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Effectiveness of Kyoto Protocol on climate in absence of US ratification discussed

While it is likely that the Kyoto Protocol will be ratified, the absence of the United States from the agreement will limit its environmental effect, MIT climate policy experts reported Feb. 17 at the AAAS annual meeting.

Ronald G. Prinn, the TEPCO Professor and head of the Department of Earth, Atmospheric and Planetary Sciences (EAPS), was co-organizer of the symposium titled "Climate Change: Integrating Science, Economics and Policy." Two of the seven invited speakers at the symposium were from MIT. One of them, EAPS Professor Peter H. Stone, said major uncertainties arise in any attempt to forecast climate changes because of uncertainties both in climate science and in our ability to project economic changes.

Henry D. Jacoby, co-director of the Joint Program in the Science and Policy of Global Climate Change, said it's increasingly likely that the Kyoto Protocol will be ratified and honored by many countries, and perhaps even become legally binding on them.

Absent from this agreement, he said, will be the United States and perhaps other nations, which will limit its environmental effect. Further, parties rejecting Kyoto may adopt a different architecture for formulating their response, threatening an extended period of fragmentation of efforts. His talk assessed the seriousness of this circumstance, considered our evolving understanding of climate-change risk and explored possible directions for what promises to be an endless round of international negotiations on the issue.

Uncertainty in climate forecasts

In science, the major uncertainties in forecasting climate change that have been identified relate to the sensitivity of the climate system, the rate at which anomalies in heating are absorbed by the deep oceans and the forcing associated with anthropogenic aerosols, Stone said. In economics, the major uncertainties include population growth, growth in labor productivity, changes in energy efficiency and changes in the cost of non-carbon-based energy technologies.

Uncertainty about future policies is intimately connected with the economic uncertainties, he said. Recently, progress has been made in quantifying scientific uncertainties, but economic uncertainties have so far only been based on expert judgment.

Estimates of the uncertainties can be propagated through models that project climate change, and the resulting changes in global mean surface temperatures and the associated uncertainties will be illustrated. Uncertainty in regional changes are even larger, and in many cases even the sign of the changes, particularly with respect to precipitation, is also uncertain.

A version of this article appeared in MIT Tech Talk on February 27, 2002.

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