91.   But Hansen said the record was still not long enough to determine if the change was linked to warming of the atmosphere from rising levels of greenhouse gases.

92.   But methane, too, is a greenhouse gas, and an odiferous one.

93.   But only a day later, they were distressed when he rebuffed calls for a specific target for reducing greenhouse gases.

94.   But it is the most abundant greenhouse gas, more prevalent than methane, nitrous oxide or other gases blamed for trapping heat that increasingly warms land and oceans.

95.   But scientists like Broecker warn that heat trapped by greenhouse gases could force the issue.

96.   But not all scientists are ready to blame global warming and greenhouse gases for the antics of El Nino and La Nina.

97.   But the biggest emitter of greenhouse gases, the United States, has decided not to play the game.

98.   But the catalytic converter does nothing to decrease emissions of carbon dioxide, the main greenhouse gas.

99.   But the Kyoto approach - negotiations to set national limits on the emissions of the greenhouse gases that are heating the earth - cannot solve the problem.

100.   But some environmentalists have expressed disappointment over the consequences of the NAFTA treaty and say the administration should have more aggressively forced industry to curtail greenhouse gases.