Billionaire fund manager Bill Ackman, a staunch President Trump ally, has warned the world is on the brink of a “self-induced economic nuclear winter” – as he begged the commander in chief to pause his sweeping tariffs. “The President has an opportunity on Monday to call a time out and have the time to execute on fixing an unfair tariff system. Alternatively, we are heading for a self-induced, economic nuclear winter, and we should start hunkering down,” Ackman wrote in a lengthy X post Sunday night. “May cooler heads prevail.” Ackman, who endorsed Trump’s run for President, issued the stark...