2011 the most expensive year for natural disasters in history
An exceptional accumulation of very severe natural catastrophes, including earthquakes in Japan and New Zealand, tornadoes and flooding in the U.S., and flooding in Australia and New Zealand, make 2011 the highest-ever loss year on record, even after the first half-year, said re-insurance giant Munich Re in a press release this week. The $265 billion in economic losses accumulated this year exceeds the previous record year, 2005, which had $220 billion in damage (mostly due to $125 billion in damage from Hurricane Katrina.) Unlike 2005, this year's losses have been headlined by two huge earthquakes--the March 11 quake in Japan ($210 billion) and the February 22 quake in New Zealand ($20 billion.) But with the Northern Hemisphere's hurricane season just beginning, this year's record losses may see a significant boost from hurricanes.
Figure 1. Stunned survivors survey the destruction left by the EF-4 Tuscaloosa-Birmingham tornado of April. With a price tag estimated at $2 billion, this was the single most expensive tornado of all-time. The record stood only three weeks, being surpassed by the $3 billion in damage from the Joplin Missouri, tornado. The two tornado outbreaks that spawned these tornadoes rank as the globe's 3rd and 5th most destructive natural disasters so far this year. Image from an anonmous posting to Twitter.
Climate change and damage from weather-related disasters
In an interview with MSNBC, Peter Hoppe, who runs Munich Re's Geo Risks Research/Corporate Climate Center, said that while the damage trend for earthquakes, tsunamis and volcanic eruptions is fairly stable, damage from severe weather events is on the upswing, even after factoring in increases in population and wealth. He cited natural events such as La Niña and El Niño as factors in some of the damaging weather events, but added that warming temperatures appear to be adding a layer "on top" of that natural variability. In particular, he noted that the floods this January in Australia--that nation's most expensive natural disaster of all time--occurred when ocean temperatures off the coast were at record warm levels. That meant "more evaporation and higher potential for these extreme downpours", and "it can only be explained by global warming."
Figure 2. The five most expensive natural disasters of 2011, as estimated by Munich Re.
However, the there is a lot of controversy on whether economic losses due to weather-related disasters is increasing due to climate change. A 2010 paper in the Bulletin of the American Meteorological Society by Netherlands researcher Laurens Bouwer titled, "Have disaster losses increased due to anthropogenic climate change?", looked at 22 disaster loss studies in various parts of the world. All of the studies showed an increase in damages from weather-related disasters in recent decades. The big question is, how much of this increase in damage was due to increases in population, and the fact people are getting wealthier, and thus have more stuff to get damaged? Fourteen of the 22 studies concluded that there were no trends in damage after correcting for increases in wealth and population, while eight of the studies did find upward trends even after such corrections. In all 22 studies, increases in wealth and population were the "most important drivers for growing disaster losses."
Bouwer's review of these 22 disaster loss studies was critiqued this year by Neville Nicholls of the School of Geography and Environmental Science of Montash University, Australia. His analysis, published in the Bulletin of the American Meteorological Society, notes that Bouwer's study of damage losses did not include the impact of improvements in building codes and weather forecasting. We can expect both factors to have significantly reduced damages due to storms in recent years. Nicholls concludes, "The absence of an upward trend in normalized losses may be due to a balance between reduced vulnerability (from improved weather forecasting and building techniques) and increased frequency or intensity of weather hazards." In his reply to Nicholls' comments, Bouwer states that Nicholls "provides no support that these factors have actually contributed to a substantial reduction in losses over the period of the last decades."