Even with a strong La Niña (see figure 2 below) and a slow exit from a deep solar minimum (see figure 3 below), the globally averaged temperature tied for the 4th warmest April on record, according to NASA’s GISS. At 0.55°C above the 1951-1980 average, April 2011’s warmth trails only 2005, 2007, and 2010. It tied with 2002 and just beat 1998. It is worth noting that in 2010 and 1998, strong El Niños were occurring. Such is the state of the climate having been forced by our species’ greenhouse gas pollution. April’s 0.55°C anomaly follows March’s 0.57°C anomaly.
The location of warm and cool temperature anomalies across the globe has shifted somewhat from the patterns observed in 2010, as the first figure below shows. While cooler than normal temperatures have occurred over the Canadian Arctic, the Eurasian Arctic remains much warmer than normal. The broad stretch of below average temperatures across the central-eastern Pacific are the remnants of the waning La Niña. Within 3-6 months, I expect to see more areas impacted by above average temperatures as the effects of La Niña go away. And unless a major volcano event occurs within the next two years, I expect that 2012 will challenge 2010 for the warmest year on record.
Figure 1 – NASA GISS‘s plots of temperature anomaly for April 2011 (top-left), Feb.-Apr. 2011 (top-right), May 2010-Apr. 2011 (bottom-left) and the GISS 12-month running mean time series dating back to 1880. The retreat from 2010’s record warmth can be seen by the latest 5 data points.
Figure 2 – Australia’s BOM time series of sea surface temperatures in the Nino3.4 region. The anomalously cool temperatures from Jul 2010 through March 2011 are indicative of La Niña conditions.
Figure 3 – Physikalisch Meteorologisches Observatorium Davos, World Radiation Center‘s time series of solar irradiance through early 2011. The extended “tail” to the right of the last solar peak in 2001 represents a deep, long-lived solar minimum. Some of the Earth’s warmest annual global temperatures were recorded during this time period, which ends the silly argument that the sun alone is responsible for the warming observed on Earth.
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