From the Washington Post
The headline to this post may surprise many Washingtonians who are still thawing out from the cold and historically snowy winter. However, not only does a new NASA draft analysis predict that 2010 will likely set a new global temperature record, but it also projects that it is “virtually certain” that a new 12-month running mean global temperature record will occur sometime this year.
Wait a second, you may say. That doesn’t make sense, given the relentless cold thus far in 2010 (at least until the past two weeks), not only in Washington, but also throughout Europe and parts of Asia.
So, where is this forecast coming from?
First, as I detailed last week, the winter of 2009-2010 wasn’t actually very cold from a global perspective. In fact, according to NOAA, the past winter (Dec.-Feb.) was the fifth warmest on record on a global basis.
Second, NASA’s projection, which is in the form of a lengthy and technical paper that is publicly available here, is based on a combination of recent observations and historical evidence. Part of the projection rests on the continued presence of a moderate El Niño, which is a natural climate event characterized by unusually warm water in the equatorial Pacific Ocean. El Niño has long been known to boost average global temperatures by warming the ocean and atmosphere. The all-time record warm year of 1998 (depending on whose statistics you cite) was a year that featured a strong El Niño, for example.
On the other hand, La Niña, which is marked by anomalously cool waters in the equatorial tropical Pacific, can lead to cooler global temperatures.
NASA’s temperature projection is based in part on the knowledge that global surface temperatures tend to lag behind El Niño by about four months. Since El Niño has continued to remain at a moderate strength, and global average temperatures are already running significantly warmer than average, it follows that there is a window of another several months of extra warming within which to set a new record.
You can think of El Niño as adding another few logs on a preexisting fire. Only in this analogy, human activities such as the burning of fossil fuels are also adding their own kindling at the same time.