evidence: 1988 turned out to be the hottest year since modern instrumental records began in the 19th century. That mark has since been broken, in 1990, 1998, 2010, 2014, 2015 and 2016. The global average temperature has not gone up quite as much as Hansen predicted—among other things, 30 years ago scientists lacked the sophisticated instruments, accumulated data and vast computing power informing today’s climate models—but he was remarkably close given the limitations, and was dead right on the overall trend. A wide variety of media marked the anniversary. Justin Gillis, writing in The New York Times, noted that, among the confounding factors in 1988, Hansen’s models assumed that we would continue emitting refrigerant gases that contributed mightily to global warming. The following year, the nations of the world agreed to control those gases—"proof that scientific warnings, if taken seriously, can be acted upon at a worldwide scale," said Gillis. "So while his temperature forecast was not flawless, in a larger sense, Dr. Hansen’s 1988 warning has turned out to be entirely on target," said Gillis Sen. Sheldon Whitehouse (D-R.I.) recounted Hansen’s testimony in a 17-minute speech on the Senate floor, noting that "30 years of added science" have proved just how right Hansen was."