Federal scientists say 2017 among warmest years on record

Nettie James
January 19, 2018

Last year was indistinguishable, so far, from 2015 as the second or third warmest behind 2016, making 2017 "the warmest year without an El Nino", the UN's World Meteorological Organisation said.

Average surface temperatures in 2017 were 1.1 degree Celsius above pre- industrial times, creeping towards a 1.5C ceiling set as the most ambitious limit for global warming by nearly 200 nations under the 2015 Paris climate agreement.

The difference between the two agencies in ranking 2017 is somewhat driven by the different methodology the two agencies use to measure temperatures in the Arctic, the fastest-warming part of the planet, said Zeke Hausfather, a climate scientist who also closely tracks annual temperatures with Berkeley Earth.

Both teams found that if it weren't for the El Nino climate pattern in 2017, it would have been the hottest year.

This is a developing story. Records go back to 1880.

The globally averaged temperature in 2017 was about 0.46°C above the 1981-2010 long-term average of 14.3°C - a 30-year baseline used by national meteorological and hydrological services to assess averages and variability of key climate parameters, which are important for climate-sensitive sectors, such as water management, energy, agriculture and health.

"Despite colder than average temperatures in any one part of the world, temperatures over the planet as a whole continue the rapid warming trend we've seen over the last 40 years", Gavin Schmidt, director of NASA's Goddard Institute for Space Studies, said in a statement.

In a separate, independent analysis, scientists at the National Oceanic and Atmospheric Administration (NOAA) concluded that 2017 was the third-warmest year in their record.

Researchers are placing blame for the trend squarely on climate change, especially because it appears the impacts of greenhouse gas emissions are able to overcome most natural warming patterns like El Nino.

The 2015 Paris agreement, which seeks to shift the world economy from fossil fuels this century, aims to limit temperatures to "well below" a rise of 2C above pre-industrial times while pursuing efforts to limit it to 1.5C.

In addition to the official USA agencies, a number of additional expert outlets have tracked temperatures and found results consistent with those of NOAA and NASA.

Climate also has a naturally occurring variability due to phenomena such as El Niño, which has a warming influence, and La Niña, which has a cooling influence.

NOAA and NASA analyses use temperature measurements from weather stations on land and at sea. Mooney reports on science and the environment.

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