Personal experience tells us that weather disasters such as heat waves, droughts, wildfires, floods, and tropical cyclones have been worsening by the year. The World Meteorological Organization (WMO) has now substantiated this impression with evidence. The WMO Atlas of Mortality and Economic Losses from Weather, Climate and Water Extremes (1970 – 2019), just released in August this year, not only confirms our observations in the U.S., but these weather disasters have been worsening around the world.
Driven by climate change and better observation and reporting, the number of weather disasters has increased fivefold over the 50-year period. But thanks to improved early warnings and emergency response, the number of fatalities decreased almost threefold.
When an extreme weather event occurs, a common question is “Was this event caused by climate change?” A simple answer is that changing climate leads to changes in the frequency, intensity, spatial extent, duration, and timing of weather and climate extremes. But scientists address this question in a different way: “Was the chance of this event happening affected by human influences on the climate, and if it was, by how much?”
Answering this question has become a very active area of research in recent years. Scientists use two sets of model runs to compare the probability, or characteristics, of the event in question. This type of study can establish the degree to which the event probability or characteristics were influenced by anthropogenic factors.
The figure below, from a BBC article that is based on the WMO report, shows overall increases in the number of recorded disasters and the reported economic losses over time; while the number of reported deaths decreased.
The WMO report breaks down these statistics into types of weather disasters. The two WMO figures below show that increases in the number of disasters are mostly from storms and floods. They also cause the most economic losses.
For the U.S., the WMO report shows that weather disasters had caused 10,000 deaths in the 50 year period, with the Hurricane Katrina in 2005 reported the highest death toll of 1,833. The total economic losses of $203 billion due to weather disasters account for 38% of losses worldwide ($1,375 billion), half of those losses occurred in last 10 years (2010s).
The WMO figure below shows that the 10 tropical cyclones that caused the most economic losses globally during the period 1970 – 2019 happened in the U.S. Three of the extreme events—Hurricanes Harvey, Maria and Irma—with the biggest economic losses occurred in 2017. Taken together, these three storms accounted for 35% of the total losses from the top 10 disasters between 1970 and 2019. However, these losses from tropical cyclones cannot be entirely attributable to the strength of the storms. In the U.S., property values are much higher than in Asia’s pacific coasts, another typhoon-prone region, and ocean front properties are often prized in the U.S.
In contrary to the developed world, deaths caused by weather disasters in developing countries far outpaced economic losses. More than 90% of the total deaths related to weather disasters have occurred in developing countries. The biggest killers have been droughts that would cause famines. Droughts have been responsible for 650,000 deaths, while extreme high temperatures took nearly 56,000 lives.
The WMO report does not cover the year 2020. In comparison with the sobering statistics that cover up to the year 2019, weather disasters in 2020 and 2021 thus far (particularly tropical cyclones, wildfires, and floods) have stood out. This trend is indeed frightening.
