Water Problems: No Prediction Needed

This is the eighteenth of a continuing series of essays and interviews from Earth Institute scientists on the prospects for a global climate-change treaty. Check with us daily for news and perspectives, and to make comments, as events unfold throughout the Copenhagen meetings.

With Copenhagen heading for an apparent impasse, the world faces an uncertain and potentially dire climate future. Of particular concern is the inability to predict how rainfall across the globe may change in intensity, frequency and seasonality. If there are droughts in some places and floods in others, there will be direct impacts on agriculture, health, energy and natural ecosystems. It is urgent that we set an agenda to adapt to these prospects, even though the predictions are uncertain.

Let’s look back in time. In most places where we have multi-century historical records of rainfall or “proxy” natural records, such as tree rings, we see persistent shifts in rainfall patterns. Presumably due to natural causes, these often go beyond ranges experienced in the 20th century, and have lasted years or decades. In the meantime human population has boomed. Many developing countries are particularly subject to such swings, and now with huge numbers of people and little infrastructure, they are particularly vulnerable. Developed countries also are now quite susceptible to systematic climate shifts, since much of their modern infrastructure, especially for water, was designed on the assumption that climate does not change with time. Today, in many places in North America, Australia and Europe, this infrastructure is at the limits of its performance, and their chance of failure is high if protracted droughts or extreme floods come along.

Given the prospects for human suffering and international conflict over water, Copenhagen offers an opportunity to focus the climate change debate in a new way, that has nothing to do with conjecture: we must increase the resilience of water resources to shifts that we already know are quite real.

There are two opportunities for water management that need impetus from Copenhagen, or any successor to it. First, we need advances in seasonal and multiyear climate forecasts, and to increase our skills in using there to make decisions on water allocation and system operation. This alone could bring a substantial reduction in impending climate risks. For instance, so far, very little effort has been invested in long-term flood forecasts, even though the likely payoffs are high.

The second opportunity is to develop a better understanding of the nature of the past climate shifts. If we can develop a strategy for anticipating and detecting such shifts, then a variety of adaptation measures could be invoked to better manage risks. For instance, North America has an extensive network of data that reveals systematic multi-decadal shifts into wet or dry conditions in many places. Only a few other countries have such an extensive data set. Stimulating the development of additional data that spans a few centuries will be invaluable for adapting to climate in other parts of the world. Water managers could use this information to better assess the probability that a drought will persist, and for how long. Insurance or financial risk managers could appropriately develop and price their products. Designers of infrastructure could consider such factors to appropriately size new storage or distribution facilities.

While there is pessimism about the prospects of a binding agreement on future carbon emissions, there are things we can do now to address problems that are already with us—and will almost certainly accompany us down the road. It is imperative that the momentum and interest generated at Copenhagen be channeled toward them.

Upmanu Lall directs the Columbia Water Center. Daniel Stellar is assistant director.