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TOM BEARDEN: A small compound of wooden buildings in Hawaii Volcanoes National Park is the modest headquarters for an ambitious global warming research project.
On this day, scientists gathered under the eaves, temporarily avoiding the rain, as they prepared for another day in their living laboratory.
This is the laboratory: a dense tropical rainforest on the slopes of Mauna Loa Volcano. They’re looking for the effects of rising temperatures due to global warming. Many scientific studies on the subject derive from computer models. But here in Hawaii, it’s a hands-on approach — one locale and one species at a time.
Scientists from numerous disciplines and agencies, including the U.S. Geological Survey, are working together, trying to understand the complete dynamics of Hawaii’s multiple ecosystems, from lava fields to rainforests.
Small changes in the climate here can immediately affect plants and animals, even wipe them out entirely. Because of that sensitivity, one goal of the so-called bio-complexity project is to see whether the Hawaiian ecosystem can serve as an early warning system for climate change elsewhere and how it may impact plants and animals.
After an hour of bumping over old lava-bed roads, the team lugged their gear into the forest and began setting up nets. They’re studying native birds, which are highly vulnerable to an avian strain of malaria, which arrived with birds imported as pets. The mosquitoes that are spreading it came from 19th century sailing ships. Microbiologist Carter Atkinson studies how the malaria spreads.
CARTER ATKINSON: We’re investigating the ecology of avian diseases here in Hawaiian forest birds across a large landscape, looking at different areas — why it’s transmitted at different rates, at different elevations — what are some of the factors that are contributing to enhancing transmission.
TOM BEARDEN: After 20 minutes, interns Christy Wyckoff and Ben Fogel recovered an I’iwi, a species of native Hawaiian honeycreeper.
Back at a temporary work station under a tarp, the skilled hands of chief technician Caleb Spiegel kept the bird subdued while he checked its weight and took measurements of beak, length and tail.
He looked under the feathers for body fat and added leg bands for identification. And he took a blood sample to monitor whether the disease was present at this altitude. Avian malaria is almost 100 percent fatal, but the birds have a safety zone of sorts.
The malaria protozoa carried in the mosquitoes can’t survive in cool temperatures. And at this elevation in the rainforest it’s cool enough to be disease-free. But that zone may shrink, even disappear, because of global warming.
The data gathered, Spiegel gave the bird a drink of sugar water and released it back into the forest. Patrick Hart is a researcher with the U.S. Geological Survey.
He says temperatures have already risen in Hawaii’s forests, shrinking the safe zone and leading to a decrease in population.
PATRICK HART: Most places you go in Hawaii , you won’t hear the numbers of species that we’re hearing right now. And that’s all because we’re out of the disease zone. If we went downhill another thousand feet in elevation, we wouldn’t be hearing acepas, we wouldn’t be hearing creepers, we wouldn’t be hearing akeapola.
TOM BEARDEN: And just 1,000 feet down you have what amounts to a partial desert?
PATRICK HART: For birds, yeah. Yeah, exactly. We’d be in a forest that looks like this, and you might not even hear a Hawaiian bird in a minute or more, not one call.
TOM BEARDEN: Silent forest.
PATRICK HART: Silent forest, yeah.
TOM BEARDEN: Do you any idea how much change in temperature can cause a threat to the birds?
PATRICK HART: Really just a couple of degrees, I would think. If the mosquitoes are able to come up the mountain just another 1,000 feet than they do now, they could be transmitting a lot more disease and could wipe out a whole community of Hawaiian birds with just a couple degree increase, we think.
TOM BEARDEN: Atkinson co-authored a study projecting what would happen if the Hawaiian temperature rose by two degrees.
Under that scenario, the healthy birds were confined to a narrow disease-free zone between 5,000 and 6,500 feet. When the temperature rose, the disease-free zone shrank on the island of Hawaii.
On the island of Kauai , it shrank even more dramatically. Dennis LaPointe was another co-author of the study. He’s a research ecologist studying the mosquitoes who carry the disease to the birds.
DENNIS LA POINTE: What we’re looking or focusing on now is disease over the broad landscape. And we’re hoping that, you know, through doing this work, we will be able to develop control strategies that will ultimately reduce disease or even eradicate disease in some areas.
TOM BEARDEN: But global warming may affect Hawaii’s forests in more ways than just raw temperature. Changing the climate may also change the way clouds form and how moisture reaches the soil.
Thomas Giambelluca, a climatologist at the University of Hawaii working with the project, is trying to understand the subtleties of the rainforest climate. He set up an 80-foot tower with moisture sensors on top. Below that, on the forest floor, an elaborate series of catchments measures rainfall that reaches the ground.
THOMAS GIAMBELLUCA: We use this system, which has a number of troughs radiating out in the up-slope direction. That directs the water down to a central funnel here. And beneath the funnel is a tipping bucket. There’s a data logger here that records the number of tips, actually records the time of each tip, and that can remain in the field without anyone attending it for quite a long time.
TOM BEARDEN: The sensors above the tree tops also measure moisture from clouds and fog.
THOMAS GIAMBELLUCA: Rainfall’s not the only input of water that we get. When fog envelopes these trees, which very often happens here, the droplets of water in the cloud directly impact the vegetation, drip down to the soil and supply water just the same way that rainfall does.
And some of the vegetation here also has aerial roots that can absorb that water directly without it getting down to the soil.
So if there’s a change in the elevation or the thickness, the range of that cloud, that could impact this forest and other areas in Hawaii.
TOM BEARDEN: Research ecologist David Foote is studying one of the first species that might be affected by a change in moisture — the Hawaiian damselfly.
He’s catching damselflies in artificial pools and numbering their wings with a marking pen. Damselflies are also valuable because, as Foote demonstrated in the lab, the larvae eat mosquito larvae.
In the forest, damselfly larvae tend to live in water droplets that collect at the base of native lily plants.
DAVID FOOTE: Here we are — right on the tip of my thumb. So, this is a much younger stage in the development. They molt through several skins as they grow larger. And I can put them side by side here on the tip of my finger, maybe on two fingers, and you can see them crawling around.
We predict that this species, because it requires such a specialized aquatic habitat that it will be very sensitive to small changes in moisture level.
TOM BEARDEN: So that little pocket of moisture at the base of those leaves might not be there?
DAVID FOOTE: That’s right. And as these forests get desiccated by drought events, we think that species like this that are highly specialized to very specific little aquatic niches are going to be the ones that are lost first.
TOM BEARDEN: The scientists on the project will also examine the role that non-climate factors have on species, like human land use — clearing forests to graze cattle and expanding towns and resorts. The Hawaiian study does not limit itself to looking at present-day conditions.
Research assistant Shelley Crausbay is studying paleoecology, the history of Hawaii’s past climate. She recreates that history by studying core samples from a Hawaiian lake bed — because there is little oxygen at the bottom of the lake bed, grains of pollen, pieces of moss, and even entire insects have been perfectly preserved. Some are as old as 12,000 years.
SHELLEY CRAUSBAY: Most scientists have come to a consensus that climate change has been initiated, and what paleoecology can offer now is how will ecosystems respond to climate change? How have they responded in the past? How sensitive have they been? What kind of climatic change does it take to initiate a change in vegetation and how intense, in what direction, and what duration?
TOM BEARDEN: The long-term goal of the whole project is to tie together the pieces from past and present, to model the entire system across the whole Hawaiian landscape.