Actor Leonardo DiCaprio accepts the award for best actor in “The Revenant.” (Mark Ralston/AFP via Getty Images)
On Sunday night while accepting a long-anticipated Oscar for best actor, for his role in “The Revenant,” Leonardo DiCaprio seized the moment to highlight the plight of the planet.
“Making “The Revenant” was about man’s relationship to the natural world,” DiCaprio said. “A world that we collectively felt in 2015 as the hottest year in recorded history. Our production needed to move to the southern tip of this planet just to be able to find snow.”
“Climate change is real. It is happening right now,” DiCaprio continued. “It is the most urgent threat facing our entire species, and we need to work collectively together and stop procrastinating.” (You can watch the full speech here.)
A little-noticed scientific study that emerged last week not only bears this out — but it also suggests that climate change could be a more urgent problem than we all assumed.
At least since 2013, it has been common to claim that the world has a limited carbon “budget” to emit if we still want good odds of keeping global warming below 2 degrees Celsius above pre-industrial levels, a widely accepted international target.
Because scientists can calculate the relationship between how much carbon there is in the atmosphere and how much temperatures are expected to rise, this concept of a “budget” implies a number beyond which emissions must cease entirely (or beyond which we must find some way of pulling carbon dioxide out of the atmosphere).
In 2013, the United Nation’s Intergovernmental Panel on Climate Change outlined such a budget in its highly influential “Summary for Policymakers for Working Group I” (as this particular, widely read document is called). The panel laid out the math to let readers reach their own conclusions. But the gist was that, taking into account how much we’ve already emitted and the role of gases other than carbon dioxide, humanity can’t emit more than about 1,000 billion tons, or gigatons, of carbon dioxide if we want a 66 percent chance or better of staying below 2 degrees.
Since then, the 1,000 gigaton figure has been quite influential. The U.N. Environment Program, for instance, puts it this way: “The IPCC in its fifth assessment report concluded that to limit global warming to below 2 degrees C, the remaining cumulative CO2 emissions — the so-called carbon budget — are in the order of 1,000 GtCO2.” The program is just one of many parties that have often cited the IPCC’s calculations.
But in a new study in Nature Climate Change last week, Joeri Rogelj of the International Institute for Applied Systems Analysis in Austria and an international team of colleagues interrogate this notion of a carbon “budget” and provide some reasons for thinking we could actually have even less wiggle room than that.
See excerpt of speech at: