During that time, a white moth actually evolved or adapted to brown, for better camouflage. After years of this century ' s cleaner air, however, the London moth seems to be turning white again, she said. More recently, power plant emissions in the Midwest have been the major cause of the acid rain that ' s been killing trees, fish and entire lakes in eastern Canada and New England. The land-clearing fires that Southeast Asians started last year got widely, wildly out of control, and the resulting airborne ash choked and sometimes killed Indonesians thousands of miles away. Nonetheless, with overall climate, the links between cause and effect aren ' t so clear.
Climate relates to factors stretching from the ocean ' s depths to the atmosphere ' s outer reaches.
Climatologists tend to need a century C not a week, month or year C to identify something that ' s a trend, rather than weather ' s natural variability. Those who believe humans are causing global warming tend to point to the Industrial Age as the starting point C in particular, to the carbon dioxide generated by the use of carbon-based fuels. That could be a hard sell with a general public trained to expect instant feedback. The countries where reducing would have the biggest impact C as well as be easiest and cheapest C are those nations least able to afford the cleanup . And, the factor overriding all three problems is a matter of politics.