by Judith Curry
Doubt and Certainty in Climate Science is an important new book that everyone should read. And its free.
It is a privilege to make available to you the book Doubt and Certainty in Climate Science, by Alan Longhurst [link Longhurst print to download the book].
The book is 239 pages long, with 606 footnotes/references. The book is well written, technical but without equations – it is easily accessible to anyone with a technical education or who follows the technical climate blogs.
In this post I provide a brief overview of the book, biosketch of Alan Longhurst, some additional backstory on the book, and my own comments on the book.
The Preface provides some interesting history, here are some excerpts:
But more recently, I became troubled by what seemed to be a preference to view the climate as a global stable state, unless perturbed by anthropogenic effects, rather than as a highly complex system having several dominant states, each having a characteristic return period imposed on gradual change at millennial scale. The research of H.H. Lamb and others on the natural changes of regional and global climate of the Holocene appeared to be no longer of interest, and the evidence for anthropogenic climate change was being discussed as if it was reducible to change in a single value that represented global surface temperature.
The complex relationship between solar cycles and regional climate states on Earth that was central to classical climatology (and is still being discussed in the peer-‐reviewed literature) had been replaced with a reductionist assumption concerning radiative balance, and the effective dismissal of any significant solar influence. I found this rejection of an entire body of scientific literature troubling, and looked for a disinterested discussion of the balance between natural and anthropogenic effects, but could not find what I wanted -‐ a book that covered the whole field in an accessible and unprejudiced manner, and that was based solely on the scientific literature: I found text-‐books on individual topics aplenty, together with a flood of others, either supporting or attacking the standard climate change model, but none that was based wholly on studies certified by peer-‐review -‐ and whose author was inquisitive rather than opinionated.
One thing led to another and this text is the result. My intention has been to examine the scientific literature that both supports – and also contradicts -‐ the standard description of anthropogenic climate change, and its effects on Earth systems: I undertook the task with an open mind concerning the interpretation of the evidence presented in individual research reports, and collectively by those who have been tasked to report to governments on the progress of climate change and to predict future states.
Because of my experience, this review leans very heavily on discussion of the role of the oceans in controlling climate states, but I make no apology for this: their role is central and critical and too often ignored.
Anthropogenic modification of climate, especially of micro-‐climates, is undoubtedly occurring but I have been unable to convince myself that the radiative contribution of carbon dioxide can be observed in the data, although modellers have no trouble in demonstrating the effect.
Because there will certainly be some who will question my motive in undertaking this task, I assure them that I have been impelled by nothing other than curiosity and have neither sought nor received financial support from any person or organisation in the prepaatio and distribution of this eBook.
Table of Contents
1 –The crisis in climatology
- 1.1 -‐ Climate change science: new paradigm or new community?
- 1.2-‐ Estimating certainty levels in the scientific literature
- 1.3-‐ Numerical climate simulation
2 -‐ Radiative forcing of atmospheric processes
- 2.1 -‐ Radiative forcing by active molecules
- 2.2 -‐ Carbon dioxide
- 2.3 -‐ Methane
- 2.4 -‐ Nitrous oxide.
- 2.5 -‐ Water vapour
- 2.6 -‐ Sulphur dioxide, and volcanic activity: a special case
- 2.7 -‐ Aerosols and particles, natural and anthropogenic
3 – Earth’s climate is not a closed system
- 3.1 -‐ The consequences of the variable geometry of the solar system
- 3.2 -‐ Environmental consequences of the Wolf sunspot cycle
- 3.3 -‐ The relationship between solar cycles and regional climate state
- 3.4 -‐ The 1470-‐year Bond cycle and the glacial-‐interglacial transitions
- 3.5 -‐ Was there a role for CO2 in the orbitally-‐forced glaciations?
- 3.6 -‐ The probable effects of the coming solar cycle
- 3.7 -‐ Lunisolar tidal cycles and global temperature
- 3.8 -‐ The Holocene CO2 and CH4 anomalies
4 – Can a global mean temperature be measured?
