evidence: Climate scientists use models to simulate and study different aspects of Earth's climate system, and to project the rate of global warming caused by human activities. These models do, in fact, simulate the rate of global warming well, and models run in the past accurately projected the rate of warming we are currently experiencing—that includes model projections from 1988. [...] At the surface models predict a rate of warming of 0.2°C per decade since 1970, while NASA observes warming of around 0.18°C during the same period[…] Similarly, the observations from all the different groups that measure global surface temperatures are well within the envelope of model projections: [...] This RealClimate post analyzes a famous set of climate model projections presented in 1988 by NASA’s James Hansen. Comparing global temperature data to the model scenario with the greenhouse gas emissions closest to what actually happened since then shows that the model was accurate.