Hawai`i Natural Resource Managers Confront Challenge of Global Warming

posted in: September 2008 | 0

In his plenary address to the Hawai`i Conservation Alliance’s annual conservation conference in July, Stephen Miller asked the questions that usually arise when people talk about global warming:

“How profound is it? … Will it be really hot, or kinda hot? … What are the potential ecological consequences we may need to deal with?’

No longer do the questions contain an “if.” Miller, a biologist with the U.S. Fish and Wildlife Service, noted that even if greenhouse gas emissions over the next 100 years are brought to low, stable levels, the planet will still see significant changes given the amount of carbon dioxide already in the atmosphere. While concentrations of carbon dioxide in the air and surface seawater might top out in 100 to 300 years, and temperatures will eventually stabilize, “sea level will continue to rise for hundreds to thousands of years,” as a result of the thermal expansion of oceans and actual melting of sea ice.

“So,” he said, “we really need to begin to deal with these things right now, and in a significant way.”

For Hawai`i, that means looking at what Miller called the “basic life zones” or “bioclimate envelopes” – sets of physical factors within which basic biological and ecological interactions occur. “As climate changes in the Hawaiian islands, these life zone conditions are going to change as well. The places where today you find wet, mesic, and dry conditions are going to be different in the future. Current communities of species may disassemble and novel communities may appear. Species and populations may go extinct, and ranges may shrink. And invasive species may begin to come into play and occupy many of these new regimes.

“Landscape areas that once used to be major Hawaiian habitats are no longer going to occur in the Hawaiian islands. The life zone conditions that created those will simply no longer be present here as climate changes unfold over a long series of time.”

In their place a new regime will arise, he said: “New life zone conditions will arise that have never before occurred in these islands.”

Natural resource managers will need to develop new approaches to the changing conditions. Right now, the system of adaptive management, Miller said – “learn – plan – do – learn – plan – do …” – has as its goal the conservation of landscapes capable of sustaining species, habitats and ecosystems at desired levels. It is based, he said, on the notion that climate conditions are relatively stable.

“As climate change hits the scene,” Miller continued, “your management plan will probably become not so useful anymore. You’ll need to evaluate climate changes, start management cycles all over again – until climate change moves your plan toward obsolescence. So the adaptive management cycle which went around and around now becomes a spiral, moving through time.”

But how does one go about developing a strategy to address natural resource management challenges in the face of substantial change?

The first element should be education, Miller said – at all levels, from individuals to presidents and world leaders. “We need them to understand what global warming really means, and to get these urgent actions that need to be done started right away. We’ve got a decade, maybe two, to decide where that level of greenhouse gases is going to be set, [the level] that will set the stage for the next thousand years of human climate. We need to act quickly on these issues.”

The second element, he said, is climate modeling. “One of the great problems right now is, we need regional climate modeling that will tell us what’s going on in the Hawaiian islands. We need hydrology models … localized models that tell us about specific areas and events, and agreed-upon standards that tell us how to interpret these models.” Along with that, Miller said, is a need for ecosystem modeling to inform managers and conservationists how ecosystems will shift over time. “That needs to start now,” he said. “Major policy decisions and management decisions need to be informed by this kind of modeling.”

At present, he said, “we’re in reactive adaptation. You manage critical systems … and habitat for resident species for as long as reasonably possible. It’s business as usual. But when extreme changes threaten to extirpate resident species, reactive adaptation can be used to provide source populations for translocation – get them moving into new areas where habitats and life zone conditions are adequate for longer survival. What it doesn’t mean is trying to maintain current populations on current landscapes. We have to shift activities as climate change unfolds.”

What is needed, Miller said, is “anticipatory adaptation.”

“Starting now, and increasingly rapidly in the future, we need to identify and enhance areas that may be suitable future habitat. We need to expand our knowledge and expertise in transition ecology. … Right now, we’re not too good at doing this. There needs to be a great deal of work on how to carry out this stuff. And it needs to be developed fairly soon.”

Already, Miller said, Hawai`i is experiencing rising temperatures. “The global trend is .18 degrees centigrade per decade. In the Hawaiian islands, Tom Giambelluca has looked at the data, and found we’re pretty much on track.

