much of southeastern Texas receiving at least two feet of rainfall. Harvey set the record for most amount of rainfall from a continental U.S. hurricane, going back at least to the 1880’s when comprehensive records begin. The previous top four rainfall producers were: Tropical Storm Amelia (1978) with 48 inches in Texas, Hurricane Easy (1950) with 45 inches in Florida, Tropical Storm Claudette (1979) with 45 inches in Florida, and Tropical Storm Allison (2001) with 40 inches in Texas. Harvey’s stalled, meandering track was similar to Tropical Storms Claudette and Allison. But the peak amount of rainfall from Harvey, as well as Harvey’s areal extent of extreme rainfall, substantially surpassed either of these earlier storms.

Several publications based on model simulations have concluded that as much as 40% of the rainfall from hurricane Harvey was caused by human-caused global warming (Emanuel 2017; Risser and Wehner 2017).

The rationale for these assessments was that prior to the beginning of northern summer of 2017, sea surface temperatures in the western Gulf of Mexico exceeded 30 oC [86 oF] and ocean heat content was the highest on record in the Gulf of Mexico (Trenberth et al. 2017). However, El Niño–Southern Oscillation (ENSO) and Atlantic circulation patterns contributed to this heat content, and hence it is very difficult to separate out any contribution from human-caused global warming.

Figure 6.2 shows that the Gulf of Mexico has warmed by about 0.7 F (0.4 C) in the last few decades (Trenberth et al. 2018).

Figure 6.2. Ocean heat content anomalies (top) for the monthly (black) and annual (red) for the upper160 m in the Gulf of Mexico and sea surface temperature anomalies (bottom) in the Gulf of Mexico (degrees C). The baseline is 1961–1990. Source: Trenberth et al. (2018)

Landsea (2017) summarizes the arguments for more rainfall from tropical cyclones traveling over a warmer ocean. Intuitively, rainfall from hurricanes might be expected to increase with a warmer ocean, as a warmer atmosphere can hold more moisture. Simple thermodynamic calculations suggest that the amount of rainfall in the tropical latitudes would go up about 4% per oF [7% per oC] sea surface temperature increase. Examining a 300 mile radius circle for nearly all of the rain implies that about 10% more total hurricane rainfall for a warming of 2-2.5 F [1-1.5 C]. The Gulf of Mexico has warmed about 0.7 oF [0.4 oC] in the last few decades. Assuming that all of this warming is due to manmade global warming suggests that roughly 3% of hurricane rainfall today can be reasonably attributed to manmade global warming. Hence, only about 2 inches of Hurricane Harvey’s peak amount of 60 inches can be linked to manmade global warming.

Figure 6.3 illustrates the role of sea surface temperature in the western Gulf on Texas major hurricane landfalls. Ten major hurricane Texas landfalls were observed to occur with anomalously cool Gulf sea surface temperatures, while 11 occurred with anomalously warm Gulf sea surface temperatures.

Figure 6.3. Texas major hurricane landfalls and Western Gulf of Mexico sea surface temperatures. Source: Roy Spencer

6.4 Hurricane Irma

Hurricane Irma made landfall on September 10, 2017 as a Category 4 hurricane. Hurricane Irma set several records. Irma was the 5th strongest Atlantic hurricane on record. Irma was the 2nd strongest Atlantic storm in recorded history in terms of its accumulated cyclone energy – a function both of intensity (wind speed) and duration of the storm. Irma is tied with the 1932 Cuba Hurricane for the longest time spent as a Category 5 hurricane. Hurricane Irma maintained 185-mph winds for 37 hours — longer than any storm on record globally.[3]

Irma formed and rapidly intensified to a major hurricane in the eastern Atlantic, where sea surface temperatures were 26.5 oC (80 oF). The rule of thumb for a major hurricane is 28.5 oC. Clearly, simple thermodynamics associated with SST were not driving this intensification, but rather favorable atmospheric dynamics. In particular, wind shear was very weak. Further, the atmospheric circulation field (e.g. stretching deformation) was very favorable for spinning up this hurricane (Curry, 2017).

While the media made much ado about a global warming link to Irma’s intensity, there have been no published journal articles to date that have examined this issue. This is presumably because the sea surface temperatures during Irma’s development and intensification were relatively cool.

Since 1900, 14 Category 4 or 5 hurricanes have struck Florida (Table 6.2).

Table 6.2 Category 4 and 5 hurricanes that have struck Florida. Source: NOAA

Figure 6.4 analyzes the time series major (Cat 3+) landfalling hurricanes in Florida since 1900. There is no significant trend in either frequency or intensity.

Figure 6.4   Florida major hurricane landfalls. Source: Roy Spencer

 6.5 Hurricane Michael

Hurricane Michael made landfall on the Florida Panhandle on October 10, 2018 as a strong Category 4 hurricane. Michael was one of the strongest hurricanes in recorded Atlantic history, and ranks #4 in terms of landfall winds (Table 6.1). The National Hurricane Center estimated peak storm surge inundation of 9-14 feet on the Florida Panhandle (Table 5.2).

