Efforts to iron out details of the Kyoto Protocol to control global warming went down in flames last week. Talks in the Netherlands collapsed over the knotty question of how to count forests, croplands and other "sinks" that remove carbon dioxide from the atmosphere.
Although it was intensely disappointing to some, last week's failure may yet provide the opportunity to do what really ought to be done: replace the 1997 Kyoto Protocol with a more effective and politically acceptable agreement to combat climate change.
The Kyoto Protocol is poorly targeted. It focuses on the wrong time frame and addresses only part of the problem. By limiting national emissions, it invites argument about how to count sinks and other emission offsets.
The Kyoto Protocol limits emissions of carbon dioxide and other greenhouse gases to a set level by 2008-2012. But emissions over such a short period hardly matter. Greenhouse warming is a cumulative process that depends on the total stock of heat-trapping gases in the atmosphere.
Because most of these gases remain in the atmosphere for a century or more, only emission reductions that are sustained for several decades can slow or reverse their accumulation.
To stabilize global climate anywhere near its current state will require that we reduce future emissions to well below today's levels, and hold them there. This will require reducing the emissions needed to support today's global population and economy, as well as controlling the dramatic increase in emissions that will be stimulated by future worldwide growth in population and economic activity.
The Kyoto Protocol fails to address the future growth in global emissions because it imposes no requirements on developing countries. Over the next century, China, India, Indonesia, Nigeria and other developing countries are likely to become some of the largest emitters of greenhouse gases.
To prevent serious climate change, we need a long-run approach to stimulate development and worldwide adoption of technologies and living patterns that will slow the growth of greenhouse-gas emissions and ultimately allow
them to be brought far below today's level. Ideally, we can do this without significantly limiting improvements in living standards.
A promising alternative to Kyoto is for national governments to adopt incentives to stimulate greater efficiency in energy use. Although well-targeted subsidies could work, they give too much power to government officials who pick the favored activities. A simpler and surer approach is a national tax on carbon dioxide and other greenhouse gases that would raise the relative price of products that yield high emissions.
The tax would be levied on fuels and other products at the point of production or importation. The revenues would be used to offset other taxes. The overall tax burden would remain the same, which would improve political acceptance.
Unlike Kyoto, this program should be acceptable to both industrialized and developing nations. The program is revenue neutral, within the control of each national government and allows for economic growth. It simply encourages growth to follow a more greenhouse-friendly path.
The tax would start low so it would not impose undue burden on firms and households that produce relatively large greenhouse-gas emissions. But the tax would be scheduled to increase substantially over the next several decades, providing the needed incentive to encourage new, more sustainable, technologies over time. Each country could decide on its own whether to offer a credit for carbon sinks within its national program.
James K. Hammitt is associate professor of economics and decision sciences at the Harvard Center for Risk Analysis.