Flooded coastal communities, dying coral reefs, stronger hurricanes, extinct animal species, increased droughts and greater rates of shoreline erosion were among the pictures of Hawai'i that experts presented yesterday at a conference on climate change.

No one can say for sure what the precise effects on the state will be if global warming, mostly caused by human activities, occurs along the lines of the wide range of scenarios scientists project by the end of the century.

But many of the possibilities discussed at the Hawai'i Conservation Conference point to a dramatically altered Island environment if substantial steps aren't taken around the world to curb the burning of fossil fuels.

Hawai'i has the opportunity to become a global leader, given its almost complete dependence on imported oil and the potential to tap the wind, waves and sun as alternative sources, said Stanford University scientist Stephen Schneider, who with a team of other researchers was awarded the Nobel Peace Prize in 2007 for their climate change work. He was the keynote speaker yesterday at the opening day of the three-day conference at the Hawai'i Convention Center.

"You have a very, very good reason for not being 92 percent dependent on foreign oil — it's security," Schneider said in an interview.

As the planet continues to warm because of a buildup of carbon dioxide from burning fossil fuels, Hawai'i will have to worry mostly about the consequences of a rising sea, more intense storms, hotter temperatures and an increasingly acidic ocean, Schneider and other experts at the conference warned.

GRIM SCENARIOS

Under the most optimistic scenarios, global temperatures are projected to rise about 3.6 degrees by the end of the century, and at those levels major coral bleaching is expected to kill some reefs around Hawai'i, the experts said. They also predicted that warmer waters will fuel stronger hurricanes in the region.

If sea levels continue to rise as projected — one estimate is 3 feet by the end of the century — portions of Hawai'i's coastal communities will be destroyed, while others will encounter more frequent severe flooding, scientists said. The more pessimistic scenarios predict that Waikiki's hotel-lined shoreline will be crippled.

Several experts said Hawai'i's land-use planning and construction regulations should take the expected impact of climate changes into account. Kaua'i, for instance, has adopted coastal setbacks based on a 2-foot rise in sea level.

Providing a glimmer of good news, Chip Fletcher, a University of Hawai'i scientist, said Hawai'i seas have risen about 1 to 2 millimeters annually in recent years, lagging the global average of more than 3 millimeters annually over the past 15 years. The effects of melting ice sheets in other parts of the world have been confined to those regions, accounting for the lower sea rise in the Pacific, Fletcher said.

"We have more time than many other parts of the world to begin to act on adaptation" to the rising seas, he said.