2010 Joint Warmest Year on Record; Most of 2000s in Top 10

NASA’s GISS Surface Temperature Analysis graph shown earlier (from 1800 to 2010) shows that temperature anomalies since 1980 have all been positive; i.e. it has been constantly hotter than normal.

As the same data shows, the hottest years have all been since 1998:

Global Top 10 Warmest Years (Jan-Dec)	Anomaly °C	Anomaly °F
Source: Annual State of the Climate Global Analysis, National Climatic Data Center, NOAA, December 2010
2010	0.62	1.12
2005	0.62	1.12
1998	0.60	1.08
2003	0.58	1.04
2002	0.58	1.04
2009	0.56	1.01
2006	0.56	1.01
2007	0.55	0.99
2004	0.54	0.97
2001	0.52	0.94

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO₂ has increased since the Industrial Revolution:

(Source: NOAA) via: Climate Change: How do we know? NASA, accessed October 27, 2009

The above covers hundreds of thousands of years and shows how atmospheric CO₂ levels have dramatically increased in recent years. If we “zoom” in on just the past 250 years, we see the following:

Global CO₂ emissions, 1751–2007, Carbon Dioxide Information Analysis Center (CDIAC), August 2010,DOI:10.3334/CDIAC/00001_V2010

NASA’s Goddard Institute of Space Studies (GISS) tracks atmospheric global temperature climate trends. As environmental engineer, D Kelly O’Day, writes on ProcessingTrends.com explains: “To facilitate assessments of long term trends, climatologists compare the mean for a base period with the annual mean. Differences between the annual mean and baseline mean are called anomalies. GISS uses the 1951 - 1980 period for their baseline period. They use the difference between the annual mean and the baseline mean to determine the global temperature anomaly for the year.”

O’Day produced a chart showing global temperature anomalies between 1800 and 2006 using data from NASA. I updated the chart he provided to include recently updated data up to 2010:

Sources: GISS Surface Temperature Analysis, NASA, accessed January 30, 2011; Global temperature, 1800-2006, ProcessTrends.com, accessed October 27, 2009

In the 1880 - 1935 period, the temperature anomaly was consistently negative. In contrast, the since 1980 the anomaly has been consistently positive. The 1917 temperature anomaly (-0.47oC) was the lowest year on record. Since 1917, global temperature has warmed, with the most recent years showing the highest anomalies of +0.6 oC in the past 120 years.