Hansen et al. 2013
, , and , 2013: Climate forcing growth rates: Doubling down on our Faustian bargain. Environ. Res. Lett., 8, 011006, doi:10.1088/1748-9326/8/1/011006.
This is a Perspective for the article "Comparing climate projections to observations up to 2011" by Rahmstorf et al., 2012, Environ. Res. Lett., 7, 044035.
Rahmstorf et al's conclusion that observed climate change is comparable to projections, and in some cases exceeds projections, allows further inferences if we can quantify changing climate forcings and compare those with projections. The largest climate forcing is caused by well-mixed long-lived greenhouse gases. Here we illustrate trends of these gases and their climate forcings, and we discuss implications. We focus on quantities that are accurately measured, and we include comparison with fixed scenarios, which helps reduce common misimpressions about how climate forcings are changing.