60 NYT > Global Warming - Narrowed by 'CHRISTMAS TREES' http://t
opics.nytimes.com/top/news/science/topics/globalwarming/index.ct
x?s=newest&field=des&match=exact&query=CHRISTMAS
TREES&&partner=rssnyt &lt;p&gt;On Feb. 2, 2007, the United
Nations scientific panel studying climate change declared that
the evidence of a warming trend is "unequivocal," and that human
activity has "very likely" been the driving force in that change
over the last 50 years. The last report by the group, the
Intergovernmental Panel on Climate Change, in 2001, had found
that humanity had "likely" played a role.&lt;/p&gt; &lt;p&gt;The
addition of that single word "very" did more than reflect
mounting scientific evidence that the release of carbon dioxide
and other heat-trapping gases from smokestacks, tailpipes and
burning forests has played a central role in raising the average
surface temperature of the earth by more than 1 degree
Fahrenheit since 1900. It also added new momentum to a debate
that now seems centered less over whether hu