It seems hardly a surprise when El Nino, blamed for everything fromtornado activity to a jump in the number of Major League Baseball rainouts, is now being linked to global warming. In this case, however, El Nino isn’t the cause but the effect: yet another piece of physical evidence, stretching for hundreds of miles across the Pacific, that global warming is here to stay. “We haven’t caused El Nino (by human activity),” Professor Raymond Bradley, Geosciences, told a Smith College Audience. “But this particular El Nino is quite extraordinary. There’s evidence that El Nino’s effect is increasing in warmer periods.” A more feisty El Nino, increasing in frequency and severity, is only one of the negative human impacts discussed by Bradley during the Smith forum on global warming. According to Bradley and many other scientists, a systematic pattern of human activity resulting in a rising atmospheric temperature could threaten the planet’s food supply and drinkable water and produce many more disease-bearing insects. Bradley also displayed diagrams and charts showing an alarming increase in the levels of atmospheric carbon dioxide and global temperature over the last four decades. Bradley has become somewhat of a global-warming guru recently after he, UMass colleague Michael Mann and University of Arizona scientist Malcolm Hughes published a ground-breaking article in Nature that used 600 years of records from tree rings, ice cores, coral reefs and human annals to document the climate over that time. Among other results, the article showed that three years during the 1990s have been the warmest in six centuries. The Nature article has been called “the clearest and most dramatic evidence that the world is experiencing global warming caused by human activity.”