Wednesday, September 2, 2015
New study reveals the possibility of hurricanes ‘unlike anything you’ve seen in history’
Satellite Movie Shows Two Hurricanes and a Depression
This animation of images captured August 29 to September 1 from NOAA's GOES-West satellite shows Hurricane Ignacio near Hawaii, followed by Hurricane Jimena and Tropical Depression 14E
Credit: NASA/NOAA GOES Project
From WashingtonPost by Chris Mooney
Last week, the nation focused its attention on the 10-year anniversary of Hurricane Katrina, the most destructive hurricane in U.S. history.
As bad as the storm was, though, it wasn’t the worst storm that could have possibly hit New Orleans.
That’s true of many, many other places, too.
And now, in a new study in Nature Climate Change, Princeton’s Ning Lin and MIT’s Kerry Emanuel demonstrate that when it comes to three global cities in particular — Tampa, Fla., Cairns, Australia, and Dubai, United Arab Emirates — there could come a storm that is much worse than anything in recent memory (or in any memory).
Granted, these theoretical storms are also highly unlikely to occur — in some cases, they are 1-in-10,000-year events, or even rarer.
The researchers refer to these possible storms as “gray swans,” riffing on the concept of a “black swan” event, an unpredictable catastrophe, or highly impactful event.
A “gray swan,” by contrast, can indeed be predicted, even if it is extremely rare.
The purpose of the study is “to raise awareness of what a very low probability, very high impact hurricane event might look like,” said Emanuel.
The gray swan storms were generated by a computer model that “coupled” together, in the researchers’ parlance, a very high-resolution hurricane model with a global climate model.
That allowed the researchers to populate the simulated world with oodles of different storms.
“When you do hundreds and hundreds of thousands of events, you’re going to see hurricanes that are unlike anything you’ve seen in history,” said Emanuel, a key theoretician behind the equations determining the “maximum potential intensity” of a hurricane in a given climate.
Indeed, he has published in the past that a theoretical “hypercane” with winds approaching 500 miles per hour is possible in scenarios where an asteroid hits the Earth and radically heats up ocean waters, far beyond their normal temperature.
So what did the researchers see?
Tampa Bay with the GeoGarage platform
Let’s take Tampa Bay, first.
It hasn’t been hit by a major hurricane since 1921 — but that storm drove a 3- to 3.5-meter (10- to 11-foot) storm surge and caused dramatic damage.
Earlier, in 1848, another storm produced a 4.6-meter surge (about 15 feet).
Why is Tampa Bay so vulnerable?
Check out any good map that shows the water depth (the bathymetry) around the Florida peninsula. It’s deep off the east coast.
But there’s an extraordinarily broad continental shelf off the west coast.
Gulf of Mexico with the GeoGarage platform
“One can get much larger surges where the offshore waters are shallow, as is true along the west, but not the east coast of Florida.
Also, surges can amplify by being funneled into bays,” Emanuel said Monday in an e-mail.
The new method allows the researchers to show that a worse storm than these historical examples is possible, especially with sea level rise and global warming.
They simulated 2,100 possible Tampa Bay hurricanes in the current climate, and then 3,100 each for three time periods (2006 through 2036, 2037 through 2067, and 2068 through 2098) in an unchecked global warming scenario.
In the current climate, the study found that a 5.9-meter (19-foot) storm surge is possible, in a strong Category 3 hurricane following a similar track to Tampa’s classic 1921 and 1848 storms.
Moreover, in a late 21st century climate with global warming run amok, the worst-case scenario generated by the model included a very different storm track, moving north along Florida’s Gulf Coast and then swerving inland at Tampa, that generated an 11.1-meter (nearly 37-foot) surge.
Granted, the study said that these two “gray swans” are exceedingly unlikely — less than 1 in 10,000 years for the 5.9-meter surge in the current climate.
But it also said that global warming shifts the odds toward the worse surges.
“The more publicity of the hurricane risk in Tampa, the better,” Emanuel said.
Cairns with the GeoGarage platform (AHS nautical chart)
The study also shows that for Cairns, Australia, a 5.7-meter (18-foot) storm surge is possible in the current climate, but that would happen less than once in 10,000 years.
