There is a new paper in the Proceedings of the National Academy. It is
Susan Solomon, Gian-Kasper Plattner, Reto Knutti, and Pierre Friedlingstein, 2009: “Irreversible climate change due to carbon dioxide emissions“. http://www.pnas.org cgi.doi10.1073pnas.0812721106.
This paper has a number of issues with its scientific robustness, however, this weblog will focus on just one. It is the continued inappropriately too narrow view of how humans are altering the climate system.
The abstract includes the text
“The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop.
Suppose another paper wrote
“The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to LAND USE CHANGE FROM HUMAN LAND MANAGEMENT is largely irreversible for 1,000 years after MANAGEMENT stops.”
[Note: Land use change is clearly a major issue in coming decades; e.g. see Feddema et al. 2005: The importance of land-cover change in simulating future climates, 310, 1674-1678; with its impacts on the landscape extending far into the future].
“The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to NITROGEN DEPOSITION is largely irreversible for 1,000 years after EMISSIONS OF NITROGEN COMPOUNDS INTO THE ATMOSPHERE , AND SUBSEQUENT DEPOSITION INTO THE OCEANS, AS WELL AS RUNOFF OF NITROGEN COMPOUNDS INTO THE OCEANS stop.”
[Note: Nitrogen deposition is clearly a major issue in coming decades; e.g. see Lamarque J.-F., et al. (2005), Assessing future nitrogen deposition and carbon cycle feedback using a multimodel approach: Analysis of nitrogen deposition, J. Geophys. Res., 110, D19303, doi: 10.1029/2005JD005825; with its impacts continuing far into the future.
The Solomon et al paper continues to erroneously perpetuate the narrow perspective that climate change is dominated by the human input of carbon dioxide and other well-mixed greenhouse gases.
The Solomon et al paper perpetuates the view that
The human influence is dominated by the emissions into the atmosphere of greenhouse gases, particularly carbon dioxide.
This hypothesis, however, has been clearly rejected as reported, for example, in my House testimony
“A Broader View of the Role of Humans in the Climate System is Required In the Assessment of Costs and Benefits Effective Climate Policy”
The hypothesis that has not been rejected is
The human influence on climate is significant and involves a diverse range of first-order climate forcings, including, but not limited to the human input of CO2,
which is supported by the 2005 NRC Report
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.
Even if Solomon et al were correct on the long time period of effect of the radiative effect of CO2, they fail in their paper by not discussing all of the long term human disturbances of the climate system. What Solomon et al are doing is selecting just one human disturbance to highlight. They fail, however to recognize and communicate to policymakers and the public that the accumulation of carbon dioxide in the atmosphere is just one symptom of a wide diversity of human influences on the climate system. By myopically focusing on just one symptom, they are misleading everyone in terms of what policy actions will have real effects on how humans are altering climate.