(Global Temperature Anomaly November 2013. Image source: NASA)
The temperature records just keep on falling. Despite a somewhat cooler than average fall and early winter for most of the US, the world continued an inexorable warming trend by shattering a previous record high global average temperature for the month of November. According to NASA GISS, November 2013 was the hottest since record keeping began in 1880. At .77 degrees Celsius above the 1951-1980 average, November 2013 was .02 degrees Celsius hotter than November of 2010, the previous hottest November.
Almost all regions of the globe showed hotter than average temperatures. The two exceptions were West Antarctica and adjacent ocean regions and central and eastern North America. Temperatures in these regions ranged from .5 to 4.1 degrees Celsius below normal. The hottest regions of the world included Antarctica, the Pacific Ocean south of Alaska and Alaska, and a large swath including Russia and the adjacent Arctic regions. The Antarctic hot patch ranged from 1 to 4 degrees Celsius above normal and covered most of the continent. Large regions of Alaska and adjacent Pacific and Arctic Ocean environs also ranged from .5 to 4 degrees Celsius above average.
But the hottest zone included a massive section of Russia and the adjacent Arctic Ocean. There, a persistent high amplitude ridge in the Jet Stream drove much warmer than average temperatures far into the north, forcing temperatures into a range of 4-8 degrees Celsius above average over a massive region and driving a wedge of heat all the way to the North Pole. According to Dr. Jennifer Francis and Dr. Jeff Masters, such high amplitude Jet Stream waves are both primary drivers of extreme weather and a direct result of massive losses of sea ice occurring since 2007.
November 2013 Prime Example of Polar Amplification
More rapid warming at the poles, or polar amplification, has been implicated in an observed slowing of the Jet Stream that has become more and more pronounced in recent years, resulting in both record heat waves and droughts as well extreme rain events. Observed temperatures showed a classic and pronounced amplification at the poles with northern hemisphere showing the most pronounced amplification. It is worth noting that the southern hemisphere is not expected to amplify as rapidly as the southern ocean acts as an enormous heat sink.
(Zonal Temperature Anomalies for November 2013. Image source: NASA)
Observed CO2 and methane readings during the period were also very high over the Arctic and Northern Russia with numerous spikes in the range of 1900 to 2200 ppb methane and CO2 levels rising above 400 ppm for much of the Arctic region by late November. Though likely contributing to Arctic amplification, these values alone were not enough to account for the very high temperatures observed in Russia during the period which, as noted above, coincided with a ridge blocking pattern in the northern hemisphere Jet Stream. Anomalous heat in Alaska also coincided with a powerful ridge that has persisted over the region for much of this year.
These record hot conditions are exceptional, especially when one considers that ENSO remains in a neutral state. Such conditions do not bode well for the next El Nino year, when it does emerge.
Hat Tip to Colorado Bob