Cause of global warming irrelevant
For more than two decades, politicians, scientists and special interest groups have argued about whether climate change caused by global warming is a real threat, or a phony contrivance of environmental extremists. In the scientific community, the debate is winding down. Many of the most respected researchers have reached a verdict: global warming is not only a threat, it's already taking place.
Scientists, of course, don't make public policy. People do, directly and through their elected representatives. Because the global warming debate has been so politicized, anyone who takes a stand on the issue runs the risk of having their motives questioned. And some eminent scientists such as Richard S. Lindzen, a professor of Earth, Atmospheric and Planetary Sciences at M.I.T., forcefully argue that the evidence for global warming as a threat doesn't add up.
But now we've got some very specific evidence of global warming, from the recently released report from the U.S. Environmental Protection Agency, "U.S. Climate Action Report 2002." The report is available from the agency's Web site at (www.epa.gov/globalwarming/publications/car/).
The report finds that the global mean temperature has risen half a point Celsius in the last 100 years, during which time levels of atmospheric carbon dioxide have risen sharply. The temperature change doesn't seem like much, but there's already signs that temperature and precipitation patterns are changing. This means dams, reservoirs, canals and other infrastructure worth tens of billions of dollars could be overtaxed or even made useless by new climate patterns not foreseen when they were built.
Critics such as Lindzen (who helped prepare the report) point out it does not conclude that human actions have caused the changes. True, but any evidence dramatic enough to satisfy critics such as Lindzen would have to include the very changes that are feared. And there is already some very specific evidence of what will happen. You need look no farther than California, the most populous and prosperous state in the Union.
Global warming's first victim?
California is called the Golden State, but it's really the aqueduct and reservoir state. Four-fifths of water used in the state is imported, coming either from the rivers and mountains in Northern California or from the Colorado River. Most of that water heads to Southern California, where companies, farmers and the public use it to exist.
The EPA report concludes that rising atmospheric temperatures will bring more rain and less snow to the Sierra Nevada range, and other Western mountains.
By 2015, the Sierra snowpack will have dropped to 50 percent of the average level from 1961 to 1990, the report states, citing the midpoint of projections from the Intergovernmental Panel on Climate Change. By 2047, the snowpack would drop to 30 percent, and by the end of the 21st century, to 10 percent of that level.
A projected rise in sea level is also a cause for concern, said Daniel R. Cayan, director of the Climate Research Division of UC San Diego's Scripps Institution of Oceanography. This may increase storm damage on the coast and the risk of salt water working its way up the San Francisco Bay/Sacramento Delta estuary, the source of most of California's fresh water.
In general, global warming means Californians will experience longer, more intense summers, with more extremely hot days and possibly a longer dry season, Cayan said.
"We might be susceptible to more wildfires," he said, "because things will get drier earlier and with hotter weather, you'll get more chances for problems."
California's Department of Water Resources closely monitors the Sierra snowpack to determine the state's water supply.
A thin snowpack means the state is in for a "dry" year. A thick snowpack means the state is in for a "wet" year. The state uses this knowledge to decide how much water to release from its reservoirs for human use and to sustain fish and other wildlife that depend on a flow of fresh water.
This exquisitely timed system feeds water into the reservoirs just before the dry, hot summer months. Because the snowmelt is so gradual and predictable, the state can calculate how much water to let loose from its reservoirs in the winter, when the danger of floods is highest.
With warmer temperatures, snow will retreat to higher altitudes. This will make it tougher to operate California's reservoirs, said Maurice Roos, hydrologist for the state.
Too little water on hand means trouble for California's cities, farms, businesses and wildlife. Too much water means not enough capacity for flood control.
"The trouble with the winter runoff is that in many years, we're operating in a flood control mode, so additional water in the winter just has to be dumped," Roos said. "You don't know when a flood is coming, so you maintain that space until the flood season is fairly well over."