During late summer, sea surface temperatures typically exceed 80 oF, which is more than sufficiently warm to sustain a major hurricane. The water in Michael’s path was 2 to 4 oF warmer than usual. Since 1985, sea surface temperatures in the Eastern Gulf of Mexico have increased by about 1 oF (Kennedy et al. 2007).

The most striking aspect of Hurricane Michael was its rapid intensification, from a Category 1 to Category 4 in 24 hours, as it traveled over a very warm patch of water off the coast of Florida. Near Florida, there are deep warm pools of water that move around (the Gulf Loop Current). If a hurricane travels over one of these deep warm pools, it will rapidly intensify if the atmospheric circulation patterns are favorable. Hurricanes Katrina and Rita in 2005 are examples of similar intensification.

For a tropical storm or hurricane to rapidly intensify, it needs three key ingredients: low wind shear, warm ocean water and high humidity. All of these ingredients were in place for Michael, which is somewhat unusual for October. Rather than the typical cold fronts bringing higher wind shear and dry air, circulation patterns were relatively stagnant, providing favorable conditions for Michael to intensify.

Figure 6.5 Sea surface temperature anomalies during Hurricane Michael. Source: Phil Klotzbach

A Category 4 hurricane striking the Gulf coast of Florida is nothing new (Table 6.2). The most notable of these storms in context of a manmade global warming argument is the 1848 Great Gale hurricane that struck Tampa Bay,[4] with a measured barometric pressure and storm surge that are consistent with a Category 4 hurricane. Global temperatures (and presumably the sea surface temperatures in the Gulf of Mexico) were substantially cooler in the mid 19th century.

6.6   Conclusions

Convincing detection and attribution of individual extreme weather events such as hurricanes requires:

  • a very long time series of high-quality observations of the extreme event
  • an understanding of the variability of extreme weather events associated with multi-decadal ocean oscillations, which requires at least a century of observations
  • climate models that accurately simulate both natural internal variability on timescales of years to centuries and the extreme weather events

Of the four hurricanes considered here, only the rainfall in Hurricane Harvey passes the detection test, given that it is an event unprecedented in the historical record for a continental U.S. landfalling hurricane. Arguments attributing the high levels of rainfall to near record ocean heat content in the western Gulf of Mexico are physically plausible. The extent to which the high value of ocean heat content in the western Gulf of Mexico can be attributed to manmade global warming is debated. Owing to the large interannual and decadal variability in the Gulf of Mexico (e.g. ENSO), it is not clear that a dominant contribution from manmade warming can be identified against the background internal climate variability (Chapter 4).

JC note:  next (and final) post in this series is 21st century projections.

64 responses to “Hurricanes & climate change: recent U.S. landfalling hurricanes

  1. Thanks, Judith. Well done.


  2. Sorry to be off topic, but I just finished reading this piece in City Journal, the magazine published by The Manhattan Institute. A great interview with Judith Curry.

  3. A thought on Harvey. It is not just that it stalled, but where it stalled. With the eye just offshore, it could continue to replenish itself for days.

    • It came in big; it rained big pretty much everywhere; it replenished big. Once there was a storm that rained almost as big. In one place, Alvin.

      • Remember, Harvey is not strictly comparable,
        because in the entire hurdat history ( since 1851 ),
        there are no Atlantic storms that stalled as much as Harvey did after landfall:

        As the post points out, it’s plausible that real Harvey could have produced 3% more rain than a hypothetical pre-industrial Harvey. But there is no counter-factual to observe, and Harvey’s worst aspects were from dynamics, not AGW.

        Another aspect might be this: AGW is supposed to increase evaporation from land and reduce soil moisture. Was Harvey’s impact worsened by 3% increased precipitation but also lessened by some amount of decreased soil moisture which lessened runoff? What else might have lessened or worsened Harvey’s impact?

      • Typically, the soil is under concrete.

      • TE, probably not, as soil moisture is actually increasing not decreasing, particularly in dry lands. But I think not so much in SW US, so maybe.

      • Increasing carbon content in soil increasing is likely providing mitigation.

    • Joe Kosanda

      A few other notes on Harvey
      I live in dallas – Harvey’s stall was due to a cold front that come through. Dallas was a very pleasant 75-85 day in august when harvey hit houston

      Several comments regarding the lack of run off due to concrete.
      two other factors that are also ignored,
      A) houston is flat as a pancake, so there is nowhere for the water to run off to.
      B) the soil is a black clay, so there is very little water absorption into the ground

      • John Prince

        Yes, I wondered about the imperviousness of soils there, which was never discussed publicly. Same in SE Virginia where now Virginia Beach has far outdone, from heavy rainfall over top impervious clay soils, and stolen the thunder of Norfolk’s flooding (just usually tidal and seasonal). But Norfolk’s soils by contrast are beautiful and perfectly pervious. And VB’s flooding cannot blame just concrete either.

