“If you have comments on this draft AMS Statements currently under
consideration, you may transmit those comments to the AMS Council by
sending a message to the following e-mail address by December 9 2006:
Below is my response which I am submitting to the AMS. I urge others that are AMS members to
submit their comments. If you do, you are invited to send them as comments to this weblog posting.
Comments By Roger A. Pielke Sr. on the draft AMS Statement on Climate Change
The American Meteorological Society is a well-respected professional
organization and I am honored to be a Fellow of this organization.
The AMS Draft Statement, however, is scientifically incomplete and misleading. Because
the statement is a draft the AMS will have ample opportunity to bring the
statement more in line with the existing peer-reviewed literature on
Here are three parts of the text, as examples, where the statement needs significant revision :
1. The statement says: “The most direct human impact is through changes in
the concentration of certain trace gases such as carbon dioxide,
chlorofluorocarbons, methane, nitrous oxide, ozone, and water vapor, known
collectively as greenhouse gases.”
Aerosols and land use/land cover change should be considered as a “direct”
human impact. They are discussed later in the Statement, but without
highlighting that their importance is comparable to the radiative effect
of CO2. Land use/land cover has been shown to be a first order human
climate forcing on the global scale even without altering the
global average surface temperature (http://blue.atmos.colostate.edu/publications/pdf/R-311.pdf).
The text in the Statement that says that with respect to changes in the
land surface, that the “net global effects are not expected to be large”
is contradicted by significant peer reviewed research. Similarly, with
respect to aerosols, the Statement ignores the finding that the spatial
gradient of diabatic heating (and thus the effect on weather patterns) due
to human caused aerosols is much larger than the spatial gradient of
diabatic heating due to the radiative effect of CO2 (http://blue.atmos.colostate.edu/publications/pdf/R-312.pdf).
Such oversights suggest that the statement is selective in its description
of climate science.
2. The statement says: “Carbon dioxide accounts for about half of the
greenhouse gas contribution to warming since the late 1800s, with
increases in the other greenhouse gases accounting for the rest…”
New evidence lowers the relative contribution of carbon dioxide with
respect to both its relative contribution of the greenhouse gases (with
methane being elevated in its relative importance), and with respect to
the total human global warming forcing. This is summarized at http://blue.atmos.colostate.edu/presentations/PPT-69.pdf
Again, the statement is selective in its summary of solid, peer-reviewed
3. “Climate models are essentially extensions of weather forecast models..”
This claim overlooks the findings in the 2005 National Research
Council Report “Radiative forcing of climate change: Expanding the concept
and addressing uncertainties.” [ http://www.nap.edu/openbook/0309095069/html/]
where it is stated that the climate system consists of the atmosphere,
oceans, land, and cryosphere (see Figure 1-1 in that Report). It is the
atmospheric portion of the climate models that are built using the weather
I reproduce a summary below of findings that have been reached on the weblog Climate Science (http://www.climatesci.org/main-conclusions/ ) which should be discussed in the AMS Statement. Based on the feedback that I have received on the weblog, a significant number of climate scientists agree with the conclusions listed below.
1. The needed focus for the study of climate change and variability is on the regional and local scales. Global and zonally-averaged climate metrics would only be important to the extent that they provide useful information on these space scales.
2. Global and zonally-averaged surface temperature trend assessments, besides having major difficulties in terms of how this metric is diagnosed and analyzed, do not provide significant information on climate change and variability on the regional and local scales.
3. Global warming is not equivalent to climate change. Significant, societally important climate change, due to both natural- and human- climate forcings, can occur without any global warming or cooling.
4. The spatial pattern of ocean heat content change is the appropriate metric to assess climate system heat changes including global warming.
5. In terms of climate change and variability on the regional and local scale, the IPCC Reports, the CCSP Report on surface and tropospheric temperature trends, and the U.S. National Assessment have overstated the role of the radiative effect of the anthropogenic increase of CO2 relative to the role of the diversity of other human climate forcing on global warming, and more generally, on climate variability and change.
6. Global and regional climate models have not demonstrated skill at predicting climate change and variability on multi-decadal time scales.
7. Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose.
8. A vulnerability paradigm, focused on regional and local societal and environmental resources of importance, is a more inclusive, useful, and scientifically robust framework to interact with policymakers, than is the focus on global multi-decadal climate predictions which are downscaled to the regional and local scales. The vulnerability paradigm permits the evaluation of the entire spectrum of risks associated with different social and environmental threats, including climate variability and change.
9. Humans are significantly altering the global climate, but in a variety of diverse ways beyond the radiative effect of carbon dioxide. The IPCC assessments have been too conservative in recognizing the importance of these human climate forcings as they alter regional and global climate. These assessments have also not communicated the inability of the models to accurately forecast the spread of possibilities of future climate. The forecasts, therefore, do not provide any skill in quantifying the impact of different mitigation strategies on the actual climate response.
I look forward to the response of the American Meteorological Society on my comments. I also look forward to the release of the names of the authors of the Statement.