Tropical cyclone behavior in a warmer world

The surfaces of most tropical oceans have warmed by 0.25-0.5 degrees Celsius during the past several decades. The Intergovernmental Panel on Climate Change (IPCC) considers that the likely primary cause of the rise in global mean surface temperature in the past 50 years is the increase in greenhouse gas concentrations. The global community of tropical cyclone researchers and forecasters as represented at the 6th International Workshop on Tropical Cyclones of the World Meteorological Organization recently released a statement on the links between climate change and tropical cyclones. During the past decade, there have been a number of high-impact tropical cyclone events around the globe. These include 10 landfalling tropical cyclones in Japan in 2004, five tropical cyclones affecting the Cook Islands in a five-week period in 2005, Cyclone Gafilo in Madagascar in 2004, Cyclone Larry in Australia in 2006, the first-ever documented hurricane in the South Atlantic Ocean in 2004, and the extremely active 2004 and 2005 North Atlantic tropical cyclone seasons - including the catastrophic socio-economic impact of Hurricane Katrina. The participants of the IWTC 6 worked out a comprehensive statement providing the latest guidance and consensus views of the tropical cyclone community on the effects of climate change on the behavior of tropical cyclones. Common questions asked by the media and the public (and addressed in the statement) include: Will the basin and global numbers of tropical cyclones go up in a warmer world? Will the intensity of tropical cyclones increase in a warmer world? Will the formation regions of tropical cyclones expand in a warmer world? Will tropical cyclones retain their destructive potential further into the midlatitudes in a warmer world? And, Are we already seeing the effects of climate change in the behavior of tropical cyclones? This talk will provide a detailed description of the observed behavior of tropical cyclones over the past 30 or 40 years, and will address the possible changes to tropical cyclone behavior that may occur in a warmer world. The consensus statements concerning tropical cyclones and climate change made by participants of the 6th International Workshop on Tropical Cyclones (IWTC-VI) are presented and critically analyzed in this talk from the perspective of an active participant in the drafting of those statements.