      • They have also, through the years, since around 1935, when Houston, as a modern city, first experienced widespread, heavy flooding of the “wake up people” variety, spent billions and billions of today’s dollars on flood mitigation. Which has, to some extent mitigated the wholly unqualified specter of their vaunted “up to 12 feet of subsidence” that keeps getting tossed out with no qualification whatsoever and the concrete and buildings. For instance, Tropical Storm Allison did enormous damage in the hospital district, which is adjacent to one of the Bayous. While I lived there they installed huge drain tubes, and fortified basements, etc. Harvey did little damage to the hospitals.

        The answer to soil moisture in August 2017 is easily answered. In 2017 Texas was not in the grips of any significant drought. July shows slightly above-average precipitation at the airport until Harvey hit, where it goes off the chart.

      • Hi John,
        I live in Virginia Beach. Much of it south of 264 was once swampland that’s now sinking. I’m looking out a window now at part of Norfolk was once a creek that was filled in.
        The city is digging out ditches a few miles from my house to deal with persistent flooding- especially in new neighborhoods that, frankly, shouldn’t have been allowed. They flood in any decent rain storm.
        The other fun thing here is hurricanes and the transient nature of much of our population (this is home to the world’s largest Naval base and that’s just one of several bases). After a decade where every year was confidently predicted to be “normal” or “above normal” hurricane seasons but actually had none, we have a huge population that is unaware of what a hurricane is actually like. My neighbors left their poolside umbrella open and out on the patio for a near miss a couple years ago. Last year, thousands evacuated in a panic thanks to inaccurate modeling. It will be hard to get them to go this year if we get hit. And those of us who’ve been around here for a while know we’ll get hit.

      • John Prince

        @Jeffnsails Yes, I’m in Norfolk (family been here 180 years). Subsidence is the major driver -not sea level which is always publicized as the issue, as if no one in this country can discern this. (I do add that the flooding we do have in Norfolk- mostly tidally and seasonally, is far less dramatic and far less regular than what is publicized, and relative to the 1930’s -50’s where my dad said it used to be worse and warmer). Suddenly VB has stolen the thunder of Norfolk’s ‘flooding’ with huge areas deeply flooding from rainfall, areas so large and so pervasive that one wonders what Norfolk was complaining about. Yes, VB should have done more work and diligence when allowing some of those neighborhoods (Norfolk too, but we needed the taxbase). And not to get me started on last year’s disastrous panic hurricane evacuation order and weeklong economic shut down -while we had the correct info that the hurricane was not coming here!- most do not know what a real ‘cane is like (as my dad used to say and he experienced far worse here.) We did have one accurate model for last per Euro, but our local officials refused to follow it. (major backlash on politicians and officials ensued). Every storm now is a potential candidate for hype, not just from media, but now from our local ‘enviro’ leaders and politicians, who should know better than dramatize. Soils in Norfolk are well-drained and well-prepared for storms. Glad VB is working on drainage. .

  4. Scientists have argued (in journal publications and media interviews) that at least some aspect of each of these storms was made worse by human-caused global warming: track, intensity, size, rainfall. Here we assess the arguments for claiming a contribution from global warming for each of these four impactful storms.

    Western anti-modernism, global warming alarmist theory, that a free people engaged in the business of living are destroying the planet and threatening every creature on it, has become the silent scream of cultural identity, transcendent knowledge and self-realization, denied. “Take Al Gore, who is sort of the chief propagandist. I think for him it really is a religion.” ~Freeman Dyson

  5. If the recorded rise in atmospheric CO2 is not responsive to the recorded changes in emissions (, how can someone detect a fingerprint of the emissions in the temperature record that certainly has not followed the CO2 rise very well.

  6. Reblogged this on Climate Collections.

  7. William Schramm

    Dr. Curry,

    In recent months I continue to see conflicting statements in the press regarding the trend of global temperatures. Some reports speak of a “pause” or even a cooling. Other talk of continued warming, warmest annual temperatures, etc. Can you shed some light on what is actually happening? What has been the actual trend in say the last 20-25 years?

    Thank you very much,

    William Schramm Captain USN (ret)


  8. Where is stands now, if you don’t believe it’s still ‘paused’ or deny a pause ever was, you then tacitly are in 100% agreement with all subsequent adjustments to the record that had the effect of adjusting the historical record down, the logical consequence of which has been to reanimate the claim that current temperatures have risen. Nothing has changed with respect to the inability of global warming alarmists to reject the null hypothesis of AGW, i.e., that all warming over the last half of the 20th century can be explained by natural variation.

  9. Robert Clark

    I believe the average temperature of the earth’s surface changes because the average temperature of the sun’s surface’s changes over the centuries, or decades. It is an active star after all. A few hundred degrees it it’s average surface temperature could easily cause the a tenth or two change in the average earth surface temperature to keep the balance.

