Last year’s global average temperature was the hottest ever by the widest margin on record, two U.S. government agencies said on Wednesday (January 20), adding to pressure for deep greenhouse gas emissions cuts scientists say are needed to arrest warming that is disrupting the global climate.
Data from U.S. space agency NASA and the National Oceanic and Atmospheric Administration showed that in 2015, the average temperature across global land and ocean surfaces was 1.62 degrees Fahrenheit (0.90 Celsius) above the 20th century average, surpassing 2014’s previous record by 0.29 F (0.16 C).
This was the fourth time a global temperature record has been set this century, the agencies said in a summary of their annual report.
The sharp increase in 2015 was driven in part by El Niño, a natural weather cycle in the Pacific that warms the ocean surface every two to seven years. But scientists say human activities – notably burning fossil fuels – were the main driver behind the rise.
“2015 would have been the warmest year on record without El Nino. But the occurrence of El Nino at the same time, starting in late 2015, pushed the the global temperatures even slightly higher than they would have been,” NASA scientist Compton Tucker said during an interview at Goddard Space Flight Center.
The latest El Niño started in late 2015 and will last until spring 2016. It is among the strongest ever recorded but Tucker and others say the weather phenomenon played just a supporting role in the earth’s temperature rise.
“Fifteen of the past 16 years have been the warmest years on record. And when you see a run like this, this is not something which people can easily dismiss and say it isn’t true. Fifteen out of 16 is a pretty good batting average,” Tucker said.
The 2015 data underscores the urgency of cutting greenhouse gas emissions if the world is to hold temperature increases to well below 2 degrees C, the target agreed to by more than 190 countries at climate talks in Paris last December.
“This is due to the accumulation of carbon dioxide in the atmosphere, which acts as an insulating blanket around the earth and traps outgoing longwave radiation. It’s just like putting an extra blanket on your bed at night. It keeps you warmer, and carbon dioxide in the atmosphere keeps the Earth warmer. More carbon dioxide keeps the earth even warmer,” Tucker said.
The summary can be found here: http://www.ncdc.noaa.gov/sotc/summary-info/global/201512
Reuters