TOOLIK LAKE -- Ground here that for tens of thousands of years was frozen solid is terra firma no more.

Across the tundra and coast of the Arctic Ocean, land is caving in. Soils loosed by freshly thawed earth set off a new era of rot, and of bloom -- dumping a bonanza of nutrients into this top-of-the-world environment.

Will nature channel the nourishment of this soil into a great flowering of plant life that soaks up greenhouse gas and tamps down the causes of climate change? Or will a microbial awakening of decomposition simply belch out more planet-heating carbon dioxide?

Scientists flock here, to the northern foothills of the Brooks Range, to find out and to guess at the planet's future. They sample water from streams and ponds, tag fish and mark their growth, count creepy crawlies squirming in clumps of moss, watch the grass and bushes grow.

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