Tuesday, November 20, 2012

Dying tradewinds? It's the water temperature.

University of Hawai`i researchers report that changes in ocean temperatures may be responsible for the dying of the trade winds over the past 60 years.

The scientist team used an amazingly low-tech data set to help them reach that conclusion—buckets hauled aboard ships to test ocean water temperature over decades.

The study, published in the Nov. 15, 2012, issue of Nature, was led by Hiroki Tokinaga, associate researcher at the International Pacific Research Center at the University of Hawaiʻi at Mānoa. 

It argues that warmer waters are linked to weakening tradewinds and an eastward shift in oceanic rainfall, toward the Central Pacific. That’s associated with a slowing of what climate scientists call the Walker Circulation, in which a regional wind pattern is created by warm, moist air rising over warm waters.

RaisingIslands.com covered the dying trades last month. 

Climate scientists have been baffled by the significant change in wind and rain patterns, because their climate models couldn’t explain them. Tokinaga felt that might simply be because the models didn’t have precise enough water temperature information.   

He tracked down archived sets of old data collected over the entire 60-year period, in which ships kept track of night time marine air temperatures as well as ocean water temperature—determined by putting thermometers into buckets of water pulled from the sea as the ships crossed the Pacific.

“To our surprise both measures showed that the surface temperature across the Indo-Pacific did not rise evenly with global warming, but that the east-west temperature contrast has actually decreased by 0.3-0.4°C, similar to what happens during an El Niño,” Tokinaga said.

When they plugged to reconstructed temperature data into four separate computerized atmospheric models, “the scientists were able to reproduce quite closely the observed patterns of climate change seen over the 60-year period in the tropical Indo-Pacific and the slowdown of the Walker circulation.”

Here is the University of Hawai`i press release on the study. An abstract of the actual paper is available here.  A nice piece on Walker Circulation from NOAA and NASA is here

 "Our experiments show that the main driver of the change in the Walker circulation is the gradual change that has taken place in the surface temperature pattern toward a more El Niño-like state. We don't have enough data yet to say to what degree the slowdown over the last 60 years is due to a rise in man-made greenhouse gases or to natural cycles in the climate," Tokinaga said.

© Jan TenBruggencate 2012

Wednesday, November 14, 2012

Spinner dolphins: you can play with them, but they also need their rest

It may come as a surprise to residents and tourists who eagerly swim or paddle out to play with spinner dolphins, but those animals are often in Hawaiian bays for needed rest, not human recreation.
(Image: Tourists interacting with spinner dolphins. Credit: David Johnston, Duke University.)

And those dolphin-loving humans may actually be driving the animals out of safe coastal habitat into danger and fatigue, according to a new study. Here’s a Duke University press release on the study. 

The study identifies coastal resting habitats, and suggests that maps developed from environmental models could be use to protect the charismatic species. It also clearly implies that this does NOT mean all dolphins ought to be off-limits; rather that there are specific resting locales that could be protected.

The spinner dolphin work was prepared by a large team of accomplished research scientists from Hawai`i, across the nation and Australia. It is entitled “Predictive Modeling of Spinner Dolphin (Stenella longirostris) Resting Habitat in the Main Hawaiian Islands.” You can go to the actual study on the peer-reviewed journal PLoS One, here, for details. 

There may be bays where dolphins come in ready for play, but in many cases, they are there to rest and sleep—and that’s critical to their alertness and thus their survival, said Johnston.

“Sleep is essential for most animals. When deprived of their necessary ‘zzzz’s,’ they gradually show a decreased ability to process information and remain attentive to environmental stimuli. In technical lingo, we call this a ‘vigilance decrement’,” he said.

The paper says: “Spinner dolphins in Hawai'i exhibit predictable daily movements, using inshore bays as resting habitat during daylight hours and foraging in offshore waters at night. There are growing concerns regarding the effects of human activities on spinner dolphins resting in coastal areas.”

With this insight, the image of dozens of excited humans paddling around in dolphin pods may be of concern.

The authors say that they are working on modeling techniques to identify which bays in the Islands are critical resting spots for the animals. They describe typical patterns of spinners, when humans aren’t interfering: 

“Spinner dolphins typically enter protected bays of the main Hawaiian Islands just after dawn, and slowly descend into a resting state over a period of up to two hours. The resting state is defined by slow movements, a cessation of aerial behavior, synchronous dives by tight groups of dolphins that are touching or almost touching, and visual, rather than acoustic, vigilance.”

Thereafter, the dolphins spend a large part of the rest of the day in slow, group swimming that may be part of the resting cycle: “Groups of resting dolphins typically move slowly within bays for four to five hours, after which dolphins undergo a period of “zig-zag swimming” and increase surface activity before moving into deeper waters near sunset to begin night-time foraging.”

