2015 Was the Hottest Year Ever, and 2016 Is Already Even Hotter
It’s official: 2015 surpassed 2014 as the hottest year on Earth since the second half of the 19th century, when humanity started burning increasing amounts of fossil fuels to power factories and transportation.
According to State of the Climate 2015, a report released Tuesday by the Bulletin of the American Meteorological Society, a strong El Niño amplified the effects of long-term climate change, thus driving 2015’s average global temperatures 1.8 degrees Fahrenheit (more than 1 degree Celsius) higher than preindustrial norms.
That beat 2014’s record high by 0.2 degrees Fahrenheit (0.1 degrees Celsius).
Sea surface temperatures and upper ocean heat also hit the highest average temperatures ever recorded, and global sea levels were the highest in the satellite measurements record, which began in 1993.
Communities around the world felt the effects. Forest fires began burning in March in Saskatchewan, Canada, torching 4.5 million acres, six times the provincial average. The fires spurred the evacuation of 13,000 people from their homes.
Record-high temperatures in Alaska helped trigger the state’s second-worst wildfire season—more than 5.1 million acres burned—and the state’s glaciers (along with glaciers around the world) lost more ice than in any other year on record.
In Karachi, Pakistan, an extreme heat wave in June killed more than 1,000 residents. In October, Hurricane Patricia forced tens of thousands to evacuate their homes on Mexico’s Pacific coast. Hitting the state of Jalisco with winds of 150 miles per hour, the hurricane killed six, destroyed around 9,000 homes, and damaged or destroyed nearly 60,000 acres of crops.
“I think clearly the report in 2015 shows not only that the temperature of the planet is increasing but all the related symptoms that you would expect to see in rising temperature are occurring,” said Thomas Karl, director of the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information. He spoke at a press conference on Tuesday to present the peer-reviewed report, which was authored by 456 scientists from 62 nations.
Concentrations of carbon dioxide, methane, and nitrous oxide all hit new record highs in 2015. Carbon dioxide, the main driver of climate change, hit 400.8 parts per million in the northern hemisphere, surpassing 400 parts per million for the first time in history. The global average was 399.4 parts per million for the year, “which means that 2016 is going to easily surpass this milestone,” climatologist Jessica Blunden, a report coauthor and lead editor at NOAA’s National Centers for Environmental Information, told reporters.
Some of 2015’s most dramatic changes occurred in the Arctic, where on Feb. 25, 2015, Arctic Ocean winter sea ice stopped growing 15 days earlier than average and covered the smallest area in the 37-year history of satellite measurements.
“Currently the Arctic is warming at more than twice the rate of lower latitudes,” said Jackie Richter-Menge, the report’s Arctic chapter editor and a research civil engineer at the U.S. Marine Environmental Laboratory.
Scientists have reported changing fish populations in Arctic Ocean waters off the coast of Norway and Russia, she said, as winter sea ice begins to melt earlier in the spring and summer. “Boreal or warm-affinity species are moving north and displacing Arctic or cold-affinity species,” Richter-Menge said, noting that all the record lows in Arctic sea ice occurred in the past nine years.
By every key measurement, the climate is changing, said Karl. “It’s more than temperature,” he said. “We’re beginning to see it in ecosystems. The impacts are beyond the physical and entering the realm of the biophysical.”
The report’s findings “underscore the urgency of taking action and the importance of moving forward in a quite ambitious way, and a speedy way, with implementing the Paris Agreement,” the international accord on reducing greenhouse gas emissions, said David Waskow, director of international climate initiative at the World Resources Institute, a nonpartisan think tank based in Washington, D.C.
“It’s clear that the impacts are not out there in the future somewhere but here in the present,” Waskow said. “That makes it very clear that the time for action also has to be in the present.”
Climate developments since the end of 2015 have only intensified the case for strong international action. NOAA recently announced that atmospheric CO2 concentrations at the South Pole had exceeded 400 parts per million for the first time in 4 million years, while the World Meteorological Organization confirmed in July that despite the end of the El Niño cycle, global temperatures for the first half of 2016 broke 2015’s record-setting heat, and that Arctic summer sea ice was approaching a record-breaking low. Scientists have also attributed this year’s severe coral bleaching event at the Great Barrier Reef and other locations to warmer oceans.
For the Paris Agreement to come into force, at least 55 nations, representing at least 55 percent of global greenhouse gas emissions, must ratify the accord. So far, 20 countries have done so, according to WRI, with four more on the cusp.
Some of the world’s major emitters, including Australia, Canada, Mexico, and the United States, promised in 2015 to ratify the agreement, although they have not yet done so.
Waskow said that based on the number of countries that have signed on to the agreement and the national plans under way to meet its targets for lower carbon emissions, he was optimistic that the agreement could be in force in time for this year’s international climate conference, scheduled for November in Marrakech, Morocco.
“Countries are now starting to develop long-term plans for 2050 as well, which is quite important to how they see their long-term arc of action,” said Waskow. “Those plans will help highlight the transformation that’s really needed to get to net zero emissions in the second half of the century.”
This post has been revised to reflect the following correction:
Correction Aug. 3, 2016: An earlier version of this article inadvertantly omitted the world “million” in describing the scope of Alaska’s 2015 wildfire season.