Saturday, April 29, 2017

Saint Malo Live webcam

Live webcam

Panoramic views

Saint Malo with the GeoGarage platform

High tides these days (Mont Saint Michel)

Live tide with MareeInfo

Friday, April 28, 2017

France SHOM layer update in the GeoGarage platform

221 international nautical raster charts added & 12 charts updated

NASA study challenges long-held tsunami formation theory

The horizontal movement of sloped seafloor during an underwater earthquake
can give tsunamis a critical boost.


A new NASA study (published in Journal of Geophysical Research -- Oceans) is challenging a long-held theory that tsunamis form and acquire their energy mostly from vertical movement of the seafloor.
An undisputed fact was that most tsunamis result from a massive shifting of the seafloor -- usually from the subduction, or sliding, of one tectonic plate under another during an earthquake. Experiments conducted in wave tanks in the 1970s demonstrated that vertical uplift of the tank bottom could generate tsunami-like waves.
In the following decade, Japanese scientists simulated horizontal seafloor displacements in a wave tank and observed that the resulting energy was negligible.
This led to the current widely held view that vertical movement of the seafloor is the primary factor in tsunami generation.

The animation shows how waves of energy from the Tohoku-Oki earthquake and tsunami of March 11, 2011, pierced through into Earth's upper atmosphere in the vicinity of Japan, disturbing the density of electrons in the ionosphere. These disturbances were monitored by tracking GPS signals between satellites and ground receivers.
A model of ocean tsunami wavefronts [Song, 2007] is overlaid in blue to show the correlation between variations in the ionosphere above and ocean surface below.
Note that traveling ionospheric disturbances (TIDs), visible throughout the animation, are correlated with the position of the tsunami. 

In 2007, Tony Song, an oceanographer at NASA’s Jet Propulsion Laboratory in Pasadena, California, cast doubt on that theory after analyzing the powerful 2004 Sumatra earthquake in the Indian Ocean. Seismograph and GPS data showed that the vertical uplift of the seafloor did not produce enough energy to create a tsunami that powerful.
But formulations by Song and his colleagues showed that once energy from the horizontal movement of the seafloor was factored in, all of the tsunami’s energy was accounted for.
Those results matched tsunami data collected from a trio of satellites –the NASA/Centre National d’Etudes Spatiales (CNES) Jason, the U.S. Navy’s Geosat Follow-on and the European Space Agency’s Environmental Satellite.
Further research by Song on the 2004 Sumatra earthquake, using satellite data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE) mission, also backed up his claim that the amount of energy created by the vertical uplift of the seafloor alone was insufficient for a tsunami of that size.
“I had all this evidence that contradicted the conventional theory, but I needed more proof,” Song said.

His search for more proof rested on physics -- namely, the fact that horizontal seafloor movement creates kinetic energy, which is proportional to the depth of the ocean and the speed of the seafloor's movement.
After critically evaluating the wave tank experiments of the 1980s, Song found that the tanks used did not accurately represent either of these two variables.
They were too shallow to reproduce the actual ratio between ocean depth and seafloor movement that exists in a tsunami, and the wall in the tank that simulated the horizontal seafloor movement moved too slowly to replicate the actual speed at which a tectonic plate moves during an earthquake.
“I began to consider that those two misrepresentations were responsible for the long-accepted but misleading conclusion that horizontal movement produces only a small amount of kinetic energy,” Song said.

Building a Better Wave Tank

To put his theory to the test, Song and researchers from Oregon State University in Corvallis simulated the 2004 Sumatra and 2011 Tohoku earthquakes at the university’s Wave Research Laboratory by using both directly measured and satellite observations as reference.
Like the experiments of the 1980s, they mimicked horizontal land displacement in two different tanks by moving a vertical wall in the tank against water, but they used a piston-powered wave maker capable of generating faster speeds.
They also better accounted for the ratio of how deep the water is to the amount of horizontal displacement in actual tsunamis.

The new experiments illustrated that horizontal seafloor displacement contributed more than half the energy that generated the 2004 and 2011 tsunamis.
“From this study, we’ve demonstrated that we need to look at not only the vertical but also the horizontal movement of the seafloor to derive the total energy transferred to the ocean and predict a tsunami,” said Solomon Yim, a professor of civil and construction engineering at Oregon State University and a co-author on the study.

Photo taken March 11, 2011, by Sadatsugu Tomizawa and released via Jiji Press on March 21, 2011, showing tsunami waves hitting the coast of Minamisoma in Fukushima prefecture, Japan.

Credits: Sadatsugu Tomizawa CC BY-NC-ND 2.0

The finding further validates an approach developed by Song and his colleagues that uses GPS technology to detect a tsunami’s size and strength for early warnings.
The JPL-managed Global Differential Global Positioning System (GDGPS) is a very accurate real-time GPS processing system that can measure seafloor movement during an earthquake.
As the land shifts, ground receiver stations nearer to the epicenter also shift.
The stations can detect their movement every second through real-time communication with a constellation of satellites to estimate the amount and direction of horizontal and vertical land displacement that took place in the ocean.
They developed computer models to incorporate that data with ocean floor topography and other information to calculate the size and direction of a tsunami.
“By identifying the important role of the horizontal motion of the seafloor, our GPS approach directly estimates the energy transferred by an earthquake to the ocean,” Song said.
“Our goal is to detect a tsunami’s size before it even forms, for early warnings.”

