Unless nations drastically reduce their greenhouse gas emissions over the next decade, the world will exceed 1.5 degrees Celsius of global warming by mid-century, with significant threats to ecosystems and human civilization, according to a new report from the Intergovernmental Panel on Climate Change.
The report examines the difference between 1.5 degrees C (2.7 degrees Fahrenheit) of warming — the target of the 2015 Paris Agreement — and 2 degree C (3.6 degrees F). The likelihood of an Arctic Ocean free of sea ice in summer, for instance, would be once per century with global warming of 1.5 degrees C, compared to at least once per decade with 2 degrees, the report found. Coral reefs would decline by 70 to 90 percent with 1.5 degrees of warming, whereas more than 99 percent would be lost with 2 degrees. Sea level rise would be nearly 4 inches lower with 1.5 degrees of warming than with 2 degrees.
The damages from just 1.5 degrees of warming would cost the world’s economies $54 trillion. That would jump to $69 trillion for 2 degrees of warming.
But the scientists warn that limiting warming to 1.5 degrees will require “rapid and far-reaching” changes to the world’s energy, transportation, agricultural, and other systems for which there is “no documented historic precedent.” Countries will need to reduce greenhouse gas emissions 45 percent by 2030, and 100 percent by 2050. Coal will have to supply less than 7 percent of global electricity, down from 40 percent today. Electricity from renewable energy will have to increase from 20 percent today to 67 percent by 2050.
While technologically possible, the report cautions that making such drastic changes may be politically unlikely and will also require heavy taxes or prices on carbon dioxide emissions, as high as $27,000 per ton by 2100, the New York Times reported.
“Frankly, we’ve delivered a message to the governments,” Jim Skea, a co-chair of the IPCC panel and a professor at Imperial College London, said at a press event following the document’s release. “It’s now their responsibility … to decide whether they can act on it.”
The new IPCC report examined findings from more than 6,000 peer-reviewed studies and was written and reviewed by 91 scientists in 40 countries.
“The next few years are probably the most important in our history,” Debra Roberts, co-chair of the IPCC and a climate resiliency expert in South Africa, said in a statement.