Years of industrial and agricultural growth have left an indelible imprint on many formerly vibrant U.S. ecosystems. While nature is adept at resilience, the depletion and contamination of natural resources, especially water, may affect human health and wellbeing, a new report suggests.
Years of industrial and agricultural growth have left an indelible imprint on many formerly vibrant U.S. ecosystems. While nature is adept at resilience, the depletion and contamination of natural resources, especially water, may affect human health and wellbeing, a new report suggests.
Released last week by the federally funded environmental think tank The Heinz Center, The State of the Nation's Ecosystems offers what the authors consider the most comprehensive look at countrywide ecosystem health.
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Following a similar report the center published in 2002, the new analysis was expanded to include additional indicators, such as invasive species, carbon storage, and stream flows. Yet the report's authors do not hide the fact that data gaps prevent an even more detailed assessment. "We don't have the entire environmental picture," said Thomas Lovejoy, president of the Heinz Center. Authors called for federal and state action that would strengthen and integrate environmental monitoring.
Among the findings, U.S. freshwater resources are being continually depleted and polluted. Between 1960 and 2000, freshwater withdrawn for consumption increased 46 percent. Meanwhile, drought and melting glaciers have reduced the flow of many water sources.
Contaminants, such as pesticides, fertilizers, and medications, have been detected in "virtually all" freshwater streambeds, the report said. Streams are contaminated above benchmarks set to protect aquatic life in 57 percent of farmland and 83 percent of urban and suburban areas. These pollutants have contributed to growing "dead zones" where aquatic life cannot survive.
Contaminants at concentrations above the benchmark for human health are found in 7 percent of urban and suburban streams. Nitrate, a runoff of agricultural fertilizers, exceeds federal drinking water standards in 20 percent of farmland groundwater wells.
"When we find barren lands and depleted water, it's a bad sign of our job as stewards," said Larry Schweiger, president of the National Wildlife Federation. "What happens to nature, happens to humans."
On a more positive note, many ecosystems, especially forests, have remained intact due to conservation and sustainable management. Timber growth has exceeded harvest-half of U.S. timberland is younger than 60 years old-which has allowed forests to store more of the greenhouse gas carbon dioxide in recent years than a decade ago.
However, wildlife within those ecosystems faces widespread threats. One-third of native plant and animal species, excluding marine species, are at risk of extinction. Global warming is shifting the climate outside the threshold that many native species can tolerate, which provides an advantage to invasive species that have more general survival requirements.
Invasive species are also out-competing native species for resources. More than half of U.S. freshwater watersheds contain at least 10 non-native fish species, and only two watersheds have no reported invasives, the report says.
Data gaps mentioned throughout the report include area measurements of several ecosystems, such as wetlands, seagrasses, and lakes, and of the rate that various ecosystems are being converted into other uses. The report also says that biodiversity and pollution data are inadequate for marine ecosystems. "The field of environmental research is fraught by extremes of political advocacy and inadequacy of scientific data," said William Clark, the chair of the project design committee and an ecology professor at Harvard University.
To address the lack in data, which will be an ongoing challenge as climate change continues to alter habitats worldwide, the White House announced a plan to develop a new set of national environmental indicators. After several attempts to impede climate change reports throughout the current Bush administration, executive offices plan to consolidate water quantity and quality indicators, which would measure the effect of climate change.
A report published by the U.S. Environmental Protection Agency on Friday expressed similar support for environmental indicators. In this case, the agency said climate change thresholds should be established for individual ecosystems to improve climate adaptation plans. "Understanding where thresholds have been exceeded in the past and where (and how likely) they may be exceeded in the future allows managers to plan accordingly and avoid tipping points where possible," the report said.
The Heinz Center recommended that Congress establish a national system of exhaustive environmental and natural resources indicators. "Once we have a decent system of monitoring what the current system is, we can become much better at predicting what the future is," said Robin O'Malley, director of the center's environmental reporting program.
Tim Keeney, deputy assistant secretary of the National Oceanic and Atmospheric Administration, represented the administration at the report's launch. "I didn't come to endorse the recommendations wholesale, but a lot of the recommendations make sense," he said.
Ben Block is a staff writer with the Worldwatch Institute. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..