    • “Most leading climate experts don’t agree with Henrik Svensmark, the 49-year-old director of the Center for Sun-Climate Research at the Danish National Space Center in Copenhagen. In fact, he has taken a lot of blows for proposing that solar activity and cosmic rays are instrumental in determining the warming (and cooling) of Earth. His studies show that cosmic rays trigger cloud formation, suggesting that a high level of solar activity—which suppresses the flow of cosmic rays striking the atmosphere—could result in fewer clouds and a warmer planet. This, Svensmark contends, could account for most of the warming during the last century. Does this mean that carbon dioxide is less important than we’ve been led to believe? Yes, he says, but how much less is impossible to know because climate models are so limited.” ~Marion Long, Discover Magazine, ’07

  10. About hurricanes

    The circulation of the Northern Hemisphere extratropical troposphere has changed over recent decades, with marked decreases in extratropical cyclone activity and eddy kinetic energy (EKE) in summer

    Extratropical cyclones cause much of the high‐impact weather over the midlatitudes. With increasing greenhouse gases, enhanced high‐latitude warming will lead to weaker cyclone activity. Here we show that between 1979 and 2014, the number of strong cyclones in Northern Hemisphere in summer has decreased at a rate of 4% per decade, with even larger decrease found near northeastern North America.

    More papers on declining cyclones

  11. Over a much longer perspective than most instrumental records are extremes of drought and flood that exceed anything seen in the modern era. Distinguishing anthropogenic change against a background of intense internal variability – not least in surface temperature – has always relied on the assumption that perpetual dynamical chaotic change in the system has suddenly ceased. Unless it is convenient to bring it up.

    Moy et al (2002) present the record of South American lake sedimentation shown above which is strongly influenced by ENSO variability. It is based on the presence of greater and less red sediment in a lake core. More red intensity is associated with El Niño. It has continuous high resolution coverage over 11,500 years. It shows periods of high and low El Niño activity alternating with a period of about 2,000 years. There was a shift from La Niña dominance to El Niño dominance that was identified by Tsonis 2009 as a chaotic bifurcation – and is associated with the drying of the Sahel. There is a period around 3,500 years ago of high El Niño frequency and intensity associated with the demise of the Minoan civilisation (Tsonis et al, 2010). Red intensity was in excess of 200 at times. For comparison, red intensity in 1997/98 was 99.

    In the words of Michael Ghil (2013) the ‘global climate system is composed of a number of subsystems – atmosphere, biosphere, cryosphere, hydrosphere and lithosphere – each of which has distinct characteristic times, from days and weeks to centuries and millennia. Each subsystem, moreover, has its own internal variability, all other things being constant, over a fairly broad range of time scales. These ranges overlap between one subsystem and another. The interactions between the subsystems thus give rise to climate variability on all time scales.’

    And while there may be a solar trigger for climate shifts – I find the resonant physical mechanisms of the Earth system more interesting. All bets are off if we hit an anthropogenic tipping point – perhaps in cloud
    stability or AMOC.

    • Robert I Ellison: Moy et al (2002) present

      Thank you for the link.

    • And while there may be a solar trigger for climate shifts – I find the resonant physical mechanisms of the Earth system more interesting.

      Yes, the internal response of the climate is generally ignored and correlations with external factors are blown way out of bounds of their influence. over the past ten thousand years, the NH has lost solar input and the SH has gained solar input. This change beyond 60 degrees is nearly 40 watts per meter squared. Both hemispheres maintained temperature cycles bounded in the same bounds based on ice core data. Each hemisphere has enough thawed ocean and evaporation and snowfall to sequester enough ice to maintain the ocean temperatures close to the freeze thaw point in polar oceans. It snows more in warm times when more ice is needed an it snows less in cold times when less ice is needed.

      This is reported by the ice core data.

  12. The problem with the Breakthrough Institute planetary diabetes metaphor – linked in the tweet at the top – is the belief that the extended metaphor is interesting or relevant.

    “But what actually happens is that when CO2 reaches a minimum and albedo reaches a maximum, the world rapidly warms into an interglacial. A similar effect can be seen at the peak of an interglacial, where high CO2 and low albedo results in cooling. This counterintuitive response of the climate system also remains unexplained, and so a hitherto unaccounted for agent must exist that is strong enough to counter and reverse the classical feedback mechanisms.”

    And in case you doubt the dust hypothesis – here’s another one.

    But for a long time I have wondered what causes transitions from interglacials to glacials. And it is not Milankovitch cycles. NH insolation provides the background to transitions both to and from glacials. But transitions to glacials involve AMOC.

    Of course there is the possibility in that the balance is hit with enough force to cause the ball to leave the track, roll off the table and under the sofa.


    Many simple systems exhibit abrupt change. The balance above consists of a curved track on a fulcrum. The arms are curved so that there are two stable states where a ball may rest. ‘A ball is placed on the track and is free to roll until it reaches its point of rest. This system has three equilibria denoted (a), (b) and (c) in the top row of the figure. The middle equilibrium (b) is unstable: if the ball is displaced ever so slightly to one side or another, the displacement will accelerate until the system is in a state far from its original position. In contrast, if the ball in state (a) or (c) is displaced, the balance will merely rock a bit back and forth, and the ball will roll slightly within its cup until friction restores it to its original equilibrium.’(1)

    In (a1) the arms are displaced but not sufficiently to cause the ball to cross the balance to the other side. In (a2) the balance is displaced with sufficient force to cause the ball to move to a new equilibrium state on the other arm.

