How is climate change going to affect Hawai`i?<\/p>\n
Little by little, scientists here and abroad are tackling that question. A lot has already been done, from Chip Fletcher\u2019s work on coastal erosion and flooding in Honolulu to Dennis LaPointe\u2019s, Carter Atkinson\u2019s and Tracy Benning\u2019s work on the forest\u2019s shrinking malaria-free zone to Jason Baker\u2019s, Charles Littnan\u2019s and David Johnston\u2019s predictions on how rising seas will shrink monk seal and green sea turtle habitat in the Northwestern Hawaiian Islands.<\/p>\n
\tLast March, the Hawai`i Conservation Alliance sponsored a forum on some of the latest research as part of the alliance\u2019s effort to educate scientists and land managers about climate change so they can incorporate predicted effects into natural resource management here.<\/p>\n
\tHeld at the University of Hawai`i\u2019s East-West Center, the forum was a chance to hear from both local and mainland scientists on the various ways climate change may affect the world\u2019s natural resources in general, and Hawai`i\u2019s in particular. Later that week, HCA members met at the U.S. Fish and Wildlife Service office in Honolulu to develop a climate change response strategy, which will be presented at this summer\u2019s annual conservation conference this July 29-31.<\/p>\n
Precipitation<\/i><\/b><\/p>\n
As National Oceanic and Atmospheric Administration climatologist Henry Diaz put it, the models used by the Intergovernmental Panel on Climate Change show that Hawai`i is in an \u201cincrease-decrease dichotomy\u201d when it comes to rainfall predictions under the most idealistic global warming scenarios. In other words, the models show a decrease in precipitation north of the island chain, an increase to the south, but directly over the islands, the models don\u2019t agree on what will happen.<\/p>\n
Diaz and other climate modelers who spoke at last March\u2019s forum suggested that, even if the 20-plus models used by the IPCC did agree, they aren\u2019t refined enough to predict small-scale, regional changes. Typically, global climate models have a resolution of 150-300 kilometers.<\/p>\n
\u201cHawai`i almost fits inside one box,\u201d Diaz said, referring to the global grid used by the IPCC models, where one box equals one data point.<\/p>\n
So, Diaz, in cooperation with Thomas Giambelluca and Oliver Timm of the University of Hawai`i, is working on ways to better predict climate change impacts on weather in Hawai`i.<\/p>\n
At the time the forum was held, there was little to report in the way of results. As Timm said, the group is still working on selecting the right model to use for Hawai`i, running different ones dozens of times to see how well they match up with observed weather data.<\/p>\n
Using one promising model, Timm said, it appears that for one region in Hilo, there may be one more inch of rain a month as a result of climate change impacts on trade winds.<\/p>\n
But even with the right model, predicting what rainfall will be throughout different climatic regions across the island chain will be difficult. How will dry Wai`anae or Pu`u Wa`awa`a be affected differently from Mt. Wai`aleale, the wettest place on earth?<\/p>\n
Diaz said the tremendous local variation in annual rainfall \u2013 which can vary from 10 inches to more than 200 inches \u2013 will complicate things, as will the fact that the islands get most of their rainfall from just a handful of rainstorms a year. Between 1961 and 2003, he said, ten percent of the annual rainfall events accounted for 50 percent of total annual rainfall.<\/p>\n
\u201cThe background noise in the system will make it difficult to predict change,\u201d Diaz said. Even so, he did say that high and mid-level elevation changes in precipitation are possible with a two to three degree Centigrade change in temperature.<\/p>\n
Giambelluca added that temperatures are not only increasing, they\u2019re doing so rather quickly in some instances, noting that high-elevation nighttime temperatures have gone up 0.79 degrees Fahrenheit per decade over the past 30 years.<\/p>\n
Also, he said that Hawai`i\u2019s temperature normally tracks the Pacific Decadal Oscillation (an El Ni\u00f1o-like pattern that affects temperatures over long periods of time), but over the last 25 years, the temperature here has been departing from the PDO index, which may be another sign of global warming.<\/p>\n
