The average global temperature in 2012 was among the 10 hottest since official record keeping began in 1880, with most of the world — from North America to far northeastern Asia — experiencing higher-than-usual temperatures, according to related reports issued Tuesday by the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration.
Last year’s average global temperature was about 58.3 degrees Fahrenheit, or about 1.0 degree Fahrenheit warmer than the mid-20th century baseline, NASA said, making it the ninth-warmest year on record. NOAA’s evaluation showed that 2012 was the 10th-warmest. The agencies’ reports are based on slightly different methodologies and data.
Still, the two agencies concurred that the data point to a planet that has grown warmer swiftly and looks to get even hotter in the near future. The reports noted that except for 1988, the nine warmest years in the 132-year record all have occurred since 2000. And 2012 was the 36th year in a row that the global average temperature was above the 20th century mean of 57 degrees Fahrenheit.
"One more year of numbers isn't in itself significant," NASA climatologist Gavin Schmidt said. “What matters is this decade is warmer than the last decade, and that decade was warmer than the decade before. The planet is warming.”
The NOAA and NASA analyses are the most recent in a week of troubling federal reports about the effects of climate change on the United States and the world.
Last week, NOAA reported that the average temperature in the contiguous 48 states in 2012 was 55.3 degrees Fahrenheit, the warmest year on record and a full degree higher than the previous record-high temperature. And on Friday, a federal panel issued a report stating that the effects are spreading through the United States faster than had been predicted, increasingly threatening infrastructure, water supplies, crops and shorelines.
Each report has prompted environmentalists and their political allies to call for action, especially from President Obama. But in a news conference Monday, the president and the White House press corps said nothing about climate change, continuing a long silence Obama broke only a few times during the campaign.
NASA said the planet was warming because of greater levels of carbon dioxide in the atmosphere as a result of human activity, mainly the increased combustion of fossil fuels. In 1880, the first year of the temperature record, “the carbon dioxide level in the atmosphere was about 285 parts per million,” NASA said. “By 1960, the atmospheric carbon dioxide concentration, measured at NOAA's Mauna Loa Observatory, was about 315 parts per million. Today, that measurement exceeds 390 parts per million."
The NOAA report showed that the warming of the planet is accelerating. Over the last 132 years, the global annual mean temperature has increased at an average rate of 0.11 of a degree Fahrenheit per decade. But since 1970, the annual mean global temperature jumped at an average rate of 0.28 of a degree per decade.
High temperatures in the United States were accompanied by drought in most of the country and wildfires in the West. Drought also afflicted major agricultural regions in Russia, Ukraine and Kazakhstan. Other places, like Britain and 15 countries in Africa, had unusually high rainfall.
The rise in average temperature means that extreme weather events — such as record heat, drought or heavy rainfall — are growing more common, said James E. Hansen, director of NASA's Goddard Institute for Space Studies in New York.
Hansen said that land temperature data from the Northern Hemisphere show that 60 years ago, anomalously high temperatures occurred 1% to 2% of the time. Now, he said, people will experience anomalous extremes more like 10% of the time.
Return to the Science Now blog.
[For the record, 4:55 p.m. Jan. 15: An earlier version of this post stated that NOAA's report showed that the global annual mean temperature had increased at an average rate of 0.11 degrees Fahrenheit over the last 132 years, but that since 1963, the mean global temperature jumped at an average rate of 0.27 degrees Fahrenheit per decade. It should have referred to annual rates per decade in both references. In addition, the time frame of the latter number has been adjusted.]