Roger A. Pielke Sr.’s Perspective On The Role Of Humans In Climate Change

There continues to be misunderstandings on my viewpoint on the role of humans within the climate system. This weblog is written to make sure it is clear, and can be used whenever someone asks the question as to where does Pielke Sr. stand on this issue.

 As I have written in the Main Conclusions of Climate Science

“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.”

and that

“Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose.”

These conclusions are different from those who claim that the global average radiative effect of carbon dioxide is by far the major human climate forcing, as well as from those who conclude that natural climate variations dominate climate change and that the human climate forcings are inconsequential.

My viewpoint is also well articulated in

National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp

and you are encouraged to read the Executive Summary of that report [a report which whas been ignored by the media despite its broad base of authorship and its extensive review before it was published].

The reason that those who focus on the global average radiative forcing of carbon dioxide are missing the bulk of human climate forcings include the following:

1. Atmosphere and ocean circulations respond to regional forcings not a global average (e.g., see and see)

2. The other human climate forcings include

  • the diverse influence of human-caused aerosols on regional (and global)  radiative heating (e.g., see).
  • the effect of aerosols on cloud and precipitation processes (e.g., see)
  • the influence of aerosol deposition on climate (e.g., see and see)
  • the effect of land cover/land use on climate (e.g., see and  see)
  • the biogeochemical effect of added atmosopheric CO2 has a greater effect on the climate system than the radiative effect of added CO2 (e.g. see).

Natural climate variations and change, have also been underestimated (and are only poorly understood) based on examination of the historical and paleo-climate record (e.g., see and see).

Human climate forcings have a more significant role in altering the weather than does a global average increase in the radiative effect of an increase in the atmospheric concentration of CO2.  This does not mean that we should not work to limit the increase of this gas in the atmosphere, but it is not the dominant climate forcing that affects society and the environment.

Policies that focus on CO2 by itself are ignoring definitive research results (such as reported in the 2005 National Research Council report) that humans have a much broader influence on the climate system than was communicated in the 2007 IPCC report.  To neglect these other climate forcings represents a failure by policymakers (and the media) to utilize this scientifically robust information.

The neglect of including the diversity of human climate forcings indicates that the real objective of those promoting the radiative effect of the addition of atmospheric CO2 as the dominant human climate forcing is to promote energy and lifestyle changes. Their actual goal is not to develop effective climate policies. 

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