When the trees move north...
An article in the Toronto Star by Cameron Smith does an excellent job of both setting global warming into context and illuminating the complexities of environmental changes that occur when the ecosystem is disturbed.
Most people wouldn't think that an annual average temperature increase of, say, 1.2 deg Celsius is significant. But in environmental terms it IS significant. It reminds me of a co-op student who once worked with me. The big environmental topic of the time was destruction of the Amazon rain forest, and the impact on oxygen levels. Being a business student, Glen (I can't recall if that was actually his name), had done some research and discovered that the Amazon rainforest "only" contributed 6% of the the world's oxygen supply. From this he reasoned that even if all the Amazonian rainforest were destroyed, world oxygen levels would have minimal impact, and it could recover.
Well, it ain't that simple, Glen. Complexity is what escapes most of the global warming deniers. And W is the leader of that pack. Maybe his Crawford ranch will experience spontaneous combustion.