Figure 6.23
Projections of carbon dioxide concentrations and surface temperatures by 2100. (A) Projections of atmospheric CO2 concentrations by 2100 range from 550 ppm to 900 ppm. This wide range of values results from uncertainties regarding future rates of anthropogenic CO2 emissions. (B) These four modeled emissions scenarios range from “low growth,” in which the rate of anthropogenic CO2 emissions grows slowly, to “high growth,” in which anthropogenic emissions increase greatly. The “no growth” scenario shows the warming that would result if anthropogenic CO2 emissions were completely stopped as of 2007. Some warming would continue to happen due to lags in the climate system. (C) IPCC temperature forecasts for North America by the 2090s under the two different emissions growth scenarios (low and high). Darker reds indicate warmer temperatures.(C. Adapted from from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Figure SPM.5.)