Global temperature changes, 1850-2000. Animated graph showing the trend in global surface temperature changes between the years 1850 and 2000. The graph shows both the observed temperature change (red line) and the changes as predicted by a climate change simulation (green line). This simulation only models changes due to variations in solar activity and the effect of volcanic eruptions. The observations diverge from the model from 1960 onwards, with a temperature change increase of around 1 degree Celsius. The divergence is due to not including the effect of human activity such as fossil fuel consumption and deforestation. For a graph showing a model that accounts for human activity, see clip K005/6415. This demonstrates how the rise in temperature is thought to be due to human activities (anthropogenic global warming).