Both NOAA and NASA have declared 2015 to be the warmest year, and December the warmest month, in recorded history—and both attribute the rising temperatures to human activity.
“Globally-averaged temperatures in 2015 shattered the previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius),” said NASA in a media release on January 20, a day after the National Oceanic and Atmospheric Administration (NOAA) announced the same thing. “Only once before, in 1998, has the new record been greater than the old record by this much.”
Not only were the year’s temperatures the highest ever recorded, but the annual average also surpassed the previous temperature high by the largest margin, NOAA said.
“Climate change is the challenge of our generation, and NASA’s vital work on this important issue affects every person on Earth,” said NASA Administrator Charles Bolden in the space agency’s statement. “Today’s announcement not only underscores how critical NASA’s Earth observation program is, it is a key data point that should make policy makers stand up and take notice—now is the time to act on climate.”
In addition, the clear reason behind the increase of 1.8 degrees Fahrenheit since the late 19th century is mainly “increased carbon dioxide and other human-made emissions into the atmosphere,” NASA said.
“2015 was remarkable even in the context of the ongoing El Niño,” said Gavin Schmidt, director of the NASA Goddard Institute for Space Studies, in the statement. “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.”
This warming was spread around the world, not concentrated in a few places, NOAA noted. In addition the temperature increases applied to both land and sea.
Moreover, December added its own impetus.
“During the final month, the December combined global land and ocean average surface temperature departure from average was the highest on record for any month in the 136-year record,” NOAA’s release said.
The video below gives a stark illustration.