Record warmth in 2010, despite cooling influences
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.
Furthermore, temperature readings from satellites also indicate that 2010 was an extremely warm year. The University of Alabama reported yesterday that, according to their satellite records, 2010 was just 0.1 degree Celsius cooler than 1998, which makes it the second-warmest year.
Remote Sensing Systems, which is another group that tracks temperatures via satellite, also ranked 2010 as the second-warmest year behind 1998.
NOAA reported that for the January to November period, the combined global land and ocean surface temperature was 1.15°F above the 20th century average, making this the warmest such period since records began in 1880.
Interestingly, according to NOAA, the warmth in the Northern Hemisphere was more noteworthy compared to that in the Southern Hemisphere. Northern Hemisphere land areas had the warmest November on record, whereas land areas in the Southern Hemisphere ranked as the 21st warmest. However, since more than two-thirds of the planet's land area is located in the Northern Hemisphere, the warmth in the north outweighed the relatively cool temperatures in the south.
This year saw some stunning all-time heat records fall worldwide - including 19 national extreme heat records (see graphic at top of post). These records, some of which are still awaiting official confirmation from the World Meteorological Organization, included a sizzling 128.3°F in Pakistan. This now stands as the new record high temperature for the entire sprawling continent of Asia.
According to meteorologist Jeff Masters of Weather Underground, as of Nov. 23, no country had set an all-time record cold temperature during 2010, although that may have changed in December given the extreme cold in parts of Europe.
There were several noteworthy heat waves during the summer in the U.S. and abroad. It was the hottest summer on record in Washington, D.C., Baltimore, New York City and 10 states - including Maryland, Virginia, Delaware and New Jersey. D.C. set a new record for most 90°F plus days in a year, with 67.
July in Washington became the hottest month of any month on record. Similar all-time records were established in July in Trenton and Atlantic City, N.J.
Warm temperature records outpaced cold ones
For a broader perspective on 2010 temperatures, it's helpful to examine the ratio of record high temperatures to record low temperatures. In a climate that is neither warming nor cooling, when the ratio is considered over a large region over several consecutive years, there should be on average about as many record highs as record lows, for close to a 1:1 ratio. However, a study published in 2009 showed that in recent years, over the U.S. as a whole, warm temperature records have been outpacing cold ones by a ratio of two to one - further evidence of an overall warming climate.
That trend has continued with the start of a new decade. According to figures compiled by Guy Walton of The Weather Channel using data from the National Climatic Data Center, there were 19,213 record daily high temperatures set in the U.S. during 2010, compared to 8,374 record daily lows. There were also 596 monthly record highs, compared to 156 monthly record lows, and 59 all-time record highs, compared to just two all-time record lows.
The domestic heat last summer was overshadowed by events in Western Russia, where Muscovites experienced an unprecedented heat wave, both in terms of the actual air temperatures (above 100°F) and the duration of the event (more than one month). Add to that toxic smoke from nearby wildfires, and the result was a story that dominated world headlines, as at least 15,000 people are believed to have perished in the event.
Scientists are investigating how human-caused climate changes affect the odds of events like the Russian heat wave, and the related heat and deadly flooding in Pakistan.
Cooling influences not so cool after all?
The record or near-record warm global average surface temperatures last year were rather surprising, given the coincidence of La Nina conditions and relatively low solar activity. La Nina is a phase of the El Nino-Southern Oscillation (ENSO), a natural cycle that affects sea surface temperatures and air pressure across the equatorial Pacific Ocean. During a La Nina, winds enhance upwelling along the west coast of South America, bringing cold ocean waters to the surface and cooling the overlying air. La Nina events, particularly moderate to strong ones such as the one currently underway, can dampen global average surface temperatures (in contrast to its sibling, El Nino, which is characterized by warmer-than-average sea surface temperatures and helps boost global temperatures).
In fact, according to NASA, November 2010 was the only "warmest month on record" to occur when La Nina conditions were present (h/t Jeff Masters).
Time will tell how natural climate variability, such as solar fluctuations and El Nino/La Nina events, will interact with the extra greenhouse gases in the air due to human activities. No one should expect global climate change to be monotonic, with each year warmer than the last. But 2010 should raise some eyebrows for its record warmth in the face of two influential cooling forces.
The views expressed here are the author's alone and do not represent any position of the Washington Post, its news staff or the Capital Weather Gang.
| January 4, 2011; 10:00 AM ET
Categories: Climate Change, Freedman, Latest, Local Climate, Science, Temperature Extremes
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