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The Recent History and Imminent Future of Global Flooding
Kundzewicz, Z.W., Kanae, S., Seneviratne, S.I., Handmer, J., Nicholls, N., Peduzzi, P., Mechler, R., Bouwer, L.M., Arnell, N., Mach, K., Muir-Wood, R., Brakenridge, G.R., Kron, W., Benito, G., Honda, Y., Takahashi, K. and Sherstyukov, B. 2014. Flood risk and climate change: global and regional perspectives. Hydrological Sciences Journal 59: 1-28.

Flooding around the world yearly results in significant losses of both life and property; and, therefore, it is a topic that figures highly in the deliberations of nations, cities and individuals. In addition, the authors of a major new study say that "this issue is very timely and important since, these days, many a large flood is attributed by some to climate change." But is this attribution correct?

What was done
In regard to the IPCC's Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation, or SREX for short, Kundzewicz et al. say that their follow-up study "assesses the literature included in the IPCC SREX report and new literature published since, and includes an assessment of changes in flood risk in seven of the regions considered in the recent IPCC SREX report - Africa, Asia, Central and South America, Europe, North America, Oceania and Polar regions."

What was learned
In terms of the past, the seventeen scientists, hailing from eleven different countries, report that "no gauge-based evidence has been found for a climate-driven, globally widespread change in the magnitude/frequency of floods during the last decades," while noting that "current studies indicate that increasing exposure of population and assets, and not anthropogenic climate change, is responsible for the past increase in flood losses." As for the future, they say that "considerable uncertainty remains in the projections of changes in flood magnitude and frequency," with the result that "there is low confidence in specific projections of changes in flood magnitude or frequency."

What it means
In the concluding paragraph of their extensive study, Kundzewicz et al. state that "although media reports of both floods and global flood damage are on the increase, there is still no Mauna-Loa-like record (see Vorosmarty, 2002) that shows a global increase in flood frequency or magnitude." Thus, they write that "blaming climate change for flood losses makes flood losses a global issue that appears to be out of the control of regional or national institutions." And they therefore state that "the scientific community needs to emphasize that the problem of flood losses is mostly about what we do on or to the landscape," which implies that individual, community, county and state responsibility "will be the case for decades to come."

Vorosmarty, C.J. 2002. Global change, the water cycle, and our search for Mauna Loa. Hydrological Processes 16: 135-139.

Reviewed 18 June 2014