It’s not a hoax. There’s no conspiracy. And no exaggeration. What follows are 137 years of diligently kept scientific records that show how humans are transforming Earth’s climate. The bright red line represents 2016—the third consecutive year to set a new record. The streak is the steepest and most sustained surge in planetary temperatures in the modern age.
To say that last year was hot is an understatement. It was 1.69 degrees Fahrenheit (0.94 Celsius) warmer than the 20th century average, according to National Oceanic and Atmospheric Administration figures released on Wednesday. That may not sound like much, but on a planetary scale it’s a profound shift that has decimated coral reefs, thawed polar ice at a near-catastrophic rate, and nudged agricultural planting zones across national borders.
Climate scientists don’t place much weight on a single record-hot month, or even a single record-hot year. What sets off alarms, said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, is the rapid accumulation of warming we’ve been experiencing over many years. Sixteen of the 17 hottest years have come to pass over the past 17 years, and temperatures are rising 10 times faster than during the bounce back from the last ice age.
“The planet is warming and we have a pretty good idea why it is warming,” Schmidt said simply. “It is warming because we are not reducing the amounts of greenhouse gases by the amounts we need to.”
Results from the world’s top monitoring agencies vary slightly, but NASA, NOAA, the Japan Meteorological Agency, and the U.K.’s Met Office all agree: 2016 was unprecedented. The heat was experienced differently around the world, but most regions were unusually warm to downright scorching for much of the year.
As climate change continues apace, unusual weather will become commonplace. In 2016, for example, wildfires dealt Canada its costliest natural disaster ever. Arctic sea ice was at its smallest winter maximum for the second year running. Temperatures in India climbed to 51 degrees Celsius (124 degrees Fahrenheit). In Southern Africa, a second year of weak rainy seasons led to serious drought, while an unusually active hurricane season in the Atlantic left more than 1,700 people dead, including 1,000 who perished in the wake of a catastrophic Category 5 storm. These are the sort of events that we’ll grow to expect in a warming world.
This week, Republican Donald Trump will be sworn in as the 45th U.S. president. Trump, 70, has falsely called climate change a hoax perpetrated by the Chinese and vowed to undo new regulations, including the U.S. Clean Power Plan, which would regulate power plant emissions. He has vowed to withdraw America from the Paris climate accord, signed by 195 countries, while proclaiming he wants to revive American coal. He is seeking to slash environmental protections built up over more than four decades by Democratic and Republican administrations alike.
Meanwhile, a quarter of the Great Barrier Reef has died. Warm waters and ocean acidification caused by carbon dioxide pollution have turned once colorful nurseries of sea life into ashen graveyards. As the belt of heat at the planet’s equator widens, the U.S. and Canada have revised northward their maps of so-called hardiness zones for growing crops. As Greenland’s ice streams flow ever faster to the sea and state-sized chunks of Antarctica destabilize, rising oceans are redrawing Louisiana’s coast and Miami streets now flood when the tide comes in, even on sunny days.
Climate change used to occur over millennia. Now it occurs over decades. Still, there will be ebbs and flows for the surface of Earth. Over the past two years, a powerful El Niño warming pattern in the Pacific Ocean contributed about a third of a degree to the extreme temperatures, but in mid-2016 conditions reversed to a weak La Niña cooling pattern. For that reason, 2017 isn’t likely to set a fourth straight annual record, according to NASA’s Schmidt.
Forecasters at the U.K.’s Met Office similarly expect a reprieve in 2017, with global temperatures roughly 0.84 Celsius (1.5 Fahrenheit) above the 20th century average. That would have been warm enough to set a new record as recently as 2014. But enjoy it while you can. At the rate the climate is changing, it won’t be long before we grow wistful for such temperate times.
—With assistance from Brian K. Sullivan.