Roos said it's still not clear whether rising temperatures will cause the total amount of precipitation will increase or decrease.
"Some models give wetter and some give drier," Roos said. "Water supply is much more driven by changes in mountain area precipitation than anything else. Having said that, if you've got a warmer world, the snow level in the Sierras is going to be higher. That's a pretty safe statement. The question is how much higher?"
A less predictable water supply probably means a less predictable output of hydroelectric power, Cayan said, because power, unlike water, isn't readily stored.
"I don't know of any really big batteries, do you?" Cayan quipped.
The EPA study finds that global warming will hasten the rise of sea level around the world, as snow and ice melts from higher average global temperatures.
In California, vulnerable coastal areas such as those in Encinitas and Monterey are likely to take more of a pounding when big storms occur, Cayan said.
During the 20th century, sea levels rose by about 4 inches to 8 inches, an increase the report states was "significantly more rapid than the rate of rise that was typical over the last few thousand years."
The report said that rise, combined with a deeper flooding from storms, has caused damage to coastal structures, especially along the Atlantic and Gulf Coast states, that earlier escaped relatively unscathed.
For the 21st century, estimates indicate sea level will rise from 4 inches to 35 inches, with a rise of about 20 inches most likely than the extreme values.
Warmer temperatures could lead to more intense storms, Roos said, because warmer air can hold more water. In that event, reservoirs would have to devote more storage to flood control.
Bay/Delta at risk
The combination of storms and higher sea levels can threaten the Bay/Delta estuary, Cayan said. The estuary is created where the massive Sacramento and San Joaquin river deltas merge in their westward flow into San Francisco Bay.
The Bay/Delta is the linchpin of the State Water Project, a critical component of Southern California's water supply. Water travels from pumps in the eastern Delta through the California Aqueduct to Southern California. Salt water is kept out of the eastern Delta by releases of fresh water from reservoirs and by a physical barrier of small peat islands that hold back the ocean's tidal surge from San Francisco Bay.
Many of these peat islands are below sea level in their centers, Roos said, because they sink as the peat dries out. The islands are protected on their circumference by berms. If a storm caused a rising sea to breach the berms, massive flooding could push salt water far up the Delta, reaching the California Aqueduct's intake pumps. The pumps would then have to be shut down until the berms were repaired.
A way out?
So far, attempts to deal with global warming have largely consisted of attempts to reduce greenhouse gas emissions. California's Legislature, for example, is acting to reduce greenhouse gases under the guise of increasing fuel efficiency. These steps are not popular, because they're seen as punitive: we must sacrifice more and lower our expectations in a world of limits. Jimmy Carter and Jerry Brown tried that schtick in the '70s, only to meet with public rejection.
An even more serious obstacle to such plans is that they require worldwide cooperation. It's cheaper to burn fossil fuels to power generators and engines if you don't have to worry about environmental restrictions. That means any reduction in greenhouse gas emissions in the United States is meaningless unless all nations comply. (Those who think the Kyoto protocol would actually limit greenhouse gas emissions are painfully naive. Nations will always flout agreements when it's perceived to be in their own interests. That's why software piracy rates are greater than 99 percent in mainland China, to name one example.)
There should be a better way, and there is one. It's called planning.
Despite the human race's reputation for short-sighted behavior, we respond well to real threats. That's why you're reading this article now on a computer monitor or a printout: the threat of Y2K demanded that scientists, companies and governments work together, and they did.
Many conservatives reject the EPA report because they don't want to encourage ineffectual and politically charged plans such as those described above. A more positive approach would be to take the report as a plan for action. If we know that water supplies will be threatened, we can plan to increase our supply or decrease our usage. For example, desalination, still very expensive, might come to look cheap compared to building huge new reservoirs to hold the winter runoff caused by the disappearing snowpack.
The difference is in the outlook. Instead of bemoaning what will happen to us, let's get busy planning on how to live in this new climate. And then let's see some action.