Links :

Thursday, April 27, 2017

Iceberg 'doodles' trace climate history

Ploughmarks formed by unusually flat-bottomed icebergs in the central Barents Sea
(Red is 240m water depth; purple is 248m)

From BBC by Jonathan Amos

It is as if a child has been doodling with large coloured crayons.
What you see are actually the great gouge marks left on the seafloor when the keel of a giant block of ice has dragged through the sediments.
The arcs and loops record the movement of the berg as it turns about, caught in the wind, currents and tides.
This "ice art" is from a stunning new collection of images that detail how glacial action has shaped the ocean floor in Earth's polar regions.

 Barents Sea in the GeoGarage platform (NGA chart)

The atlas is the work of more than 250 scientists from 20 countries and represents our most comprehensive view yet of what the seabed looks like at high latitudes.
"We now have a critical mass of high-resolution imagery, of the imprints left by the action of ice," explained Dr Kelly Hogan, one the collection's editors from the British Antarctic Survey (BAS).
"We can see where the ice has been and what it's done, and this allows us to compare and contrast. Looking at what has happened in the past can help us understand what may happen in the future with modern ice sheets as they respond to climate change."

 In the most extreme places in the world, the most remarkable people gather scientific evidence about our changing planet.
From the discovery of the hole in the ozone layer, to the effects of climate change, the polar regions act as early warning systems.
With the help of the British Antarctic Survey, governments and world leaders have been able to use the evidence gathered to make better decisions for the future of the Earth.

The book, published as a "memoir" of the Geological Society of London, has taken four years to put together.
It contains mostly images produced from ship echosounders, which pulse the ocean bed and then build depth maps from the resulting return signal (the "false colours" will usual denote different depths).
A first version of the book came out in 1997, but comprised really only low-resolution data.
The new tome, on the other hand, benefits from 20 years of multibeam swath technology, which is capable of creating spectacular perspectives of the ocean floor, often at sub-metre resolution.
All ships now entering polar waters will routinely map the bed in this way.

An almost circular iceberg plough mark off Svalbard.
(Red is 25m water depth; green is 50m)

"Today's icebreakers and ice-strengthened vessels all carry these high-res systems; they are standard. No longer do we get just single points, but a whole fan of sound goes down to the seafloor to collect 3D data. And we're finding all these weird and wonderful features," Dr Hogan told BBC News.
As well as the iceberg ploughmarks, there are the classic forms left by marine glaciers.
These include long striations, drumlins (egg-shaped mounds) and moraines (bulldozed sediment ridges).

Drumlins (elongate hills aligned with the ice flow direction) from the Gulf of Bothnia in the Baltic Sea

"When the moraines are pushed close together, they're most likely annual features, but move a bigger distance offshore and you might find moraines that are from thousands of years ago and are spread further apart. We could go date the sediments to look at how quickly ice has retreated. So, this gives you an idea of how we can use the imagery to help us understand what is going on."

Another of the more intriguing features is the permafrost polygon.
A great expanse of these shapes is captured on the floor of the Laptev Sea off the Siberian coast in the Arctic.
These were actually created above water in ground that contracted and expanded in multiple cooling and warming cycles - only then to be submerged beneath the waves.

These shapes were made on land and then submerged around 7,000-8,000 years ago

They illustrate how the sea can sometimes preserve a record that might otherwise be lost on land, perhaps covered over by vegetation or human development, or lost entirely through erosion.
And flicking through the book, it is clear that not all ice action has been constrained to today's polar waters.
You will find, for example, images in the atlas from around the UK.
But then 25,000 years ago, Britain was covered by a colossal ice sheet that extended down from the north.

An iceberg ploughmark showing rotation, from the central Barents Sea
(Red is 240m water depth; purple is 252m)

Likewise, Libya makes an entry with glacial lineations in the Murzuq Basin that are several kilometres long.
These ice features are present because 450 million years ago, north Africa was centred over the South Pole, forming a part of the Gondwana supercontinent.
But as impressive as all this imagery is, it still only represents a small fraction of the total seafloor currently found above 60 degrees latitude.
As with the ocean more generally across the globe, our knowledge of the shape of bed is poor.
If you were to divide the polar seas into 500m boxes, more than 85% of them would have no depth soundings.
"That will change in time as all these vessels routinely gather multibeam data," said Dr Hogan.

That part of the berg which lies underwater can be scouring the bed
NASA/ Jane Peterson

This beautiful multibeam data shows bulldozed sediments (moraines)
created as ice retreated and advanced

The unmistakable grooves cut in the seafloor off West Antarctica as ice flowed right to left

Wednesday, April 26, 2017

Climate change is making algal blooms worse

Blooming Gibraltar

From Nature by Daniel Cressey

Rising ocean temperatures drive more intense and longer lasting toxic outbreaks.

Researchers have long suggested that climate change could mean more damage from algal blooms — runaway growths of algae that can strangle marine ecosystems and devastate coastal economies.
Now, a study has unpicked how warming ocean temperatures have already driven an intensification of blooms around North America — the first time this link has been established at an ocean scale.

Harmful algal blooms can occur when changes in water conditions lead to a huge growth in the number of a particular species of algae.
The blooms can produce toxins, become so large that they kill marine life, and even turn water a different colour.

Research has established that one factor that helps blooms to spread is a sudden increase in nutrients such as nitrogen and phosphorus — often from agricultural fertilizers — and it has also linked warming temperatures to individual events.
But the broader influence of climate change on these outbreaks is less well quantified.

Turquoise Tendrils

Blooms abound

Christopher Gobler, who studies coastal ecosystems at Stony Brook University in Southampton, New York, and his colleagues looked at the relationship between blooms in the North Atlantic and North Pacific oceans and temperature changes in the region to investigate whether the events there were linked to were linked to ocean warming.
Previous research has studied the influence of climate change on algal blooms in individual coastal systems, says Gobler, but this is the first to assess ocean-basin-wide trends.

