The greenhouse debate: Time for action?



In recent years, debate has intensified over whether to act now or delay actions that would reduce emissions of greenhouse gases. In a recent contribution to this debate in Nature, Schlesinger and Jiang [1991] conclude that “the penalty is small for a 10-year delay in initiating the transition to a regime in which greenhouse-gas emissions are reduced.” This conclusion is premature, since these authors did not consider a number of pertinent factors.

Schlesinger and Jiang used a simple energy- balance climate model with an upwelling- diffusion ocean to examine the surface temperature response to transitions between various Intergovernmental Panel on Climate Change (IPCC) [Houghton et al., 1990] trace gas scenarios. They found that “a delay of 10 years in initiating a 20-year transition from the IPCC [business as usual] scenario to any other IPCC scenario has only a small effect on the projected warming in 2100.” From this they concluded that “the penalty for a 10-year delay is small.” We offer several reasons why we think this is a non sequitur.