Dubaï with the GeoGarage platform (UKHO nautical chart)
And perhaps most strikingly, it also suggests that an extremely powerful hurricane is theoretically possible where we’ve never yet seen them occur — the Persian Gulf.
The waters in the Persian Gulf are very hot and so contain considerable potential hurricane energy, but the atmosphere is normally too dry for hurricanes, Emanuel explained.
Nonetheless, “physics says that you can have one,” he said.
“‘It’s not likely, but it’s not impossible.”
Indeed, there have been several hurricanes or tropical storms that have entered the Arabian Sea, though none have made it into the Persian Gulf.
But the study showed that in extraordinarily rare circumstances, it’s also possible for a hurricane to be generated there.
Indeed, it found that with 3,100 simulated events in today’s climate, it is theoretically possible to get a hurricane with winds of over 250 miles per hour — stronger than anything we’ve seen on Earth — and a storm surge of 7.4 meters (24 feet) affecting Dubai.
Granted, it is hard to emphasize enough that this is a rare phenomenon — storms like this have “return periods of the order of 30,000–200,000 years,” the study said.
So, is all of this just a mathematical exercise — or something more?
In the end, it’s kind of in the eye of the beholder, as it’s up to us to decide how much to worry, if at all, about an extraordinarily rare event.
But you could make the case that a study like this helps us think a lot better about what risk is all about.
“You go out on the tail, the risk gets tinier and tinier and tinier, but the consequences of that event get exponentially larger,” Emanuel said.
Links :
- CSMonitor : Why researchers are concerned about 'grey swan' hurricanes
- ClimateCentral : ‘Grey Swan’ Hurricanes Pose Future Storm Surge Threat
- Google : Improving Public Alerts for hurricane season
- NASA : Cabo Verde Hit by First Hurricane in a Century
Tuesday, September 1, 2015
NZ Linz update in the GeoGarage platform
9 charts has been updated in the GeoGarage platform
Linz June update published July 24, 2015 (Updated to NTM Edition 15)
see : GeoGarage blog
Linz June update published July 24, 2015 (Updated to NTM Edition 15)
see : GeoGarage blog
Seabirds 'blighted by plastic waste'
Plastic swallowed by albatrosses in the Pacific ocean
Hawaii: Message in the Waves - BBC
From BBC by Jonathan Amos
About 90% of seabirds have eaten plastic and are likely to retain some in their gut, a new analysis estimates.
The study concludes that matters will only get worse until action is taken to stem the flow of waste to the oceans. Researcher Erik Van Sebille says the oceans are now filled with plastic and it is "virtually certain" that any dead seabird found in 2050 "will have a bit of plastic in its stomach".
Dr Van Sebille and his colleagues report their work in the journal PNAS.
On one level, the analysis is shocking, but on another, its findings seem depressingly familiar.
Numerous studies have now catalogued the rising mass of plastic debris being dumped, blown or simply washed out to sea; and it is having a deleterious impact on the marine environment.
To the foraging bird, a discarded plastic cigarette lighter or a shiny bottle top can look like a fish.
If ingested, this litter may simply stay in the gut, unable to pass through, putting the animal's health at risk.
As more and more plastic waste finds its way into the oceans - about eight million tonnes a year in one recent estimate - so the hazards to wildlife increase.
Midway Island is an uninhabited island about 2000 km from any other coast line.
It lies roughly equidistant between North America and Asia, and almost halfway around the world from England.
In their PNAS paper, the Australian and UK scientists reviewed decades of peer-reviewed literature to trace the evolution of seabirds' exposure to plastic debris.
Back in 1960, the data showed that maybe fewer than 5% of birds would be found with waste fragments in their stomach.
Today, this figure is roughly 90%.
And, on current trends, by 2050, the team predicts that plastic ingestion will touch 99% of the world's seabird species, with nearly every individual affected.
"Plastic in seabirds is ubiquitous, and it's increasing," study leader Chris Wilcox from CSIRO, Australia's federal research agency, told BBC News.
