GLASGOW—Calling the agreement a historic moment in the fight against the generation-defining threat, world leaders at the COP26 climate conference told reporters Wednesday that they had set the ambitious goal of phasing out fossil fuels entirely by the time the Earth runs out of them. “This conference recognizes the pressing need to take action against the scourge of climate change, and so it brings me great pleasure to announce a strategic initiative to reduce our fossil fuel use to zero once we’ve used up all the fossil fuels on the planet,” said US climate envoy John Kerry, stressing that the pact between 192 nations also ensured that “not a single drop of oil” would be burned in cars or planes once every last drop had been consumed. “Wealthy countries will lead the way here, ensuring we bear the burden of using as much oil as possible in industries ranging from transportation to manufacturing. That will help move up our timeline for the day we can finally no longer physically use oil because no trace of it remains on the face of the earth. After that, of course, we’ll probably have a hundred years of natural gas.” Kerry added that countries had unanimously agreed to impose steep fines on nations using fossil fuels after the date when they no longer exist.