BOSTON — Last year was one of the world’s 10 hottest in records going back to the 19th century as concentrations of climate-changing greenhouses gases rose, a study showed.
Four international agencies reported the global average temperature was 0.2 to 0.21 Celsius (0.36 to 0.38 Fahrenheit) above the 1981 to 2010 average, making 2013 the second- to sixth-warmest year ever, according to the research edited by Jessica Blunden, a climatologist with ERT Inc., and Derek Arndt, chief of the climate monitoring branch at the National Climatic Data Center in Asheville, North Carolina.
“I think the take-home message here is that the planet, the state of its climate, is changing more rapidly in today’s world than at any time in modern civilization,” Thomas Karl, director of the data center, said in a conference call with reporters Thursday.
The assessment of the world’s heat was part of a report compiled by 425 scientists in 57 nations for the State of the Climate 2013. The 262-page report also surveyed storms, ice caps and chemicals in the air. Two of the largest events of the year were Super Typhoon Haiyan and the Australian drought.
“You can think of it as an annual checkup on the planet’s health,” said Kathryn Sullivan, administrator of the National Oceanic and Atmospheric Administration.
The global temperatures were compiled by NASA’s Goddard Institute for Space Studies, which found a rise of 0.21 degree Celsius; the Climatic Data Center, also a 0.21; the Hadley Centre of the U.K. Met Office, with 0.20; and the Japan Meteorological Agency, also 0.20. It was based on information from land sensing stations and buoys and ships at sea.
“The year 2013 was the warmest since 2010 and among the top 10 warmest years since records began in the mid- to late-1800s,” the researchers wrote in the Bulletin of the American Meteorological Society. “While their methods differ, leading to minor differences in anomalies and ranks, all four analyses are in close agreement.”
The temperature on land alone was 0.32 to 0.38 Celsius above the 1981-2010 average, making it the third-warmest at the higher end and sixth-warmest at the lower, the report showed. The 1981-2010 average temperature used by NOAA is 57.8 degrees Fahrenheit. U.S. temperature records date back to 1880.
While most of the earth’s land surface was warmer than normal, central Canada and the central and eastern United States were cooler.
China reported its hottest August ever, and 44 people died from the heat, the report said. Japan had its warmest summer temperatures since 1946. On Aug. 12, the Ekawasaki station in Shimanto-city Kochi Prefecture recorded a temperature of 41 degrees Celsius (106 Fahrenheit), the highest ever in Japan.
“Some regions of the Southern Hemisphere had record or near-record high temperatures for the year,” the researchers said. “Australia observed its hottest year on record, while Argentina and New Zealand reported their second- and third- hottest years, respectively.”
In addition, 2013 ranked within the top 10 years for the frequency of warm days, and the bottom 10 for the number of cool days, they said.
The lack of either an El Nino or La Nina in the equatorial Pacific Ocean also contributed to the overall temperature of the Earth during the year. Typically, the world is cooler during a La Nina because the ocean’s temperature is below normal, while the opposite is true during an El Nino.
As the temperature has risen, so has the amount of greenhouse gases in the atmosphere, the report showed. In May, a monitoring station at Mauna Loa, Hawaii, reported the daily average mixing ratio of carbon dioxide exceeded 400 parts per million for the first time since measurements began in 1958.
The initial concentration when the readings were first recorded was 315 parts per million. Along with carbon dioxide, the amount of methane and nitrous oxide also rose.
The amounts of the compounds in the Arctic region rose at the same rate as elsewhere. This has led researchers to believe that the increase isn’t being caused by the melting of the permafrost, the report showed.
“Natural emissions of these gases are of particular interest in the Arctic, where there are large vulnerable reservoirs of carbon in soil and clathrates that may eventually be released to the atmosphere by thawing and decomposition,” the researchers said.
Arctic sea ice was the sixth-lowest since satellite observations began in 1979. The seven lowest amounts have all occurred in the past seven years.
“In recent decades the Arctic has warmed at least twice the rate of the rest of the Northern Hemisphere,” the researchers said.
At the other end of the earth, Antarctica set a high for sea ice extent in October. While ice grew, so did the temperature. The Amundsen-Scott South Pole State reported its highest readings since records were first kept in 1957.
The difference in the sea ice extent between the poles is something of a “conundrum” for scientists, said Martin Jefferies, arctic and global prediction program officer for the U.S. Office of Naval Research.
“It’s an interesting time to be a polar scientist,” Jefferies said on Thursday’s conference call.
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