Posted by: JeffMasters, 5:23 PM GMT on January 16, 2011

The year 2010 was tied with 2005 as Earth's warmest year in history, according to separate calculations performed by NASA and the National Oceanic and Atmospheric Administration (NOAA). Temperatures during 2010 were 1.12°F (0.62°C) above the 20th century average. Reliable global temperature records go back to 1880. NOAA reported that the Northern Hemisphere had its warmest year on record in 2010, the Southern Hemisphere its 6th warmest, land areas their 2nd warmest, and the oceans their 3rd warmest. Global satellite-measured temperatures of the lowest 8 km of the atmosphere during 2010 were virtually tied with 1998 for warmest on record, according to the University of Alabama Huntsville (UAH). The 1998 temperatures were 0.01°C warmer than 2010, but the difference is so small that the two years should be considered tied for first place. These measurements are very sensitive to the effect of major El Niño events that warm the waters and atmosphere over the Eastern Pacific. Thus the 1998 El Niño--the strongest such event ever recorded--set a global lower atmospheric temperature record that had been impossible to match until 2010.

Figure 1. Departure of temperature from average for 2010. Image credit: NOAA's National Climatic Data Center.

Earth's warmest temperatures in 2010, relative to average, occurred in western Greenland and eastern Canada, where record-duration sea ice loss contributed to temperatures that were 9°F (5°C) above average for the year (Figure 1.) The coolest temperatures, relative to average, were in central Siberia, 5.4°F (3°C) below average. In addition to being the warmest year on record globally, it was also the wettest (Figure 4.)

Figure 2. The latest rankings by NOAA of the hottest years globally since 1880. Earth's ten hottest years have all come since 1998, and the decade of the 2000s was by far the warmest decade in the historical record. Image credit: NOAA's National Climatic Data Center.

Figure 3. Global departure of temperature from average for 1880-2010, as computed by NASA.

Figure 4. Global departure of precipitation from average for 1900 - 2010. The year 2010 set a new record for wettest year in Earth's history. The difference in precipitation from average in 2010 was about 13% higher than that of the previous record wettest year, 1956. Image credit: NOAA's National Climatic Data Center.

A record warm year during a deep solar minimum: an unusual occurrence
The 2010 record warmth was unusual in that it occurred during a period when energy from the sun was at its lowest levels since satellite measurements began in the 1970s. The 11-year sunspot cycle causes a 0.1% variation in the amount of energy reaching the Earth. White et al. (1997) found that sea surface temperatures varied by about 0.04 - 0.07°C on time scales of 11 - 22 years due to this change in solar energy, with temperatures lagging the sunspot cycle by 1.5 - 3 years (because the ocean is slow to heat up and cool down in response.) So, although solar activity began to pick up somewhat in 2010, the 1.5 - 3 year lag in ocean temperature response meant that the record low solar activity of 2008 - 2009 was what affected global temperatures in 2010. Given that the departure of Earth's temperature from average during 2010 was 0.62°C, this difference would have been perhaps 10% greater had we been 2 - 3 years past the peak of the 11-year sunspot cycle. The previous global temperature record, set in 2005, occurred 3 - 5 years after the twin-peaked previous solar cycle. It is very difficult to get a record warm year during a deep solar minimum, making the 2010 record one likely to be broken later this decade as the sun begins to exert a greater warming influence on the planet.

Figure 5. During 2008 - 2009, the energy from the sun arriving at the top of Earth's atmosphere (Total Solar Irradiance, or TSI) as measured by satellites fell to its lowest value since satellite measurements began in 1978. Image credit: Physikalisch-Meteorologisches Observatorium Davos World Radiation Center.

References has an in-depth discussion of Solar activity & climate: is the sun causing global warming?

Wunderground climate change blogger Dr. Ricky Rood has a comprehensive 5-part series on how the sun affects climate.

Gray, L.J., J. Beer, M. Geller, J.D. Haigh, M. Lockwood, 2010, "Solar Influences on Climate", Accepted in Rev. Geophys, 2010.

White, W.B., J. Lean, D.R. Cayan and M.D. Dettinger (1997), Response of global upper ocean temperature to changing solar irradiance, J. Geophys. Res., 102, 3255-3266.

Thunderstorms hurl antimatter into space
NASA announced this week that mature thunderstorms can produce antimatter when exceptionally powerful lightning bolts occur. The antimattter beams were detected by the Fermi Gamma-ray Space Telescope. The amount of antimatter produced is tiny, though, and probably not enough to help power a starship.

"Cap'n, we're running low on antimatter to power the warp engines. Can you fly in low over those thunderstorms to replenish our reserves? We'll use the transporters to gather the antimatter and funnel it into the antimatter containment vessel."

"OK, Scotty!"