The world becomes safer from floods

For the world climate conference to be held in Glasgow, we need a well-informed conversation about the impacts of climate change and the possible costs of the climate policies that are adopted. Some scientific data on climate is in the public domain and is repeated regularly. For example, that climate change is a real and man-made phenomenon, and that it will generally have negative effects. However, there are other scientific facts about climate that are rarely reported, but are just as important to know. Each week, Dr. Bjorn Lomborg presents these interesting facts here.

Although we often hear about costly floods, the relative cost of floods to property and lives has decreased over time. In the United States, which has some of the best long-term data, the relative costs of flooding have fallen almost tenfold in the last 117 years, from 0.5% of GDP at the beginning of the last century to 0.05% in the actuality. The risk of death has been reduced almost three times. Global data is scarcer, but flood research shows that costs relative to GDP and deaths relative to population have decreased globally from 1980 to 2010.

The scary headlines about rising flood costs often come from misleading statistics on total damage, which say more about US economic growth than climate change.

Since the early 1900s, America’s population has quadrupled and annual GDP has increased 36-fold. There are more people and structures in the United States than ever before, even in floodplains. A flood affecting, for example, Atlanta, will encounter many more people and buildings today than 30 years ago. The number of exposed homes in the city’s floodplain increased 58% from 1990 to 2010. At the same time, greater wealth and better technology have made people and property in low-lying areas safer from floods. Only when damage is examined in the context of GDP can one filter what is a sign of growing wealth and what indicates resilience or vulnerability to floods.

Although not widely publicized, the UN’s Intergovernmental Panel on Climate Change says it has “little confidence in human influence on changes in upper river flows on a global scale.” He expects the frequency of flooding to increase in more areas than it decreases, a negative impact of climate change, but much less dramatic than media coverage might suggest. And as the world grows richer, infrastructure and technology are likely to reduce the relative costs of floods and deaths. The data shows that they already are.

The author is president of the Copenhagen Consensus and visiting fellow at the Hoover Institution of Stanford University (California). His most recent book is “False Alarm: How Climate Change Panic Costs Us Trillions, Hurts the Poor, and Fails to Fix the Planet.”