Global Heat Talks to Open on Cool Note : Environment: Second-round negotiations will begin in Geneva today. The U.S. has already rejected a comprehensive British proposal.

A second round of negotiations on an international accord to combat global warming opens in Geneva today with the United States already giving a cold shoulder to a new British proposal for reducing greenhouse gases in the atmosphere.

Months after most industrial powers have set timetables for reducing their production of carbon dioxide--the pollutant most prominently identified with the potential warming of the Earth’s climate--the Bush Administration remains adamantly opposed to a U.S. commitment.

According to government and environmental sources, Administration officials last week refused to endorse a proposal by British Environment Secretary Michael Heseltine that was designed to meet Washington’s chief concerns about specific objectives and deadlines.

Five months after an opening round of negotiations that produced little of substance, the 10-day Geneva meeting is expected to start off with several days of bureaucratic wrangling before turning to suggested drafts of a global climate convention. The international pact is supposed to be signed next year at the United Nations Conference on Environment and Development in Brazil.

By the estimate of some scientists, global temperatures could be 5 to 10 degrees warmer during the next century than they were before the Industrial Revolution. Many experts believe that the anticipated warming is attributable to the burning of fossil fuels and the production of other pollutants that trap sunlight in the same manner as a greenhouse.

Some skeptics take sharp issue with such climate change projections and with evidence that global warming is being caused by man-made pollution. But an exhaustive international study undertaken in preparation for the current round of negotiations concluded that it is a certainty that the Earth’s natural greenhouse effect is being enhanced by such activities.

The world’s largest producer of carbon dioxide pollution, the United States has insisted from the outset of international discussions that strategies to combat global warming should address other greenhouse gases as well--specifically chlorofluorocarbons, or CFCs, and methane.

During a visit to Washington last week, Heseltine proposed a comprehensive approach aimed at all greenhouse gases, to be implemented as more knowledge and control technology becomes available. In response to another point often made by the Bush Administration, the British proposal also offered the possibility of providing countries with credits for already having reduced emissions of CFCs, which damage the Earth’s ozone layer.

While the Administration, under pressure from the utility and automotive industries, has resisted a national attack on carbon dioxide emissions, the United States has led international action against CFCs. Production of the substances are to be banned by industrialized countries by the year 2000 and by developing nations by 2005.

According to sources familiar with the discussions, Heseltine suggested that the touchy subject of firm targets and deadlines could be avoided by allowing each country to put forward a general strategy for reducing greenhouse emissions.

The Administration, however, is unwilling to embrace the British proposal, the sources said. As a result, the U.S. delegation is expected to propose a technology cooperation initiative in an effort to avoid being viewed as obstructionist.

After the Geneva session, the negotiators are set to meet twice more in 1991--in Nairobi in the fall and in Geneva again near the end of the year.

The global warming issue will be a key element in congressional debate over pending energy legislation. Environmentalists contend that dramatically increased automobile efficiency standards, which are opposed by the Administration, would be the most effective near-term action the United States could take to reduce carbon dioxide emissions.