Q & A Is The Human Addition Of Carbon Dioxide The Primary Human Climate Forcing?

Today, I am going to start a series of Q&A posts with respect to the climate issue. The first question is

 Is The Human Addition Of Carbon Dioxide The Primary Human Climate Forcing?

This is the focus of the Copenhagen meeting. The clear answer, based on a wide range of peer-reviewed papers is NO.

The human addition of carbon dioxide is an important climate forcing, as I have posted on previously (e.g. see) but it is not the only important forcing and does not appear to even be the most important (e.g. see our paper Matsui and Pielke, 2006 with respect to aerosols where the forcing of wind circulations from the heterogenous spatial distribution of human caused aerosols was around 6oX greater than that of the radiative effect of CO2).

As I wrote in the post

Is The Human Input Of CO2 A First Order Climate Forcing?

Thus, while I agree that the human addition of CO2 is a first order climate forcing, the claims that it is the primary human climate forcing is not supported by the science. This means that attempts to “control” the climate system, and to prevent a “dangerous intervention” into the climate system by humans that focuses just on CO2 and a few other greenhouse gases will necessarily be significantly incomplete, unless all of the other first order climate forcings are considered.

 Moreover, as I have written on extensively, climate change is much more than global warming and cooling (e.g. see  and see).  Human caused climate change can occur even in the absence of global warming (such as from land use change).  This makes attempts to mitigate climate change a much more daunting problem than assuming that all we need to do is control the human emissions of CO2 from fossil fuel combustion into the atmosphere.

Thus the Copenhagen COP15 meeting is only addressing a relatively small portion of the issue of how human climate forcings influences society and the environment.

Moreover, natural climate variability and change in the past, even without significant human intervention., has played a major role in society; e.g see

Meko, D., C. A. Woodhouse, C. A. Baisan, T. Knight, J. J. Lukas, M. K. Hughes, and M. W. Salzer (2007), Medieval drought in the upper Colorado River Basin, Geophys. Res. Lett., 34, L10705, doi:10.1029/2007GL029988


Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas, 2004: Nonlinearities, feedbacks and critical thresholds within the Earth’s climate system. Climatic Change, 65, 11-38.

We need a robust and effective set of comprehensive policies to address adaptation and mitigation to the entire spectrum of human- and natural- caused climate change and variability, such my son has proposed (e.g. see the end portion of the text in his post of October 30, 2009).  The Copenhagen COP15 completely fails in this requirement.

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