Monthly Archives: August 2007

Advocacy In The Guise Of Climate Science – A New Paper That Exemplifies This Approach

There is a new paper that presents a claim that the Earth’s climate system is dominated by positive radiative feedbacks, and that includes the heading in section of the paper “Planet Earth today: imminent peril”. This sensationalism, however, in the view of Climate Science, is unsubstantiated by examining even the most basic of measures, where if the 2007 values of the IPCC radiative forcing are accepted, and the observed ocean heat storage data is used to diagnose what has been the sum total of real world radiative forcings and feedbacks in the last few decades, the climate feedbacks have been negative (as is discussed below)! This contradicts the fundamental premise of the paper

Hansen, J., M. Sato, P. Kharecha G. Russell, D. W. Lea, M. Siddall, 2007: Climate change and trace gases; Phil. Trans. R. Soc. A (2007) 365, 1925–1954 doi:10.1098/rsta.2007.2052 Published online 18 May 2007.

The abstract reads,

“Palaeoclimate data show that the Earth’s climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the ‘albedo flip’ property of ice/water, provides a powerful trigger mechanism. A climate forcing that ‘flips’ the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent
greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the third largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon (‘black soot’) has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice,
while also having major benefits for human health, agricultural productivity and the global environment.”

One statement in the conclusion reads,

“Earth’s climate is remarkably sensitive to forcings, i.e. imposed changes of the planet’s energy balance. Both fast and slow feedbacks turn out to be predominately positive. As a result, our climate has the potential for large rapid fluctuations. Indeed, the Earth, and the creatures struggling to exist on the planet, have been repeatedly whipsawed between climate states.”

This is obviously an erroneous statement! If all of the feedbacks were predominately positive, the climate would long ago evolved to a a very extreme state. This clearly has not occurred, and such statements in this article are unsubstantiated scientifically in the paper, and, even more importantly, fail to represented the dynamics of the current climate system, where, as has been summarized on Climate Science, the net effect of all of the feedbacks, assuming the 2007 IPCC estimate of climate forcings is correct, is negative!

That the feedbacks must be negative in recent years (or the 2007 IPCC net forcing is in error) is discussed in

The Net Climate Feedbacks Must Be A Negative Effect On The Global Average Radiative Imbalance If The IPCC Conclusion Of Net Anthropogenic Radiative Forcings Is Correct.

Just two excerpts from the paper are needed to recognize what the Hansen et al paper is all about, i.e.

“The Arctic epitomizes the global climate situation. The most rapid feasible slowdown of CO2 emissions, coupled with focused reductions of other forcings, may just have a chance of avoiding disastrous climate change.”


“The potential of these ‘amber waves of grain’ and coastal facilities for permanent underground storage ‘from sea to shining sea’ to help restore America’s technical prowess, moral authority and prestige, for the sake of our children and grandchildren, in the course of helping to solve the climate problem, has not escaped our attention.”

This paper is clearly an advocacy article using the guise of cherrypicked science to promote a particular political and policy agenda. It very much fits into the definition of “stealth issue advocacy” as discussed in

Pielke, R. A. Jr., 2007: The Honest Broker: Making Sense of Science in Policy and Politics
Roger A., Jr. University of Colorado, Boulder

The Hansen et al paper is clearly not an example of serving as an honest broker of climate science.

Hansen et al, of course, are correct that the climate system is nonlinear and sudden transitions on a variety of space and time scales do occur, as we discussed in

Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas, 2004: Nonlinearities, feedbacks and critical thresholds within the Earth’s climate system. Climatic Change, 65, 11-38.

The Hansen et al article, however oversimplifies the climate system as being dominated by the radiative effect of human added CO2. Such a perturbation, of course, just as easily could move us away from undesirable climate transitions, instead of toward such transitions. Prudence suggests that we work to minimize our disturbance of the climate system since we do not understand the climate system well enough.

However, to focus on just a small subset of forcings is seriously misleading policymakers on the most effective way to deal with our social and environmental vulnerability from the entire spectrum of the actual environmental risks and other threats that we face.

Leave a comment

Filed under Climate Science Misconceptions, Climate Science Reporting

Deferred Forecasts Of Global Warming – An Example Of The Misuse of Science

A blatant example of masking an untested hypothesis as a scientific paper has been published in Science. The paper is

“Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Modelâ€? Doug M. Smith, Stephen Cusack, Andrew W. Colman, Chris K. Folland, Glen R. Harris, and James M. Murphy (10 August 2007) Science 317 (5839), 796. [DOI: 10.1126/science.1139540].

The abstract reads,

“Previous climate model projections of climate change accounted for external forcing from natural and anthropogenic sources but did not attempt to predict internally generated natural variability. We present a new modeling system that predicts both internal variability and externally forced changes and hence forecasts surface temperature with substantially improved skill throughout a decade, both globally and in many regions. Our system predicts that internal variability will partially offset the anthropogenic global warming signal for the next few years. However, climate will continue to warm, with at least half of the years after 2009 predicted to exceed the warmest year currently on record.â€?

