Short answers, pulled from the story.
The IPCC Sixth Assessment Report defines an extreme weather event as one that is rare at a particular place and time of year, normally as rare as or rarer than the 10th or 90th percentile of a probability density function estimated from observations. Weather can also be classified as extreme when it causes substantial disruption to the impacted community or ecosystem, even if it is not statistically unprecedented.
A 2021 study found that extreme temperatures accounted for 9.4 percent of global deaths between 2000 and 2019, roughly 5 million people annually. A 2023 study in The Lancet Planetary Health estimated extreme cold events caused over 130,000 excess deaths annually and extreme heat events over 13,000 excess deaths annually in European urban areas during the same period.
A 2023 study estimated that extreme weather caused by climate change cost approximately US$2.86 trillion between 2000 and 2019, equivalent to roughly US$143 billion in losses each year. The IPCC noted in 2011 that annual losses since 1980 had ranged from a few billion to above US$200 billion, with the highest losses occurring in 2005, the year of Hurricane Katrina.
Climate models indicate that rising global temperatures will intensify extreme weather events worldwide. There were around 6,681 climate-related events reported during 2000-2019, compared to 3,656 during 1980-1999. NOAA predicted in 2020 that Atlantic hurricanes would decline in frequency by 25 percent over the 21st century while their maximum intensity would rise by 5 percent.
Poor urban planning, the destruction of wetlands, and building homes along floodplains all amplify the effects of extreme weather. Impervious surfaces such as roads and roofs prevent storm water from being absorbed, while coastal wetland destruction removes the natural buffer that limits storm surge penetration inland. Urban structures also alter wind patterns and contribute to heat islands that raise local temperatures.
Deaths from natural disasters have declined by over 90 percent since the 1920s, even as the global population quadrupled and temperatures rose 1.3 degrees Celsius. In the 1920s, around 5.4 million people died from natural disasters in a decade; by the 2010s, that figure had fallen to around 400,000. This decline is most dramatic in south Asia, where Cyclone Amphan killed 120 people in 2020 compared to the 300,000 killed by a 1970 cyclone of similar scale in the same region.