The study suggests that spinner dolphins are looking for a predictable blend of water depth, bottom configuration and nearness to deep water for feeding. Using those features, they feel it is possible to identify bays where resting dolphins ought to be protected.

That doesn’t means all spinner dolphins should be off limits for humans seeking interaction, they write: “Limited observations suggest that socially active spinner dolphins might be relatively tolerant of human presence, while resting spinner dolphins may leave an area if forced to interact with humans.”

The authors include Lesley H. Thorne, David W. Johnston, Dean L. Urban5 Julian Tyne4 Lars Bejder, Robin W. Baird, Suzanne Yin, Susan H. Rickards, Mark H. Deakos, Joseph R. Mobley Jr., Adam A. Pack, and Marie Chapla Hill. Their affiliations include Stony Brook University, Duke University Marine Laboratory, Pacific Islands Photo-Identification Network in Honolulu, Cetacean Research Unit atMurdoch University in Western Australia, Nicholas School of the Environment at Duke University, Cascadia Research Collective of Washington State, Hawai'i Marine Mammal Consortium of Kamuela, Hawai'i Association for Marine Education and Research of Lahaina, The Dolphin Institute of Honolulu, Marine Mammal Research Consultants of Honolulu, Psychology and Biology Departments of the University of Hawai'i at Hilo, and Joint Institute for Marine and Atmospheric Research of the University of Hawai'i at Mānoa.

© Jan TenBruggencate 2012

Sunday, November 11, 2012

Flooding from sea level rise will double due to groundwater rise: UH scientists

As the sea level continues to rise, low-lying parts of Hawai`i will face attack on two fronts.

We can plan for driving through vast pools of brackish water throughout much of low-lying Honolulu, including much of Waikīkī.

(Image: Flooding in Māpunapuna. Credit: University of Hawaii.)

 The rising seas will push shoreward, but at the same time, groundwater will back up and further raise the water level, says a new study: “Assessment of groundwater inundation as a consequence of sea-level rise.”

The report, published in the journal Nature Climate Change, was written by Kolja Rotzoll of the Water Resources Research Center at University of Hawaii, and by Charles “Chip” Fletcher, of the University of Hawai`i School of Ocean and Earth Science and Technology.

“Besides marine inundation, it is largely unrecognized that low-lying coastal areas may also be vulnerable to groundwater inundation, which is localized coastal-plain flooding due to a rise of the groundwater table with sea level,” they write.

Their work suggests that sea level rise alone can’t be isolated as the source of flooding.

“The flooded area including groundwater inundation is more than twice the area of marine inundation alone,” they write.

Looking just at Honolulu, their work concludes that, particularly at high tide, there will be massive regions of flooding—ponds and lakes of standing brackish water that could represent 10 percent of all the low-lying land within a kilometer of the coast as sea level rise reaches one meter.

In many parts of the Islands, groundwater is already very near the surface in the lowest lying areas like Waikīkī and other parts of Honolulu. In some areas, including parts of Māpunapuna, the streets already flood during the highest tides. 

“With groundwater tables near the ground surface, excluding groundwater inundation may underestimate the true threat to coastal communities,” said Rotzoll.

 “Finding that the inundated areas double when including groundwater inundation in coastal flooding scenarios will certainly be a surprise for everyone assessing the effects of (sea level rise) without considering the local groundwater table,” Rotzoll said.

The authors recommend continuous groundwater level monitoring in the coastal zone, along with “rigorous planning” for the impacts of brackish water inundation.  And they recommend residents of coastal communities everywhere study their own potential situations.

“We hope other coastal communities use our research as the basis for conducting their own localized analysis,” Rotzoll said.

Fletcher, an associate dean at the University of Hawai`i and a coastal geologist who has been studying sea level rise and erosion issues statewide, said the planning won’t be easy.

“This research has implications for communities that are assessing options for adapting to (sea level rise). Adapting to marine inundation may require a very different set of options and alternatives than adapting to groundwater inundation,” Fletcher said.

The paper: Rotzoll, K. and Fletcher, C.H. Assessment of groundwater inundation as a consequence of sea-level rise. Nature Climate Change, DOI: 10.1038/NCLIMATE1725

The abstract can be viewed here.

Fletcher’s website on Hawaiian sea level rise impacts includes a virtual fly-through of those impacts. 

© Jan TenBruggencate 2012

Saturday, November 10, 2012

Climate change: worse is more likely

Climate is changing faster than we’ve been told, and it’s going to get worse than the consensus estimates.

