FUNAFUTI, Tuvalu (AP) - The rising sea is eating at the shores of low-slung Funafuti, a spit of coral and coconut palms in the remote Pacific. Unseen fingers of ocean even reach beneath the sands, surfacing inland in startling places, among nervous islanders.

``It used to be puddles. Now it's like lakes,'' said Hilia Vavae, local meteorologist.

Far to the north in the Marshall Islands, 1,250 miles away, trees are toppling before aquamarine waves. Watching, perplexed, from the edge of a lagoon, teenager Ankit Stephen asked a visitor, ``Why is this happening?''

Six hundred miles west, on tiny Kosrae, Alokoa Talley pondered the same question. Neighbors are moving their homes up the lush slopes, away from the encroaching Pacific. ``I don't know,'' the government worker said, ``but I think it's because of `green' something.''

The ``greenhouse effect,'' climate change, has languished on the world's agenda since the 1970s, a seemingly distant threat. But year by year, inch by inch, it is rising to the top - as ocean islets flood, glaciers retreat, Arctic permafrost melts, and leading voices raise new alarms.

``We may already be seeing - in the increased incidence of drought, floods and extreme weather events that many regions are experiencing - some of the devastation that lies ahead,'' U.N. Secretary-General Kofi Annan said in March, when he urged all governments to ratify the Kyoto Protocol to reduce the world's ``greenhouse gas'' emissions.

That long-stalled 1997 accord is opposed in Washington, where U.S. government and industry object that emission controls would handicap the U.S. economy. Now only ratification by Russia can revive it, making this a critical year on the political front in a long, difficult debate over what to do about climate change.

On the scientific front, meanwhile, signs of global warming mount.

Like the glass of a greenhouse, carbon dioxide, methane, nitrous oxide and some other gases in the atmosphere let sunlight in but tend to warm the Earth by trapping heat it emits back toward space. That's scientific fact; the scientific puzzle involves other factors that might lessen - or worsen - the warming and what it does to the planet.

Concentrations of carbon dioxide, a byproduct of fossil fuels burned in everything from automobiles to electricity plants, reached record levels in the atmosphere this past winter, a Hawaii observatory reported in March.

Then, in April, other U.S. scientists reported NASA satellite readings showed an average increase in the globe's land surface temperatures of 0.77 degrees Fahrenheit between 1981 and 1998. This reinforced earlier findings, from ground stations, that global temperatures rose 1 degree over the 20th century.

These rising curves, of greenhouse gas and global temperature, parallel the analysis of the Intergovernmental Panel on Climate Change, a U.N.-organized network of hundreds of climatologists and other scientists worldwide.

In a pivotal 2001 report, the IPCC listed as a key finding: ``Most of observed warming over last 50 years likely due to increases in greenhouse gas concentrations due to human activities.''

If emissions are brought under control too slowly, temperatures could rise an additional 10.4 degrees by the year 2100, the IPCC said. Even with quick rollbacks in smokestack, tailpipe and other emissions, temperatures could rise 2.5 degrees Fahrenheit by the end of the century, the scientists said.

Warming is expected to be unevenly distributed and to change regional climates in powerful ways, shifting climate zones hundreds of miles, possibly making farmlands drier, deserts wetter; melting ice caps; intensifying storms; spreading diseases to new areas; and raising ocean levels - by anywhere from 3.5 inches to almost 3 feet by 2100, depending on emission controls, the IPCC said.

The seas would rise because water expands as it warms, and because of the runoff of ice melt from the continents.

In fact, the oceans have expanded, rising an average 1 to 2 millimeters a year - up to one inch every 12 years - during the 20th century, as measured by tide gauges.

More recently, satellites show ``the rise has been highly accelerated,'' to 3 millimeters a year, said Walter Munk of San Diego's Scripps Institution of Oceanography.

Pacific islanders aren't alone. Rising seas are a growing threat from Alaska, where Eskimos are relocating an Arctic island village, to New Orleans and to Shanghai, China - near-coastal cities already below sea level, sinking on their own, and further endangered by expanding oceans.

Prevailing winds, tidal peculiarities and other factors can make sea levels vary from place to place. Here at Funafuti, capital of a mini-nation midway between Hawaii and Australia, the gauges have shown the sea rising 5 to 6 millimeters a year since 1993, meteorologist Vavae said.

