The difference between climate hazards and climate disasters

Ilan Kelman in Reuters AlertNet: Many claims are made that climate change is increasing disasters, particularly water and weather-related disasters such as floods, hurricanes and heat waves. But such claims make a basic scientific error: Weather hazards and disasters are not the same thing. A disaster requires both a weather hazard and lack of preparedness for it.

A dangerous environmental event such as a tornado or a landslide is a "hazard." It is influenced by climate and climate change. The other, and usually more important, half of the equation is the human and societal inability to cope with that event, termed "vulnerability".

Vulnerability arises when houses are built in a floodplain, when people cannot afford insurance or when governments allocate money to weapons instead of addressing disaster risks. Climate and climate change do not necessarily influence vulnerability. For a disaster to occur, both a hazard and vulnerabilities to it need to be present. Climate change mainly affects hazards, changing the rates, sizes, and locations of storms and floods.

…Climate change's influence is often overemphasized even on the hazard side of risks. Variation in climate patterns has long existed, with cycles of various kinds running from every few years to every few decades or centuries. Scientists are doing their best to separate long-term climate change trends from normal climate trends and variability. That is not always easy, especially at the local level….

Saint Bernard, Republic of the Philippines in February 2006: An aerial view of the mudslide, which destroyed the town of Guinsahugon the morning of Feb. 17. Guinsahugon is located in the southern part of the island of Leyte in the Philippines. US Navy photo