We’re Halfway to Global Warming’s 'Dangerous Limit'

We're blowing past another major climate milestone. And it isn't a good one.

Nov 9 2015, 5:39pm

Image: NASA

Scientists and climate leaders have pegged 2˚ Celsius (3.6˚ F) as the degree of temperature rise to which we must, at all costs, limit global warming. The number itself has been nigh-endlessly debated, but the reasoning goes that if temps rise any more than 2˚C, we risk triggering what scientists say are "dangerous" levels climate change—think melting polar ice sheets, scorching temps, and rapidly rising sea levels that could seriously disrupt human civilization itself. And, as of this year, it looks like we're already halfway there.

The UK's major meteorological outfit, the Met, says we're entering what it calls "uncharted territory" this year. According to the organization, "data for 2015 so far shows that, for the first time, global mean temperature at the Earth's surface is set to reach 1˚C above pre-industrial levels. This represents an important marker as the world continues to warm due to human influence."

The milestone, while alarming, doesn't exactly come as a surprise.

"It was inevitable that we would cross this threshold soon," climatologist Michael Mann told me. "Boosted by a huge El Nino event, 2015 will cross that mark even sooner than we expected. Yet another reminder that, by many standards, climate change is proceeding even faster than we expected."

NASA's Gavin Schmidt told me, meanwhile, that according to his models, "It's pretty much on schedule."

So we're halfway to hell, or, rather, nearly halfway.

"It's important to keep in mind that this is just a single individual year, subject to the usual random fluctuations, so it isn't really quite yet a measure of the true shifting baseline," Mann told me. "That having been said, it is a frightening reminder that we're nearing the 2˚C "dangerous limit", particularly given that another 0.5˚C of warming (as the climate catches up to the carbon we've already emitted) is almost certainly in the pipeline."

UK Met Office

Some scientists say that allowing the planet to warm even 2˚C will beckon calamity. Ex-NASA climatologist James Hansen published a paper that concluded that amount of warming would have "disastrous consequences," and "would practically guarantee irreversible effects." Others have already resigned themselves to the fact that we're already on track to blow past the 2˚C marker, and argue we should plan on adaptation right here, right now.

One of the key goals—if not the key goal—of the major global climate conference in Paris this year will be forging a binding climate treaty that will force nations to reduce emissions to limit warming to 2˚C. As Mann and others make clear, there's extremely little room to maneuver if we're hoping to hit that goal—we're already rolling towards at least 1.5˚C of warming as it is.

"That means we've got less than 0.5C of wiggle room left, emphasizing the importance of immediate reductions in carbon emissions," Mann said.

We'll soon see if the international community can get there.