The August 9, 2007 Reuters reports on this article by writing

“Global warming is forecast to set in with a vengeance after 2009, with at least half of the five following years expected to be hotter than 1998, the warmest year on record, scientists reported on Thursday.

Climate experts have long predicted a general warming trend over the 21st century spurred by the greenhouse effect, but this new study gets more specific about what is likely to happen in the decade that started in 2005….

The real heat will start after 2009, they said.”

This is a very convenient and clearly contrived presentation to defer the expectation that significant global warming will occur for a few years, so that the particular policy actions (on energy policy as concluded on Climate Science; e.g. see) can occur.

The UK Met Office had a press release on this paper on August 10, 2007 titled

“The forecast for 2014…”

They write in this press release,

“These predictions are very relevant to businesses and policy-makers who will be able to respond to short-term climate change when making decisions today. The next decade is within many people’s understanding and brings home the reality of a changing climate.”

However, no one has shown any predictive skill on this time scale! That Science published this article speaks more for their use of this forum for advocacy, rather than as a science paper. Policymakers are bing misled if they accept that this prediction is skillful.

Climate Science has presented documentation on the inability of the multi-decadal global models to make skillful predictions (e.g. see and see, as just two examples).

Readers of paper such as Smith et al should recognize that the publication of climate process studies as predictions is misleading. Such predictions are just hypotheses, which can be tested only after the time period has passed.

Leave a comment

Filed under Climate Science Misconceptions, Climate Science Op-Eds, Climate Science Reporting

More On Another Climate Forcing Effect – Ozone

There is a paper in Nature which discusses an effect of increased ozone on the carbon assimilation and release into the atmosphere. The paper is

S. Sitch, P. M. Cox, W. J. Collins and C. Huntingford, 2007: Indirect radiative forcing of climate change through ozone effects on the land-carbon sink, Nature 448, 791-794 (16 August 2007) | doi:10.1038/nature06059; Received 9 September 2006; Accepted 3 July 2007; Published online 25 July 2007

The abstract reads,

“The evolution of the Earth’s climate over the twenty-first century depends on the rate at which anthropogenic carbon dioxide emissions are removed from the atmosphere by the ocean and land carbon cycles. Coupled climate–carbon cycle models suggest that global warming will act to limit the land-carbon sink, but these first generation models neglected the impacts of changing atmospheric chemistry. Emissions associated with fossil fuel and biomass burning have acted to approximately double the global mean tropospheric ozone concentration, and further increases are expected over the twenty-first century. Tropospheric ozone is known to damage plants, reducing plant primary productivity and crop yields, yet increasing atmospheric carbon dioxide concentrations are thought to stimulate plant primary productivity. Increased carbon dioxide and ozone levels can both lead to stomatal closure, which reduces the uptake of either gas, and in turn limits the damaging effect of ozone and the carbon dioxide fertilization of photosynthesis6. Here we estimate the impact of projected changes in ozone levels on the land-carbon sink, using a global land carbon cycle model modified to include the effect of ozone deposition on photosynthesis and to account for interactions between ozone and carbon dioxide through stomatal closure. For a range of sensitivity parameters based on manipulative field experiments, we find a significant suppression of the global land-carbon sink as increases in ozone concentrations affect plant productivity. In consequence, more carbon dioxide accumulates in the atmosphere. We suggest that the resulting indirect radiative forcing by ozone effects on plants could contribute more to global warming than the direct radiative forcing due to tropospheric ozone increases.”

This paper clearly identifies a new interaction among the components of the climate system.

The paper, however, neglects to also discuss the role of added ozone in altering the surface energy budget, as reduced carbon assimilation will also result in changes in the surface albedo (due to less green plant material) and in the portioning of net radiation between sensible and latent heat fluxes. Since vegetation is geographically heterogeneous, the role of the ozone in altering regional patterns of diabatic heating may be at least as large as its effect on the global average radiative forcing effect due to altering the atmospheric concentrations of CO2!

Leave a comment

Filed under Climate Change Forcings & Feedbacks

A Summary Of “Causes Of Land-use And Land-cover Change By Eric Lambin and Helmut J. Geist

A summary article by Eric Lambin and Helmut J. Geist entitled “Causes of land-use and land-cover change” succinctly summarizes the reasons for land-use and land-cover change [thanks to Jason English for alerting us to this!].

The Introduction reads,

“Identifying the causes of land-use change requires understanding both how people make land-use decisions (decision-making processes) and how specific environmental and social factors interact to influence these decisions (decision-making context). It is also critical to understand that land use decisions are made and influenced by environmental and social factors across a wide range of spatial scales, from household level decisions that influence local land use practices, to policies and economic forces that can alter land use regionally and even globally.”

They do not discuss the role of these changes within the climate system, however, their article provides an excellent summary of how humans are altering this climate forcing.

Leave a comment

Filed under Climate Change Forcings & Feedbacks

New Paper On The Role Of Landscape Degradation And Resultant Dust On The Climate System

There is an interesting paper on the role of dust within the climate system that may also be relevant for the record loss of Arctic sea ice in recent years. It is

Painter T. H., A. P. Barrett, C. C. Landry, J. C. Neff, M. P. Cassidy, C. R. Lawrence, K. E. McBride, G. L. Farmer (2007), Impact of disturbed desert soils on duration of mountain snow cover, Geophys. Res. Lett., 34, L12502, doi:10.1029/2007GL030284.

