2009 Warmest Year on Record in Southern Hemisphere

Data just released from NASA indicates that 2009 was the hottest year on record in the Southern Hemisphere, and globally comes in for a "three way tie" as the second-warmest year in the instrumental record (with 2007 and 1998), as Reto Ruedo, co-author of the NASA report, told Joe Romm of Climate Progress last week.

Global land-ocean mean surface temperature

According to surface temperature analysis from the NASA Goddard Institute for Space Studies (GISS), the southern hemisphere was 0.88 degree Fahrenheit (0.49 Celsius) warmer in 2009 than for the baseline period (known as the "climatology" period) of 1951-1980. Global mean temperatures in 2009 were 1 degree F (0.57 C) warmer for the same period.

Despite persistent assertions that 1998 is the warmest year on record with "global cooling" occurring since then, 2005 holds the current top spot as warmest year on record according to GISS analysis. Further, the first decade of the 21st century was warmer the the 1990's and 0.54 degree C warmer than the 20th century average, according to recent research from the National Oceanic and Atmospheric Administration (NOAA) and the World Meteorological Organization (WMO) .

Solar minimum and trailing indicator of climate

Oceans warm more slowly and with less variability than on land, making the southern hemisphere - which is mostly water - a "trailing indicator" of climate change, says Ruedo. Globally, 2009 resulted in some of the warmest ocean surface temperatures on record. We are also now at the deepest solar minimum in nearly a century, according to NASA.

All indictions are that, in spite of the persistent reoccurrence of winter (which seems to confuse some folks), the trend continues toward warming, with anthropogenic forcings as the apparent primary cause.