2016 has been a feverish year so far, and not just because of politics or Pokémon.
The year's first six months were the hottest half-year in recorded history, two U.S. science agencies announced this week, continuing a trend of 14 consecutive months with record-breaking heat. There's a 99 percent chance that 2016 will end up as the hottest year on record, a title currently held by 2015 (and by 2014 before that).
Globally, every month of 2016 so far is the hottest respective month since record-keeping began in 1880, according to NASA's Goddard Institute for Space Studies (GISS) and the National Oceanic and Atmospheric Administration (NOAA). January to June of 2016 was also the warmest half-year on record, with an average temperature 1.3 degrees Celsius (2.4 degrees Fahrenheit) higher than the late 19th century.
That's bad news for Earth's sea ice, which is much more vital to humans than it might seem. Sea ice always waxes and wanes with the seasons, but its annual late-summer minimum has recently been shrinking by about 13 percent per decade. And sea ice has been especially scarce in 2016, with five of the first six months setting records for smallest respective monthly Arctic sea ice extent, NASA reports. The one exception was March 2016, which saw the second-smallest total for that month.
It's no mystery why this is happening, of course. We're seeing the effects of human-induced climate change, fueled by greenhouse gas emissions and unfolding far more quickly than the natural climate shifts of pre-human history. This is an ongoing trend: Of the 15 hottest years since 1880, 14 have occurred since 2001.
But Earth's climate is complex, and 2016's surge isn't due to greenhouse gases alone. It has also been influenced by El Niño, part of a natural climatic cycle that periodically amplifies Earth's overall temperature, among other effects. It's sort of like if you broke a water pipe and flooded your backyard, then it also rained. Your flooded yard is your own fault, but a natural phenomenon made the problem worse.
As this NASA chart illustrates, the long-term trend is obvious:
Unfortunately, fixing climate change isn't as simple as fixing a broken pipe. The greenhouse gases we've already emitted, namely carbon dioxide, will linger in the sky for centuries, so we're already locked in to a certain amount of disastrous warming.
The good news, however, is that we can still cut our losses by cutting our emissions. And thanks to a nudge from El Niño, the increasingly familiar experience of living through a hottest year on record has seemed more noteworthy this year. 2016 would've broken heat records anyway, scientists say, but by making it slightly hotter, El Niño has provided a potent reminder of the dangerous path we're on.
These maps show projected temperature changes for midcentury (left) and end-of-century (right) in the United States under higher (top) and lower (bottom) emissions scenarios. (Image: EPA/U.S. Global Change Research Program)
While 2015 was hot, 2016 "has blown that out of the water," GISS director Gavin Schmidt said in a press briefing Tuesday. About 40 percent of the increase is due to El Niño, Schmidt added — the other 60 percent is due to longer-term climate change. Global warming is already under way, and this year's heat is further evidence.
But as this El Niño fades, 2017 could end up slightly cooler than 2016, which is the kind of thing some people incorrectly offer as proof that Earth's climate isn't changing at all. The trend line for climate change is bumpy, and a dip in 2017 would disprove its existence no more than El Niño proved it was real in 2016.
We already know human-induced climate change is real, and that it threatens us with long-term crises such as megadroughts, sea-level rise and biodiversity loss. Cycles like La Niña or El Niño may obscure or accentuate its effects, but they shouldn't be confused with the underlying problem.
For anyone with a stake in future human generations, 2016 offers a wake-up call: Things have gotten a little too heated this year, but the world isn't necessarily as bad as it seems. If this heat can inspire us to see the big picture and get serious about stopping climate change, 2016 could actually turn out to be a pretty cool year.