Delaying cuts in greenhouse emissions.

When negotiators from 150 nations meet in Kyoto, Japan, next week to hammer out international limits on greenhouse gas pollution, advocates of a wait-and-see approach can point to some new research to strengthen their position. A study of different policy options suggests that industrialized and developing countries can delay cutting emissions for a decade or more and still stabilize greenhouse gas concentrations at an oft-cited target--double the value seen before the Industrial Revolution.

Tom M.L. Wigley of the National Center for Atmospheric Research in Boulder, Colo., used a computer model of the global carbon cycle to analyze how various emissions options would affect concentrations of greenhouse gases in the atmosphere. One case assumed that industrialized countries decrease their emissions by 1 percent a year, starting in 2000. A more restrictive scenario assumed a 2 percent annual drop after 2000. The least restrictive case let industrialized emissions grow until the year 2010, remain constant until 2020, and then decline by I percent per year thereafter.

In the Nov. 20 Nature, Wigley reports that even the most permissive of these options will lead to stabilization of greenhouse gases at double the preindustrial amount, provided developing countries begin to reduce emissions by 2030.

Kilaparti Ramakrishna of the Woods Hole (Mass.) Research Center argues in the same issue that negotiators should not use Wigley's work to justify a delay in curbing emissions. Ramakrishna cites studies that suggest greenhouse gas concentrations must be stabilized well below twice the preindustrial amount to avoid dangerous climate change. Furthermore, taking early action provides a better chance of successfully stabilizing emissions and may actually save money in the long run, he argues.