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These undated handout images provided by NASA shows the extent of surface melt over Greenland’s ice sheet on July 8, left, and July 12, right. Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. Nearly every part of the massive Greenland ice sheet suddenly and strangely melted a bit this month in a freak event that concerned scientists had never witnessed before. NASA says three different satellites saw what it calls unprecedented melting from July 8 to July 12. Most of the thick ice remains, but what was unusual was the widespread area where some melting occurred. (AP Photo/Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory

Global warming

Global warming is leading to such severe storms, droughts and heat waves that nations should prepare for an unprecedented onslaught of deadly and costly weather disasters, an international panel of climate scientists said in a report issued earlier this year.