An analysis of global temperature data by scientists with the U.S. National Aeronautics and Space Administration (NASA) found that 2017 was the second-hottest year on record since 1880 — which the scientists say is especially significant given that there was no El Niño last year.
According to scientists at NASA’s Goddard Institute for Space Studies in New York City, global average temperatures in 2017 were 1.62 degrees Fahrenheit (or 0.90 degrees Celsius) warmer than the 1951 to 1980 average, which makes 2017 temperatures second only to 2016.
“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 the Goddard Institute for Space Studies, said in a statement.
In their own analysis, scientists at the U.S. National Oceanic and Atmospheric Administration (NOAA) determined that 2017 was the third-warmest year on record, behind 2016 and 2015. Despite the small discrepancy in rankings, which is due to the different methods each team employed for analyzing temperature data, both agencies’ analyses find that the five warmest years on record have all occurred since 2010 and that Earth’s long-term warming trend continued through 2017.
The BBC reports that a third major agency that tracks global temperature data, the UK Met Office, concluded that average global temperatures in 2017 were lower than 2016 but virtually identical to 2015.
All three agencies noted that 2017 had no El Niño phenomenon, which warms tropical Pacific Ocean waters and causes corresponding short-term variations in global average temperatures, whereas an El Niño event was in effect for most of 2015 and the first four months of 2016. In fact, a La Niña event, which creates cooler Pacific waters and hence tends to drive down global average temperatures, started in late 2017.
An additional analysis by NASA found that if the effects of recent El Niño and La Niña events were excluded, 2017 would have gone down as the warmest year on record.
“It’s extraordinary that temperatures in 2017 have been so high when there’s no El Niño. In fact, we’ve been going into cooler La Niña conditions,” Peter Stott, acting director of the UK Met Office, told BBC News. “Last year was substantially warmer than 1998 which had a very big El Niño. It shows clearly that the biggest natural influence on the climate is being dwarfed by human activities – predominantly CO₂ emissions.”
According to NASA, Earth’s average surface temperature has risen about two degrees Fahrenheit, or a little more than one degree Celsius, over the course of roughly the last century, and this change has been “driven largely by increased carbon dioxide and other human-made emissions into the atmosphere.” The agency added that “Last year was the third consecutive year in which global temperatures were more than 1.8 degrees Fahrenheit (1 degree Celsius) above late nineteenth-century levels.”
Weather dynamics can have a large impact on regional temperatures, however, which is why different regions of the planet might not have experienced the same amount of warming in 2017. According to NOAA, South America experienced its second-warmest year on record last year, while Asia experienced its third-warmest year, Africa its fourth, Europe its fifth, and North America and Oceania experienced their sixth-warmest year.
Data released by NOAA last week showed that 2017 was the third-hottest year on record in the 48 contiguous states in the U.S. — but the costliest in terms of weather and climate disasters, of which the U.S. saw 16 last year that inflicted damages of $1 billion or more.
Banner image: The map shows Earth’s average global temperature from 2013 to 2017, as compared to a baseline average from 1951 to 1980, according to an analysis by NASA’s Goddard Institute for Space Studies. Yellows, oranges, and reds show regions warmer than the baseline. Image Credit: NASA/GSFC/Scientific Visualization Studio.