The occupants of planet Earth, like astronauts on a space station, are dependent on an elaborate life-support system that maintains the air we breathe, regulates temperature, supplies reserves of food and water and shields us from deadly radiation. This system, provided by nature free of charge, offers a broad array of critical services: purifying the air and water, maintaining soil fertility, decomposing and detoxifying wastes, recycling essential nutrients, stabilizing the climate, protecting us from the sun's ultraviolet rays, mitigating floods and droughts, pollinating our crops and controlling agricultural pests.
The world's soggy realms called wetlands - transitional zones between chronically wet and predominantly dry environments - are often considered worthless real estate, yet they filter and clean our water, mitigate the effects of floods, and offer a home to a variety of plants and animals that cannot thrive on dry ground. Although the services afforded by wetlands and other ecosystems are generally taken for granted, it is difficult to overestimate their true worth. A 1997 study published in Nature tried to do that, concluding that one wetland acre is seven times more valuable than an acre of tropical forest in terms of ecosystem benefits. People may quibble with the numbers, but it is hard to argue that current technology could duplicate the feats of nature on a significant scale. And even if we could do so, the effort would surely bankrupt us. A recent experiment in the Arizona desert serves as a case in point: About $200 million was spent in an attempt to sustain eight human beings for two years in an enclosed, three-acre structure in Arizona called Biosphere 2. Atmospheric concentrations of oxygen within the sealed living quarters plummeted from 21 to 14 percent - to a level comparable to Andean peaks - as microbes in the overly rich soil gobbled up the precious gas. Meanwhile, dangerous levels of nitrous oxide pervaded the environment, as glass walls prevented the sun's ultraviolet rays from destroying the gas. Nor could the crew grow enough food to sustain itself within the greenhouse habitat. It is apparent from the Arizona experience that any thought of supporting the billions of human inhabitants on Earth (sometimes referred to as Biosphere 1) by artificial means would be entirely out of the question.
Human know-how still cannot replace nature, but we have acquired the means of disrupting natural processes on a global scale. With this newfound ability comes a responsibility to manage the planet's resources wisely. By safeguarding vital ecosystems whose services we depend on, rather than plundering them for immediate gain, we can ensure that nature flourishes. In so doing, humans will benefit too.
More than half of the wetlands in the United States have been lost to human activities and as much as 90 percent of the wetlands in states such as California and Ohio have been wiped out.