A new study of global temperature change reports that Earth's surface has warmed at a rate of approximately 0.2°C (0.36°F) per decade during the past thirty years, pushing temperatures to their highest levels in the last 12000 years. The study (Hansen et al., 2006) also provides evidence that global warming of another 1°C could result in more significant climate change impacts, including rapid sea level rise, wide-spread biodiversity loss, and an increased intensity of El Niño events.
A research team led by Dr. James Hansen of the National Aeronautics and Space Administration Goddard Institute for Space Studies (NASA-GISS) utilized a global network of instrumental temperature records to analyze temperature trends during the last century.
Source: Hansen et al. 2006; NASA.
Their findings, reported in the September 26 issue of Proceedings of the National Academy of Sciences, show that recent anomalous warming is happening nearly worldwide, with the greatest warming occurring in polar regions.
While temperature anomalies have been greater over land than the oceans (due to the higher heat capacity of water), significant warming has occurred in the western Pacific. This warming has increased the equatorial temperature gradient and could potentially lead to strengthened El Niño events, which have caused severe regional droughts and floods and have had well-documented negative impacts on global fisheries and coral reefs.
Most importantly, comparisons with paleoclimate records indicate that further warming of 1°C will place global temperatures at a level higher than at any point during the past million years. A warming increase of 2-3°C would likely dramatically alter the planet as we know it; this temperature threshold has not been reached since the Middle Pliocene--3 million years ago--when sea level was 25-35 meters higher than today.
REFERENCE:
Hansen, J., Mki. Sato, R. Ruedy, K. Lo, D.W. Lea, and M. Medina-Elizade 2006. Global temperature change. Proc. Natl. Acad. Sci. 103, 14288-14293, doi:10.1073/pnas.0606291103.
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