He added that the weather phenomenon known as the trade-wind inversion, which is associated with less precipitation, has also in the last 25 years become more frequent and may become more so with global warming.<\/p>\n
The Ocean<\/i><\/b><\/p>\n
While climate modelers have their hands full with Hawai`i\u0092s unique weather system, Fletcher, a University of Hawai`i coastal geologist, has already made some highly publicized predictions about potential sea level rise effects on O`ahu. Earlier this year, when the East-West Center hosted President Bush\u2019s international climate talks, environmentalists and students took to the streets, marking them with blue chalk to indicate which parts of Honolulu Fletcher predicts will be below sea level if global warming causes ocean levels to rise another meter, which it is predicted to do later this century.<\/p>\n
\tAt the March forum, Fletcher showed pictures of areas that are already threatened by saltwater inundation \u2013 cars driving through ocean-flooded streets in Mapunapuna, and an open manhole along the Ala Wai canal just inches from overflowing.<\/p>\n
In addition to calling for a statewide retreat from Hawai`i\u2019s disappearing shorelines, Fletcher said that government agencies with jurisdiction over coastal areas that will be affected by sea level rise need to start working better together.<\/p>\n
On a broader scale, Stanford University chemical oceanographer Ken Caldeira offered some predictions about what high levels of carbon dioxide might do to the world\u2019s coral reefs and other calcium carbonate-reliant organisms. Right now, our carbon dioxide output is on track to reach an atmospheric concentration level of about 550 parts per million in the next few decades, a level not seen on this planet since the dinosaurs went extinct, he said.<\/p>\n
Based on computer simulations of ocean chemistry under various levels of atmospheric CO2, Caldeira and other scientists with the Carnegie Institution\u2019s Department of Global Ecology have calculated that if current emission trends continue, by 2050, 98 percent of reef habitats will have become too acidic for reef growth.<\/p>\n
Caldeira presented a map of what the ocean chemistry will be with an atmospheric CO2 concentration of 550 ppm that shows how areas where corals can survive will not only shrink dramatically, but they will move to places where they\u2019ve never been before.<\/p>\n
Local coral reef consultant Rick Grigg asked how such levels could be bad for reefs when 550 ppm is about the level that existed when corals first formed. Caldeira responded that the emission rate, not the atmospheric level, is what will kill corals, as well as other species that need calcium carbonate to survive. It takes a long time for the ocean to interact with sediments and to neutralize gases that it absorbs, he said.<\/p>\n
\u201cIf humans had released [carbon dioxide] 100 times slower, it wouldn\u2019t be a problem,\u201d Caldeira said.<\/p>\n
Species<\/i><\/b><\/p>\n
In 2004, the journal Nature<\/i> published an article that claimed the world could lose about 25 percent, or roughly 1 million, terrestrial species as a result of climate changes between now and 2050. Conservation International researcher Lee Hannah, one of the article\u2019s co-authors, discussed how climate changes might affect Hawai`i, which has been described as the endangered species capital of the world.<\/p>\n
\tWhile he pointed to the work by Denis LaPointe of the U.S. Geological Survey\u2019s Volcano field office and others on the startling shrinkage predicted for the malaria-free zone of the Big Island and Kaua`i\u2019s Alakai swamp, Hannah also highlighted the positive: The Big Island has a large elevational gradient that allows for upward movement of species displaced by warmer temperatures. Also, Hawai`i has steep drop-offs to deep water, which may alleviate coral bleaching caused by rises in sea temperatures, he said.<\/p>\n
\tWhatever happens to the climate and waters around Hawai`i, Hannah concluded, there won\u2019t be a sea change in the way managers try to protect species.<\/p>\n
\u201cConservation tools will be pretty much the same, but managers will need to be able to deploy them in a dynamic environment,\u201d he said.<\/p>\n
— Teresa Dawson<\/p>\n
Volume 18, Number 11 May 2008<\/p>\n","protected":false},"excerpt":{"rendered":"
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