Hurricane Katrina struck in 2005 and was twice as costly as any previous hurricane — in addition to more than 1,000 deaths, it caused over $80 billion in damages in the United States. Three years later Hurricane Ike inflicted nearly $30 billion in damages in the U.S. The frequency and size of such storms has raised questions about a possible connection between climate change and economic losses from weather disasters.

A 2011 metastudy by the Institute for Environmental Studies at Vrije Universiteit in the Netherlands, “Have Disaster Losses Increased Due to Anthropogenic Climate Change?” analyzes the results of 22 peer-reviewed studies on economic losses from weather disasters and the potential connection to human-caused global warming.

The findings include:

• Economic losses from various weather-related natural hazards, such as storms, tropical cyclones, floods and small-scale weather events such as wildfires and hailstorms, have increased around the globe.
• Corrected for population and capital increases, the studies show no trends in losses that could be attributed directly to anthropogenic climate change.
• All 22 studies show that increased exposure of costly assets to weather events is by far the most important driver for growing disaster losses.

The author states that considerable uncertainties remain, as factors such as vulnerability can only be roughly accounted for over time. He suggests that research projecting losses in the future may be more accurate than analyzing historical costs.

A related study from the University of Colorado and Macquarie University, Australia, “Emergence Time Scales for Detection of Anthropogenic Climate Change in U.S. Tropical Cyclone Loss Data,” suggests that detecting a pattern of increased storm losses could be possible, but would require several decades or longer.

Keywords: disasters, global warming, metastudy