The abstract is

“Snow cover duration in a seasonally snow covered mountain range (San Juan Mountains, USA) was found to be shortened by 18 to 35 days during ablation through surface shortwave radiative forcing by deposition of disturbed desert dust. Frequency of dust deposition and radiative forcing doubled when the Colorado Plateau, the dust source region, experienced intense drought (8 events and 39–59 Watts per square meter in 2006) versus a year with near normal precipitation (4 events and 17–34 Watts per square meter in 2005). It is likely that the current duration of snow cover and surface radiation budget represent a dramatic change from those before the widespread soil disturbance of the western US in the late 1800s that resulted in enhanced dust emission. Moreover, the projected increases in drought intensity and frequency and associated increases in dust emission from the desert southwest US may further reduce snow cover duration.”

The discussion includes the text,

” Expansion and intensification of grazing, recreational use and agriculture over the past ~140 years has increased the dust emission from the Colorado Plateau and other desert regions of the western US [Belnap and Gillette, 1997; Neff et al., 2005; Reynolds et al., 2001]. Therefore it is likely that the above changes in snow cover duration and surface radiative forcing increased significantly with human activity in the late-1800s, as desert surface crusts were disturbed and dust was more freely emitted to the Rocky Mountains and other mountain ranges of the western US that are downwind of disturbed soils. Analyses similar to those performed for the San Juan Mountains and an analysis of time series of dust deposition from mountain lake sediments across the western US will provide a clearer understanding of the spatial and temporal extent of this shortening of snow cover duration.

The phenomenon of increasing dust emission exists beyond the western US and is global in nature with the potential to continue to perturb resource-critical mountain snowmelt systems. Dust emission frequency in China from the Taklimakan and Gobi deserts (proximal to the Tien Shan and Altai ranges) has increased from one event in ~35 years for the period AD85-1949 to annual since 1990 [Liu and Diamond, 2005]. A four-fold increase in dust deposition over the previous two centuries was found in the Dasuopu glacier ice core at elevation 7200 m in Tibet [Thompson et al., 2000], with the continuum increase attributed to increased land usage whereas the interannual variability attributed to interannual changes in precipitation. The drying of the Aral Sea has affected enormous increases in dust emission that frequently deposits in the Tien Shan, Pamir, Himalaya, and Altai Mountains [Waltham and Sholji, 2001]. Dust deposition to the Antarctic Peninsula has doubled in the 20th Century due to the coupled effects of changing climate and land degradation”

The article continues with assuming that droughts will become worse with “global warming”, which, as Climate Science has discussed (e.g. see), has not been shown to be a robust prediction. Nonetheless, the paper does show that even without “global warming” the human intervention in landscape management (deliberate and inadvertent) has major consequences in altering the climate system on the global scale.

Leave a comment

Filed under Climate Change Forcings & Feedbacks

Climate Science Is Retiring – Thank You To Everyone For Your Participation!

I want to thank everyone who has contributed to the diverse subjects on Climate Science! The site has been active since July 2005. However, the maintenance and preparation for the weblog requires quite a bit of time, and I have decided to move onto other activities. I have also extensively presented my perspective on climate science. The weblog will remain available as an archive on our research website.

After the remaining weblogs have posted (on September 2), the last weblog will identify where the archive can be found. Comments, of course, will not be accepted after that time, but the entire history of the weblog will be available for those who are interested.

Leave a comment

Filed under Uncategorized

Further Analysis Of Radiative Forcing By Norm Woods

In the book

Cotton, W.R. and R.A. Pielke, 2007: Human impacts on weather and climate, Cambridge University Press, 330 pp,

we presented results by Norm Woods (who works with Graeme Stephens) on the magnitude of radiative forcing for three types of vertical temperature and moisture soundings (tropical; winter subarctic and summer subarctic). Climate Science has summarized this study in the past (e.g., see the May 5th blog entitled Relative Roles of CO2 and Water Vapor in Radiative Forcing).

This weblog presents further analyses of these soundings by Norm Woods.

The total forcings are evaluated as the increase in flux convergence at the tropopause, and also divided these into the atmospheric and surface portions. As before, these results are for a change from 280 to 560 ppmv of CO2 [Norm presented this values with the same precision as the model output to show that they balanced].

Among the interesting results that he found is that the subarctic winter has the weakest total forcing, but the greatest surface forcing.

These results illustrate why presenting a single number of radiative forcing as a metric of climate change (such as given in Figure SPM.2 in the 2007 WG1 Statement for Policymakers of the IPCC) is a poor way to assess how the radiative forcing of CO2 and water vapor actually affect weather and other aspects of the climate system. Both the regional and vertical forcing vary geographically and with season, and obviously a global average top of the atmosphere radiative forcing does not capture this important heterogeneity in the climate forcings (also see).

Leave a comment

Filed under Books, Climate Change Forcings & Feedbacks, Climate Change Metrics