Instruments like these help scientists study ecosystems in the closed Bioshpere 2 environment.

You might remember Biosphere 2 only as the failed experiment of the early 1990's in which eight scientists attempted to live in the 3.1-acre, self-contained model of the Earth. In 1996, however, Columbia University gave Biosphere new life as a center for climate research.

In "The Second Earth," Biosphere scientists examine the effect of rising atmospheric carbon dioxide levels on natural ecosystems. carbon dioxide is the gas that causes global warming.

Today, about one-third of the carbon dioxide generated by humans is absorbed by and locked up in the Earth's rainforests. In Biosphere's two-thirds-acre rainforest, Guanghui Lin and his colleagues measure how ever-higher carbon dioxide levels might affect this forest storage capacity. When Lin runs the experiment with about twice as much carbon dioxide in the air as today--levels forecast for the mid-21st Century--the forest reaches its limit and begins to give off the gas.

Research on Bioshere 2's artificial reef indicates the higher levels of CO2 that we'll reach in 50 years decreases coral growth dramatically.

Research in Biosphere's simulated Caribbean reef also yielded alarming results. Increased levels of carbon dioxide disrupt the way corals build their calcium carbonate skeletons. According to marine biologist Les Kaufman, these findings warn of what's to come in all the world's oceans, since many other organisms-including clams, lobsters and shrimp-also build calcium carbonate skeletons.

Biosphere forest biologists are looking for ways to lock up excess carbon dioxide permanently--an idea known as sequestration. For the last three years, they have grown young poplar trees at different carbon dioxide levels -- today's level, double and triple that. In year one, the trees subjected to high levels of carbon dioxide grew faster than the others, but in year two they didn't--a puzzling result hat could spell trouble for sequestration. Biosphere scientists will continue to pursue this puzzle and many others related to global climate change.

For more on this topic, see the web feature:
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