    So AGW seems more a simple bacterial infection that can be healed with the judicious application of carbon sequestration in living agricultural soils and thriving ecosystems.

    And 21st century technology.

    We should avoid of course development of antibiotic resistance in the body politic to homilies of disease and catastrophe.

    • This counterintuitive response of the climate system also remains unexplained, and so a hitherto unaccounted for agent must exist that is strong enough to counter and reverse the classical feedback mechanisms.”

      Actually, we have ice core data that explains it all.

      In the cold period, low frozen oceans do not evaporate much and there is not enough snowfall to maintain the ice and the great ice sheets thaw and deplete and retreat and causes a warm period.

      In the warm period, high and warm and thawed oceans promote more evaporation and snowfall and build the sequestered ice until it advances and causes a cold period.

      This is recorded in the data and in history.

      • Forget the models until they get reliable, and look at actual data.
        Correct answers are only found in actual data.

      • Again much more science is needed.

      • When actual data is available, the most important part of the science is done, Study and understanding of the data is the next part of science that not many are willing of undertake against the supposed consensus. The alarmists and luke-warmers attack anyone who proposes ideas that do not include significant influence by CO2.

        Weather events have changed as climate changed, but climate has always changed and water and ice caused the changes.

      • Robert Clark

        I did look at the only record we have showing data from the past. That is the Vostock Ice core from the Antarctic. It shows the new Ice Age began about 18,000 years ago, CO2 has nothing to do with the actions of the Ice Age. It is controled by the green foliage. The ice shelf is breaking off because water expands as it cools from 39’F to 32’F; Radient heat is reflected by water. Those two laws of science explain the Ice Age. Humans have little to no affect on it.

      • Quote: “Actually, we have ice core data that explains it all. “. The ice core data say it all, like several other proxies. but explain nothing. They only point to the ‘unaccounted for agent’.

        I have made an addition to a very good chart courtesy of Andy May. Find it here: That identifies the ‘unaccounted agent’. But it will serve for nothing as long as one stays looking for the agent under the Milankovitch streetlight.

        The Rattan Youtube video is very interesting and makes much sense. However it is not all AGW. There are cycles (~980yr – Eddy) that have great influence on soil productivity, when and where. Another recent example (check its timing with the Eddy cycle; a root) :

      • “Now imagine that you have never seen the device and that it is hidden in a box in a dark room. You have no knowledge of the hand that occasionally sets things in motion, and you are trying to figure out the system’s behavior on the basis of some old 78-rpm recordings of the muffled sounds made by the device. Plus, the recordings are badly scratched, so some of what was recorded is lost or garbled beyond recognition. If you can imagine this, you have some appreciation of the difficulties of paleoclimate research and of predicting the results of abrupt changes in the climate system.”

        Data – what little is precise and definitive – is interpreted through the lens of paradigm. Paradigm is an uncertain and evolving understanding of a complex and dynamic system. What we don’t know as yet seems more important than what we do.

        I have little regard for overly simple and certain climate paradigms.

      • RI Ellison. Thanks for the link to the book.

        Re the piece quoted, yes, much of science research is like that. But there are rare occasions when someone stumbles on a key piece of info while looking in the dark for something quite different. In my case I (the maverick in me —-) was looking for an agrarian calendar in what was supposed to be pure ignorant cult. I found it, more than 16 such instances spread on more that 3000 years. All simple techniques. But what all said was that obliquity was never 23.xx deg but considerably less. A 23.xx deg only after about 2400bce. The indelible tell-tale of the ‘unaccounted agent’. It is where the polar ice cores show abrupt temp increase, but the reverse at equatorial ice. Simple then to figure why, but the ice cores don’t explain.

        The problem for me was not to prove it correct but to find a way to debunk it (the eureka moment was very short-lived; I didn’t like it one bit once its meaning sunk in). It is also why Rattan is very right (though perhaps for wrong reason) in his urging.

      • The evolution of the solar magneto has the form of a discontinuous Hamiltonian with a quasi regularity given the relative mass of the sun and planets. Solved if possible in finite time steps a la Poincaré.

        Then we get hit by an asteroid that sets up a wobble.

        But there are multiple feedbacks in ice, cloud and atmosphere, biology and oceans that have their own resonant frequencies.

