WASHINGTON - Human-caused global warming is here, visible in the air, water and melting ice, and is destined to get much worse in the future, an authoritative global scientific report will warn next week. "The smoking gun is definitely lying on the table as we speak," said top U.S. climate scientist Jerry Mahlman, who reviewed all 1,600 pages of the first segment of a giant four-part report. "The evidence ... is compelling." Andrew Weaver, a Canadian climate scientist and study co-author, went even further: "This isn't a smoking gun; climate is a batallion of intergalactic smoking missiles." The first phase...