- 4.1 -‐ Consequences of patchy observations and doubtful assumptions
- 4.2 -‐ Adjusting the observations and extrapolating over a global grid
- 4. 3-‐ Sea and land surface temperatures are incompatible
- 4.4 -‐ Regional patterns of warming of the troposphere
- 4.5 -‐ Cooling of the stratosphere
5 – The ocean: main global sink of solar heat
- 5.1 -‐ How does heat enter the ocean and how is it stored there?
- 5.2 -‐ Progressive warming of the ocean
- 5.3 -‐ Cloud cover-‐ a difficult-‐to-‐measure variable aperture
- 5.4 -‐ Does global cloud cover respond to solar and galactic forcing?
6 – Regional patterns of temperature change over land surfaces
- 6.1 -‐ Regional anomalies in the evolution of SAT during the 20th century
- 6.2 -‐ The use of proxies to understand the past: the trees do still speak clearly
- 6.3 -‐ The thermal footprint of changes in land use and vegetation cover
- 6.4 -‐ The thermal consequences of urban development
- 6.5 -‐ The regional effects of anthropogenic heat of combustion
7 – The North Atlantic: moderator of climate states
- 7.1 -‐ Consequences of changing wind patterns over the North Atlantic
- 7.2 -‐ The density-‐driven circulation
8 -‐ The top and bottom of the world: two special cases
- 8.1 -‐ Arctic ice cover during previous centuries
- 8.2 -‐ Is surface air temperature really increasing over the Arctic Ocean?
- 8.3 -‐ Why is the Arctic climate and ice cover so strongly variable?
- 8.4 -‐ Is the loss of the Greenland ice cap imminent?
- 8.5 -‐ The bottom of the world
9 – Intensification of extreme weather events
- 9.1 -‐ The variability of cyclonic storms
- 9.2 -‐ Droughts, floods and the ‘expansion of the tropics’
- 9.3 -‐ Concerning storminess to come
10 – The ocean: sea level and acidification
- 10.1 -‐ Rising sea levels
- 10.2 -‐ On living on islands and coasts
- 10.3 -‐ Acidification of sea water: uncertainty levels
- 10.4 -‐ Experimental evidence for acidification effects
11 – Attribution and detection: natural or anthropogenic?
- 11.1-‐ Formal attribution of cause
- 11.2 -‐ Conclusions
Attribution and Detection – Natural or Anthropogenic?
The conclusions from Longhurst’s analysis are presented in section 11.2:
While I am aware that the general opinion of the relevent scientific community is that no further debate is necessary after five successive assessments by the IPCC, I suggest that this is premature because these conclusions concern topics that have not yet been properly addressed by that body, and so should be accorded status in a continuing debate concerning the influence of anthropogenic effects on regional climates.
If the peer-‐reviewed scientific literature, with all the levels of uncertainty associated with individual contributions, has anything to say collectively in assessing the standard climate model, then a small number of conclusions may be drawn from the 600 peer-‐reviewed papers that I have consulted:
• -‐ the global archives of surface air temperature measurements are unreliable estimators of the consequences of atmospheric CO2 contamination, because they are already themselves contaminated by the effects of deforestation, land use change, urbanisation and the release of industrial particulates into the lower atmosphere (Sections 6.3, 6.4, 6.5).
• -‐ users of these data are not able to judge the consequences of the adjustments that have been made to the original observations of surface air temperature ashore, although the limited investigations now possible show that the adjustments have changed the long-‐term trends that had been recorded by some reputable national meteorological services (Sections 4.1, 4.2).
