Leaked u.n. draft report sees ‘very high risk’ the planet will warm beyond key limit – the washington post electricity 2pm

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A draft United Nations climate science report contains dire news about the warming of the planet, suggesting it will likely cross the key marker of 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, of temperature rise in the 2040s, and that this will be exceedingly difficult to avoid.

The 31-page draft, a summary of a much-anticipated report on the 1.5 degrees Celsius target expected to be finalized in October, was published by the website ClimateHome on Tuesday. The website said the document had been “publicly available on the U.S. federal register over the past month.” Last month, several news outlets, including Reuters, quoted from the draft but did not publish it in full.

The 1.5 C target is crucial to small island nations worried about rising seas, and other nations particularly vulnerable to warming, and was explicitly included in the Paris climate agreement as the more ambitious of two climate goals , the other being 2 degrees C (3.6 degrees Fahrenheit).

The draft document states that there is a “very high risk” of the planet warming more than 1.5 degrees above the temperature seen in the mid-to-late-19th century. Maintaining the planet’s temperature entirely below that level throughout the present century, without even briefly exceeding it, is likely to be “already out of reach,” it finds.

Although worrying, the conclusion will not be surprising to those who have followed a growing body of research on just what it would take to stop warming short of 1.5 degrees Celsius. The planet has already warmed by 1 degree Celsius or more.

A serious risk is already emerging to highly sensitive marine ecosystems, such as coral reefs, the document states, and 1.5 C may already be too much for them. Reefs “are at risk that at 1.5 C and at 2 C they will no longer be dominated by corals,” the draft report notes.

Two of those years have already elapsed, as of this writing. A third will have nearly elapsed by the time the draft report is finalized and released in October. (In December in Poland, it will feed into a broader United Nations deliberation about the adequacy of countries’ current promises to cut emissions.)

Since such rapid and severe cuts aren’t likely, the report notes that it’s virtually unavoidable that the planet will “overshoot” 1.5 degrees Celsius. To cool Earth afterward and avoid staying at dangerously high temperatures for long, it would then be necessary to remove carbon dioxide from the air at a massive scale — but that, too, is highly problematic.

Carbon removal scenarios generally involve reforesting large amounts of land, or growing trees or other plants on that land and using it for energy, and storing the resulting carbon dioxide emissions underground. But “increased biomass production and use has the potential to increase pressure on land and water resources, food production, biodiversity, and to affect air quality,” the draft notes. “Therefore, the scale and speed of implementation assumed in some 1.5 C pathways may be challenging.”

“Avoiding a 1.5 C warming would be very, very difficult without a significant overshoot,” said Princeton University climate scientist Michael Oppenheimer, noting that he was commenting solely on the state of the science itself, rather than the leaked document. “Such a warming would cause increased bleaching and perhaps destruction of living coral reefs at some locations, although at other places, reefs would probably survive a warming closer to 2 C.”

“Some of the high level messages I think come as no surprise, in that we are not on track anywhere near toward 1.5 C, and getting there would require enormous changes,” added Shindell, noting that he was not speaking as an author of the draft report or on behalf of the IPCC, but simply as a scientist with expertise in the matter. “That basic conclusion, I think it’s okay to say that it’s not a surprise to anybody. Any climate scientist would have told you that even without the report.”

In 2013, a leaked draft of part of the Intergovernmental Panel on Climate Change’s fifth assessment report helped lend credence to the questionable idea that global warming had slowed or “paused,” based on a brief passage suggesting that the rate of warming had declined somewhat between 1998 and 2012. The final draft addressed the issue with more nuance, largely undermining the notion of any significant slowdown.

The authors have until May 15 to include any new published material in the report. Still, it’s unlikely to change the fundamental conclusion that there is too little time to avert 1.5 C degrees of warming — barring some massive technological intervention.