Global warming: compromise is not a realistic option
December 8th, 2008 by Jim JustThe 2000s are on track to be nearly 0.2°C warmer than the 1990s. And global warming is accelerating, as predicted.
Joseph Romm at Climate Progress has graphed the data.
At the U.K. Guardian, George Monbiot looks at Lord Taylor’s plan to cap global warming at two degrees or a little more by cutting greenhouse gas pollution in the UK by 80% by 2050 and by 31% by 2020. As Monbiot says, this isn’t nearly enough.
An 80% cut for the UK more or less is in line with a global target of 50% by 2050. Lord Taylor’s report says a 50% global cut would make roughly two degrees of warming a “central expectation” and would reduce the probability of four degrees (which it calls “extremely dangerous climate change”) to less than 1%. The report claims that to keep the temperature rise close to two degrees, the world’s greenhouse gas emissions must peak in 2016 then fall by either 3% or 4% a year. A 3% rate of decline is most likely to deliver a temperature rise of 2.2 degrees this century; a 4% annual cut would produce about a 2.1 degree rise.
Monbiot points out that the report gets the science wrong:
But a recent paper in the Philosophical Transactions of the Royal Society, using the same sources, comes to completely different conclusions. It agrees that to deliver a reasonable chance of preventing more than two degrees of warming, greenhouse gases in the atmosphere need to stabilise at a maximum of 450 parts per million, carbon dioxide equivalent (ppmCO2e). But it shows that to achieve this, global emissions of greenhouse gases from the parts of the system we can control need to peak by 2015, then fall by 6%-8% a year between 2020 and 2040, leading to “full decarbonisation sometime soon after 2050?. Even this, it shows, relies on an optimistic reading of the current data. Turner’s suggested cuts are more likely to produce four degrees of warming than two degrees.
Scientists including James Hansen are issuing even starker warnings, arguing that we must stabilize CO2e at no more than 350 ppm CO2e if we are to avoid runaway global warming.
Monbiot points to what could be the first hard evidence that runaway global feedback has begun:
In 2007 methane levels in the atmosphere, which had previously levelled off, began rising again. The most likely reason is that the Siberian permafrost is melting, as a result of the runaway warming of the Arctic. This wasn’t supposed to begin for another 80 years. The great global meltdown appears to have started, yet Turner proposes that we carry on with the old plan as if nothing has changed.
Two decades of procrastination have ensured that only emergency measures now have a chance of preventing a climate disaster. Environmentalists have to resist their impulse to be “realistic” and go along with what seems politically feasible. There’s nothing realistic about compromises which make catastrophe inevitable.