        It’s dragon-kings all the way down…

      • Water is a positive energy capacitor and ice is a negative energy capacitor.
        Water is abundant, water changes state. Water is stored as liquid with positive energy capacity and water is stored as ice with negative energy capacity. The energy comes from the sun at an almost constant rate. When the energy from the sun changes there are instant changes where the sun is shining. The sun heats the Northern Hemisphere the most part of the time and heats the Southern Hemisphere the most at other times. There are internal cycles of the giant capacitors, the oceans and the ice on land. When the warm capacitor is charged, there is the most positive energy stored in the oceans and the least negative energy stored in the ice sequestered on land. When the cold capacitor is charged there is the most negative energy stored in sequestered ice on land and the least positive energy stored in the oceans. Sea ice is a barrier that is placed on top of the warm capacitor to prevent it from losing energy by evaporation and to keep it from receiving more energy from sunlight. This switch is turned on and off as needed by thawing and freezing polar oceans. This works in both polar regions and does switch direction of the flow of energy between the capacitors. In the tropics the flow of energy is always turned more toward the oceans. The sunlight adds energy and evaporation removes energy and energy is transported to the polar regions. In polar regions the flow of energy is always removing energy from the warm ocean capacitors. When oceans are cold and frozen the flow of energy in the polar regions between the capacitors is turned off and the oceans stop cooling and the cold capacitor discharges more and the warm capacitor charges more. An ice age starts when the warm capacitor is sufficiently charged. An ice age ends when the cold capacitor is depleted. This causes long term cycles that have evolved as continents moved and ocean currents changed and carried more water between tropical and polar regions. The amount of ice that can be sequestered on land depends on the amount of warm ocean that can evaporate from oceans, especially warm currents in colder regions. Shorter term correlations are easier to identify, especially with the abundance of “short term” thermometer records, but those records only cover a small part of the most recent full cycle of cooling out of the Medieval Warm Period and warming into this Modern Warm Period. Thermometers were not available for the cooling, only for part of the warming.

        The cycles grew larger and colder over the last fifty million years with more and more water and ice taking part in the cycles, but every cycle sequestered ice on Antarctic and did not return all to the oceans in warm periods. We have ice cores that are 800 thousand years old to confirm this. Now, enough ice is sequestered in cold places that less converts to water and then enters the oceans, such that warm periods have less warm water energy capacity to create ice ages. Each hemisphere has polar sea ice that thaws and increases evaporation and snowfall to keep enough ice sequestered in that hemisphere. Then the sea ice forms and reduces evaporation and snowfall in that hemisphere until the next cycle reversal. Tropical cooling is constantly cooling depending on ocean temperature. Polar cooling is removing the most energy when the oceans are evaporating and creating ice to be sequestered in the negative energy ice. Polar cooling is removing the least energy when the oceans are frozen and prevented from evaporating.

        Over the last ten thousand years, the earth orbit has changed to reduce the solar into the NH and increase the solar into the SH, but in that time ice cores in both hemispheres show the polar cycles adjusted to keep the cycles in the same bounds, but they are not synchronized. Each hemisphere has different heat and cold energy capacity and each hemisphere adjusts the sequestered ice to keep the ocean temperatures around the freeze thaw point that switches the direction of energy flow. These cycles did adjust to the huge difference in energy in that orbit cycles caused, a few watts per meter squared from CO2 will not matter. The SH has more positive capacity in warm oceans and more cold negative capacity in ice on Antarctic. Over the last ten thousand years, Ice was increased in SH as more energy came in and ice was decreased in NH as less energy came in. Yes, our NH glaciers are smaller now than ten thousand years ago because less sequestered ice is needed. The tropics seek equilibrium, the Polar regions cycle. The NH glaciers and ice sheets will grow when the sun comes more to the NH again.

        This is a natural cycle and we do not cause it and we can not stop it. Water, in all its states and changing states, regulates temperatures in narrow bounds, in smaller and colder cycles on the top end and warmer cycles on the bottom end, than would happen without water. Without water where the sun was shining would be hotter than now and without water where the sun was not shining would be colder than now. The average might be close to what is now. This does not disprove the suns influence, it supports it, it needs the sun. This does not disprove that more atmosphere might influence the temperature, it supports that, it needs the atmosphere.

        This does explain what causes ice ages and what causes then to end, ICE causes ice ages and lack of ice after it depletes causes the ice age to end..

      • I have little regard for overly simple and certain climate paradigms.

        many problems have simple correct paradigms and you will always dismiss those.

      • The objective of course is to make it as simple as possible but no simpler.

        “One of the most remarkable emergent properties of natural and social sciences is that they are punctuated by rare large events, which often dominate
        their organization and lead to huge losses. This statement is usually quantified by heavy-tailed distributions of event sizes. Here, we present evidence that there is “life” beyond power laws: we introduce the concept of dragon-kings to refer to the existence of transient organization into extreme events that are statistically and mechanistically different from the rest
        of their smaller siblings. This realization opens the way for a systematic theory of predictability of catastrophes, which is outlined here and illustrated.”

        Is there a life beyond power laws? Evidently so. Is the idea useful in predicting shifts in Pacific state in 1976/77 or 1998/2000?

        Or now?

      • I agree that some event could cause something different to happen but I believe the last ten thousand years is the new normal. The balance between ice on land and water in the oceans have reached the point of repeating cycles and they will continue to repeat as they have for the past ten thousand years. It will snow as much as needed to rebuild ice every time the polar oceans get warm and thawed. It will snow as little as needed to deplete ice every time the oceans get cold and frozen. This has repeated for fifty million years. The cycle changed as continents drifted and changed ocean currents. As water currents that flowed around the earth inside the tropics, there was no warm water flowing in polar regions so there was little evaporation and snowfall to sequester significant ice on land. Gradually the cycles got larger over the recent millions of years. Eighteen thousand years ago, when we came out of the last major ice age, less water and ice was available because of the large amount that had been sequestered in cold places that the new cycles of the last ten thousand years are much smaller. That was not a dragon king, it was a dragon slayer. It killed the major ice ages. Our next climate dragon will be many thousands or millions of years in the future. Unless you close the entrance to the Arctic for the Gulf Stream, the evaporation and snowfall will repeat every time the Arctic opens and ice will deplete every time the Arctic freezes over. That will maintain ice on Greenland and other cold places where ice is sequestered.

