Hawaii Travel

Archive for March, 2010

A research team studying global impacts of climate change has found that Hawai’i will generally have few major disruptions, although weaker trades could reduce rainfall.

Much of the rest of the world may see dramatic changes in rainfall, in temperatures, in storm frequencies, but the Islands appear to be in a kind of mid-Pacific sweet spot.

That’s one conclusion from a paper, Global Warming Pattern Formation: Sea Surface Temperature and Rainfall, by Shang-Ping Xie and Jian Ma of the University of Hawai’i School of Ocean and Earth Science and Technology’s International Pacific Research Center, along with Clara Deser and Haiyan Teng of the National Center for Atmospheric Research, and Gabriel Vecchi and Andrew Wittenberg of the NOAA Geophysical Fluid Dynamics Laboratory.

Their paper was published in the Feb. 15, 2010, “Journal of Climate” of the American Meteorological Society. It uses a range of climate models to study potential changes in global weather patterns.

It’s a complex paper, but among its conclusions:

With the anticipated changes in global temperatures over the coming half century, rainfall for Hawai’i will probably not be significantly impacted. Maybe some reduction in rain overall, maybe some local changes depending on specific geographic features like mountains and valleys.

Other studies have suggested a slight reduction in rainfall in the Islands.

Xie and co-authors do see a weakening of tradewind flow, which could result in some reduction in Hawai’i rainfall. Depending on when it occurs, it could also change the comfort levels for people living in the Islands.

The researchers find that tropical storm frequency will not change significantly in Hawaiian waters.

One of the key piece of information—and this has been a big feature of recent debate over climate change—is that while warming is occurring, it’s not distributed evenly across the globe.

As an example, while Hawai’i's changes are comparatively minor, the models suggest significant increases in rainfall in the Intertropical Convergence Zone to the south of the Islands. And while our storm frequency is not anticipated to change much, the hurricanes in the Pacific south of the equator are expected to be more common, in association with significant warming of the ocean in that area.

For Samoa, the Cooks, French Polynesia and other nations in that part of the sea, that’s not good news.

© Jan TenBruggencate 2010

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woah look at that maybe i should clean my lens filter thing. either that or there were some evil black orbs that didn’t want me to leave honolulu last week. “don’t leave don’t leave aaaaaa”….

nah nah. i did have to go to hong kong tho. i couldn’t not. i was sitting with Race and jasper [...]
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It’s been more than a century since Hawai’i sugar planters recognized that the dramatic deforestation of Hawai’i in the 1800s, much of it for firewood, had played havoc with water resources.

They began a reforestation effort whose impacts can still be seen today. Much of the reforestation was with hardy and often fast-growing imported species, like eucaluypts, pines, silver oak and others.

(Image: Degraded pasturelands in 1940 on the Edwards Plateau in Texas, where spring flows revived after woody plants were allowed to return. Credit: Charles Taylor and American Geophysical Union.)

The reforestation theory, in part, is that the trees shade the ground, reducing evaporation, and reduce ground-level wind, further reducing evaporation. That gives rainfall an opportunity to soak into the ground and recharge groundwater supplies.

But there have been naysayers who suggest that trees actually suck water out of the ground more than they preserve.

The correct answer, as often is the case, may be that it depends. Not all trees are created equal as protectors of the watershed. And some dryland species like kiawe and tamarisk have been accused of sending down deep roots that suck up groundwater. A welldigger once told me that you could actually see the impact of kiawe on water supplies, causing groundwater levels to drop as soon as the sun rose and the trees started the process of evapotranspiration.

But a complex forest with trees and shrubs does appear to significantly improve an area’s water retention.

And not only in Hawai’i.

A new paper to be published by the American Geophysical Union’s Geophysical Research Letters says that groundwater levels improved dramatically in Texas after severely overgrazed lands were better managed. http://www.agu.org/news/press/pr_archives/2010/2010-06.shtml

The study says that an “analysis of many decades of historical records for four central Texas river basins challenges widespread perceptions that woody plants have the opposite effects on streams and aquifers.”

Bradford Wilcox of Texas A&M University and Texas AgriLife Research, and former Texas A&M graduate student Yun Huang studied the Edwards Plateau, whose Edwards aquifer provides much of the water for San Antonio. The semi-arid plateau had been overgrazed for a century starting about 1880.

But when stocking rates were reduced, and trees and shrubs came back, they saw a change.

“These landscapes are recovering, but they’ve also converted to woody plants. We’re also seeing large-scale increases in the amount of spring flows. This is opposite of what everybody is presuming —[which is that] the trees are there sucking up all of this water. The trees are actually allowing the water to infiltrate,” Wilcox said.

The flow of water from springs has doubled since before 1950, and the flows in three of the region’s four rivers has increased in the same period, they said.

These results will not be a shock to anyone who has walked under the cool shade of the native forest in The Nature Conservancy’s Kanepu’u reserve on Lana’i, and then compared the environment to the sun-baked, eroded environment outside the fenced reserve.

© Jan TenBruggencate 2010

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When anything slips out of the Great Pacific Garbage Patch, say hello. Because chances are it ends up on a Hawaii beach.

Teams of researchers have been working on the fate of marine debris in both the Atlantic and Pacific.

(Image: This Laysan albatross chick died with its belly full of plastic, some of which may have been picked up by its parents in the Great Pacific Garbage Patch. A lesson about controlling the flow of plastic debris into the marine environment.)

“In the North Pacific, Hawai’i is the final destination of marine debris,” said Nikolai Maximenko, a senior researcher with the International Pacific Research Center, and the University of Hawai’i's School of Ocean and Earth Science and Technology.

He reported last week from the American Geophysical Union 2010 Ocean Sciences Meeting in Portland, Oregon.

As we understand it, when trash gets lost or dumped off fishing boats, falls off big ships or washes into the ocean from the shore in the North Pacific, it begins a nearly endless transit around the ocean on a vast current system.

A large amount of that trash slowly moves toward the interior of the the North Pacific Current, and eventually gets trapped in the immense field of garbage in the eastern North Pacific, between Hawai’i and California.

And when currents and winds drive anything out of that system, it tends to get swept south and westward. The only thing in its way at that point is the 1,400-mile-long Hawaiian archipelago.

So our Hawaiian reefs and beaches get trashed with tangles of rope and net, plastic tubes from Japanese oyster farms, bottles, multicolored cigarette lighters, and endless fields of tiny bits of unidentifiable plastic.

A research program in the Atlantic, involving thousands of graduate students, reported on 6,100 plankton net tows in that ocean. They found that 62 percent of the nets contained plastic—64,000 pieces of plastic. Most of it, 83 percent, was found in the central latitudes, between 22 and 38 degrees north, said Kara Lavender Law, Oceanography Faculty Scientist of the Sea Education Association at Woods Hole, Massachusetts.

Another Woods Hole faculty scientist, Giora Proskurowski, said that while researchers have towed nets through the water for hundreds of miles, no one knows just how much of that stuff is out there, in part because any amount of wind or wave causes much of the debris to mix deep into the upper layers of the ocean. There, it doesn’t show up in surface-towed plankton nets.

If you do a tow on a dead calm day, the stuff floats to the surface and you get a lot. If you tow when there’s any kind of weather, the results under-represent reality, he said.

Law said that the majority of the smaller bits of plastic are not identifiable as to their source, unless they are bits of fishing line or industrial plastic pellets. Some plastic debris is denser that seawater and sinks to the bottom, where its impacts have not been well studied.

© Jan TenBruggencate 2010

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