“But when you compare low versus high elevations, the high elevation is where major temperature changes are taking place — .27 degrees centigrade per decade. This is where the best habitat is,” he said.

More worrying is the fact that nighttime temperatures at high elevations are rising at a faster pace – “.441 degrees centigrade per decade at upper elevation forests,” Miller said. “This will have a profound effect on plant and bird species. Most natural vegetation and agriculture crops in non-frost areas are negatively affected by higher nighttime temperatures, due to increased [plant] respiration. Increased temperature and stress on natives could favor invasives. Also, warm night temperatures will undoubtedly affect the distribution of malaria in Hawaiian forests and its impact on birds.”

The Hawai`i Conservation Alliance has developed a “rough outline” for developing a strategy to deal with climate change, Miller noted, and had placed him at the helm. The subject will be the focus of next year’s HCA conference. “If you have comments, input,” Miller said, “feel free to send us an email: [email]hcastaff@hawaii.edu[/email], with the subject heading ‘climate change comments.’”


Among those in the forefront of Hawai`i climate change study is Jonathan Price, a professor of geography and environmental studies at the University of Hawai`i. Amid the gloom and doom of dire forecasts, Price still managed to proclaim, “We are NOT doomed.”

“We have a number of tools necessary right now to cope with climate change,” he said.

Price is part of a team of scientists trying to develop regional climate change models that will be able, among other things, to project future habitat for individual species of Hawaiian plants and animals.

Already the effects of climate change are beginning to be observed in Hawai`i, he said. “There’s been an increase over the last 100 years at high elevations, sharpening over the last 30 years,” with similar trends at low-elevation stations, he said.

Price described an approach he and other team members are using to look at how climate change might affect local ecosystems. “Historically, Hawai`i ecosystems have been greatly altered,” he said. “A major consequence of climate change is the exacerbation of stressors.” And when the impacts of global warming are seen essentially as the continuation or exacerbation of stressors that are already present, he said, it is possible to see that “management techniques employed today will be vital to coping with climate change.”

As an example, Price cited the anticipated rise in elevation of the areas where mosquitoes will be present – and, with them, the avian diseases they transmit. By removing ungulates “at the landscape scale,” Price said, mosquito habitat can be reduced. “And we can reduce other stressors, such as nest predators” – rats – as another means of helping to protect diminishing forest bird habitat. “Fencing, removal of ungulates and predators, could help keep their habitat useful for the next hundred years,” Price said.

Plants also will be affected by rising temperatures. “We don’t know what will occur in warmer, lower levels,” he said. “Different species respond to climate change at different rates,” as illustrated by the migration of different species of trees after the last ice age in North America.

How that will play out in Hawai`i is still the subject of speculation. But, in light of aggressive invasive species, Hawai`i plants may be at a disadvantage. Price noted that the introduced strawberry guava (waiawi, or Psidium cattleianum) is comparable in many ways to the native kopiko (Psychotria spp.), a tree much valued by Hawaiians for its hard wood. Both are mid-canopy trees and occupy similar ranges, from sea level to 5,000 feet elevation, in mesic to wet areas. (The kopiko, although native, “doesn’t have a website devoted to protecting it,” Price wryly observed, as he displayed a slide showing the webpage of savetheguava.com, sponsored by the Good Shepherd Foundation and Sydney Ross Singer, who opposes release of a biocontrol agent for waiawi.)

“The traits of waiawi probably mean it will establish in upland areas earlier than kopiko,” Price said. But, he added, with “early detection and removal of incipient populations, pre-emptive control of future source populations, and reduction of alien sources of dispersal,” the natives would have a better chance of surviving the coming changes.

“Certainly, in the next 100 years, elements of Hawai`i ecosystems will be lost, I hate to say, but there will be overlap between what we have in the future and what we have today,” he said.

And size will matter: Price noted that different scales are needed for different organisms. “Birds require a larger scale to have viable populations,” he said. “By protecting, managing larger areas, we’re not putting all our eggs in one basket that’s subject to natural or unnatural processes. There’s a safeguard in having larger and larger conservation areas.”

— Patricia Tummons

Volume 19, Number 3 September 2008

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