• -‐ sea surface temperature is not a substitute for air temperature over the oceans because it responds to changes in vertical motion in the ocean associated with coastal and open-‐ocean upwelling; the resultant change in surface temperature is independent of any changes in atmospheric temperature caused by CO2, yet these changes are integrated into the GMST record which is used to estimate the effects of CO2 (Section 4.3)
• -‐ surface air temperatures respond to cyclical changes within the Sun, and to the effect of changing orbital configurations in the solar system: the changes in the resultant strength of received irradiance (and of tidal stress in the oceans, which also has consequences for SAT) are both predictable and observable (Sections 3.2, 3.3, and 3.4),
• -‐ our description of the evolution of the global heat budget and its distribution in multiple sinks is inadequate for an understanding of the present state of the Earth’s surface temperature, or to serve as the initial state for complex modelling of climate dynamics. Future states are therefore unpredictable, cannot be modelled, and will certainly surprise people living through the next century (Sections 4.1, 4.2, 4.4, 4.5),
• -‐ the planetary heat budget is poorly constrained, perhaps principally by our inability to quantify the mechanisms that control the accumulation and loss of heat in the ocean, where most solar heat accumulates; the quantification of changes in cloud cover is so insecure that we cannot confidently describe its variability -‐ yet clouds are the most important control on the rate of heat input at the sea surface (Sections 5.1-‐ 5.4),
• -‐ the evidence for an intensification of extreme weather events and, in particular, tropical cyclones is very weak and is largely due to the progressively-‐ increasing reliability and coverage of weather monitoring: todays frequency of cyclones and other phenomena does not appear to be anomalous when longer data sets can be examined (Sections 9.1, 9.2),
• -‐ global climate in the present configuration of the continents falls naturally into a limited number of patterns that are forced externally and patterned by internal dynamics. Some of these climate patterns will tend to conserve global heat, some will tend to permit its dissipation to space, while all move heat from one region to another. Two dominate the whole: the North Atlantic Oscillation that describes the flux of tropical heat through the North Atlantic Current into Arctic regions, and the Southern Oscillation that describes the strength of trade winds, especially in the Pacific, and thus the relative area of cold, upwelled water that is exposed to the atmosphere (Sections 7.1, 7.2),
• -‐ the recent melting of arctic ice cover over larger areas than 20 years ago in summer is not a unique event, but is a recurrence of past episodes and is the result of cyclically-‐variable transport of heat in warm North Atlantic water into the Arctic basin through the Norwegian Sea; the present episode will likely evolve in the same way as earlier episodes (Sections 8.1-‐8.3),
• -‐ sea level is indeed rising as described by the IPCC and others, but the causes -‐ especially at regional scale -‐ are more complex than suggested by that agency and involve many processes other than expansion due to warming. Had the human population of some very small islands remained within carrying capacity, their occupation could have been permanent, but this is not the case (Sections 10.1, 10.2),
• -‐ the consequences of acidification of seawater is one of the most enigmatic questions, and may bring serious biological problems, although it seems now that (i) marine organisms are more resilient to changing pH than was originally feared, because of the genetic diversity of their populations and (ii) the history of pH of seawater during geological time suggests that resilience through selection of genomes has emerged when appropriate in the past (Sections 10.3, 10.4).
Unfortunately, the essential debate on these issues will not take place, at least not openly and without prejudice, because so many voices are today saying – nay, shouting -‐ ‘enough, the science is settled, it is time for remediation’. In fact, many have been saying this for almost 20 years, even as fewer voices have been heard in the opposite sense. As discussed in Chapter 1, the science of climate change -‐ like many other complex fields in the earth sciences -‐ does not function so that at some point in time one can say “now, the science is settled”: there are always uncertainties and alternative explanations for observations.
Alan Longhurst is a biological oceanographer who has studied the ecology of the continental shelf of the Gulf of Guinea (1954-‐63), and the trophic structure and flux of energy through the pelagic ecosystems of the eastern Pacific (1963-‐71), the Barents Sea (1973), the Canadian Arctic (1983-‐89) and the Northwest Atlantic (1978-‐94). He coordinated the international EASTROPAC expeditions in the 1960s and directed the NOAA SW Science Center on the Scripps campus at La Jolla (1967-‐71), the Marine Ecology Laboratory at the Bedford Institute of Oceanography (1977-‐79) and was Director-‐ General of that Institute (1970-‐86). He has published 80-‐odd research papers and his most recent books are “Ecological Geography of the Sea” (Elsevier, 1998 & 2007) and “Mismanagement of Marine Fisheries” (Cambridge, 2010).
