SOURCE: National Geographic and Nature Climate Change

DATE: March 12, 2019

SNIP: A new scientific analysis of millions of possible climate futures found only a narrow window to keeping global warming to levels the international community has deemed safe.

Out of 5.2 million possible climate futures, carbon emissions must reach zero by 2030 in every country in the world if we are to stay at less than 3.6 degrees Fahrenheit (2 degrees Celsius) by 2100 of warming, the target set by the United Nations to avoid the worst impacts of climate change, from rising seas to deadly heat waves.

And unlike last fall’s “Special Report on Global Warming of 1.5°C” from the Intergovernmental Panel on Climate Change (IPCC)—which held out the possibility of a 2.7 degree Fahrenheit (1.5 degree Celsius) climate future—the new paper published March 11 in the journal Nature Climate Change employed three practical constraints: spending to cut carbon emissions would be no more than three percent of global GDP per year; no use of geoengineering or technologies to remove carbon; and the climate’s response to doubling carbon in the atmosphere would be at the median level or higher. The latter is called climate sensitivity—how much warming happens when carbon is added to the atmosphere.

“We show that our generation has an important responsibility to ensure that coming generations have a tolerable future,” the paper concluded.

Global emissions are currently over 40 billion tons a year and increased the last two years. Meanwhile the International Energy Agency announced on March 11 that oil consumption will continue to grow over the next five years, driven by increased demand for jet fuel and petrochemicals.

Cutting emissions to zero by 2030 to meet the 3.6 degrees Fahrenheit (2 degrees Celsius) target will be exceptionally difficult, said lead author Jonathan Lamontagne of Tufts University. And there is no path to 2.7 degrees Fahrenheit given the constraints used in the paper, he said.