Why the Lima Agreement Is a Failure

California flooding
A lifeguard building destroyed by Hurricane Marie’s waves in Point Mugu, California, on August 28, 2014. A rise in sea level threatens to wipe out many coastal communities over the next century. Mario Anzuoni/Reuters

When a draft international climate agreement was finally solidified in Lima, Peru, last week, negotiators shrugged. It was a significant step forward for the typically inert international climate talks. But it was not perfect. Its highly general language leaves room for any number of potential emissions commitments at the Paris talks next year, outlined only as "common but differentiated responsibilities and respective capabilities, in light of different national circumstances."

Environmental groups worry that it keeps us, as Secretary of State John Kerry recently put it, on "a course leading to tragedy."

Now a new assessment by six European research bodies confirms what experts have already warned about: The international climate agreement drafted in Lima fails to prevent us from passing the previous do-not-pass benchmark of 2 degrees Celsius (3.6 degrees Fahrenheit) of warming by 2100.

With the Lima agreement, "we are on track to [be] between 3 to 3.5 degrees [by 2100] so far," says Massimo Tavoni, deputy director of the climate change unit at Italian research body Fondazione Eni Enrico Mattei, one of the institutions involved in the report. Three degrees warming, he says, is achievable in the "most optimistic case" assessed by the report, in which the researchers assume that the Lima agreements are augmented by a more ambitious agreement in the near future.

That would require other major emitters, like Indonesia and other countries in Southeast Asia, to adopt emission-cutting plans comparable to the ones adopted by the U.S., the European Union and China. In a more pessimistic scenario, where future agreements are less ambitious, we could see 3.5 to 4 degrees of warming. And if we do nothing beyond implementing the agreements in the Lima talks, Tavoni says, we're looking at warming of between 4 and 5 degrees.

"Four or 5 degrees would be a disaster," Tavoni says. "We need to get on the right track to get at least to 3 degrees. I'm not very optimistic that what we see now will do that. I'm not sure. [But] I'm hopeful that if we step forward, we can."

The discussion of 2, 3 and 4 degrees warming reflect a global average—but temperatures at the poles warm faster and will see greater temperature increases than that. For perspective, scientists say 4 degrees of warming would be enough to melt most or all of the glacial ice at the poles. As climatologist and former NASA Goddard Institute for Space Studies chief James Hansen put it in a paper published in the journal Nature last year, "4 degrees of warming would be enough to melt all the ice.... You would have a tremendously chaotic situation as you moved away from our current climate towards another one. That's a different planet. You wouldn't recognize it.... We are on the verge of creating climate chaos if we don't begin to reduce emissions rapidly."

But even 2 degrees is a threshold many scientists say would be calamitous to cross. Global warming of 2 degrees is the tipping point at which the Greenland Ice Sheet may switch into unstoppable melting, raising sea levels by 23 feet over an unknown period, according to The New York Times.

According to the six separate models analyzed in the new report, keeping warming to a 2-degree maximum is possible only if global carbon dioxide emissions peak between 2020 and 2030—or, barring that, if nations invest significantly more resources into drastically changing the energy consumption patterns of their citizens and in developing new, clean-energy technologies. The agreement drafted in Lima would not even come into effect until 2020 and falls far short of that goal. It stipulates policies that would set peak emissions in several countries fast enough to reduce warming by a degree to a degree and a half more than what would be achieved without a policy, but not enough to keep us within 2 degrees of warming, the report says.

The World Bank warned in a 2012 report that a world where temperatures rose 4 degrees by the end of the century would trigger "a cascade of cataclysmic changes that include extreme heat-waves, declining global food stocks and a sea-level rise affecting hundreds of millions of people."

Even if leaders surpass expectations and emissions peak between 2020 and 2030, there are "inherent uncertainties" when modeling future climate change that could make even that scenario fail in preventing greater than 2-degree warming, explains Tavoni. Elements crucial to climate forecasts—like cloud dynamics and ocean behavior—are impossible to predict with accuracy.

"Even if you were to do everything, there is no assurance that you will get to 2 degrees," he says.

For example, if leaders somehow achieve peak global emissions by 2020, there is a 33 percent chance that we still would exceed the 2-degree limit regardless, according to the research. If leaders wait to achieve peak global emissions until 2030, the picture is even less certain: There is a 50 percent chance that global temperatures would exceed 2 degrees warming anyway.

Tavoni says there are scenarios that still offer hope to keep average temperature within 2 degrees, even if countries reach peak emissions later than they should. The catch is that those scenarios are far more expensive. Countries would have to invest huge sums in clean technology and drastically change the way their citizens use energy. In the long run, probably in the second half of the century, Tavoni says, we will have to invest in technology to remove existing carbon from the atmosphere to keep warming in check.

"Because of the combined emissions we have already put into the atmosphere, there is a limit to what we can reduce," he says. "Even with all best practices, even if we were to implement stringent policies right away, there is that historic CO2."