Weather Extremes: Coping with the Changing Risks

In its 2012 Special Report, the Intergovernmental Panel On Climate Change concluded that “A changing climate leads to changes in the frequency, intensity, spatial extent, duration, and timing of extreme weather and climate events, and can result in unprecedented extreme weather and climate events.”  The science of detecting, attributing, and projecting extreme events and changes in extreme events poses many challenges, but recent progress has been rapid.  Existing data indicate increases over the last 50 years in several kinds of climate extremes, including high temperatures, the fraction of precipitation falling in the heaviest events, and extremes associated with high sea levels.  Some parts of the world have seen increases in the length or severity of droughts.  Climate models project continuing changes in these extremes.  Over the last 30 years, economic losses from weather related disasters have also increased.  The available evidence points to increasing exposure (an increase in the amount and/or value of the assets in harm’s way) as the dominant cause of this trend.  Economic losses, however, present a very incomplete picture of the true impacts of disasters, which include human and environmental components.  The risk of climate-related disaster emerges from the overlap of weather or climate extreme, exposure, and vulnerability of the exposed humans, ecosystems, and investments.  The relationship between the magnitude of the weather extreme and the ensuing disaster is not strong.  Moderate extremes can lead to major disasters, especially in communities subjected to other stresses or in cases when extremes are repeated.  There is a wide range of opportunities for reducing disaster risk and improving disaster response.  The most effective options tend to produce both immediate benefits in sustainable development and long-term benefits in reduced vulnerability.  Solutions that emphasize a portfolio of approaches, multi-hazard risk reduction, and learning by doing offer many advantages for resilience and sustainability.  Some options may require transformation, including questioning assumptions and paradigms, and stimulating innovation.