The researchers looked at two species of algae: Alexandrium fundyense and Dinophysis acuminata. (These species produce toxins that can cause illnesses — sometimes fatal — in humans who eat shellfish contaminated with them).
They used detailed data on sea-surface temperatures to model trends in the growth rates of the algae species and the periods when blooms occurred from the early 1980s into the twenty-first century.

The Treacherous and Productive Seas of Southern Africa
The light blue swirl to the east of Cape Agulhas is a phytoplankton bloom in an area of cool, upwelling water. 

At dozens of sites, their model suggests that new blooms could occur where they hadn't happened before.
The researchers found higher potential growth rates and longer bloom seasons for both species in many parts of the Atlantic coast and along Alaska.
In some places, they found the bloom season to now be more than a month longer than it was in 1982.

The team used its model to retrospectively predict what harmful blooms might have occurred in the time period and found good agreement with actual events.
“What’s different about this study is they’re going beyond just saying 'Look, warmer is bad' and trying to do a rigorous quantitative analysis,” says Anna Michalak, who studies climate change and water quality at the Carnegie Institution for Science in Stanford, California.

Gobler points out that that the ocean does not warm uniformly, with some regions warming faster than average and some cooling.
This means blooms will appear in new regions, and may actually reduce in some places they currently occur.
Factors other than temperature are still clearly important, he says.

Many factors

Michalak points out that for events such as major droughts and floods, researchers can now often estimate how much more likely such events will be as a result of climate change.
But there is less research on the relationship between water quality and climate change.
“We don’t have that science on the water quality side,” she says, adding that this paper is one step in that direction.

In 2011, North America’s Lake Erie experienced one of its worst algal blooms in decades.
NASA acquired October 5, 2011

Sediment and Algae Color the Great Lakes
Michalak’s team has previously studied a massive 2011 bloom in Lake Erie — one of the largest ever on the Great Lake.
They pinned the event on a combination of weather conditions and agriculture putting huge nutrient loads in the lake.
That interplay of different factors is one reason why not everyone is yet prepared to say that climate change will necessarily lead to more harmful algal blooms.

Dynamic Spring Weather in North Atlantic Waters

Mark Wells, who studies harmful algal blooms at the University of Maine in Orono, points out that that rising temperatures alone may not always cause more harmful algal blooms.
In 2010 in the Gulf of Maine, he says, there were very high water temperatures, and many blooms were expected.
But in fact, water temperatures were so high that the layers of sea water became stratified and prevented mixing and the transfer of nutrients, so in the end there were fewer blooms than expected.
Still, he says, the latest study “provides a lot of new evidence” and represents a believable trend.

Links :

Tuesday, April 25, 2017

Receding glacier causes immense Canadian river to vanish in four days

A view of the ice canyon that now carries meltwater from the Kaskawulsh glacier, seen here on the right, away from the Slims river and toward the Kaskawulsh river.
Photograph: Dan Shugar/University of Washington Tacoma

From The Guardian by Hannah Devlin

First ever observed case of ‘river piracy’ saw the Slims river disappear as intense glacier melt suddenly diverted its flow into another watercourse 

An immense river that flowed from one of Canada’s largest glaciers vanished over the course of four days last year, scientists have reported, in an unsettling illustration of how global warming dramatically changes the world’s geography.

 One of Canada's rivers has vanished.
The Slims river has been flowing through Canada for 300 years, but in 2016 something happened that caused it to vanish in the blink of an eye.
In just four days, the river dipped in height so much that it could not recover.
Today, the only evidence of the Slims river is its empty, thirsty channel.
Scientists attribute the river's disappearance to our warming climate and predict that future rivers may suffer the same fate.

The abrupt and unexpected disappearance of the Slims river, which spanned up to 150 metres at its widest points, is the first observed case of “river piracy”, in which the flow of one river is suddenly diverted into another.

The mouth of the Slims River at Kluane Lake

For hundreds of years, the Slims carried meltwater northwards from the vast Kaskawulsh glacier in Canada’s Yukon territory into the Kluane river, then into the Yukon river towards the Bering Sea.
But in spring 2016, a period of intense melting of the glacier meant the drainage gradient was tipped in favour of a second river, redirecting the meltwater to the Gulf of Alaska, thousands of miles from its original destination.

The continental-scale rearrangement was documented by a team of scientists who had been monitoring the incremental retreat of the glacier for years.
But on a 2016 fieldwork expedition they were confronted with a landscape that had been radically transformed.

The retreat of the Kaskawulsh glacier has resulted in a drastic change in the destination of its meltwater

“We went to the area intending to continue our measurements in the Slims river, but found the riverbed more or less dry,” said James Best, a geologist at the University of Illinois.
“The delta top that we’d been sailing over in a small boat was now a dust storm. In terms of landscape change it was incredibly dramatic.”

Climate change is causing thick ice deposits that form along Arctic rivers to melt nearly a month earlier than they did 15 years ago, a new study finds.
In the past, river icings have melted out around mid-July, on average.
But a new study measuring the extent of river icings in the U.S. and Canadian Arctic shows most river icings disappeared 26 days earlier, on average, in 2015 than they did in 2000, melting around mid-June.
In addition, the study found most icings that don’t completely melt every summer were significantly smaller in 2015 than they were in 2000.

Dan Shugar, a geoscientist at the University of Washington Tacoma and the paper’s lead author, added: “The water was somewhat treacherous to approach, because you’re walking on these old river sediments that were really goopy and would suck you in. And day by day we could see the water level dropping.”

