Hawai'i in the coming century will face rising temperatures and sea levels, eroding shorelines and more acid in ocean waters as the amount of carbon dioxide in the atmosphere increases.

"No one's ready for this," said Charles "Chip" Fletcher, the state's premier coastal geologist.

A map developed by Fletcher to illustrate the impact of a 23-inch rise in sea level — the high end of estimates for the year 2090 — shows parts of Waikiki under water and the Ala Wai Canal "leaking up over its banks at high tide," he said. The ground floor of the Hawai'i Convention Center, located just steps from the canal, also would be vulnerable.

Springs could start popping up in low regions, and higher elevation areas also would be at risk, as ocean water pushes up into streams.

"When flash flooding occurs, streams won't be able to flow into the ocean. They'll back up and flood," said Fletcher, a University of Hawai'i professor.

Hawai'i residents already are seeing some effects of higher sea levels, such as flooding in Mapunapuna during extraordinary high tides, Fletcher said, adding that "we've seen Ala Moana Beach completely covered with water once or twice a year. In a couple of decades, it'll be happening a couple of times a month."

The issue of global climate change has had high-profile boosts from former Vice President Al Gore's 2006 documentary, "An Inconvenient Truth," which is vying tonight for an Academy Award, and also from British billionaire Richard Branson's offer of $25 million to anyone who devises a system to remove large amounts of greenhouse gases from the atmosphere.

Meanwhile, nations are battling over efforts to develop sustainable societies that minimize greenhouse warming.

PREPARING FOR CHANGE

In Hawai'i, preliminary steps are being taken to adapt the Islands to the effects of climate change.

Maui County has established a new coastal building policy that increases shoreline setbacks based on likely erosion in specific areas due to sea level rise, changes in coastal wave and current patterns, and other causes. Kaua'i County is considering a similar policy.

In another initiative, interim UH-Manoa Chancellor Denise Eby Konan earlier this month named a climate change commission comprising climate scientists, lawyers, engineers and others to study the direct effects of climate change here. The panel will be headed by oceanographer Lorenz Magaard, who said sea level rise may be the most critical issue facing this island state.

Others agree.

"Sea level rise is unavoidable, and if that's a couple of feet (over the next century), we're going to have to have adaptation," said Kevin Hamilton, chairman of the UH Meteorology Department and a group leader in the university's International Pacific Research Center, which studies climate variation and predictability in the Asia-Pacific area.

Some hotel industry officials already are considering such adaptations to accommodate predicted sea-level rises in future construction, said Murray Towill, president of the Hawai'i Hotel and Lodging Association.

"I'm aware of discussions at specific (coastal) properties, some of it focused on what to do when the property is rebuilt in the next generation," Towill said.

CLIMATE CHANGE REPORT

The climate-change discussion has been energized by the release of initial sections of the Intergovernmental Panel on Climate Change's "Climate Change 2007" report. The IPCC is a joint project of the World Meteorological Organization and the United Nations Environment Programme.

"It's an incredibly serious and objective document," said UH oceanographer Axel Timmermann, who wrote three chapters in the IPCC's 2001 report but did not participate in the current one.

While the IPCC report has a global focus, it is possible to derive regional impacts from some of its data. Local coastal engineers, oceanographers, meteorologists and others who have studied the early data say it forecasts significant impacts on Hawai'i.

The sea level by the last decade of this century is estimated to be anywhere from 7 inches to 23 inches higher than at present, levels that could put parts of Waikiki and other low-lying areas under water and promote severe coastal erosion.

Temperatures in the region are estimated to rise 5 to 9 degrees Fahrenheit, making Hawai'i a significantly less comfortable place, particularly in summer. A hotter climate could impact tourism and dry out the landscape.

"Agriculture may be affected (and) ranching. You get more evaporation when it's warmer," said Jim Weyman, meteorologist in charge with the Honolulu Forecast Office of the National Weather Service. Even the fishing industry can be impacted by warming conditions, since some favored species of fish follow specific temperature zones in the ocean, he said.

A sleeper in the climate-change discussion is acidification of the ocean. A weak solution of carbonic acid is formed when water is exposed to carbon dioxide. So, as carbon dioxide builds up in the atmosphere, the oceans turn more acidic.

At Station Aloha, an oceanographic monitoring station in the deep Pacific north of O'ahu, a 20-year record of seawater acidity shows a clear trend to a more acidic ocean.

"It's just really become clear that acidification has become a serious concern," said Roger Lukas, a UH professor of oceanography.

UH oceanographer Dave Karl, a member of the National Academy of Sciences, said oceanic acidification could become one of the most significant affects of the increasing amount of carbon dioxide in the atmosphere. A more acid ocean interferes with the ability of animals and plants to create calcium carbonate, the stuff that makes up limestone, coral, seashells and, among other things, the protective outer layer of a class of organisms called cocolithophores that are at the base of the marine food chain.

"Everybody gets hurt. People all over the world are now looking at this. It will have a bigger effect than coral bleaching ever will," Karl said.

Eventually, organisms will adapt and evolve, but there are likely to be severe disruptions in oceanic production in the meantime, he said.

ECONOMIC IMPACTS

Hawai'i researchers, policymakers and others say the state needs immediately to begin planning for the impacts of climate change because of its potential impacts on coastal property values, the economy and the environment.

"I think the public is somewhat confused (about global climate change). The state of Hawai'i and people generally in the state need to be aware of how this will challenge us," Lukas said.

The state's Civil Defense Agency is aware of the impacts facing Hawai'i, but hasn't yet launched any significant programs to respond to climate change, according to Ed Teixeira, vice director of Civil Defense. In fact, few states have, other than establish commissions to study the problem.

"We should be dealing with and addressing potential impacts of global warming. I've been reading and paying attention all I can, but there's nothing formal. At this point, it's a thinking process," Teixeira said. "Perhaps we've got to be more formal in involving the governor and Legislature, to look at what actions we ought to be taking right now, what we need to be doing to mitigate this."

Vicky Holt Takamine, president of 'Ilio'ulaokalani, a grass-roots coalition of Hawaiian cultural practitioners, and kumu hula, said her group has been pushing for expanded coastal building setbacks and feels there are many other impacts that aren't being considered.

"We're going to have to be a lot smarter about how we build our homes, our communities," she said. "We need to plan for climate change when we give out permits. We're not planning for future generations."

GASES, ENERGY

Sierra Club Hawai'i Chapter chief Jeff Mikulina said it is important not to lose the connection between the impacts of warming and their partial cause: the increasing amounts of greenhouse gases in the atmosphere.

"If we're building more power plants even as we're armoring Waikiki (against sea level rise), that's insanity," he said.

"We know enough already to know that the map of the Islands is going to look very different, but we haven't seen much policy response," Mikulina said.

Renowned retired UH oceanographer Klaus Wyrtki said he believes governments and industry will do little to stop climate change, and that the most obvious solution is a controversial one.

"There will and should be attempts to reduce energy consumption, but this will not help much as long as world population is rising. The most important measure would be a switch to atomic energy," Wyrtki said.

The only good news in the IPCC report for Hawai'i is that two areas previously viewed as potential problems — storms and disturbances in rainfall patterns — appear to be less worthy of concern.

There is no clear signal in the data that hurricanes will become significantly more numerous or stronger in Hawaiian waters due to climate change, although that may be only because of lack of data about Pacific storms. And the latest figures suggest rainfall might increase about 3 percent over the next century — "not a significant change," Hamilton said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.