The world's mountainous regions are home to about 800 million people and the source of some of the world's major rivers. In these regions, runoff is strongly affected by temperature. This suggests that flooding could be quite sensitive to global warming, but there has been some lack of scientific consensus on the effects of temperature variations on floods.
Allamano et al. show that global warming does increase flood risk significantly. The authors analyzed runoff data recorded by 27 stations in the Swiss Alps and used a simple probabilistic model to study how flood risk varies with temperature, precipitation, and elevation in mountainous regions.
The researchers found that large floods have occurred more frequently in recent years than in the past, and they predict that global warming will result in such floods occurring even more often in the future.
In particular, they found that if global temperatures increase by 2 degrees Celsius (3.6 degrees Fahrenheit), then large floods that occurred about once every 100 years could occur up to 5 times more often.
The research appears in the journal Geophysical Research Letters.
Authors include P. Allamano, P. Claps, and F. Laio, Dipartimento di Idraulica, Trasporti ed Infrastrutture Civili, Politecnico di Torino.
- Allamano et al. Global warming increases flood risk in mountainous areas. Geophysical Research Letters, 2009; 36 (24): L24404 DOI: 10.1029/2009GL041395
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