To get to its 2050 extrapolation, the team had to understand the hotspots of risk, by overlaying the known foraging behaviour of the world's 400 or so seabird species on to the known distribution of plastic waste at sea.
This approach demonstrated that the regions of highest risk are not where most floating plastic congregates, which is in the centres of the great ocean gyres, sometimes dubbed "garbage patches" or "islands" for the way the debris just goes round and round.
Rather, the zones of highest concern are where most seabirds are found, which is in a band in the Southern Ocean, near Australia, South Africa and South America.
Once thought of as having pristine waters, this region is now sufficiently polluted to ensure a great array of species encounters some waste.
"A pristine ocean doesn't exist anymore," said Dr Van Sebille, who is affiliated to Imperial College London.
"Every ocean is now filled with plastic. Some have more than others, but what we found is that even the oceans that are not known for their plastic - they still have quite a bit of plastic and they can be where the harm is really done just because that's where all the birds live."
Open up any dead bird, and most are likely to contain plastic fragments
Another key finding from the research is that the problem really is solvable.
If only the stream of plastic waste getting into the oceans can be shut off, then seabirds have the capacity to recover quite quickly.
Dr Wilcox explained: "Because exposure to plastic turns out to be a strong predictor of how much plastic the birds have in them; that is, the more plastic they're exposed to, the more they ingest - this implies that if we reduce the amount of plastic going into the oceans, you would expect all these species to essentially respond.
"And this makes this problem different from something like climate change. It ought to be relatively easy to fix."
Jenna Jambeck from the University of Georgia, US, is an expert on plastic waste issues.
She was not involved in the study but said it had eloquently made the link between solid waste management practices on land, the plastic input into the oceans, and the impacts being felt by seabirds globally.
"It illustrates that if we implement solutions to reduce plastic input into the oceans, we can reduce impacts to individual seabirds.
"Solutions include improving solid waste management where it is lacking, and also working upstream on product redesign and materials substitution moving towards a more circular system," she told BBC News.
This is a solvable problem, say the scientists: Just shut off the waste stream
Links :
Monday, August 31, 2015
Monterey Canyon: Stunning deep-sea topography revealed
From MBARI
About the canyon
The canyon head lies just offshore of Moss Landing on the Central California coast.
From there, the main channel meanders over 400 kilometers seaward to a depth of more than 4,000 meters on the abyssal plain.
Repeated mapping in certain areas of the canyon have shown that the terrain changes substantially every few months due to large sediment-transport events involving both debris flows and turbidity currents.
If the water drained from Monterey Bay, the newly revealed terrain would be stunning, with cliffs, gorges, valleys, and spires matching the scenery found in some of our most beautiful national parks.
Monterrey Canyon with the GeoGarage platform
How these maps were created
The ship travels back and forth, sending sound waves toward the ocean floor.
When the sound waves hit the bottom, they bounce back to the surface, where the sonar receivers use the returned signals to indicate the depths of the seafloor.
Modern multibeam sonars use numerous narrow beams covering wide swaths of the seafloor to create maps like the bathymetric map shown here.
The more detailed maps overlaid on the base map were created with the Monterey Bay Aquarium Research Institute's mapping autonomous underwater vehicle (AUV).
Although the AUV uses the same technology, it flies closer to the bottom, allowing higher resolution maps to be made.
The AUV bathymetric maps show details as small as one meter (three feet) across, and are among the most detailed maps ever made of the deep seafloor.
Researchers use the detailed maps to understand seafloor morphology and the movement of sediment within submarine canyons.
Cross-sections of the Monterey Canyon (left) and Grand Canyon (right)
shown at the same scale demonstrate that these features are similar in
size and shape.
Both canyons are conduits through which massive volumes
of sediment move.
While water flowing in the Colorado River carved the
Grand Canyon, a directly analogous process is not known to have occurred
within Monterey Canyon.
Canyon life
Monterey Canyon and the waters above it provide a wide array of habitats, from rocky outcrops and the soft seafloor to the dark midwater, where there is little or no sign of light from above nor of the seafloor below.
MBARI researchers often encounter rarely seen biological communities, observe novel behaviors of deep-sea organisms, and discover new species in the deep sea.
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