Thursday, January 10, 2013

What do fish, water, and methane have in common?

In previous blogs, I have advocated particular approaches to fisheries and suggested an analogy with climate change. This week, I will describe the analogy more explicitly and make the case for its broad applicability, using water management as an example.

The Pineapple Express
I can talk with at least a little authority on water management systems. While working for the National Oceanic and Atmospheric Administration (NOAA), I had the great fortune to be selected for its Leadership Competencies Development Program. Though I worked for NOAA’s Fisheries Service, the program assigned me to work details in the agency’s Office of Oceanic and Atmospheric Research (OAR), which provides national leadership in climate science and gave me some early exposure to issues I wrote about the last couple of weeks.

OAR also develops new weather forecasting technologies. My mentor for the Leadership Program was Marty Ralph, a meteorological researcher who has played a major role in identifying and describing atmospheric rivers, which rapidly carry warm moist air from the tropics to temperate regions and are responsible for many of the major winter storms that batter the U.S. West Coast. I explained my ideas on managing uncertainty to Marty, and he was interested in having me look at the potential benefits that his research might provide to society. We focused on the Folsom Reservoir, a man-made lake above Sacramento, California.

The Folsom Dam, California
This reservoir is a key water source for central California but also protects Sacramento from floods. Visitors to California’s capital will notice that the buildings of old town are raised above street level, an old technology to confront Sacramento’s great flood risk (second only to New Orleans in the U.S. even with the current dam/reservoir). Managing the reservoir is tricky. The water it contains is extremely valuable from mid-spring through mid-fall, when central California gets virtually no rain or snow. However, warm wet storms have the potential to bring vast quantities of water rushing down from the snow-covered Sierra Mountains. The dam has only so much capacity to release water safely, and so reservoir operators must plan ahead. They risk a flood if they do not release enough water and provide space in anticipation of a storm. However, they risk a water shortage during the dry season if they release too much water. Marty recognized that more accurate weather forecasts could result in better information to guide the choices the dam operators face.

To me, the dam operator challenge sounded strikingly familiar. The water in the reservoir is like fish in the ocean. Let’s call this phenomenon the stock. The decisions about releases are like catch quotas. Let’s call this phenomenon the flow. The dam operator faces two fundamental choices: a target stock level, and rules that govern flow. Both involve trade-offs. Larger stocks of water are good for water supply but bad for floods, just as larger stocks of fish are good for ecosystems but may dampen the productivity of fisheries. More responsive flows will keep reservoirs closer to target water levels and can reduce the chances of a flood, but are more costly in terms of required technology on the dam, greater stress on the riverbed and low-lying development downstream, and lost opportunity to generate electricity (which is done using turbines with carefully controlled water flows). Similarly, more responsive fisheries policies will keep fish stocks closer to target levels and reduce the chance of a stock collapse, but require more management infrastructure and impose economic and social costs of unpredictable incomes for fishing operations and their distribution chains.

Climate change can also be thought of in terms of stock—greenhouse gases in the atmosphere; and flows—production of greenhouse gases. In this context, our current policy can be interpreted in one of two ways. One interpretation is that we have a target stock level that is much higher than current greenhouse gas levels and we are willing to accept the possible consequences of those higher levels. The other interpretation is that we have a target that is somewhere near current levels, but unresponsive flow policies that will allow the stock to grow a fair amount before we gradually adjust it downward. Since we do not fully understand the consequences of much higher greenhouse gas levels, the most accurate depiction of current policies might be one of waiting and seeing. The problem is, if it turns out that high stock levels are as bad as several models predict, we will then be forced into a tough decision between adapting to the new conditions versus enacting expensive or risky responsive policies to bring greenhouse gas levels down quickly.

With all three of these systems—water management, fisheries, and climate—we can make smarter policies by considering stock and flows following a common formula. It involves only a few steps, but each requires specialized knowledge. We need three interconnected models: one of the environmental system of concern, another of the management system, and finally one of the socioeconomic system. The environmental model must describe how stock size will change under various flow rules and consider scientific uncertainties. Similarly, the management model must take into consideration choices managers can make and the degree to which these choices will change flows, including implementation uncertainties. The socioeconomic model must translate uncertainties into risks, and be capable of predictions about stock and flows related to the set of objectives (sometimes conflicting) that various user groups have. In combination, this set of models can then be used to evaluate various policy options and give advice on their relative strengths and weaknesses. This advice can be instrumental in helping people to rationally navigate uncertainties by giving them concrete advice about what options they have to reduce future risks and what they would have to give up to achieve these reductions.

Not all environmental issues have stock and flow properties, but many do. Recognizing this commonality should help us to devise means to use science more effectively when crafting environmental policies.

Next week, I plan to switch gears somewhat. Feel free to suggest topics either by commenting here or by contacting me directly.

Wishing you a Happy 2013,

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