STEPHANIE NEBEHAY EXTREME weather events have increased dramatically in the past 20 years, taking a heavy human and economic toll worldwide, and are likely to wreak further havoc, the United Nations said on Monday. Heatwaves and droughts will pose the greatest threat in the next decade, as temperatures continue to rise due to heat-trapping gases, experts said. China (577) and the United States (467) recorded the highest number of disaster events from 2000 to 2019, followed by India (321), the Philippines (304) and Indonesia (278), the U.N. said in a report issued the day before the International Day for Disaster…