The National Oceanic and Atmospheric Administration has just released its global temperature calculations and has concluded that 2013 is the fourth hottest year on record since 1880. From NOAA:
The year 2013 tied with 2003 as the fourth warmest year globally since records began in 1880. The annually-averaged temperature across global land and ocean surfaces was 0.62°C (1.12°F) above the 20th century average and marks the 37th consecutive year (since 1976) that the annual temperature was above the long-term average. Currently, the warmest year on record is 2010, which was 0.66°C (1.19°F) above average. To date, including 2013, 9 of the 10 warmest years on record have occured during the 21st century. Only one year during the 20th century—1998—was warmer than 2013. The global annual temperature has increased at an average rate of 0.06°C (0.11°F) per decade since 1880 and at an average rate of 0.16°C (0.28°F) per decade since 1970.
NASA calculates global average temperature differently. As the Associated Press reported, NASA…
…ranked last year as the seventh warmest on record, with an average temperature of 58.3 degrees (14.6 Celsius). The difference is related to how the two agencies calculate temperatures in the Arctic and other remote places and is based on differences that are in the hundredths of a degree, scientists said.
Both agencies said nine of the 10th warmest years on record have happened in the 21st century. The hottest year was 2010, according to NOAA.
According to the satellite temperature data from University of Alabama in Huntsville climatologists John Christy and Roy Spencer, 2013 was the fourth warmest year since that data began being collected in 1979.
NOAA notes that the global average temperatures increased at rate of 0.16 degrees C per decade from 1970 until 2013. However, its own data shows that the per decade rate of increase since 1998 until now is 0.04 degrees C, i.e., one-fourth the rate since 1970 and about one-fifth the 0.21 degrees C per decade average rate predicted by computer climate models.
What is causing this recent "hiatus" in warming is hotly contested. On the one hand, some argue that the "missing" heat is hiding in the deep ocean, and on the other hand, some assert the computer climate models' climate sensitivity to extra atmospheric carbon dioxide is way too high. More data needed.