There needs to be recognition that there are three distinctly different viewpoints with respect to the extent that humans alter the climate system.
This subject is discussed in our paper
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. An edited version of this paper was published by AGU. Copyright (2009) American Geophysical Union.
I have listed the three viewpoints below:
- 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.
This is the “skeptics” viewpoint.
- 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.
This is the viewpoint that has been mostly ignored in the climate science/policy discussions.
- 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.
This is the 2007 IPCC viewpoint and, therefore, the focus of the 2009 Copenhagen Conference that starts next week.
As we discuss in our EOS paper, in our view, the first and third viewpoints presented above have been refuted. Thus the plans being made in Copenhagen will necessarily be inadequate to address the diversity of the climate issues that society and the environment face in the coming decades. What are needed is a multiple pronged approach to address the different types of natural and human climate forcings as articulated in one of my son’s posts (see) where he wrote
“As the community begins to realize these significant, multi-faceted and hideous complexities, it would not be a surprise to learn that a policy framework design 20 years ago is now somewhat out of step with current scientific understandings. The upshot is that as presently designed, international climate policy is both too complex and too simplistic. It is too simplistic because it is built upon a set of scientific perspectives on climate change that are increasingly seen as outdated and appropriate only for dealing with a narrow set of very important human influences — long-lived greenhouse gases. It is too complex because in trying to deal with added complexity it has become unwieldy and clearly impractical from the standpoint of not just implementation but the politics of even reaching an agreement about implementation.
Climate policy can be improved by reconstructing climate policy from the bottom up. This process should begin by recognizing that no single policy instrument will ever deal with “climate change” (human caused or otherwise). An approach to climate policy that is decentralized and more focused in its elements will be better able to adjust as science evolves (and it will continue to evolve, to be sure) and allows for progress to be made incrementally along a set of parallel paths. The all-or-nothing approach to climate policy that dominates the present agenda is incapable of keeping pace with evolving scientific understandings as they relate to policy implementation, and from a pragmatic perspective, pretty much guarantees the “nothing” outcome.”