Observed changes in the climate system
Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.

Source: IPCC – Working Group 1 2013

(a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. Top panel: annual mean values, bottom panel: decadal mean values including the estimate of uncertainty for one dataset (black). Anomalies are relative to the mean of 1961−1990.

(b) Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends determined by linear regression from one dataset (orange line in panel a). Trends have been calculated where data availability permits a robust estimate (i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Grid boxes where the trend is significant at the 10% level are indicated by a + sign.


Anthropogenic Climate Change »Anthropogenic Climate Change
Is the Earth's climate changing? »Is the Earth's climate changing?
Warming of the climate system is unequivocal »Warming of the climate system is unequivocal
Observed changes in the climate system
Observed changes in carbon and other biogeochemical cycles »Observed changes in carbon and other biogeochemical cycles
Observed changes in the atmosphere »Observed changes in the atmosphere
Observed cryospheric changes »Observed cryospheric changes
Observed sea level changes »Observed sea level changes
Ocean warming »Ocean warming
Ocean faces multiple, interconnected threats »Ocean faces multiple, interconnected threats
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