All nations must face up to the threat of a climate disaster and take steps against global warming, Prime Minister Margaret Thatcher of Britain said Tuesday. Thatcher, in a keynote speech to a United Nations meeting of ministers on the issue, said much more research is needed but a ``clear case for precautionary action'' exists now. ``It is a race against time ... to save our planet,'' French Prime Minister Michel Rocard told the officials from some 120 countries, including more than 80 ministers. In an appeal aimed in good part at the United States and the Soviet Union, Mrs. Thatcher demanded all countries begin work on binding commitments to rein in rising pollution by ``greenhouse gases.'' The limits would be for a planned global treaty on climate change to be ready in 1992. But there were increasing signs Tuesday that ministers, contrary to European Community hopes, will fail to agree on targets or deadlines so as not to endanger Wednesday's conference-ending declaration. ``Not to come to a result would be a very bad signal,'' German environment minister Klaus Toepfer told reporters. ``We have to do our best to come to a minimum compromise.'' Environmental groups said the draft declaration looks ``more like a non-declaration as all the crucial points on carbon dioxide reduction targets, dates and the urgent call for immediate action have been removed.'' Carbon dioxide pollution, much of it from burning fossil fuels, is seen as the leading cause of global warming. Methane and chlorofluorocarbons are other heat-trapping ``greenhouse gases.'' Americans and Soviets are the biggest contributors of man-made carbon dioxide emissions. Washington opposes immediate targets against carbon dioxide pollution, saying more scientific data is needed to justify the enormous costs involved in changing ways of life. The Soviet Union, Saudi Arabia and some other countries also have reservations. China sounded a Third World note of reluctance. ``Measures to protect the global climate should not hinder the economic development of developing countries,'' delegate Song Jian told the two-day meeting. Mrs. Thatcher, who holds a chemistry degree, warned climate change could occur more quickly than current computer models suggest. ``Should this happen it would be doubly disastrous were we to shirk the challenge now.'' Many steps would be ``sensible in any event'' - improving energy efficiency, developing alternative sources of supply, reforestation, rethinking industrial processes and tackling the waste problem, she said. Mrs. Thatcher and Rocard followed the lead of scientists from some 100 countries, who met last week in the conference's first part. The experts made plain that global warming undoubtedly exists and appealed to politicians for immediate measures. Scientists say global temperatures could rise at their fastest rate in 10,000 years next century if nothing is done. Among the feared upheavals are rising sea levels that would displace coastal dwellers, desertification and vast changes affecting wildlife. Bikenibeu Paeniu, prime minister of Tuvalu, told delegates they may hold the key to the ``continued existence'' of his South Pacific coral atoll group and other islands. ``We in the Pacific, the Carribbean and elsewhere have done the least to create these hazards but now stand the most to lose,'' he said.