Last year was the hottest year on record, two U.S. agencies announced Wednesday. It clocked in at 1.62 degrees Fahrenheit above the 20th century average, nearly one-third of a degree above the previous record, which was only a year old, set in 2014.
The strong El Niño currently hovering over the Pacific Ocean is only partially to blame, scientists from NASA and the National Oceanic and Atmospheric Administration told reporters Wednesday.
"2015 did not start with an El Niño event," said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies. "The warmth, it was there right from the beginning."
"This is part of long-term underlying trend" due to the buildup of greenhouse gases in the atmosphere, he continued. "There is no evidence that that trend has paused, slowed, or hiatused in the recent decade."
Ten of the last 12 months broke monthly temperature records since recordkeeping began in 1880. It was the United States' second hottest year, behind 2012, and its third wettest. The Northern Hemisphere measured 2.59 degrees Fahrenheit hotter than the 20th century average.
The news from NOAA and NASA comes the same day that the UK Met Office, Britain's climate research agency, also confirmed the new record.
Increasing atmospheric temperatures are fueling extreme weather events across the planet, the scientists said. Intense rainstorms and heat waves have become more frequent. Wildfires are more severe as hot temperatures and intense droughts dry out forests. Evidence shows that hurricanes are shifting their tracks poleward, hitting communities that historically haven't had to deal with the storms before. Last year played host to a variety of devastating climate change-fueled disasters.
"The result of 2015 being the hottest year on record meant that for millions of people worldwide, the consequences were painful, costly and frightening," Aaron Packard, head of 350.org's Climate Impacts Program, said in a statement. "We witnessed terrible consequences that resulted from a warmer atmosphere, including: devastating floods in parts of India, the US, UK and China; deadly heat waves across India, Pakistan and the Middle East, severe drought from Africa to California, and an exacerbated El Niño event."
Odds are 2016 will be even hotter than last year, said Tom Karl, director of NOAA's National Centers for Environmental Information.
World leaders pledged last December in Paris to limit global warming to 2 degrees Celsius, or if possible 1.5 degree Celsius. But the scientists warned on Wednesday that even if nations drastically curb their greenhouse gas emissions immediately, it will take decades before the warming will stop.
Global warming "can't be turned around instantly," said Schmidt. "We need a sustained conversation, discourse and monitoring of the situation for this problem to get under control. That is not something that will be done in one year or two years. It depends on our long-term ability to maintain focus on this issue."