•extremely unlikely without external forcing
•very unlikely due to known natural
causes alone
Observed widespread warming
Global
ocean
1955
2005
1980
AnnualTrend 1979
to 2005
Surface
Troposphere
The
spatial pattern of observed temperature change shown on the left panel
indicates widespread warming. We also have evidence that the lower
troposphere warmed (right, shown from the late 70ies on), and that the global
ocean gained heat since the mid 20th century.
This
strengthens our confidence that variability generated within the climate
system cannot explain these changes.