The team flew a helicopter over the glacier and used drones to investigate what was happening in the other valley, which is less accessible.
“We found that all of the water that was coming out from the front of the glacier, rather than it being split between two rivers, it was going into just one,” said Best.

The Kaskawulsh River, seen here near its headwaters, 
is running higher now thanks to the addition of water that used to flow into the Slims River.
Photograph: Jim Best/University of Illinois

While the Slims had been reduced to a mere trickle, the reverse had happened to the south-flowing Alsek river, a popular whitewater rafting river that is a Unesco world heritage site.
The previous year, the two rivers had been comparable in size, but the Alsek was now 60 to 70 times larger than the Slims, flow measurements revealed.
The data also showed how abrupt the change had been, with the Slims’ flow dropping precipitously from the 26 to 29 May 2016.

Geologists have previously found evidence of river piracy having taken place in the distant past.
“But nobody to our knowledge has documented it happening in our lifetimes,” said Shugar
 “People had looked at the geological record, thousands or millions of years ago, not the 21st century, where it’s happening under our noses.”

A satellite image of the Kaskawulsh glacier and Slims and Kaskawulsh rivers.
The yellow lines represent the pre-2016 flow direction of the Slims and Kaskawulsh rivers.
Daniel Shugar / University of Washington

Prof Lonnie Thompson, a paleoclimatologist at Ohio State University who was not involved in the work, said the observations highlight how incremental temperature increases can produce sudden and drastic environmental impacts.
“There are definitely thresholds which, once passed in nature, everything abruptly changes,” he said.

Between 1956 and 2007, the Kaskawulsh glacier retreated by 600-700m. In 2016, there was a sudden acceleration of the retreat, and the pulse of meltwater led to a new channel being carved through a large ice field.
The new channel was able to deliver water to the Alsek’s tributary whose steeper gradient resulted in the Slims headwater being suddenly rerouted along a new southwards trajectory.

In a geological instant, the local landscape was redrawn.
Where the Slims once flowed, Dall sheep from Kluane National Park are now making their way down to eat the fresh vegetation, venturing into territory where they can legally be hunted.
The formerly clear air is now often turned into a dusty haze as powerful winds whip up the exposed riverbed sediment.
Fish populations are being redistributed and lake chemistry is being altered.
Waterfront land, which includes the small communities of Burwash Landing and Destruction Bay, is now further from shore.

Sections of the newly exposed bed of Kluane Lake contain small pinnacles.
Wind has eroded sediments with a harder layer on top that forms a protective cap as the wind erodes softer and sandier sediment below.
These pinnacles, just a few centimeters high, are small-scale versions of what are sometimes termed “hoodoos.”
Photograph: Jim Best/University of Illinois

A statistical analysis, published in the journal Nature Geoscience, suggests that the dramatic changes can almost certainly be attributed to anthropogenic climate change.
The calculations put chance of the piracy having occurred due to natural variability at 0.5%.
“So it’s 99.5% that it occurred due to warming over the industrial era,” said Best.

The Yukon region is extremely sparsely inhabited, but future river piracy could have catastrophic effects on towns, villages and ecosystems that have sprung up around available water, according to an analysis accompanying the paper, by Rachel Headley, a geologist at the University of Wisconsin-Parkside.
“If a river changes course so drastically that the drainage basin no longer reaches its original outlet, this change might eventually impact human and biological communities that have grown around the river’s original outlet,” she said.

Thompson, who has documented glacial retreat on Mount Kilimanjaro, predicts that there will be an acceleration in the observations of river piracy events as glaciers retreat globally.
“I think we could see similar divergence in streams in the Himalayas as well as throughout the Third Pole region, the Andes of Peru, other sites in northern Canada and Alaska,” he said.
“Often these events occur in remote and poor parts of our planet and thus go largely unnoticed by the larger population but greatly impact the livelihood of many families downstream.”

Links :

Monday, April 24, 2017

The mysteries of the first-ever map of the North Pole

  The second draft of the Septentrionalium Terrarum, released in 1606.

From Atlas Obscura by

Gerard Mercator’s 16th-century attempt at mapping the Arctic includes such guesses as a giant whirlpool and polar pygmies. 

These days, climate scientists are looking hard at Arctic maps.
As winter sea ice shrinks and cracks appear, they try to understand the reasons for these changes, and determine what we should expect in the future.
Centuries ago, though, when people tried to map the Arctic, they weren’t too concerned with what was happening to it—they just wanted to know what the heck was up there.
And, if they didn’t know, they pretty much made it up.
Such was the case with the first known map of the Arctic: the Septentrionalium Terrarum, which is filled with magnetic stones, strange whirlpools, and other colorful guesses.
The map’s creator, the Flemish cartographer Gerardus Mercator, is best known for the “Mercator projection,” the now-famed method of taking the curved lines of the Earth and transforming them into straight ones that can be used on a flat map.
The Mercator projection was invented for sailors, who, thanks to its design, could use it to plot a straight-line course from their point of origin to their destination.
In 1569, Mercator came out with a map of the world based on this principal, which stretched from East to West and promised, in his words, “no trace… of any of those errors which must necessarily be encountered on the ordinary charts of shipmasters.”
In order to make his map useful for navigation, though, Mercator had to sacrifice accuracy in other areas—specifically, he had to stretch out the top and bottom parts of his map, making the lands and seas in the far North and South appear disproportionately larger than those nearer the equator.
(This is also why so many people think Africa is the same size as Greenland, when it is really about 14 times bigger—the Mercator projection is still very common in schools.)

