Keeping global warming below 1.5 degrees Celsius is still possible, a new study indicates. In fact, the world's economies can emit an additional 700 billion tons of carbon dioxide before exceeding 1.5 degrees - more than twice previous estimates, according to research published in Nature Geoscience. "That's about 20 years at present-day emissions," said Richard Millar, a climate scientist at the University of Oxford and lead author of the study (via E360).
But the change in the estimate of how much more carbon the world can emit and still keep climate change to a minimum is not because - as some have reported - the effects of carbon emissions are not as bad as previously thought. Rather, the authors say, the study took a better account of past emissions and where we are today in terms of human-induced warming. "The single most important factor in the extent of future global warming is our cumulative emissions of CO2," the authors wrote in a blog post when the study was released last week.
While a study published last July gave the world only a 1% chance that it can limit climate change to 1.5 degrees Celsius, Millar says the new research means that "keeping global warming to 1.5 degrees C still remains a geophysical possibility."
The study, from the Intergovernmental Panel on Climate Change, finds that nations can emit a total of about 1,000 more gigatons of CO2 (calculated from 2011) to keep global warming below the Paris Agreement target of 2 degrees C - that's compared to the 2015 study that said emissions would have to be limited to under 400 gigatons. Currently, the world emits 41 gigatons of CO2 per year.
At the current pace, and if the new study is correct, the world would have an additional 20 years before the carbon budget is spent - compared to less than four years suggested by existing research.
But is the new study correct? Some scientists are skeptical. "When it’s such a substantial difference, you really need to sit back and ponder what that actually means,” Glen Peters, an expert on climate and emissions trajectories at the Center for International Climate Research in Oslo, says (via The Washington Post). Because the implications of a substantial revision to the "carbon budget" are profound, "you're going to have some extra eyes really scrutinizing that this is a robust result," Peters says.
Additionally, news about the study has been reported in confusing and sometimes inaccurate ways, with some articles using the study as a way of downgrading the threat of climate change. Millar and another author of the study, Myles Allen, took to The Guardian to clarify: "We knew this finding would be controversial, since previous estimates had indicated that to meet the same goal, emissions might have to reach zero in well under a decade, which really is inconceivable."
The reason for the new estimate is not that the authors had a different view on how climate is affected by metric ton of CO2 emitted; in fact, they used exactly the current consensus range. Rather, the study "took better account of past emissions and where human-induced warming has got to already," they wrote.
