The world’s top climate researchers today have for the first time put an upper limit to how much carbon pollution in the atmosphere Earth can support in order to keep global warming below the agreed target increase of 3.6 degrees Fahrenheit.
The limit - 1 trillion tons of carbon - is also expected to be reached by 2040, according to one of the authors of the new report, Myles R. Allen of the University of Oxford.
That is not a lot of time to reduce current greenhouse gas emissions. But besides increasing renewable energies, another alternative suggested is to dramatically improve efforts to prevent the carbon that is burned in fossil fuels from reaching the atmosphere.
But will this new climate science assessment from the Intergovernmental Panel on Climate Change (IPCC) make any difference? Will this upper limit help to motivate success where diplomacy and politics have failed? After all, the United States, China and India are the three biggest carbon polluters and also the three biggest holdouts when it comes to signing international climate treaties.
The report released today in Stockholm from more than 250 scientists with the IPCC is the group’s fifth report since 1990. It predicts temperatures will rise by 0.3 to 4.8 degrees Celsius (0.5-8.6 degrees Fahrenheit) this century, depending on various scenarios involving humanity's commitment to reducing greenhouse gas emissions.
The Nobel-winning group also raised their conviction level that humans are responsible for more than half of the warming over the past 60 years, from 90 percent in 2007 to now 95 percent, calling it "extremely likely."
Scientists from all major nations are represented on the IPCC, and the climate assessment is the product of several years of scientific review. One of the long-awaited revaluations was on sea level rise. The group now projects sea levels to rise between 26 and 82 centimeters (10.4 and 32.8 inches) by 2100.
While its conclusions are the latest in what has become an incremental assessment and thus scientifically already expected rather than earth-shattering, the IPCC report can still help galvanize public opinion, according to John Reilly, co-director of the Joint Program on the Science and Policy of Global Change at the Massachusetts Institute of Technology.
“There’s not a lot of surprising new information that will change things,” Reilly said. “These sorts of reports serve as a marker to bring more external pressure on countries to respond.”
Reilly says that the science underlying climate change has been well understood for some years.
“The challenges for the U.S. or China or India in doing something (on climate change) have more to do with how they see themselves in the world or domestic politics,” he said.
Here’s a quick look at how things stand in each nation:
China took over the top spot as the world’s biggest emitter of carbon in 2008, but has also made huge strides in renewable energy such as wind and solar, according to Reilly. Even with plans to boost nuclear plants and become the biggest wind and solar producer, that won’t put a dent in China’s appetite for coal. In China, “there’s this incredible demand for energy,” he said.
The United States remains the world’s biggest energy hogs per capita, according to estimates by the European Commission. President Obama has bypassed Republicans in Congress by issuing new EPA rules to cut carbon emissions from coal-fired power plants. Overall, U.S. carbon emissions dipped nearly 7 percent during the recession and could fall 17 percent by 2025 if more is done to boost efficiency and burn less fossils fuels, according to a State Department report released this week.
Even though India hasn’t signed U.N. climate treaties, it is making a big push for solar and wind power, according to Gireesh Shrimali, assistant professor of energy economics at the Monterey Institute of International Studies. Shrimali expects that emissions in India will likely rise in the coming years. “A lot of Indians still don’t have electricity,” Shrimali said. “Between 10 and 30 percent. There is always this tussle between development and being green.”
Yet the country has developed a serious climate plan, and with nearly 20 gigawatts of generation, India ranks as the world’s fifth-biggest producer of wind power. (China is first with nearly 80 gigawatts; the U.S. ranks second).
Both experts say that the rise in extreme weather, such as Hurricane Sandy-like storms, or floods that left millions people homeless in southern India in 2012, will likely do more to push the public and governments more than the IPCC report.
“Climate change is not a simple problem; it’s a problem in all of our backyards,” Shrimali said. “We all take responsibility, but how do we share the burden?”