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A Broader Viewpoint: Roger Pielke Sr. on the State of the Climate Change Debate

By Chip Knappenberger -- March 16, 2011

Recently, Roger Pielke Sr., Senior Research Associate at the University of Colorado-Boulder in the Department of Atmospheric and Oceanic Sciences (ATOC) at the University of Colorado Boulder, participated in the March 8, 2011 House of Representatives Energy and Commerce Committee Hearing, Climate Science and EPA’s Greenhouse Gas Regulation.

His succinct testimony, reprinted below, provides a viewpoint on climate change science that is (refreshingly) different from the somewhat limited one espoused by the IPCC. While the IPCC sports blinders that prevent it from seeing much beyond human emissions as being the primary culpable agent of climate change, Roger sees the much bigger, more complex, picture. And Roger suggests that a response considered for the big climate change picture would likely be much different from that being considered for human emissions alone.

(Other testimony from scientists and House members, including Q&A, can be found here.)


Testimony to the Subcommittee on Energy and Power entitled “Climate Science and EPA’s Greenhouse Gas Regulation”

Roger A. Pielke Sr.
University of Colorado at Boulder and Colorado State University
8 March 2011

I have worked throughout my career to improve environmental conditions, including air quality, by conducting research, teaching and also by providing scientifically rigorous information to policy makers. At the state level, I served two terms on the Colorado Air Quality Control Commission where we developed the oxygenated fuels program to reduce atmospheric CO emissions from vehicles, promulgated regulations to mandate strict controls on wood and coal burning in residential fireplaces and stoves, and on asbestos concentrations in the air.

Four Main Points

In my testimony today (and in more detail in my written testimony) I have four main points:

1. Research has shown that a focus on just carbon dioxide and a few other greenhouse gases as the dominant human influence on climate is too narrow, and misses other important human influences.(1)

2. The phrases “global warming” and “climate change” are not the same. Global warming is a subset of climate change.

3. The prediction (or projection) of regional weather, including extremes, decades into the future is far more difficult than commonly assumed. As well, the attribution of extreme events to a particular subset of climate forcings is scientifically incomplete, if the research ignores other relevant human and natural causes of extreme weather events.

4. The climate science assessments of the IPCC and CCSP, as well as the various statements issued by the AGU, AMS and NRC, are completed by a small subset of climate scientists who are often the same individuals in each case.

Models–Buyer Beware

The production of multi-decadal climate predictions of regional impacts, whose skill cannot be verified until decades from now, is not a robust scientific approach. Models themselves are hypotheses. The steps of hypothesis written with respect to climate predictions as

1. Make a Prediction

2. Quantitatively Compare the Prediction With Real World Observations [i.e. Test the Hypothesis]

3. Communicate The Assessment the Skill of the Prediction

There is no way to test hypotheses with the multi-decadal global climate model forecasts for decades from now as step 2, as a verification of the skill of these forecasts, is not possible until the decades pass.

Back to Basics: What is Global Warming/Climate Change?

There has also been a misunderstanding of the relationship between global warming and climate variability and longer term change.

Global Warming is typically defined as an increase in the global average surface temperature. A better metric is the global annual average heat content measured in Joules. Global warming involves the accumulation of heat in Joules within the components of the climate system. This accumulation is dominated by the heating and cooling within the upper layers of the oceans.

Climate Change is any multi-decadal or longer alteration in one or more physical, chemical and/or biological components of the climate system. Climate change includes, for example, changes in fauna and flora, snow cover, etc which persists for decades and longer. Climate variability can then be defined as changes which occur on shorter time periods.

With respect to climate change, in 2009 18 Fellows of the American Geophysical Union accepted an invitation to join me in a paper where we discussed three different mutually exclusive hypotheses with respect to the climate system:

Hypothesis 1: Human influence on climate variability and change is of minimal importance, and natural causes dominate climate variations and changes on all time scales. In coming decades, the human influence will continue to be minimal.

Hypothesis 2a: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and involve a diverse range of first- order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades.

Hypothesis 2b: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and are dominated by the emissions into the atmosphere of greenhouse gases, the most important of which is CO2. The adverse impact of these gases on regional and global climate constitutes the primary climate issue for the coming decades.

Hypothesis 2b is the IPCC perspective. In our EOS paper, we concluded that only Hypothesis 2a has not been refuted. Hypotheses 1 and 2b are inaccurate characterizations of the climate system.

In our 2009 paper we wrote

“In addition to greenhouse gas emissions, other first- order human climate forcings are important to understanding the future behavior of Earth’s climate.

These forcings are spatially heterogeneous and include the effect of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot) [Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]), and the role of changes in land use/land cover [e.g., Takata et al., 2009]. Among their effects is their role in altering atmospheric and ocean circulation features away from what they would be in the natural climate system [NRC, 2005].

As with CO2, the lengths of time that they affect the climate are estimated to be on multidecadal time scales and longer.”

We concluded that

“Therefore, the cost- benefit analyses regarding the mitigation of CO2 and other greenhouse gases need to be considered along with the other human climate forcings in a broader environmental context, as well as with respect to their role in the climate system”


“The evidence predominantly suggests that humans are significantly altering the global environment, and thus climate, in a variety of diverse ways beyond the effects of human emissions of greenhouse gases, including CO2. Unfortunately, the 2007 IPCC assessment did not sufficiently acknowledge the importance of these other human climate forcings in altering regional and global climate and their effects on predictability at the regional scale.”

A major conclusion indicated from these studies is that regional atmospheric and ocean circulation features produce extreme weather events, not a global annual average surface temperature anomaly. It is the multi-decadal change in the statistics of these circulation features, in response to natural and human forcings and feedbacks, which must be skillfully predicted. This level of predictive skill has not yet been achieved even in hindcasts of past decades.

Policymakers and the public rarely encounter this broader view of the climate system, in part due to the limited number of scientists who are leading climate assessments. As just one example, I present my experiences with the first CCSP report. My experience is documented in a public comment. In the executive summary of that report, I wrote:

“The process for completing the CCSP Report excluded valid scientific perspectives under the charge of the Committee. The Editor of the Report systematically excluded a range of views on the issue of understanding and reconciling lower atmospheric temperature trends.

Future assessment Committees need to appoint members with a diversity of views and who do not have a significant conflict of interest with respect to their own work. Such Committees should be chaired by individuals committed to the presentation of a diversity of perspectives and unwilling to engage in strong-arm tactics to enforce a narrow perspective. Any such committee should be charged with summarizing all relevant literature, even if inconvenient, or which presents a view not held by certain members of the Committee.”

Bottom-Up Approach Needed

I have proposed a new approach in the climate community based on a bottom-up, resource-based perspective.

There are five broad areas that we can use to define the need for this type of vulnerability assessment: water, food, energy, human health and ecosystem function. Each sector is critical to societal well-being. The vulnerability concept requires the determination of the major threats to these resources from extreme events including climate, but also from other social and environmental pressures. After these threats are identified for each resource, relative risks can be compared in order to shape the preferred mitigation/adaptation strategy.

(1) IPCC: Intergovernmental Panel on Climate Change; CCSP: U.S. Global Change Research Program; AGU: American Geophysical Union; AMS: American Meteorological Society; NRC: National Research Council

For more of Roger Pielke, Sr.’s views at MasterResource, see Towards Climate Science Pluralism–and Starting Over With Climate Policy and be sure to check out his excellent Climate Science website.)

One Comment for “A Broader Viewpoint: Roger Pielke Sr. on the State of the Climate Change Debate”

  1. Ronald Chappell  

    Your testimony seems rational and spot on. It represents the viewpoint of hundreds of experts and 10’s of thousands of informal reviewers of the literature. However as long as we permit the government to fund the AGW view with 10’s of billions of dollars, I fear that the sheer volume of noise generated by this largess will continue to drown out any possibility of a balanced discussion and view of the climate subject.
    Thank you for your continued efforts.


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