Climate change activism is warming up this week with climate strikes, a U.N. summit, plus extra media coverage. Naturally, the apocalyptic rhetoric is warming up, too. To take only two examples among many: “2020 could be your last chance to stop an apocalypse,” warned a Los Angeles Times editorial last Sunday. What’s more, Rep. Alexandria Ocasio-Cortez responded to criticism that her Green New Deal is unrealistic by saying, “What’s not realistic is Miami not existing in a few years.”

Before anyone is tempted to start believing any of these predictions, it’s worth recalling that similar predictions of impending environmental doom have been made regularly for the past half-century. They have been made by leading scientific experts as well as journalists and politicians.