 Mercator’s 1569 map of the world, the first to feature his famous projection.
The Arctic inlet is on the bottom left. Gerardus Mercator/Public Domain

Under the terms of this Mercator math, the North Pole would appear so large as to be almost infinite.
So instead of including it in the overall projection, Mercator decided to set a small, top-down view of the Arctic in the bottom left corner of his world map.
Geographical historians consider this to be the first true map of the Arctic.
Over the subsequent decades, as new information came to light, Mercator and his protégés enlarged and updated this original map—the draft above is an attempt from 1606, updated by his successor, Jodocus Hondius—but those original bones remained in place.
By the 1500s, not very many people had ventured up to the Arctic—no explorer would set foot on the Pole itself until 1909.
This didn’t stop Mercator, who dug into some dicey sources to suss out what he should include. The most influential, called Inventio Fortunata (translation: “Fortunate Discoveries”) was a 14th-century travelogue written by an unknown source; in Mercator’s words, it traced the travels of “an English minor friar of Oxford” who traveled to Norway and then “pushed on further by magical arts.”
This mysterious book gave Mercator the centerpiece of his map: a massive rock located exactly at the pole, which he labels Rupus Nigra et Altissima, or “Black, Very High Cliff.”

 At the time, many assumed the pole itself featured a giant, magnetic mountain.

The presence of this formation was widely accepted at the time.
Most people thought it was magnetic, which provided an easy explanation for why compasses point north.
But Mercator was not quite convinced by this argument, and included a different rock, which he labels “Magnetic Pole,” in the top left corner of the map, just north of the Strait of Anián.

Mercator draws the Arctic in four large chunks separated by channels of flowing water, which meet in the middle in a giant whirlpool. He got this idea from two 16th-century explorers, Martin Frobisher and James Davis, who each made it as far as what is now Northern Canada. Both documented their experiences with vicious currents, which, they wrote, pulled giant icebergs along like they were nothing. “Without cease, it is carried northward, there being absorbed into the bowels of the Earth,” Mercator wrote on his original map.

 The supposed home of “Pygmeis.”

Each piece of the Arctic also has particular qualities.
According to Mercator’s labels, the one in the lower right is supposedly home to “pygmies, whose length is four feet”—likely another reference to the Inventio Fortunata, which described groups of small-statured people living in the polar regions.
(It’s possible that the author of the Inventio was referring to the indigenous inhabitants of Lapland.)
The one next door, on the bottom left, is apparently “the best and most salubrious” of all the chunks, although no evidence is given to support this—or to explain why the pygmies wouldn’t want to live there, instead.
After Mercator died in 1594, explorers continued to gain new knowledge of the Arctic, and cartographers revised their view of both Poles.
By 1636, up-to-date maps of the region lacked Mercator’s four regions, along with the Rupus Nigra and the central whirlpool.
Instead, they showed one large piece of land, surrounded by smaller islands and, often, adorned with the ship’s routes that enabled this geographical knowledge in the first place.
As we peer at modern Arctic maps, wondering what changes are ahead, it’s fascinating to think back to Mercator’s original version, mysterious and broken from the beginning.

Links :

Saturday, April 22, 2017

Diving down to the deep ocean

Even in the perpetual darkness of the deepest ocean, scientists discover the discarded rubbish of modern life.

Friday, April 21, 2017

The pristine Arctic has become a garbage trap for 300 billion pieces of plastic

 Here’s a map the researchers provided, showing the ocean circulation in the Atlantic and where that, in turn, has delivered plastic particles:
Locations and plastic concentrations of the sites sampled.
The white area shows the extension of the polar ice cap in August 2013, and green curves represent the North Atlantic Subtropical Ocean Gyres and the Global Thermohaline Circulation poleward branch.
(Andres Cozar)

 From The Washington Post by Chris Mooney

Drifts of floating plastic that humans have dumped into the world’s oceans are flowing into the pristine waters of the Arctic as a result of a powerful system of currents that deposits waste in the icy seas east of Greenland and north of Scandinavia.
In 2013, as part of a seven-month circumnavigation of the Arctic Ocean, scientists aboard the research vessel Tara documented a profusion of tiny pieces of plastic in the Greenland and Barents seas, where the final limb of the Gulf Stream system delivers Atlantic waters northward.
The researchers dub this region the “dead end for floating plastics” after their long surf of the world’s oceans.
The researchers say this is just the beginning of the plastic migration to Arctic waters.
“It’s only been about 60 years since we started using plastic industrially, and the usage and the production has been increasing ever since,” said Carlos Duarte, one of the study’s co-authors and director of the Red Sea Research Center at the King Abdullah University of Science and Technology in Saudi Arabia.
“So, most of the plastic that we have disposed in the ocean is still now in transit to the Arctic.”

A seal lies on an iceberg in front of the research vessel Tara.
The nonprofit organization Tara Expeditions has been active since 2003, sailing across the world's oceans to study biodiversity, the impacts of climate change and other research topics. In 2013, the schooner sailed around the Arctic Ocean to collect plastic debris floating in the water.
photo : Anna Deniaud / Tara Expeditions Foundation

The results were published Wednesday in the journal Science Advances.
The study was led by Andrés Cózar of the University of Cádiz in Spain along with 11 other researchers from universities in eight nations: Denmark, France, Japan, the Netherlands, Saudi Arabia, Spain, the United Kingdom and the United States.
The researchers estimated that about 300 billion pieces of tiny plastic are suspended in these Arctic waters right now, although they said the amount could be higher.
And they think there is even more plastic on the seafloor.

