Record Warmth in 2010, Despite Cooling Influences

(Originally published on Washington Post's Capital Weather Gang blog)

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No matter how you crunch the data, 2010 is certain to go down in history as one of the warmest — if not the warmest — years since the beginning of instrumental records in the late 19th century. This is despite the recent cold and snowy weather in much of the U.S. and across Europe.

All three widely-cited surface temperature datasets show that 2010 will most likely rank near the very top of the list - a remarkable feat considering that two factors that tend to cause cooler-than-average conditions were present for all or part of the year — a La Nina event and a “quiet” sun. Both of these sources of natural climate variability make it more difficult to set monthly and annual global average temperature records than during a period of high solar activity or an El Nino year.

The fact that 2010 turned out to be so warm despite these factors begs the question as to what role rising concentrations of greenhouse gases, especially carbon dioxide, had in this outcome. We know that they are playing an increasingly dominant role in many aspects of our changing climate system. However, the “signal” of manmade climate change is most evident when viewed over longer time periods, such as decades, as I discussed in a recent post. Detecting their influence in short-term events requires a much more complex approach that, as of now, lies at the cutting edge of climate science.

Both the National Oceanic and Atmospheric Administration (NOAA) and NASA have reported that January to November 2010 was the warmest such period on record. While their data closely matches one another, the two agencies use slightly different methods to calculate changes in global average surface temperatures. Data from a third group, based in the U.K., also depicts record warmth in 2010.


Read more at Washington Post's Capital Weather Gang blog