Have one major economy take the lead and have other nations follow, and global warming can be kept below two degree Celsius (3.6°F) .
These are the recommendations made by a new study published Oct. 26 in the journal Nature, saying that the European Union or the United States roughly doubling its ongoing 2030 emissions reduction goal appears to be "one of the few options to stay on track" to prevent sea-level rise and weather extremes.
"If [they] would pioneer and set a benchmark for climate action by others, the negotiation logjam about fair burden sharing could be broken," said Malte Meinshausen, study lead author and from University of Melbourne's Potsdam Institute for Climate Impact Research.
The study found that if these recommendations would be followed, the EU national target for emissions would be minus 60 percent, not the current 26 percent below its 2010 levels by 2030. For the U.S. it would be about 50 percent, not the current 22 to 24 percent below 2010 levels.
Experts warned that achieving the collective goal of limiting warming to two degree Celsius to avoid the perils of climate change entails knowing who should do what for reaching the target, making the allocation of greenhouse gas emission reductions a critical factor in COP21, the upcoming Paris climate change agreement.
Based on current emissions reduction pledges of various countries for the Paris conference, it is not enough to keep warning within the 2-degree limit, warned co-author Sebastian Oberthur from Vrije Universiteit Brussel.
A key factor to address is the two conflicting fairness criteria: one favoring "distributive justice" leading to per-person emissions to be about the same for every nation by 2050, the other leaning toward "corrective justice" and factoring in past emissions to obtain equal per-person cumulative emissions. On board the first criterion are the Europe and U.S., with China and India for the second one.
Emission reduction commitments as well as past negotiations showed that nations tend to vote for what will allow for the least reduction in their emissions. India and China, for instance, were fairly recently industrialized and therefore had fewer emissions than U.S. and the Europe in the past.
Study co-author Louise Jeffery from Potsdam Institute said that data dictates how much a major economy would have to slash its greenhouse gas emissions if all others follow reduction targets based on the same-per-capita scheme or historical emissions records.
"This seems less utopian than a uniform regulation," Jeffery said, adding it highlights the role of the leading economies in the world in mitigating global warming.
The road ahead is hazy for a China leadership as well, with the study indicating that the country has to target a 32 percent reduction below 2010 levels by 2030. In an equal per-capita emissions scenario, however, it only needs to cut emissions by four percent - appearing insignificant but would be "a most crucial contribution."
International Institute for Applied Systems Analysis' Joeri Rogelj said that their research can offer a good look at how major economies can be leaders in a "highly fragmented playing field."
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