        It would be interesting if some people read and thought about this before they spout the standard consensus responses. and yes the luke warmers have their own consensus. Ewing and Donn presented this theory in the 1950’s, it was not exactly this but it led down the correct path of thinking.

      • the solar cycles can add or subtract energy, CO2 may add some, but these things do not change the temperature that polar oceans thaw and increase evaporation and snowfall. It will snow as much as needed and when it is needed, every time and it will stop when the oceans get cold and freeze and reduce snowfall on sequestered ice. Many people do understand this but they do not want to be attacked for going against consensus.

  13. Perhaps this brand new paper is interesting, Trenary at al: .
    From the conclusions: “These results strongly suggest that formal attribution of the forced response of PI in the tropical North Atlantic is not currently feasible because there is too much model disagreement about the total response and reanalysis products disagree too much in their estimates of low-frequency PI variability.” (PI=hurricane potential intensity).
    They looked at CMIP5 models and reanalyses, with no success. Hopefully this is also the end of some media rumble when the next hurrican arrives…

    • frankclimate
      One must ask what the modellers use as drivers in TC intensification, if they do not know what initiates genesis and rapid intensification. Not knowing what causes rapid intensification means that one doesn’t fully understand general intensification over a period of time. See notes below.
      The modellers are becoming more disconnected with reality as time passes.

  14. Judith
    Your TC report is a great easy to read analysis. It saves a lot of research for what is known, unknown and real. Thank you.

    The definition of why TC occur or exist at all possibly needs clarification. That is – what is their purpose.

    Given that important factors such as genesis and rapid intensification are currently not known, perhaps these are best stated at the start of the report. I respect your better judgement.

    Your summary of Michael gives clear understanding of the three important local environment conditions required, but those alone do not account for rapid intensification. They simply provide efficiency to intensify. There Is a fourth element and that appears to be linked to why they exist at all.

    TC Michael peaked on the 10th October, so did Leslie H1 Atlantic and Luban H1 Indian Ocean.
    The previous day (9th) Nadine TC Atlantic peaked. As did Titli H2 in the Indian Ocean.
    This is not coincidence, they are all united by a common global driver.

    There is suggestion by some that a super mega TC will occur of monstrous proportions. This is pure nonsense. As we see with the list above for the 9th and 10th October, that as the fourth element increases in intensity, more TC activate in response, and as a result reduce the impact of the fourth element. They kill themselves.

    Globally, TC frequently occur in clusters which again makes local conditions secondary. In 2005 there were nine TC active at the same time (H1 and above) during a very active high energy year that created clusters. There were numerous highly active TC between the late September and 12th October when the fourth element was persistent.

    A report is well overdue, made difficult by continuous travel and only one typing finger.
    Martin Cropp

    • Ozonebust said:

      “Given that important factors such as genesis and rapid intensification are currently not known, perhaps these are best stated at the start of the report. I respect your better judgment.

      Your summary of Michael gives a clear understanding of the three important local environment conditions required, but those alone do not account for rapid intensification. They simply provide efficiency to intensify. There Is a fourth element and that appears to be linked to why they exist at all.”


      “TC Michael peaked on the 10th October, so did Leslie H1 Atlantic and Luban H1 Indian Ocean. The previous day (9th) Nadine TC Atlantic peaked. As did Titli H2 in the Indian Ocean. This is not a coincidence, they are all united by a common global driver.”


      The fourth element (aka the common global driver) in spawning tropical cyclones (that become hurricanes, typhoons, and cyclones) is the change in the tidally induced lunar acceleration and de-acceleration of the Earth’s rotation rate. These conditions occur roughly every 1/4th of a lunar tropical month = 4 to 9 days (mean period 6.83 days) when the Moon either crosses the Equator or reaches its maximum latitude above or below the Equator (i.e. lunar standstill). At these time the semi-diurnal lunar tides in the tropics are reaching an ebb i.e. they are either at a minimum or a maximum in their weekly variation.

      I am claiming that the effects of the (weekly) lunar tidal variations on the Coriolis forces between about 10 and 30 degrees are responsible for the sudden intensification and organization of tropical low-pressure cells that lead to the “sudden” appearance of tropical depressions and tropical storms that go on to produce tropical hurricanes.

      You can see my evolving arguments at:

  15. Correction
    “There were numerous highly active TC between the late September and 12th October 2018 when the fourth element was persistent”.