 Tara Oceans expedition route

Several factors support the idea that the plastic entered these waters via ocean currents rather than local pollution.
First, the Arctic has a very small population that is unlikely to directly contribute so much waste. Also, the aged and weathered state of the plastic, and the tiny size of the pieces found, suggested that it had traveled the seas for decades, breaking down along the way.
“The plastic pieces that may have been initially inches or feet in size, they have been brittled by exposure to the sun and then fragmented into increasingly smaller particles, and eventually led to this millimeter-size plastic that we call microplastic,” Duarte said.
“That process takes years to decades. So the type of material that we’re seeing there has indications that it has entered the ocean decades ago.”

 Manta net used to collect microplastics
© Anna Deniaud / Tara Expeditions Foundation

Finally, the study didn’t find much plastic in the rest of the Arctic ocean beyond the Greenland and Barents seas, also suggesting that currents were to blame.
Instead the plastic had accumulated where the northward-flowing Atlantic waters plunge into the Arctic depths. Presumably, the plastic then lingers at the surface.
The Greenland and Barents seas contained 95 percent of the Arctic’s plastic, the research found (the ship sampled 42 sites across the Arctic Ocean).
The Barents Sea happens to be a major fishery for cod, haddock, herring and other species.
A key question will be how the plastic is affecting these animals.
Here’s a collage that the researchers provided showing the types of plastic they found:

 Photo collage of plastic fragments found in the Arctic Ocean.
Although plastic debris was scarce in most of the Arctic waters, it reached high concentrations in areas of the Greenland and Barents seas. (Credit: Andres Cozar)

The study’s results sent a troubling message to one researcher who has also focused on the consequences of plastic debris in the oceans and other waterways.
“Isn’t it kind of ironic that days before Earth Day there is more demonstrated proof of widespread contamination of our plastic waste in places that are so far from the human footprint and thus locations we consider to be pristine,” said Chelsea Rochman, a marine ecologist at the University of Toronto who was not involved in the study but praised it as “a great contribution to the field.”
The ocean circulation system in the Atlantic responsible for this plastic transport is part of a far larger “thermohaline” ocean system driven by the temperature and salt content of oceans.
It is also often called an “overturning” circulation because cold, salty waters sink in the North Atlantic and travel back southward at deep ocean depths.

As humans now put 8 million tons of plastic in the ocean annually, learning how such currents affect the plastic’s global distribution is a key scientific focus.
Researchers, including Duarte, previously found that plastic slowly travels the world’s oceans but tends to linger in five “gyres,” or circular ocean currents in the subtropical oceans in both the northern and southern hemispheres.
One of those gyres is located in the Atlantic, which then feeds the Arctic.

 Aurora, a three-year-old polar bear, was found with her sister in the Arctic Ocean in May 2010 and brought to the Royev Ruchey Zoo in Siberia.
photo : Ilya Naymushin / Reuters

Scientists noted that the vast majority of ocean plastic becomes lost before it reaches the Arctic.
They aren’t sure where most of the plastic falls out and are researching to determine those locations.
“The plastic that escapes those traps is the one that actually makes it into the Arctic,” Duarte said.
“But when it enters the Arctic, there is no way out, it just stays there and is stuck there.”
Because it takes such a long time for plastic to travel across the world in ocean currents, the study concludes that the current waste is largely the work of North Americans and Europeans, who dumped it in the Atlantic.
Waste from other parts of the world that dump huge volumes of plastic into the oceans is still in transit.
Rochman said she feared that as the Arctic becomes more accessible because of ice melt linked to climate change, more plastic could wash in.
“As the ice melts, we may see increasing concentrations of plastic in the Arctic due to the opening of passageways for vessels and plastics in surface currents,” she said, “as well as plastics in the ice becoming free to float and interact with marine animals upon melting.”

Links :

Thursday, April 20, 2017

Canada CHS update in the GeoGarage platform

84 nautical raster charts updated

A banned Indian island: Watch video of Sentinelese tribe rejecting attempts at communication

After numerous failed attempts to make contacts with the Sentinelese tribe since 1964, the Indian government has finally backed away.

From Indian Express

Surprisingly there has been only one instance when outsiders didn't have to face a hostile reception.

A rare footage of the Sentinelese, one of the last uncontacted tribes in the world, has emerged, showing its members on the beaches of North Sentinel Island in Andaman & Nicobar.

North Sentinel Island with the GeoGarage platform (NGA chart)
Thought to be direct descendants of the first humans who emerged from Africa, the tribe is believed to be living on the tiny Indian island for almost 60,000 years.
Little is known about their exact population and could reportedly have as low as 40 members or as high as 500.

 North Sentinel island, NASA

Efforts to reach out to them have been met with hostility and there are several horror stories of how Sentinelese have treated their guests.
People return from the island either injured or not at all. In 2006 two fishermen, aged 48 and 52, were killed after they slept overnight in their boat near the North Sentinel island.

Following the 2004 tsunami, helicopters from the Indian Coast Guard were sent to drop food parcels, but this tribesmen responded by firing an arrow at the rescue team

They were hostile even during emergency rescue missions after Tsunami in 2004 as gifts, food and clothing are of no importance to them.
A photo was captured of one of the tribesmen taking aim at a rescue helicopter with an arrow.

According to a video footage which is a part of a documentary by LoveBite Productions on the Sentinelese tribe, an Indian anthroplogist T N Pandit who conducted several government trips to the island in the late 80’s and the early 90’s in an attempt to reach out confessed, “Sometimes they would turn their backs and sit on their haunches as to defecate. This was meant to insult us as we were not welcomed. It doesn’t matter if you are a friend or an enemy or you arrive at the island’s shores by purpose or by accident, the locals would greet you the same way with spears and arrows.”

