Picture Global average temperature 1856-1999
© UNEP

In the past:
Global mean surface temperature has increased by between about 0.3 and 0.6°C since the late 19th century, a change that is unlikely to be entirely natural in origin.

In the future:
The mean annual global surface temperature will increase by 1 - 3.5°C by 2100 (with a "best estimate" of 2°C).