What drives climate change?

Actually, what IS climate change, again?

From page 7 of the leaked Summary for Policymakers from the IPCC WGI Fifth Assessment Report comes this statement about CO2 “driving” climate change (emphasis added):

Natural and anthropogenic drivers cause imbalances in the Earth’s energy budget. The strongest anthropogenic drivers are changes in greenhouse gas concentrations and aerosols. These can now be quantified in more detail, but the uncertainties of the forcing associated with aerosols remain high.

Globally, CO2 is the strongest driver of climate change compared to other changes in the atmospheric composition, and changes in surface conditions. Its relative contribution has further increased since the 1980s and by far outweighs the contributions from natural drivers. CO2 concentrations and rates of increase are unprecedented in the last 800,000 years and at least 20,000 years, respectively. Other drivers also influence climate on global and particularly regional scales.

It’s a mere fragment of grit from a mountain of a report, but still curious enough because it raises the definition of the problem, and statements about climate change have no clearer meaning just because we stopped questioning it. Continue Reading →