Surprisingly there has been only one instance when outsiders didn’t have to face a hostile reception.
On January 4, 1991, 28 people which included men, women and children approached Pandit and his team saying the tribe voluntarily came forward to meet them.
However, after numerous failed attempts to make contacts with them since 1964, the Indian government has finally backed away.
In 2005, the administration of Andaman & Nicobar stated that they have no intention of interfering with the lifestyle of the Sentinelese tribe or pursuing any further contact with them.
Also, the Indian navy enforced a 3 mile buffer zone to keep tourists and explorers away.

Links :

Wednesday, April 19, 2017

Climate change to deliver regular flooding to Europe

The 1824 flooding for St. Petersburg, Russia.
Once-a-century floods could become commonplace as the planet heats up.

From NexusMedia by Marlene Cimons

Sea-level rise threatens coastal communities.

The kind of devastating flooding that occurs once every century along Europe’s northern coastline could become an annual event if greenhouse gas emissions continue to climb, according to a recent study published in the journal Earth’s Future.

New analysis takes into account changes in sea-level rise, tides, waves and storm surge over the 21st century and found that climate change could prompt extreme sea levels — the maximum levels seen during major storms, which produce massive flooding — to increase significantly along the European coastline by 2100.
This scenario will likely stress coastal protection structures beyond their capacity, leaving much of the European coastline vulnerable to dangerous flooding, according to study authors.
“Unless we take different protection measures, five million people will be exposed to coastal flooding on an annual basis,” said Michalis Vousdoukas, a coastal oceanographer at the Joint Research Centre of the European Commission and lead author of the study.
The study described the projected rise in extreme sea levels as “a serious threat” to coastal communities, noting, “their safety and resilience depends on the effectiveness of natural and man-made coastal flood protection.”
Kevin Trenberth, a scientist with the climate analysis section of the National Center for Atmospheric Research, who was not involved in this research, said the signs of extreme sea levels are already worrisome, not just in Europe, but in the United States as well.
“Witness the sunshine flooding in Florida already, the flooding that shows up even with no storm on many streets any time there is a slightly high tide,” he said.

 A Florida road flooded by tropical storm Arlene in 2005.
Florida is especially susceptible to rising seas.
Source: FEMA

“Sea level is going up because the ocean is warming and hence expanding, and because land ice — glaciers, etc. — are melting and putting more water into the ocean. But it is not the gradual rise that matters,” Trenberth said. “Rather, it is the storm surge on top of a high tide riding on top of the increase in sea level that crosses thresholds and causes things to break.”
Richard Alley, professor of geosciences at Pennsylvania State University, who also did not take part in this study, noted that the study didn’t consider the possible collapse of the West Antarctic ice sheet. “If that happens, then sea-level rise and impacts to coasts could be much higher than in this paper,” Alley said. “Rapid West Antarctic collapse could cause enough rise to make many of these other factors of secondary importance. So, the ‘worst case’ in this paper isn’t really the worst case.”
The new paper predicted that some regions could experience an even higher increase in the frequency of these extreme flooding events, specifically along the Mediterranean and the Black Sea, where the present day 100-year extreme sea level could occur as often as several times a year.

Information about the number of people at risk from flooding can be used to determine how large the social and economic impact of these events will be, said Marta Marcos, a researcher at the Mediterranean Institute for Advanced Studies in Spain, who was not involved in the new study. “In terms of adaptation strategies and policy-making, it is very relevant,” she said.
The researchers studied changes in extreme sea levels by 2100 under different greenhouse gas scenarios and considered how all these components — mean sea level, tides, waves and storm surge — will be affected by climate change.

 The Netherlands is particularly vulnerable to sea-level rise.
Source: Pexels

If emissions continue to rise unabated throughout this century, extreme sea levels along Europe’s coastlines could increase by more than 2.5 feet, on average, by 2100.
Under a more moderate situation, where greenhouse gas emissions peak in 2040, 100-year extreme sea levels still could jump by nearly 2 feet, on average, by the end of the century — with flooding events occurring every few years — according to study’s authors.
In a related study appearing in Geophysical Research Letters, scientists found that if greenhouse gases continue to rise, there could be disturbing changes by the end of the century in the energy that waves carry to the coast.
In the southern hemisphere, extreme waves could carry up to 30 percent more energy by 2100, according to the study, meaning that stronger waves will become more frequent, and have a greater impact on the coast, said Lorenzo Mentaschi, a researcher at the Joint Research Centre and lead author of the study.
The new study attributed the changes in wave energy to the intensification of weather patterns, like El Niño.
The new research will be provided to European Union policymakers.
The data will also be made public so it can be used by scientists, engineers and coastal managers.
Michael Mann, professor of atmospheric science at Pennsylvania State University, said the research once again underscored how climate change, “which has already increased the threat to our coastlines through a combination of sea-level rise and intensified coastal storms, will be catastrophic for coastal communities if we don’t reduce global carbon emissions.”

Links :

Tuesday, April 18, 2017

Mediterranean rescuers accuse Europe of 'leaving migrants to drown'

From CNN by Barbie Latza Nadeau

Calm seas, desperate migrants and ruthless human traffickers all played a role in a record-breaking weekend of maritime rescues in the Mediterranean Sea between Italy and Libya.
But even as the rescue vessels race against time to save lives, another battle is brewing with accusations from the European Union's border control agency Frontex against nongovernmental organizations like Doctors Without Borders and the Mobile Offshore Aid Station, or MOAS, that run so-called charity rescue ships.

