Heat record: 2015 was hottest year by huge margin

Last year wasn't just the Earth's hottest year on record — it left a century of high temperature marks in the dust.

El Nino partly to blame, but human activity was the main driver, NASA and NOAA scientists say

The Associated Press · Posted: Jan 20, 2016 11:00 AM EST | Last Updated: January 20, 2016

A man takes a sunbath at an artificial beach during a heat wave in Brussels, Belgium, July 4, 2015. Globally, 2015's global average temperature was the hottest on record by a huge margin, NASA and NOAA reported Wednesday. (Eric Vidal/Reuters)

Last year wasn't just the Earth's hottest year on record — it left a century of high temperature marks in the dust.

The National Oceanic Atmospheric Administration and NASA announced Wednesday that 2015 was by far the hottest year in 136 years of record keeping.

NOAA said 2015's average temperature was 14.79 degrees Celsius (58.62 degrees Fahrenheit), passing 2014 by a record margin of 0.16 C (0.29 F). That's 0.90 C (1.62 F) above the 20th-century average. NASA, which measures differently, said 2015 was 0.13 C (0.23 F) warmer than the record set in 2014.

A graphic shows what parts of the Earth were warmer and cooler than average in 2015. It was the warmest year since modern record-keeping began in 1880, according to a new analysis by NASA’s Goddard Institute for Space Studies. (Scientific Visualization Studio/Goddard Space Flight Center)

Because of the wide margin over 2014, NASA calculated that 2015 was a record with 94 per cent certainty, about double the certainty it had last year when announcing 2014 as a record.

4th record in 11 years

Although 2015 is now the hottest on record, it was the fourth time in 11 years that Earth broke annual marks for high temperature.

"It's getting to the point where breaking record is the norm," Texas Tech climate scientist Katharine Hayhoe said. "It's almost unusual when we're not breaking a record."

A boy cools off in a public fountain in Rio de Janeiro, Brazil, October 16, 2015, when temperatures reached a record-breaking 42.8 degrees Celsius. The sharp temperature increase in 2015 was driven in part by El Nino, scientists say. (Pilar Olivares/Reuters)

Scientists blame a combination of El Nino and increasing man-made global warming.

Michael Mann of Pennsylvania State University said a strong El Nino, like this year's, can add about a third of a degree of warming to Earth's temperature.

"Records will happen during El Nino years due to the extra warming boost they provide," Mann said in an email. "That boost of warmth however sits upon the ramp of global warming."

And it's likely to happen this year, too. NASA scientists and others said there's a good chance that this year will pass 2015 as the hottest year on record, thanks to El Nino.

Road markings appear distorted during a heat wave, in New Delhi, India, 27 May 2015. At that time, more than 1,150 people were reported dead from the heat wave. (Harish Tyagi/EPA)

"2015 will be difficult to beat, but you say that almost every year and you get surprised," said Victor Gensini, a meteorology professor at the College of DuPage outside of Chicago.

Measurements from Japan and the University of California at Berkeley also show 2015 is the warmest on record. Satellite measurements, which scientists say don't measure where we live and have a larger margin of error, calculate that last year was only the third hottest since 1979.