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Restoring the Everglades

The Florida Everglades is the largest single wetland and the last remaining subtropical wilderness in the United States. Comprising more than 1.5 million acres, the Everglades is known as the "River of Grass" for its main source of water — a shallow river approximately 120 miles long and 50 miles wide that runs from Lake Okeechobee to the Florida Bay. This once-constant water supply — augmented by periods of torrential rain — and the warm climate historically have helped support a wide variety of plants and wildlife, including rare and endangered species such as the American crocodile, Florida panther, and West Indian manatee.

The Everglades is also a major source of water for surrounding communities. Canals and levees capture and divert water for drinking, irrigation, and flood control. But since the mid-1800s, more than half of the wetland has been drained to provide land for agriculture and urban development. The current water management system has been tapped so often that it soon will not be able to provide adequate supplies of water to agricultural and urban areas, or sufficient flood protection, let alone support the remaining natural ecosystems. As a result, the South Florida Ecosystem Restoration Task Force — a group representing several federal, state, and local entities — has mounted an intense effort to restore and protect the Everglades and its water sources.

At the request of the U.S. secretary of the interior, who chairs the task force, a new committee of the National Research Council has been formed to provide technical advice on aspects of the restoration efforts such as hydrological and ecosystem modeling, land and water management, species diversity, and related agricultural and urban issues. The project is expected to continue indefinitely as restoration efforts proceed. — Molly Galvin (See listing under New Projects.)

The Warming Earth

Scientists have been concerned about global warming for many years. Measurements indicate that the Earth’s surface temperature rose by about 1 degree Fahrenheit during the last century. Many researchers are convinced that this rise in temperature is a result of increasing amounts of "greenhouse" gases. But an apparent incongruity between surface and upper-air temperatures has fueled a debate over whether global warming is actually occurring. Although surface temperatures are rising, data collected by satellites and weather balloons since 1979 show that temperatures in the upper atmosphere have changed very little.

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A new report from a panel of the Research Council concludes that despite these differences, the warming of the Earth is undoubtedly real. In fact, surface temperatures in the past two decades have risen at a rate substantially greater than average for the past 100 years. The panel cautioned, however, that this rapid temperature increase is not necessarily representative of how the atmosphere is responding to long-term, human-induced changes, such as increasing amounts of carbon dioxide and other greenhouse gases.

While a combination of human activities and natural causes has contributed to rising surface temperatures, other human and natural forces may actually have cooled the upper atmosphere, the panel said. For example, natural events such as the eruption of Mt. Pinatubo in 1991 tended to decrease atmospheric temperature for several years. And burning coal and oil for energy produces tiny aerosol particles in the atmosphere that can have a cooling effect. Upper-air temperatures also can be reduced by depletion of ozone in stratosphere, caused by chlorofluorocarbons and other chemicals being emitted into the atmosphere. When these variables are accounted for in atmospheric models, satellite and balloon data more closely align with surface-temperature observations.

Because global warming is a long-term process that can be masked by year-to-year climate variability, warming trends are most clearly revealed by surface-temperature measurements, which have been recorded daily at hundreds of locations for more than a century. These data indicate that the Earth is, in fact, warming. Satellites have been collecting data from the upper atmosphere for only about 20 years.

The differences between surface temperature and upper-air temperature records also may be partially attributed to uncertainties in temperature measurements. The nations of the world should establish a better climate monitoring system to ensure continuity and quality in data collection, the panel said. Measurements should include not only temperature and wind, but also ozone, water vapor, clouds, and aerosols. — M.G.

Reconciling Observations of Global Temperature Change. Panel on Reconciling Temperature Observations, Climate Research Committee, Board on Atmospheric Sciences and Climate, Commission on Geosciences, Environment, and Resources (2000, 100 pp.; ISBN 0-309-06891-6; available from National Academy Press, tel. 1-800-624-6242; $25.25 plus $4.50 shipping for single copies).

The committee was chaired by John M. Wallace, professor of atmospheric sciences at the University of Washington, Seattle. The study was funded by the National Oceanic and Atmospheric Administration and the Aluminum Corporation of America.

Our Common Journey

The world’s population is expected to hit 9 billion by 2050 and then level off by the next century. How can the transition to a stabilizing population also become a transition to sustainability — one in which human needs are met while the planet’s environment is nurtured and restored? And how can science and technology contribute to that process?

A new report by a committee of the National Research Council argues that societies should approach this monumental goal not as a destination but as an ongoing, adaptive learning process. Speaking to the next two generations, it proposes a strategy for using scientific and technical knowledge to influence future action to reduce fertility, enhance urban systems and agricultural production, and improve energy and materials use, ecosystem restoration, and biodiversity conservation. It also recommends an approach for building a new research agenda for "sustainability science."

The report documents large-scale historical trends in social and environmental change. And it identifies the greatest threats to sustainability — in areas such as human settlements, agriculture, industry, and energy — and explores the most promising opportunities for circumventing or mitigating these threats. It also discusses what indicators of change — from human birthweights to atmospheric chemistry — will be most useful in monitoring the planet’s transition to sustainability.

Our Common Journey: A Transition Toward Sustainability. Board on Sustainable Development, Policy Division (1999, 363 pp.; ISBN 0-309-06783-9; available from National Academy Press, tel. 1-800-624-6242; $49.95 plus $4.50 shipping for single copies).

The study was co-chaired by William C. Clark, the Harvey Brooks Professor of International Science, Public Policy, and Human Development, John F. Kennedy School of Government, Harvard University; and Robert W. Kates, Emeritus Director of the Feinstein World Hunger Program, Brown University. The study was funded by grants from the Mitchell Energy and Development Corp., the George and Cynthia Mitchell Foundation, and the National Academy of Sciences.

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