But some islands also are subsiding, sinking under their own weight. ``In many islands, I think the answer is that both are happening - subsidence and rising levels,'' said University of Hawaii oceanographer Roger Lukas.

Similarly uncertain: What will a swelling ocean do to a Funafuti?

One rule of thumb, disputed among specialists, holds that each millimeter rise in sea level can claim 1.5 meters - 5 feet - of shallow ocean beach. Some theorize, however, that a moderately higher Pacific would ``rearrange,'' but not obliterate, an atoll like Funafuti - a ring of islands around a central lagoon.

Rearrangement would be bad enough for Lototele Malie, 75, whose pastel-blue concrete house, with 15 adults and children inside, sits at the edge of Funafuti's dwindling ocean beach.

``A month ago the tide came right here,'' the sarong-clad old man said, pointing 3 feet away to the lip of his concrete-slab patio. ``It's getting dangerous,'' he said, with the thunder of waves as a backdrop.

The Malies and others along Funafuti's fringe have little room to maneuver. Just 300 yards from their rear doors, the choppy waters of the 9-mile-wide lagoon are rising. In between sit other salt-caked plywood or cinderblock houses, beside gaping pits dug in the island's coral foundation long ago, by U.S. troops in World War II.

Those pits, filling now with seeping seawater, supplied the crushed material for Funafuti's airport, where today some of Vavae's ``lakes'' have begun to appear at peak tides.

``People got especially worried when the runway flooded. That's new,'' Margaret Bita, 45, told a visiting reporter after Sunday church services.

The church and little airport lie on the broadest part - 600 yards across - of slender, steamy, 7-mile-long Funafuti, home to about half the 11,000 people of Tuvalu, an impoverished nation getting by on fees from foreign fishing fleets, international aid and money sent home by Tuvaluan merchant seamen.

This main island narrows elsewhere to a mere 50 yards of sand, swaying palms and roadway between lagoon and sea. Its elevation is seldom more than a few feet. When February's ``king'' tides washed out a small causeway, children swam to school.

``I think it would be better if my kids were somewhere else,'' said hospital worker Beia Fetau, 40, preparing to help with Sunday school in shirt, tie and traditional male ``sulu,'' or skirt.

As recently as the 1980s, Vavae said, the peak king tides came only in January and February. Now, she said, they crash ashore from September to May. But it's the quiet seepage from below that most alarms Tuvaluans.

Because of intruding saltwater, many have abandoned their gardens of deep-rooted ``pulaka,'' a tuber crop grown in pits here for centuries. On the nearby islet of Vasafua, the coconut trees are dying. Another small uninhabited island, Tepuka Savilivili, has vanished beneath the waves.

``It went under water in the cyclone in 1997,'' Vavae said.

Disentangling long-term climate change from short-term natural variability is a challenge at the local level, especially in the Pacific, where the periodic climatic phenomenon El Nino raises and lowers ocean levels, causes droughts and stirs up severe storms. But people across the Pacific feel sure something unusual is happening.

In Kiribati, another mini-state north of Tuvalu, they've also lost an islet in the main atoll of Tarawa. On Majuro, the Marshalls' capital, the lagoon outside Ankit Stephen's home has undercut dozens of towering coconut palms, as islanders futilely try to stop the waves with piles of debris.

On Kosrae, a ``high island'' of volcanic peaks in the Federated States of Micronesia, the people have always lived along a flat coastal strip, but some are now dismantling their simple homes and heading for the hills, as recommended by the government.

``Nobody remembers such tides before. The sea is actually moving inland,'' said Simpson Abraham, head of Kosrae's Resources Development Authority. Some offshore islets have vanished, he said.

Here in Tuvalu, devoutly Christian since missionary days, many talk not of greenhouses, but of Genesis, reminding each other of God's promise to Noah: As long as rainbows cross the sky, there will be no more great floods. ``God will protect us,'' one woman churchgoer assured a visitor.

Saufatu Sopoanga, as Tuvalu's prime minister, must look into the future, not the Bible. He is talking to New Zealand about a kind of 21st century Noah's ark - a standby plan for a mass migration there.

``In 50 or 100 years, the islands are expected to go under water. What can we do?'' Tuvalu's leader asked, on a day when a tropical morning downpour soon gave way to a rainbow in a blue, very warm sky.

Back To The Study