2015 shatters record for warmest year: why climate scientists are celebrating

Last year was the planet's hottest on average since record-keeping began, and the reports released Wednesday have the scientists who predicted it thumping backs.

NASA, the British Met Office, and US National Oceanic and Atmospheric Administration (NOAA) agreed that warming due to greenhouse-gas build-up and an active Pacific El Niño combined to make 2015 a record year.

"2015 was remarkable even in the context of the ongoing El Niño,” the director of NASA’s Goddard Institute for Space Studies Gavin Schmidt said in a press release. “Last year’s temperatures had an assist from El Niño, but it is the cumulative effect of the long-term trend that has resulted in the record warming that we are seeing.”

The global average temperature for 2015 was 0.23 degrees Fahrenheit or 0.13 Celsius higher than 2014, which held the previous record, according to NASA. NASA analyzed raw data from 6,300 weather stations and tried to account  for local weather patterns while comparing to a baseline of average temperature from 1951 to 1980.

NOAA used much of the same raw data but a different baseline, reporting the average temperature in 2015 was 1.62 degrees Fahrenheit or 0.90 Celsius over the 20th-century average.

A temperature drop after 1998 has been described by some scientists as a short break in a long-term process and others as proof that risks of a warming climate have been exaggerated. For those who placed money on the planet's average temperature changing, the announcement heralded a day of recompense.

Still, not all scientists see the data as confirmation of problematic warming.

"2015 is not the warmest year, according to some sources," Galina Mashnich, an expert at the Institute of Solar-Terrestrial Physics in Irkutsk, Russia, told Reuters in an email, attributing the rise to El Niño. 

Benny Peiser, director of Britain's Global Warming Policy Foundation, a think tank that takes a skeptical view of climate change, told Reuters that the temperature increase "is not something that people ... need to be greatly concerned about."

However, for the majority of climate scientists who stand behind predictions that human-induced global warming holds significant consequences for life on Earth, last years' data is confirmation that world leaders need to take immediate steps to address further warming.

“This new record highlights how critical it was to get an agreement in Paris and the importance of countries not only following through on their commitments, but going further," Astrid Caldas, climate scientist at the Union of Concerned Scientists said in a statement delivered to The Christian Science Monitor. "A massive ramp-up of renewable- and low-carbon- energy will be essential to stay within 2°C of warming and avoid new records being set.”

This report contains material from Reuters.