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climate, but the two areas of study had always been viewed as separate. We were just starting to realize we needed a more integrated understanding." For Shindell, it was a case of being in the right place at the right time, with the right skill set. ANSWERING ° °1 °'" III°° -III III;;; S 1K II;;; III ° °1 °'" III 0 S Major papers soon followed, including two seminal works published one month apart in 1999. The first study, published in March in Nature, revealed that the greenhouse effect from burning fossil fuels was affecting weather and stratospheric wind patterns over the northern hemisphere more than previously thought, partially as a result of chemical processes. This was causing dramatic regional shifts in median temperatures. Some Arctic regions such as Greenland were warming during winter at a rate nearly 10 times that of the global average. The second study, published in April in Science, showed that the interaction of increased solar activity and anthropogenic chemicals in the upper atmosphere also affected wind patterns and caused regional climate shifts. Taken together, the two studies yielded strong new proof that increased emissions of manmade pollutants in Earth's atmosphere were inextricably linked to climate change, especially on regional scales. What the studies didn't prove was equally important, Shindell stresses. Neither study found evidence to support skeptics' claims that increased solar activity or natural variability was the primary driver of global temperature increases. "Our model clearly confirmed that greenhouse gases were playing the dominant role," he says. A third paper, published in Science two years later, built on this foundation and, in the process, took aim at one of the denier camp's most oft cited objections to mainstream climate change theory: the Little Ice Age of the 17th century. "During the Maunder Minimum, or the so- called Little Ice Age, there were almost no sunspots, and it got really cold in the eastern United States and Europe. This was the only time in recorded history that New York harbor froze over completely," Shindell explains. In 1998, however, when climatologist Michael Mann and two colleagues published their now - famous large -scale reconstruction of Earth's climate dating back to the year 1400, their model showed only slight changes in climate during the 17th century. The only major global temperature flux reflected in the model was rapid warming in the modern era, represented by a short, sharp upward spike at the end of a long, relatively flat line of temperature averages, giving the model a shape that vaguely resembled a hockey stick. The following year, Mann and his team published a revised large -scale reconstruction dating back to 1000. Once again, it showed only slight changes during the 17th century. To compound matters, the new model also showed only a modest change during a time prior to 1250 known as the Medieval Warm Period.