The somewhat arbitrary number represents the hard limit to the amount of global warming we can permit before we hit the point of no return.
Last year, experts at the Intergovernmental Panel on Climate Change contended that while the window to slow down carbon emissions was closing, there was still time to slow down the Earth’s irreversible demise by increasing the share of renewable energy to 80 percent up from 30 percent. But a new report from meteorologist Eric Holthaus in Slate makes it clear that the northern hemisphere has breached that two-degree mark over normal, pre-Industrial temperatures. We have, it seems, already failed.
He explains that February was somewhere between 1.15 and 1.4 degrees Celsius above the long-term average, making it “the most above-average month ever measured.” While the “official” temperature data sets haven’t been released yet — data from NOAA’s MLOST, NASA’s GISTEMP, and the UK’s HadCRUT are the most highly cited — Holthaus argues that it really doesn’t matter because the recent numbers are so high that tiny fluctuations wouldn’t make much of a difference.
Emphasizing that temperatures are not only rising but that the rate at which they’re increasing is speeding up, he writes:
Keep in mind that it took from the dawn of the industrial age until October 2015 to reach the first 1.0°C rise. That means we have come as much as an extra 0.4°C further in just the last five months.
If Holthaus is right — that it’s too late to turn back — it signals a need to switch the focus of our climate change plans from prevention to contingency. Scientists like Stanford University’s Rob Jackson, Ph.D., already skeptical of the efficacy of the two-degree limit, have suggested chasing options such as “negative-emission energy,” which will allow us to retract the emissions we’ve already dumped into the atmosphere. That technology doesn’t exist yet, but it’s clear that it’s going to have to happen much sooner rather than later.
“This is a milestone moment for our species,” Holthaus writes. “Climate change deserves our greatest possible attention.”