That’s a conclusion of a new report from the National Center for Atmospheric Research (NCAR).

Much of the science industry has been understating its science, perhaps because the most dire scenarios seem so outrageous, perhaps because they’re reeling from the denier attacks.

The Intergovernmental Panel on Climate Change’s 2007 report says its projections “do not include uncertainties in climate-carbon cycle feedbacks nor the full effects of changes in ice sheet flow, therefore the upper values of the ranges are not to be considered upper bounds for sea level rise.” 

Translation: We left out the really scary stuff.

For Hawai`i, where climate change predicts significantly reduced rainfall and coastal flooding from higher sea levels, it’s also important stuff.

Even so, IPCC in 2007 projected contracting snow cover, disappearance of Arctic summer sea ice, increase of extreme hot weather, increased hurricane intensity, less rainfall in subtropical land areas and more. Sound familiar? Let’s see. Glaciers are melting, you can now run ships over the north sides of both the Americas and Asia, Hurricanes Katrina and Sandy, the expanding Sahara and Gobi deserts.       

NCAR, in an article in this week’s issue of Science, is suggesting that the more severe estimates of global warming are more likely to be the accurate estimates.

“Our findings indicate that warming is likely to be on the high side of current projections,” say NCAR scientists John Fasullo and Kevin Trenberth.

The two researchers come to their conclusion based on global humidity patterns. Many earlier studies have tried to link climate change to cloud patterns, but clouds are notoriously ephemeral and difficult to model. On the other hand, humidity is well researched and provides a useful tool for analysis of climate patterns, they said.

They looked at relative humidity figures for cloud-free subtropical areas, which they said are “easier to observe than the cloud properties themselves.”

Why the subtropics? “The dry subtropics are a critical element in our future climate. If we can better represent these regions in models, we can improve our predictions and provide society with a better sense of the impacts to expect in a warming world,” said Fasullo.

“Because we have more reliable observations for humidity than for clouds, we can use the humidity patterns that change seasonally to evaluate climate models,” says Trenberth. “When examining the impact of future increases in heat-trapping gases, we find that the simulations with the best fidelity come from models that produce more warming.”

NCAR’s press release on the study says it “could provide a breakthrough in the longstanding quest to narrow the range of global warming expected in coming decades and beyond.”

© Jan TenBruggencate 2012

Friday, November 9, 2012

Election's over, let's get back to saving the planet

Now that the Presidential election is over, maybe we can get back to saving the planet.

Allen Hershkowitz, senior scientist with the Natural Resources Defense Council, is vacationing on Kaua`i, and took, the time to give a couple of talks.

His message: The planet needs saving, and the job is so huge that you might despair. His further message: You can’t do everything, but be sure to do something.

“We’re facing urgent ecological pressures,” he said. The climate is changing. Species are going extinct at a rate of one every 20 minutes. Forests are being destroyed at a rate of an acre per second (38 million acres last year). Most of the plastic in the world is not recycled, and a lot of it ends up in the ocean, where it outweighs a lot of biological organisms.

Hershkowitz is considered the father of the “greening” movement, which he describes as reviewing a business or industry’s operations with an eye to reducing impact.

Individuals and communities can “green” themselves, too. 

His message to his Kaua`i audiences: If you do one thing, recycle. The impact of using raw materials in manufacturing is immense, and recycling is an answer. It saves energy, it saves money, it creates jobs, it saves forests (does it make any sense at all to use virgin fiber for toilet paper?) and mountains (mountaintop-removal coal mining).

We’re cutting down tropical forests and destroying entire ecosystems for paper, when we could make the same paper out of agricultural waste like corn stalks.

That used plastic bottle is entirely lost if it goes into a landfill. It creates a tiny bit of energy if it’s burned in Honolulu’s HPOWER waste-to-energy plant. But if recycled, it saves far more energy than is used to make a bottle out of virgin materials—and it also saves raw.

Hershkowitz doesn’t much care whether your community separates your recyclables at home (more efficient waste stream with lower processing cost, but lower participation, higher collection cost) or uses a single stream system that separates the recyclables after collection (threat of recyclable contamination, higher participation, lower collection cost but higher processing cost).

He just wants you to do something. And indeed, the communities of Hawai`i have been stumbling along the path to doing something for some time. As an example, Kaua`i County has been talking about a Materials Recovery Facility for two decades.

“There’s no MRF on Kaua`i. That makes no sense to me,” Hershkowitz said. “There are companies that will come and build them and pay to do so.”

Here’s a YouTube piece on how a MRF works.  http://www.youtube.com/watch?v=7CFE5tD1CCI

© Jan TenBruggencate 2012