Last year was among the 15 warmest since record keeping began in the late 19th century, despite a La Nina weather pattern that should have cooled global temperatures, according to an annual climate assessment.
La Nina’s failure to cause significantly cooler global temperatures is one of many indications of long-term climate warming, according to the U.S. National Oceanic and Atmospheric Administration’s State of the Climate report compiled by 378 scientists from 48 nations. La Nina was responsible for droughts in eastern Africa and North America, the scientists reported.
Last year “will be remembered as a year of extreme events, both in the United States and around the world,” Deputy NOAA Administrator Kathryn D. Sullivan said in a statement today. “Every weather event that happens now takes place in the context of a changing global environment.”
Texas had the hottest summer since data collection began in 1895 and extreme heat may be more common in the future.
“Conditions leading to droughts such as the one that occurred in Texas in 2011 are, at least in the case of temperature, distinctly more probable than they were 40-50 years ago,” according to the study. It used as a proxy 2008, another La Nina year, in which it found extreme heat was about 20 times more likely than in the 1960s.
Thailand’s 2011 floods weren’t the result of climate change because the amount of rain that fell “was not very unusual,” the report concluded.
Carbon dioxide emissions increased in 2011 and the yearly global average surpassed 390 parts per million for the first time since records started.