LE BOURGET, France — Even as progress appeared to slow at the U.N. climate conference here Friday — with a new text not now expected until Saturday, a day after the event’s previously anticipated end — a panel of scientists criticized the current draft for embracing ambitious climate targets without necessarily showing how to achieve them.
The response hinted at the possible emergence of new battle lines that could characterize a post-Paris world — one in which countries embrace strong temperature goals like 1.5 degrees Celsius but stay vaguer about how to get there, and carbon-calculating scientists point out the inconsistencies.
Whether this actually occurs to be sure, still depends on the content of a final Paris text, which still remains up under negotiation.
The researchers — including Kevin Anderson, director of the Tyndall Centre for Climate Change Research at the University of Manchester and a major critic of unrealistic assumptions about how easily the world can limit warming to below 2 degrees C — were reacting to the latest draft agreement text, released late Thursday.
The document embraces a goal of limiting warming to “well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C”– a strengthening of goals that many scientists and also vulnerable nations have applauded. But the text goes on to say that this will be achieved through “the peaking of greenhouse house gas emissions as soon as possible” followed by “rapid reductions thereafter towards reaching greenhouse gas emissions neutrality in the second half of the century.”
It is the second part of this that drew the scientists’ ire. It’s not clear that a mere peaking “as soon as possible,” or “greenhouse gas emissions neutrality” thereafter, will be enough to hit the most ambitious climate targets, they suggested.
Rather, the researchers said, to stay within a given temperature threshold emissions have to be taken to zero — a word that does not appear in the current text — and for 1.5 degrees C in particular, they need to be cut rapidly and immediately.
The current text is “not consistent with science,” said Anderson.
“The frustration as a scientist at this point is that once you set that global planetary guardrail, everything else must be consistent with that target,” added Steffen Kallbekken, research director for the Climate Economics Unit at the University of Oslo. “It means reaching…70 to 95 percent reduction in emissions by 2050 as an absolute minimum, and it actually means being careful with statements like ‘greenhouse gas neutrality.'”
Kallbekken, Anderson, and the other scientists suggested that the language about “greenhouse gas neutrality” could open up a massive door to so-called “negative emissions” technologies that could theoretically remove large amounts of carbon dioxide from the air, even as humans keep on emitting it. If we emit too much carbon dioxide to stay within a given temperature target, meanwhile, negative emissions technologies might theoretically cool the planet back down again, allowing for a temporary overshoot without too much lasting planetary harm.
However, scientists have recently been highly critical of assumptions that we can launch these technologies on a mass scale without suffering major knock-on impacts, such as using vast amounts of land that might otherwise be used to grow food. At the panel on Friday, Anderson suggested that relying on these technologies may lead us to believe in “spurious options for the future.”
Another researcher present, Joeri Rogelj, Research Scholar at the International Institute for Applied Systems Analysis, is one of the few scientists to have published a study on precisely what it would take to keep warming below 1.5 degrees Celsius in the long term. The current draft text’s language about “greenhouse gas neutrality,” he said, “kind of obscures the fact that global carbon dioxide emissions will have to become zero to stabilize warming at any level.”
“To limit warming below 1.5 by the end of the century, there are no scenarios available that basically delay global mitigation action beyond 2020,” Rogeli added — the start date of the proposed agreement. “That means that from 2020 onwards, and preferably before that we need to be starting rapid emissions reductions.” In contrast, the current draft text’s call for merely peaking emissions “as soon as possible” leaves vast wiggle room.
To be sure, the researchers praised the inclusion of a 1.5 degree Celsius temperature aspiration in the current text, along with the idea of holding warming well below 2 degrees Celsius. And they emphasized that the current text could change again by Saturday, perhaps in the direction they’re hoping for – but also perhaps becoming weaker.
“It’s incredibly positive that world political leadership has now recognized the science,” said Kallbekken. “It has to then stay scientifically consistent right through.”
