Since we seem to lack the will to reduce this threat by cutting greenhouse-gas emissions, we should at least make ourselves more resilient to severe weather.
So it's encouraging to see cities and states worldwide work on better protecting themselves from storms. Rotterdam, for one, has set a goal of being "climate-proof" by 2025. It is, among other things, building climate-proof architecture. One example of what this city is aiming for is the already-existing Floating Pavilion -- three bubble-like hemispheres that, as the name implies, float on the river, making it impervious to flood surges. Many other such structures are in the planning stages.
Rising water caused by increased rainfall is one of the main threats that climate change poses to cities. Increasing concentrations of greenhouse gases in the atmosphere could raise water-vapor levels by as much as 30 percent, new research from the National Oceanic and Atmospheric Administration has found. As a result, says Kenneth Kunkel of the National Climatic Data Center, "We have high confidence that the most extreme rainfalls will become even more intense, as it is virtually certain that the atmosphere will provide more water to fuel these events." Polluted Runoff Heavy rains in cities whose stormwater and sewage systems are linked, in turn, can overwhelm water-treatment capacity, causing flooding and contamination. When rains are heavy in Philadelphia, for example, the runoff from roads and buildings overwhelms the city's water-treatment facility. This is why, each year, 13 billion gallons of a nasty mix of polluted water and untreated sewage flow into the city's waterways.
Philadelphia is responding with a new set of incentives. Most cities charge each property a stormwater fee based on potable water usage -- even though usage has little or nothing to do with how much the property contributes to stormwater runoff. A building with a hard parking lot contributes much more to stormwater runoff than a green property with swales and infiltration trenches does, regardless of how much water is used by the occupants.
So Philadelphia is moving toward a fee based on the stormwater attributable to a property. The city will use software that enables it to map a property's area and measure how much of it is "impervious" to stormwater, in that it prevents the water from soaking into the ground. The larger the share of impervious area, the higher the fee.
This should give fee payers an incentive to make their properties more absorbent and to adopt other strategies to reduce runoff. And there is much more that can be done.
A recent brief published by the Natural Resources Defense Council, Eko Asset Management Partners and the Nature Conservancy proposes that cities aggregate retrofitting projects into bundles for financing, to bolster the attractiveness of the individual projects. It also proposes a trading system -- so that if I'm willing to reduce the runoff from your building, I can finance that improvement and get credit for it on my own stormwater charge.
These ideas are all worth trying. Many of them have been discussed this week at a conference of mayors and private-sector leaders, convened by President Bill Clinton and New York Mayor Michael Bloomberg, focused on how to build resilient urban infrastructure.
Making our cities more resilient to stormwater is the type of "no regrets" effort that would make sense even in the absence of climate change. At the same time, as we work to manage the risks, we shouldn't lose sight of the need to also reduce the threat of climate change itself. Attaching a price to carbon -- through either a national carbon tax or a permit-trading system -- could raise hundreds of billions of dollars a year while cutting greenhouse-gas emissions. And some of the revenue could be invested in making U.S. cities more resilient.
Peter Orszag is vice chairman of corporate and investment banking and chairman of the financial strategy and solutions group at Citigroup Inc. and a former director of the Office of Management and Budget in the Obama administration.