Everyone agrees that this must be done, but not on who, exactly, should do it. Given the deadlock, an America-led plan to try tackling other sorts of greenhouse gas, announced on February 16th, is especially welcome. It is not a breakthrough; but it is progress.
Six countries—America, Canada, Mexico, Sweden, Ghana and Bangladesh—have agreed to a five-year programme to cut their emissions of "short-term climate forcings", a suite of pollutants that linger less long in the atmosphere than carbon dioxide, but which nonetheless have a profound affect on the amount of solar energy it absorbs. These pollutants (soot, methane and hydrofluorocarbons, or HFCs) are believed to contribute about a third of the human-caused rise in global temperatures.
The countries concerned hope to persuade others to join their scheme, which is called the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants.
This is an excellent idea. Methane, which comes from decaying organic matter, stays in the air for only 12 years but absorbs some 20 times as much energy as carbon dioxide. Soot hangs around for just a few days; but also absorbs heat and, when it falls to the ground on snow-covered mountain ranges, increases the amount sunlight abosrbed, which makes snow and ice melt faster. HFCs, emitted by refrigerants and solvents, have a warming effect 1,440 times more powerful than carbon dioxide.
Reducing emissions of these forcings would slow the current rate of warming: America's State Department estimates its proposed measures could slow warming by 0.5°C by 2050. Nor do they look especially costly.
The initial budget is $15m, with most of that coming from America. There is already a template for dealing with similar problems. The Montreal Protocol of 1987 successfully eliminated ozone-damaging chloroflourocarbons from the atmosphere. And they promise other benefits, unrelated to the climate.
For example, these pollutants cause millions of premature deaths every year. They also lower crop yields.
But excellent as this is, the world's soaring carbon dioxide emissions remain the elephant in the atmosphere. They are the single biggest contributor to rising temperatures, will remain in the atmosphere for 100 years, and unless drastic action is taken to mitigate them, costly and dangerous climate change will not be averted.
economist.com
