To stabilize the climate and avoid catastrophe (such as sea level rise, shrinkage of Arctic Ocean ice and global heat waves), we will need to cut carbon emissions by a minimum of 70 percent, according to a recent study by scientists at the National Center for Atmospheric Research in Boulder, Colo. That level of reduction would stabilize atmospheric concentrations of CO2 at about 450 parts per million — roughly 17 percent higher than current levels.
Their study, which will be published in the journal Geophysical Research Letters, states that "we can no longer avoid significant warming during this century," but implies that we do still have the opportunity to control it. By the end of this century, the research says, a 70 percent reduction in CO2 emissions could hold temperature increases to roughly 1 degree F above current levels.
But we know that 450 parts per million is not where we need to be. An overwhelming majority of scientists, including NASA scientist James Hansen, state that where we need to be looks a lot more like 350 ppm, if we are to stay in the Holocene. The way we see it, what this study is inadvertently saying is that we need zero, now, before the world becomes a much different, much less inhabitable place.
The headline asserts that, "New Study Shows that a 70 Percent Cut in CO2 Could Stabilize Climate."
That seems rather improbable, given that the Earth's climate has changed radically throughout the planet's history. And, of course, humans were not around for most of that history.
Climate changes -- that is what is does. However, I'll grant that it is likely to stabilize after the sun goes supernova and shrinks into a red dwarf. Of course, subterranean bacteria might well alter even the climate in that era.
That is a valid point about separating the concepts "stabilize" and "climate." Two points made by the study's authors are pertinent: first, the study itself emphasizes steps needed to avoid "dangerous climate change," the most disruptive aspects of the changes associated with current emissions trajectories. Second, lead author Warren Washington is clear that "this research indicates that we can no longer avoid significant warming during this century."
If people are led to expect a return to a vague but comforting "stability," and yet continue to see mounting evidence of climate-linked disruption in coming years, political support to achieve deep emissions cuts could be jeopardized as people lose confidence that policy can address the problem and yield results. That would be unfortunate -- we need to be especially careful about language that could jeopardize the will to act, when actions might make such a huge difference in long-term outcomes.
This is a tough call. Any efforts for the positive are good, or at least better than nothing, but I would also make the point that slow-onset changes like variability in climate trends cannot be easily curtailed. Estimates are looking at emission cuts by the end of the century- practical if we're going to be stubborn, but terrible given the sensitive framework we are all operating in.
My personal belief is that we can't expect any real motivation to change until our comfort is threatened or even disrupted. (our being Americans like myself and other first-worlders)