AWASH IN A RISING SEA - How global warming is overwhelming the islands of the tropical Pacific.(Cover Story)

OUR ALUMINUM SKIFF plows through Tarawa Lagoon's emerald waters, throwing up a spray that glitters in the sunlight like a cascade of diamonds. North and west is the barely visible village of Naa, and beyond that lies what I've come to see or, more accurately, not see: Tebua Island.

According to local legend, Tebua has existed since creation. But now, I've been told, it is gone, swallowed by the sea. Its fate, some say, was triggered by global warming--the unnatural increase in the Earth's temperature caused by air pollutants that trap solar heat.

Tebua's disappearance is not the only sign that global warming is making itself felt in the distant reaches of the Pacific, where scientists have long predicted that rising waters would engulf low- lying islands. Other islands have disappeared, too. Cemeteries are crumbling into the ocean. Salt has poisoned water supplies. Malaria and other diseases have spread. And large ocean surges have engulfed once- safe homes with no warning.

Events like these provide a powerful confirmation that global warming is not just a distant threat but is underway, with dire implications for the people of the Pacific. "The hard truth is that it is probably too late to save mid-Pacific islands like Tarawa," says climate authority Irving Mintzer of the Pacific Institute for Studies in Development, Environment and Security. "Absent a miracle or something comparable, many will almost certainly disappear within our lifetimes."

For me, the true test will be spelled by the answer to a simple question: Has Tebua really disappeared beneath the waves as reported? To see for myself, I've traveled 12,000 miles over three hard days for International Wildlife.

Tebua lies off Tarawa Atoll on the extreme western edge of the nation of Kiribati (KEER-ri-bas), a group of islands stretching across the Pacific in an area nearly the width of the United States. Kiribati is so low--three feet or less above sea level in most places--that from a distance, islands disappear into an azure vault of sky. It is "the place where heaven meets ocean," according to its people, the I- Kiribati.

Despite its immense size, Kiribati has no railroads, military, newspapers or manufacturing facilities. It covers roughly 2.5 million square miles of ocean--into which Alaska could be dropped with room left over for another 20 to 30 U.S. states. But the land area itself is a mere fly speck--just 275 square miles. Economically, Kiribati is even tinier. Its total gross national product (mostly from export of copra, or coconut meat, used to make soaps and oils) is roughly equal to that of about 2,900 Americans.

To understand Tarawa's geography, picture the open jaws of a crocodile. The bottom jaw is South Tarawa. At its tip lies Betio (BAY-see-oh), site of the bloody battle for "one square mile of hell," where more than 1,700 U.S. Marines and sailors were killed pioneering the amphibious landing techniques that made island-hopping victory …