It's official: The winter of 1996-97 was one of the wettest in United States history. In the last few years trends in flooding have been rewritten in many regions of the country, along with heat waves, record heat days, severe rains, and dry spells. The weather has gotten peculiar everywhere, and this past winter's rainfall and flooding is symptomatic of this larger trend.
Scientists suspect that our emissions of greenhouse gases are part of the reason for our odd new weather patterns. In Kyoto, Japan, this December, the United States, Japan, and more than 150 other parties to the 1992 Rio Treaty on Climate Change will consider setting binding global limits on greenhouse gas emissions. These are produced primarily by burning fossil fuels for a wide variety of human needs.
Scientists have tied the escalation of atmospheric greenhouse gases to long-term climate changes, such as global warming and intensified water cycles. According to the Intergovernmental Panel on Climate Change (IPCC), a group of 2,500 expert scientists from around the world, atmospheric concentrations of greenhouse gases - carbon dioxide, nitrous oxide, and methane - have grown significantly by about 30 percent, 15 percent, and 145 percent respectively since the Industrial Revolution began.
They are expected to more than double next century, and are growing faster than at any time in our geological record. As a result, by the end of the next century global temperatures are expected to rise between 1.8 and 6.3 degrees F., with a best guess of 3.6 degrees - the largest warming the earth has seen in 100 million years. The IPCC reached consensus that these climate changes are beyond natural variation and reflect "a discernible human influence."
It depends on where you live
Depending on where you live, the potential adverse impact of these trends on human habitation, water supplies, food supplies, infectious diseases, forests, fish and wildlife populations, urban infrastructure, floodplain, and coastal developments may be enormous.
Solutions to these problems could include energy-efficient technologies, incentives for conservation, flexible emissions-permit trading by industries, reduced energy subsidies, and other methods to reduce emissions.
Together, these issues constitute the most serious and complex environmental issue ever faced by the international community.
The winter rainfall and a long list of other peculiar weather events indicate that long-term changes in the earth's climate already are having widespread impacts on the water cycle, weather patterns, natural resources, and human systems here in the US. Scientists with the National Climatic Data Research Center (NCDRC) in Asheville, N.C., recently analyzed a century of data from thousands of United States weather stations and made some compelling findings:
* Over the past 100 years the average US surface temperature has increased almost 1 degree F. In some locations, such as southern California, it has increased as much as 4 degrees. In others, such as Mississippi, it has actually cooled, but these areas are expected to warm in the future.
* Extreme temperature events, such as the 1993 Chicago heat wave, have increased on a steady trend that is expected to continue as average temperatures shift upward. A small shift in the average means that low-probability extremes of the past, such as 100-degree days, will become far more common.
* Yearly rainfall in the US has increased 4 percent over the last 100 years (the equivalent of half the annual flow of the Mississippi River falling in new rainfall each year). In some coastal areas, like my own state of Connecticut, it has increased as much as 20 percent. In California and Wyoming, it has fallen by a corresponding amount.
* A greater proportion of rain now falls in severe weather events (deluges of two inches or more of rain in a day). Most of it comes during cool months when it does little to help crops or forests, or as flash floods that leave too fast to relieve drought-stricken areas. Actuarial statistics for severe flooding are being rewritten by a wave of record-breaking rainfall events nationwide. The need for federal disaster-relief funding has grown.
The trend documented by NCDRC continued steadily over the last century. Extensive climate modeling by the IPCC indicates it is likely to intensify. An exact scenario is not clear, but even low-end forecasts are serious.
The water balance in drier areas of the United States could be dramatically affected, squeezing supplies for agriculture, fisheries, urban, commercial, and recreation uses.
Higher temperatures and lower rainfall have already contributed to recent droughts in the Southwest and intermountain regions that have rivaled the dust bowls of the 1930s and 1950s. Deserts could expand beyond current areas in the Southwest. Climatologists say a 5 percent decrease in precipitation in Texas, coupled with a 3.6-degree F. temperature increase, could result in 35 percent less water in the state's rivers, aquifers, and estuaries, potentially triggering major resource problems.
The Great Lakes could lose two to eight feet of water level, shrinking already very tight hydroelectric supplies and complicating water supply problems in cities like Chicago. Upper Midwest corn production could fall 15 to 30 percent, and soybean production 10 to 25 percent, unless costly adjustments are made by farmers.
Forests could gradually move north or die out. Under worst-case scenarios the "wood baskets" of the Northwest and Southeast could disappear at the same time in the middle of the 21st century, with major economic implications. Forest-dependent wildlife could become endangered as forests die out faster than new habitats evolve.
Diseases such as malaria, dengue fever, and encephalitis are forecast to migrate northward and intensify. Sea level has risen a foot in the last century in the Chesapeake Bay, about half from global warming, and this trend is expected to accelerate in the next century. Summer heat waves and drought conditions could intensify this problem as farmers pump more water from aquifers and the ground subsides.
Some climate changes could be favorable, at least in the short term. Fruit growers in Florida and south Texas could face fewer killing frosts. Some Northern states could gain longer growing seasons and new crops. Some diseases would decline from an overdose of temperature and flooding. Increased carbon dioxide uptake by plants could partially offset some greenhouse gas emissions. And higher water use by plants could counteract higher rainfall to a point.
But when projected negative and positive consequences of climate change are netted out, the result appears to be largely negative. Major adjustments in our quality of life and cost of living could be required.
To find an effective way
Given these potential scenarios, and a host of other problems becoming apparent worldwide, it is not surprising that the international community is trying to find an effective way to deal with the problem of climate change.
If we don't set long-term greenhouse emissions limits now, and instead wait to see just how our climate changes, it may be too late when we do act. Greenhouse gases remain in the atmosphere for decades - even centuries - before leaving the atmosphere, so we need to begin reductions soon to achieve a useful long-term effect. A new generation of energy-efficient technologies requires a long lead time for development and implementation.
As we enter full-scale international negotiations this year, I hope we will take a hard look at climate changes already occurring here, and the implications for our future if they continue and grow. If nations of the world fail to act in concert in the face of hard facts, consequences for humankind will be enormous. There are no benefits from delay.
* Sen. Joseph Lieberman (D) of Connecticut is a member of the Senate Environment and Public Works Committee.