  16. Noting the expression ‘simple thermodynamics’ occurs twice in this report, it might be noted that even simpler thermodynamics tells us 95% of a constant energy stream entering a ‘black box’ at 5500K and exiting at 250K is being dissipated. Dissipation, or work done, represents the conversion of one high energy photon into dozens of lower energy ones through unspecified internal processes, i.e. weather/climate/oceans/etc. A calculation, of course, can enhance dissipation by recycling dissipated energy as is commonly done in the design of perpetual motion engines.

  17. Robert Clark

    Radiant heat lost by the earth and the sun to Black Sky radation can be considered dissipated. During Global Ice Making (Global Cooling), the first half of the Ice Age, the radiant heat lost by the Earth is more than that gained from the sun. Nature makes up for the loss by removing heat from the oceans. During Global ice Melting (Global Warming), the second half of the Ice Age, the earth gains more heat from the sun than it looses. Nature makes up for that by melting the ice at the poles and storing the extera heat in the oceans. Nature keeps the average surface temperature of the earth constant.

  18. I am surprised there is no mention of the unique interaction of multiple systems that contributed to Sandy’s unusual track and the 1,000+ mile fetch that she produced and pointed right at the East coast.

    • Actually, Hurricane Irma has been estimated at 178-mph (155 knots) in the post-analysis of NHC. Therefore, Irma did not beat any record (as 185-mph or 160 knots during 37hrs).When Irma reached an intensity of 178-mph (155 knots) on 5th Sep., the ocean temperature was at 29.2°C from the surface to 30 meters.

  19. To be more accurate, I found ocean températures where Irma became a Tropical Depression, Tropical Storm, then a Major Hurricane.

    30-0000Z 30 knots TD 16.1N/26.9W
    30-0600Z 35 knots TS 16.2N/28.3W
    XBT 2017-08-28, 07:01Z, 15.43N, 25.16W, 0, 28.22°C
    XBT 2017-08-27, 20:26Z, 16.04N, 27.59W, 0, 27.63°C

    As seen below, Irma intensified into a TD and TS over ocean temperature around 27.5°C/27.6°C.

    31-1200Z 80 knots Hu 16.7N/33.4W
    31-1800Z 95 knots Hu 17.1N/34.2W
    01-0000Z 100 knots Hu 17.5N/35.1W
    XBT 2017-08-30, 22:48Z, 16.15N, 33.17W, 0, 27.79°C
    Buoy 1301524,2017-09-01, 06:00Z, 17.56N, 35.92W, 27.01°C

    And Irma became a Major Hurricane with SST of 27°C.

    And remember that Super Typhoon Wutip reached 140 knots (Cat 5) on 25th February with SST of 27.5°C near Guam in the western North Pacific.

    Therefore, the 28.5°C mentionned are not the low limite to get a Major Hurricane.


  20. Pingback: Weekly Climate and Energy News Roundup #351 | Watts Up With That?

  21. “The previous top four rainfall producers were: Tropical Storm Amelia (1978) with 48 inches in Texas, Hurricane Easy (1950) with 45 inches in Florida, Tropical Storm Claudette (1979) with 45 inches in Florida, and Tropical Storm Allison (2001) with 40 inches in Texas.”

    Not to pick nits, but, Wikipedia (perhaps not the best source of knowledge) indicates Claudette dumped 45 inches in Texas. The rainfall graphic shown there does not show any impact on Florida.


    • Hurricane Claudette dropped 45 inches on a little town called Alvin. It’s Nolan Ryan’s home town. How much rain did Claudette drop anywhere else? Houston? Katy? Beaumont? Conroe?

      Hurricane Harvey dumped a massive amount of rain on, how to describe it how about, just for starts: Harris County.

      • According to, “Lynn Nolan Ryan Jr. was born on January 31, 1947, in Refugio, Texas, to Lynn Nolan Ryan Sr. and Martha Lee Hancock Ryan. Six weeks after their youngest child’s birth, the family moved to Alvin, Texas, a quiet area on the outskirts of Houston.”

        I agree that Alvin, TX is where the most rain appears to have fallen. I still don’t see any significant rain in the State of FL. Is there a town near Alvin in Texas named Florida? Perhaps that’s where my confusion lies.

      • Sorry I am not being clear. I am making no assertions about Harvey or anything other than pointing out a possible minor mistake in the article. The article states
        “Tropical Storm Claudette (1979) with 45 inches in Florida”
        I believe that should read:
        Tropical Storm Claudette (1979) with 45 inches in Texas

      • I incorrectly called it a hurricane. There is at least one Hurricane Claudette.

        In 1979 in Texas it was Tropical Storm Claudette. That is usually used to suggest that something akin to Hurricane Harvey happened in the recorded history, and I do not think many people involved in flood mitigation in Harris County would agree.

        With respect to 45 inches, I suspect “Florida” should be replaced with Alvin, a little dot on the Texas map.

      • I believe it is correct in the article as Tropical Storm. The WordPress editor mangled my carets which were meant to emphasize Florida and Texas. Unfortunately, I was unable to edit that message after posting. Downside to being a lurker is bumbling with the editor. I will step quietly back into the shadows now and continue to enjoy your blog and work.