NOAA released their 2010 State of the Climate report on Tuesday, in which they confirm their preliminary finding that 2010 has tied 2005 as the warmest year on record, when combining globally averaged land and ocean temperatures.
368 scientists in 45 countries compiled thousands of measurements to complete the 220-page report.
Says Thomas R. Karl, director of NOAA’s National Climatic Data Center in Asheville, N.C., “We tracked 41 climate indicators [and] the long term trend [shows] unequivocally the world continues to warm.”
It has now been a quarter-century since global temperatures were below the recorded average.
And, says Karl, our weather is changing.
"It is very likely that large-scale changes in climate, such as increased moisture in the atmosphere and warming temperatures, have influenced -- and will continue to influence -- many different types of extreme events, such as heavy rainfall, flooding, heat waves and droughts.”
Warmer temperatures increase the rate of evaporation over the oceans. Additional water vapor increases the likelihood of exceptionally heavy rains, such as those that displaced 20 million while flooding one-fifth of Pakistan in July 2010.
NOAA also found evidence of the amplification of the water cycle in ocean salinity, which was unusually high in areas of greater evaporation, and unusually low where heavy rains increased the freshwater content of the ocean.
Warm waters, melting ice
Despite the cooling influence of La Nina, the global average sea-surface temperature in 2010 was the third warmest on record. And NOAA reports that sea levels continue to rise, due to thermal expansion and melting land-based ice.
NOAA also says the Greenland ice sheet lost more mass in 2010 than during any of the last 10 years. The melt area was 8 percent higher than the previous record, set in 2007, and the rate of melting was the fastest on record. Climate scientists say that Greenland ice melt could lead to even greater changes, by disrupting the Meridional Overturning Circulation, or MOC.
According to NOAA, a slowdown has been detected in the MOC, but their report states that “substantial progress has been made on developing a coordinated observing system to begin to measure the MOC.”
Arctic sea ice also shrank in 2010, to the third smallest areal extent on record. Says Dr. Walt Meier of the National Sea Ice Data Center, “we’ve seen the changes in the Arctic essentially continuing and even accelerating in 2010.”
The glaciers of the world continue to recede as well, for the 20th consecutive year.
And though persistent stormy weather and other factors actually increased the sea ice in Antarctica to an all-time maximum in 2010, recent studies have shown that land-based Antarctic ice is decreasing.
But what about the winters?
NOAA also reported on the influence of major cyclical oceanic and atmospheric patterns, including El Nino, La Nina, and the North Atlantic Oscillation, or NAO. Record negative NAO values in 2010 were linked to major cold outbreaks, and some scientists say “there is strong observational evidence connecting Arctic sea ice decline with the increasing NAO trend” (Strong 2009).
In other words, warming may be causing colder winters in the US.
Such seeming contradictions illustrate the complexity of the science. Says Karl, “we’re continuing to closely track these indicators because it is quite clear that the climate of the past cannot be assumed to represent the climate of the future. These indicators are vital for understanding and making reliable projections of future climate.”
News Source: Weather.com