Frontex says the charity rescue vessels create a pull factor for migrants and traffickers; the NGOs say they are out there in the absence of an EU strategy to save lives at sea and a lack of initiative to provide a safe corridor option for migration and asylum.

 Here is a map of Frontex’s patrol area compared to where the shipwrecks happen.

On Sunday evening in Italy, the Italian Coast Guard estimated the number of those rescued since Friday was approaching 7,000, though that number will surely grow as a steady stream of rubber dinghies and rickety wooden fishing vessels were still being spotted off the coast of Libya.
At least 20 cadavers, including that of an 8-year-old boy recovered during rescue operations, were also brought to Sicily and the Italian mainland with the survivors.

The migrants and refugees were rescued by Italian Coast Guard boats, passing merchant ships and more than a dozen NGO charity ships that have filled the vacuum created when Italy's Mare Nostrum search and rescue program ended in 2014 because of budget concerns.
The Mare Nostrum project cost Italian taxpayers €9 million ($9.5 million) a month, according to the Italian Navy.
The charity ships, which rely on donations, have estimated operating costs of around €11,000 ($11,666) a day, charities say.

European authorities and charity ships face a daunting task.
Since the beginning of the year, 32,750 migrants and refugees have arrived on European shores, not including those rescued this weekend, according to UNHCR. In 2016, the total number topped 355,000.
Frontex has two programs at sea.
The Sophia program is designed to destroy smuggler's ships after rescues are complete and to train the Libyan Coast Guard to stop boats from leaving.
The Triton program enlists member states to provide assets for search and rescue operations.
Over the busy weekend, Frontex says the Norwegian Siem Pilot, currently on rotation for Frontex's Triton program, rescued more than 500 of the nearly 7,000 people pulled to safety.

In March, Italian prosecutor Carmelo Zuccaro from Catania launched an investigation into the funding of the charity ships, essentially accusing them of colluding with the traffickers.
"I am convinced that it is not always the operational center that calls on the NGOs," he told a parliamentary committee in Rome in March.
"We also need to investigate the evolution of the phenomenon and find out why there has been such a noted proliferation of these ships and how they deal with such high operational costs without having a return in terms of economic profit."
No charges have been filed but Zuccaro told CNN he would seek to sequester the charity ships if he found just cause to do so.
The NGOs have accused Zuccaro of starting the investigation on behalf of Frontex as an attempt to remove them from the sea.
Zuccaro says he is not acting on behalf of Frontex, but that he is concerned that the rescue vessels are creating an open border into Europe as thousands of irregular migrants reach Italy each year.
With this weekend's rescues, the number to reach Europe this year so far has topped 40,000, according to United Nations High Commissioner for Refugees.
When reached for comment about Zuccaro's legal case, Frontex did not provide a comment.
The NGOs, on the other hand, have not minced words.

"We are surprised at the timing of these allegations, more than a year after we and others have been in service," said Sophie Beau, co-founder and vice-president of SOS Mediterranee, which runs the Aquarius rescue boat together with Doctors Without Borders.
"We know exactly what will happen if we are not out there. More people will die. We know we need to be out there, we have to be out there."
In a press release, MOAS co-founder and director Regina Catrambone agreed.
"Every day people continue to risk their lives while we, as civil society, stand witness. We must continue to call on European governments to act so that people, such as those rescued by us today, do not die, not in Libya nor in the Mediterranean Sea."

Those frustrations are echoed by the other NGOs, with many of the rescue operators tweeting accusations directly against the European Union and Frontex.
Doctors Without Borders, or MSF, tweeted, "EU 'leaving migrants to drown' say rescuers who saved 2,000 in single day."
And "How many lives could have been saved in the last two years if the #EU had conducted a proactive search and rescue operation? #WhereIsFRONTEX"

Two of the charity ships, each filled beyond capacity after rescuing scores of migrants from rubber dinghies and unseaworthy wooden fishing vessels, made May Day calls to the Maritime Rescue Coordination Center run by the Italian Coast Guard in Rome to ask for assistance on Sunday.
The Iuventa rescue ship operated by the German NGO Jugend Rettet reported navigational failure under the weight of the migrants and the German NGO Sea Eye also reported difficulty due to overcrowding.
"#Iuventa and @seaeyeorg are unable to move due to the high amount of people on board and nearby us in rubber boats!
We need help by #MRCC" the Jugend Rettet tweeted.
It reported having as many as seven pregnant women on board.
Italian Coast Guard confirmed that vessels were headed to the area to assist offloading some of the migrants.

MOAS also tweeted messages about its rescue ship Phoenix after spending the night watching a number of packed rubber dinghies whose passengers the ship was unable to assist because of its own overcrowding.
"Hour 40 of ongoing rescues & crisis management for #Phoenix crew.
They are still waiting for help to arrive; and we have lost all words #Med"
The voice that is often missing from the discussion is often that of the migrants themselves. On Sunday, 649 people rescued in a number of operations by the MSF Prudence arrived in Reggio Calabria.
Among them were men with gunshot wounds from traffickers and women who were tortured, according to rescuers at the scene.
At the port, a group of teenage Nigerian boys who had arrived as unaccompanied minors by way of sea rescues earlier this year waited at the shore to see if their missing family members were among the arrivals.
When asked if the charity boats made a difference in their decision to make the dangerous crossing, they had no idea what was meant by the question.
"The gun to my head made the difference," a young man called Caleb said after describing how he was forced onto a rubber dinghy late one night and losing sight of his father.
"We don't have a lot of choices. We are just lucky we got out of Libya alive."

Links :