Tuesday, June 24, 2014

Strange days in the Indonesian straits

Among the very strange and spooky impacts of climate change: changes in the behavior of massive oceanic current patterns.

(Image: The Indonesian Straits, which provide a conduit between the Pacific and Indian Oceans. They are described as the only place on the planet where oceans interact the way they do here, and the only place in the tropics where oceans are able to interact. Source: University of Hawai`i.)

New research suggests that climate change will alter the flow between the Pacific and Indian Oceans through the Indonesian straits. That’s on top of changes in the flow that are driven  by the alternating El Nino-La Nina climate cycles.

What this will mean longer-term is not yet entirely clear, but there are suggestions that the changing flow could change the climate in both oceans. A better understanding of the changes could result in better forecasts of climate activity, according to a new paper.

The flow of ocean water through the Indonesian strait appears to have become both shallower and stronger, according to a study published June 22 in the journal Nature Geoscience. The paper is entitled “The Indonesian seas and their role in the coupled ocean-climate system.”

UH Mānoa physical oceanographer James Potemra is a co-author. The lead author is Janet Sprintall of Scripps Institution of Oceanography at UC San Diego, and other co-authors are Arnold Gordon of Lamont-Doherty Earth Observatory at Columbia Unversity, Ariane Koch-Larrouy of LEGOS in France, Tong Lee of the Jet Propulsion Laboratory in Pasadena, Calif., Kandaga Pujiana of Oregon State University and Insitut Teknologi Bandung in Indonesia, and Susan Wijffels of the Commonwealth Scientific and Research Organization in Australia.

Eric Lindstrom, co-chair of NASA’s  Global Ocean Observing System Steering Committee, which funded part of the study, talked about its importance:

“This is a seminal paper on a key oceanographic feature that may have great utility in climate research in this century. The connection of the Pacific and Indian oceans through the Indonesian Seas is modulated by a complex circulation, climate variations, and sensitive ocean-atmosphere feedbacks.  It’s a great place for us to sustain ocean observations to monitor potential changes in the ocean’s general circulation under a changing climate.”

Lead author Sprintall said: “Now that we have a better understanding of how the Indonesian Throughflow responds to El Niño and La Niña variability, we can begin to understand how this current behaves in response to changes in the trade wind system that are brought on through anthropogenic climate change.  Changes in the amount of warm water that is carried by the throughflow will have a subsequent impact on the sea surface temperature and so shift the patterns of rainfall in the whole Asian region.”

Here’s some complex language from the paper on what’s going on with the currents: “A synthesis of observational data and model simulations indicates that the temperature, salinity and velocity depth profiles of the Indonesian throughflow are determined by intense vertical mixing within the Indonesian seas. This mixing results in the net upwelling of thermocline water in the Indonesian seas, which in turn lowers sea surface temperatures in this region by about 0.5 °C, with implications for precipitation and air–sea heat flux.”

A University of Hawaii press release discusses the paper. 

More information on this kind of stuff at the website of the International PacificResearch Center at University of Hawai`i at Mānoa. 
© Jan TenBruggencate 2014

Saturday, June 14, 2014

The energy storage that gets Hawai`i to 100% renewable--just around the corner.

We’re not quite there yet, but there’s lots of progress toward the battery that will change the energy world.

That, of course, is the energy storage system that will store cheap solar power cheaply, deliver It efficiently, use non-toxic materials, and keep working long enough to make economic sense.

For Hawai`i, it’s the battery that turns solar and wind power into firm power, and it may be the ultimate key to getting to 100 percent renewable energy in the Islands.

Existing batteries haven’t gotten us there. 

The old standby lead-acid has its applications, but it’s not cheap, the lead toxicity is an issue, and while your solar panel might last 20 years, a lead-acid battery is lucky to last a third of that in daily cycling.

Lithium-ion is interesting, and last many more cycles, but it’s still not cheap.

Lithium-air has tantalizing qualities—it’s very energy dense—but they’re having trouble getting it to survive enough cycles to be economically feasible. It’s discussed deep in this article in The Economist.

Here’s a report from the blog The Engineering Economist on a graphene battery that may be running on nothing but the heat in the room. If you read the article, you’ll see that there are still some questions about it, but it’s an intriguing concept. 

There has been lots of discussion of heat-based energy storage. Most of it, though, has involved converting the stored heat (in molten salts or rock) into electricity with old-school steam engines. And thus far, the economics haven’t been great.

But researchers are working on it, and hard. One team has developed what it hopes will be a cheap form of energy storage using a heat transfer mechanism that doesn’t uses a steam engine. Rather, it stores heat in crushed rock surrounded by argon gas. As the argon moves between a hot chamber and a cold chamber, it runs through a pump hooked up to a generator.

In this article in The Economist, engineer Jonathan Howes figures he can store and then generate energy at less than five cents per kilowatt-hour. They call their system Pumped Heat Electrical Storage (PHES), and their company is Isentropic.

Of course, they haven’t built the thing yet.

Nature magazine wrote last month about Michael Aziz and his cheap quinone battery, a flow battery. It shows great promise, although it’s still in testing and has some toxicity problems. I’ve met Aziz, and his work is taken very seriously by his colleagues in the field. 

There’s lots going on in energy storage technology.

The breakthrough, as they say, is just around the corner.

But nobody’s predicting just when we get to that corner.

© Jan TenBruggencate 2014

Sunday, June 1, 2014

Antarctic ice sheets unstable, massive sea level rise possible

Models of sea level rise tend to suggest gradual action, which will provide reasonable time for coastal communities to respond.

But a new study by University of Hawai`i researchers suggest that catastrophic sea level rise is possible. It has happened before.

(Image: Calypso corer onboard the research vessel Marian Dufresne II in the Scotia Sea. Credit: Michael Weber.)

Axel Timmermann, a professor with the International Pacific Research Center at UH is the co-author of a paper in Nature that looks at evidence of past cases of fast sea level rise. 

An international team of researchers studied deep sea sediment cores taken between the Falkland Islands and Antarctica.

They found evidence of multiple melting events, which they said suggest that warming conditions can lead to catastrophic melting of the immense Antarctica ice sheet. One such event took place 14,600 years ago. In that case, there was evidence that oceans rose 3 meters in a century. 

That works out to an inch and a half a year—many times the current rate of sea level rise and one that would very quickly overwhelm existing coastline development.

“An unusually strong flow of warm water towards Antarctica may have triggered these events. Our model experiments reveal further that the associated melting in turn increased the warm water flow, thus providing a positive feedback. This is a perfect recipe for rapid sea level rise,” Timmermann said.

“This is the first direct evidence that instabilities of the Antarctic ice sheet caused rapid sea level rise during the last glacial termination,” said Peter Clark, professor at Oregon State University.

The University of Hawai`i’s press release on the paper says it nmeans the Antarctic ice sheet is far less stable than previously understood.

Citation: Weber, M. E., Clark, P.U., Kuhn, G., Timmermann, A., Sprenk, D., Gladstone, R., Zhang, X., Lohmann, G., Menviel, L., Chikamoto, M. O., Friedrich, T. Ohlwein, C., 2014. Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation, Nature, http://dx.doi.org/10.1038/nature13397

© Jan TenBruggencate 2014