Starting Monday in Lima, Peru, representatives of about 190 countries began their latest in more than two decades of meetings to discuss how to slow and reverse long-term, manmade global warming.
The discussions, technically known as the 20th conference of the parties to the 1992 U.N. Convention on Climate Change (UNFCCC), are aimed at producing a blueprint that can be molded into a new global climate agreement by next year, and would enter into force in 2020.
One can be forgiven for viewing these talks with considerable skepticism, considering that they have resulted in a world in which greenhouse gas emissions continue increasing, not decreasing, and where the chances of averting the worst consequences from global warming -- such as the virtual disappearance of the Greenland ice sheet, which would send global average sea levels soaring -- are declining.
“The window of opportunity to reduce emissions will close soon,” said Peru's environment minister and president of the new climate talks, Manuel Pulgar-Vidal, at the opening session of the climate talks.
As Pulgar-Vidal alluded to in his remarks, the Lima climate talks are occurring at a time of unprecedented momentum in the climate arena. They are the first round of climate talks to take place post-Peoples' Climate March, post-U.S.-China emissions announcement, and post-Green Climate Fund commitments.
They are also taking place during what is likely to be Earth's warmest year since at least the dawn of instrument records in 1880, and very likely much longer than that.
However, the new, post-2020 agreement, even if it is politically ambitious, is unlikely to avert the stated intention of the UNFCCC itself (which even the U.S., which is often skittish about global treaties, signed onto). That agreement calls for the avoidance of "dangerous... interference with the climate system."
Politically, that rather vague wording has been interpreted to mean that warming would have to be limited to at or below 2 degrees Celsius above preindustrial average temperatures (what the global average temperature was in about 1850). World leaders agreed to this target during the Copenhagen climate summit in 2009 and again in Cancun in 2010.
However, growing emissions of greenhouse gases since then mean that this target is slipping further from our grasp.
Speaking before delegates to the climate talks on Monday, Rajendra Pachauri, who chairs the U.N. Intergovernmental Panel on Climate Change, said the definition of "dangerous" global warming is not one for scientists to determine, but rather belongs in the political realm. Still, he presented the task of meeting the 2-degree goal as a near Herculean one, considering the level of ambition going into the Lima meeting.
“Science cannot tell us what is dangerous” interference with #climate system, @IPCC_CH chair Pachauri tells #COP20— Andrew Freedman (@afreedma) December 1, 2014
Pachauri - Meeting 2 deg C emissions target requires emissions to be reduced to 0 or “negative” by 2100. #COP20— Andrew Freedman (@afreedma) December 1, 2014
Pachauri told delegates that the world has used well over half (65%) its "carbon budget" that is compatible with the 2-degree goal, with just about 35% of the budget left. (The carbon budget is the estimated maximum amount of carbon dioxide that could be emitted over time while staying within the 2-degree Celsius limit.)
In order to keep the 2-degree target viable, Pachauri said, global emissions of greenhouse gases, such as carbon dioxide, would need to peak within a decade, and decline to zero or even negative numbers by the year 2100. The less we cut emissions now, the more expensive and steeper we'd need to cut emissions in coming decades, studies show.
Nothing of that scale is currently being considered. Take the U.S.-China joint announcement about emissions cuts on Nov. 12, for example. It was appropriately hailed as a landmark development in climate policy, but didn't even commit one of the parties to cutting emissions at all. Instead, it addressed the major challenge of China's rapidly growing emissions.
China, which is the world's largest absolute carbon emitter, for the first time committed to capping its emissions by 2030 or earlier, and also vowed to increase its use of renewable energy to 20% of national energy production. The U.S., for its part, committed to cutting emissions by between 26 to 28% below 2005 levels by 2025, which represents a doubling of the rate of emissions reductions that had previously been planned.
All eyes in Lima are now on India, where the new government of Prime Minister Narendra Modi has yet to announce a post-2020 climate commitment. India is the third largest emitter, and as a rapidly developing country, it is also on a growing emissions trajectory. Therefore, its reaction to the U.S.-China moves will have major consequences for the future climate.
Right now, in the absence of more ambitious emissions reduction targets, scientists have said we're on course to see an increase in global average temperatures of between 4.5 degrees Fahrenheit to 14 degrees Fahrenheit by 2100.
Studies have shown that warming on that scale would compromise the stability of the Greenland ice sheet, destabilize parts of Antarctica, cause sweeping changes in ecosystems and raise the risk of deadly heat waves and other extreme weather events, among other impacts.
As scientists put it in a recent report: "The consequences of such a temperature rise would be catastrophic."
Even if warming were limited to 2 degrees Celsius above preindustrial levels, we're still in for more severe and longer-lasting heat waves, more precipitation extremes, and dramatic changes in global ecosystems that could threaten many species' survival.