Based on comprehensive data from multiple sources, the report defines 10 measurable planet-wide features used to gauge global temperature changes. The relative movement of each of these indicators proves consistent with a warming world. Seven indicators are rising: air temperature over land, sea-surface temperature, air temperature over oceans, sea level, ocean heat, humidity and tropospheric temperature in the “active-weather” layer of the atmosphere closest to the Earth’s surface. Three indicators are declining: Arctic sea ice, glaciers and spring snow cover in the Northern hemisphere....According to the report, the years 2000-2009 stand as the warmest decade on record. The full State of the Climate in 2009 report is available as a pdf and is accompanied by a site where you can examine the data behind the report.
The report emphasizes that human society has developed for thousands of years under one climatic state, and now a new set of climatic conditions are taking shape. These conditions are consistently warmer, and some areas are likely to see more extreme events like severe drought, torrential rain and violent storms....
While year-to-year changes in temperature often reflect natural climatic variations such as El Niño/La Niña events, changes in average temperature from decade-to-decade reveal long-term trends such as global warming. Each of the last three decades has been much warmer than the decade before. At the time, the 1980s was the hottest decade on record. In the 1990s, every year was warmer than the average of the previous decade. The 2000s were warmer still.
“The temperature increase of one degree Fahrenheit over the past 50 years may seem small, but it has already altered our planet,” said Deke Arndt, co-editor of the report and chief of the Climate Monitoring Branch of NOAA’s National Climatic Data Center. “Glaciers and sea ice are melting, heavy rainfall is intensifying and heat waves are more common. And, as the new report tells us, there is now evidence that over 90 percent of warming over the past 50 years has gone into our ocean.”
NOAA also created a portal for the government's climate data, www.climate.gov.
about the paper that first used the term "global warming." That journal article, "Are we on the brink of a pronounced global warming?" by Wally Broecker, will be 35 years old as of August 8. At the time, the climate was near the end of a 30-year cooling trend that had canceled the effect of carbon dioxide emissions. Broecker foresaw that increasing emissions of carbon dioxide would reverse this trend and cause rapid warming. He predicted a 0.8°C temperature rise over the 20th century, which is fairly close to what happened. RealClimate explains what led him to those conclusions.