If you wanted to question whether global warming is indeed upon us, last week was not the time to do it. Two weeks before the official beginning of summer, a heat wave baked the eastern third of the U.S. and Canada, driving temperatures high into the 90s and even 100s. At the same time, a flurry of scientific papers was released that seemed to explain all the late-spring suffering. In one study, French researchers reported that heat-trapping greenhouse gases are at their highest levels in 420,000 years. In another, U.S. scientists found that 57 species of butterfly may be altering their...
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