Three part series on global warming by Elizabeth Kolbert in The New Yorker, about 50 pages overall, excellent reportage on current science and politics on this topic.

A snip from part one:
Global warming is routinely described as a matter of scientific debate—a theory whose validity has yet to be demonstrated. This characterization, or at least a variant of it, is offered most significantly by the Bush Administration, which maintains that there is still insufficient scientific understanding to justify mandatory action. The symposium’s opening session lasted for more than nine hours. During that time, many speakers stressed the uncertainties that remain about global warming and its effects—on the thermohaline circulation, on the distribution of vegetation, on the survival of cold-loving species, on the frequency of forest fires. But this sort of questioning, which is so basic to scientific discourse, never extended to the relationship between carbon dioxide and rising temperatures. The study’s executive summary stated, unequivocally, that human beings had become the “dominant factor” influencing the climate. During an afternoon coffee break, I caught up with Corell. “Let’s say that there’s three hundred people in this room,” he told me. “I don’t think you’ll find five who would say that global warming is just a natural process.”
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The entire 3-part series is online;
here's a link to part 3 which has links to the first two parts:
http://www.newyorker.com/fact/content/?050509fa_fact3