Book Review: Doubt and Certainty in Climate Science

Doubt and certainty coverDr. Judith Curry, Professor and former Chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, has introduced a new book by Alan Longhurst titled Doubt and Certainty in Climate Science. You can read Curry’s extensive remarks here.

Curry says, “Doubt and Certainty in Climate Science is an important new book that everyone should read. 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.” She opines, “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.”

The author, Alan Longhurst, is a biological oceanographer at the Bedford Institute of Oceanography in Dartmouth, Nova Scotia, Canada. He has published more than 80 peer-reviewed papers and several books. You can download the book as a PDF file for free (4.4Mb).

In the Preface, Longhurst explains why he wrote the book. Here is an excerpt:

“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.”

Longhurst writes in his conclusions:

While I am aware that the general opinion of the relevant 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, urbanization and the release of industrial particulates into the lower atmosphere.

• — 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.

• — 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.

• — 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.

• — 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 modeling of climate dynamics. Future states are therefore unpredictable, cannot be modeled, and will certainly surprise people living through the next century.

• — 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.

• — 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: today’s frequency of cyclones and other phenomena does not appear to be anomalous when longer data sets can be examined.

• — 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, up-welled water that is exposed to the atmosphere.

• — 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.

• — 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.

• — 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.
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