See also Longhurst’s biosketch at Elsevier [link].
I have been communicating with Alan for several years about the book. In preparing the blog post, I asked him to provide some backstory, and here is what he wrote:
“It started out with my being asked to talk abut climate change to an informal evening seminar club here in rural SW France, as the only scientist in the group. So I had to started reading into the subject, and because I can no longer give off-the-cuff seminars (my mind clogs up) I had to write a text. Then, since I was pretty much written-out in my own subjects, I didnt stop reading once the semiar was out of the way, so it snowballed and grew to book-length. My previous publishers (Elsevier for “Ecological Geography of the Sea” and Cambridge for “Mismanagement of Marine Fisheries”) wouldnt touch it, nor would any of the other top-line houses that I tried, and I thought that the book would not carry much weight if it were to go to a small publisher specialised in stirring things up.
One of my motivations for completing the book was finding to what extent ‘climate change’ had become a religion and the strength of imperatives to conform – which seemed to me not to bode at all well for the future of science. I have tried to emphasise that I really dont think the science is as settled as many pretend.
One of the things my research career taught me was that you cant understand how the ocean works from studying one region – just as I know that you cant make any solid conclusions about how the climate works from studying just the short period since 1960, which is what many people are doing.
I wouldnt have known that but for the fact I’ve had personal experience working (and travelling by sea, in the old days) in all the major oceans and in many dfferent marine environments: the tropical Gulf of Guina (where I spent almost 10 years) works totally differently from the tropical eastern Pacific, where I next worked from Scripps, and was able to compare the tropical pelagic ecosystem with that of the California upwelling region; later, I had the good fortune to work in the arctic (Barents Sea and Canadian archipelago, each totally different environments), and on both sides of the North Atlantic. Tthe fact that my research work has been done on similar processes in many diverse regions has given me (I hope) a good understanding of regional characteristics that prepared me for thinking about diverse and changing climates.
I was also lucky that although I held administrative posts at the NOAA lab on the Scripps campus, and later at the Bedford Institute in Canada, I was always able to keep my plankton lab going and get to sea at least once a year. My last 10 years were free of admin, and I got involved in the Canadian climate change programme and had a very productive time. The group I was with produced the first global computation of ocean primary production from the first satellite data and some of the first evidence for the dominance of photosynthetic bacteria in tropical oceans during a cruise that I organised in the eastern Pacific – which was a game-changer. My own work, once I left the African labs, was on the exploration of the details of how the production and consumption of organic material was organised in th pelagic realm.”
This is a remarkable book, a tour de force. There are fresh insights in each chapter, borne of Longhurst’s objective analysis of the data and the literature. The papers he cites are from Nature, Science, PNAS, Journal of Climate and other mainstream, high impact journals. I doubt that John Cook’s activist abstract classifiers would classify many if any of these papers as ‘skeptical’. However, each of these papers provides a critical link in Longhurst’s reasoning that produces conclusions that do not agree with the ‘consensus.’
I am reminded of this quote by Galileo: “In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.” The value of an independent assessment of this broad range of topics, by a scientist who does not have a dog in this fight, is extremely high. Very, very few climate scientists have personally dug as deeply as Longhurst over such a broad range of climate science topics. This reminds us that the broad range of complex issues surrounding detection and attribution of climate change are outside the scope of what most climate scientists consider, and one can only infer that their support for the consensus conclusions is based on second-order belief regarding many topics outside of their personal expertise and research experience.
Will everyone agree with Longhurst’s analyses? Of course not, although he presents arguments from both sides and extensively discusses uncertainty and doubt. The important factor here is that he presents carefully reasoned arguments supported by data analysis and citations of the elite published literature. In the coming weeks, I will select individual sections for discussion, that I regard as either provocative or controversial.