Global Temperature Record
The time series shows the combined global land and marine surface temperature record from 1850 to 2012. This year was the tenth warmest on record. This record uses the latest analysis, referred to as HadCRUT4 (Morice et al., 2012).
The period 2001-2010 (0.477°C above 1961-90 mean) was 0.217°C warmer than the 1991-2000 decade (0.270°C above the 1961-90 average). The warmest year of the entire series was 2010, with a temperature of 0.540°C above the 1961-90 mean. The value for this year, given uncertainties discussed in Morice et al. (2012) is not distinguishable from the years 1998 (0.523°C) and 2005 (0.534°C). The coldest year of the 21st century (2008 with a value of 0.383°C) was warmer than all years in the 20th century with the exception of 1998 and 1997 (0.390°C). The first two years of the present decade (2011 and 2012) are cooler than the average for 2001-2010, but warmer than all years before 2000 except for 1998.
This time series is compiled jointly by the Climatic Research Unit and the UK Met. Office Hadley Centre. Increased concentrations of greenhouse gases in the atmosphere due to human activities are most likely the underlying cause of warming in the 20th century. The warmth or coldness of individual years is strongly influenced by whether there was an El Niño or a La Niña event occurring in the equatorial Pacific Ocean.
Figure and text from Jones (2013).