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</o:shapelayout></xml><![endif]--></head><body lang=ES link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><i><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>Science </span></i><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'> 03 Jan 2020:<br>Vol. 367, Issue 6473, pp. 10-11<br>DOI: 10.1126/science.367.6473.10 <o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span lang=EN-US style='font-size:24.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>Past megadroughts hit North and South America in tandem<o:p></o:p></span></b></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>Paul Voosen<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span lang=EN-US style='font-size:18.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>Summary<o:p></o:p></span></b></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>For several decades, scientists have suspected that decades long droughts occurred in North and South America simultaneously during medieval times. Until recently, however, there were not enough tree ring measurements from South America to confirm this. Now, new work presented at a meeting of the American Geophysical Union, which uses nearly 3000 paleoclimate records to guide a global climate model, has found that these megadroughts often did occur simultaneously, and were frequently driven by unusually frequent and severe La Niņa conditions in the Pacific Ocean. The research reveals a heightened hemisphere wide risk should such megadroughts become more frequent with global warming.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>