The Economic Case for Slashing Carbon Emissions

The climate change news from Washington is cautiously encouraging. No one in power is listening to the climate skeptics any more; the economic stimulus package included real money for clean energy; a bill capping U.S. carbon emissions emerged, battered but still standing, from the House of Representatives, and might even survive the Senate. This, along with stricter emission standards in Europe and a big push for clean energy and efficiency standards in China, provides grounds for hope for genuine progress on emissions reduction.

But while climate policy is finally moving forward, climate science is moving faster. One discovery after another suggests the world is warming faster, and climate damages are appearing sooner, than anyone had expected. Much of the policy discussion so far has been aimed at keeping the atmospheric concentration of CO2 below 450 parts per million (ppm) – which was until recently thought to be low enough to prevent dangerous levels of warming. But last year, James Hansen, NASA’s top climate scientist, argued that paleoclimatic evidence shows 450 ppm is the threshold for transition to an ice-free earth. This would imply a catastrophic rise in sea levels, eventually flooding all coastal cities and regions

To avoid reaching such a crisis stage, Hansen and a growing number of others now call for stabilizing CO2 concentrations at 350 ppm.

…The range of cost estimates for reaching 350 ppm, combined with uncertainties about oil prices and future technologies, make it difficult to choose a single estimate of the total economic cost. Suppose that, for the sake of argument, 2.5 percent of world output must be spent on climate stabilization for years to come. Is that an unacceptably large number?

Imagine an economy growing at 2.5 percent every year (a little slower than the recent U.S. average). Suppose it skips one year’s growth – all too easy to imagine in 2009 – and then resumes growing. That makes GDP 2.5 percent smaller than it would have been, forever. So the “skip year” has the same effect as spending 2.5 percent of output on climate protection every year. Household incomes would take 29 years to double, instead of 28.

…If the worst happens, our grandchildren will inherit a degraded Earth that does not support anything like the life that we have enjoyed. On the other hand, if we prepare for the worst but it does not quite happen, we will have invested more than was absolutely necessary – in perfect hindsight – in clean energy, conservation, and carbon-free technologies. Which extreme presents the greater danger.

Reuters