New Greenland maps show more glaciers at risk

UCI’s BedMachine ice mapping technique enabled the creation of a three-dimensional image of a portion of the northwest coast of Greenland.

Ocean bathymetry is shown in blue and ice surface topography are displayed in white and orange.

Mathieu Morlighem / UCI

From UCI

UCI-created high-resolution charts will inform future ice and sea level forecasts

New maps of Greenland’s coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting as had previously been thought.

Researchers at the University of California, Irvine, NASA and 30 other institutions have published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland’s bedrock and coastal seafloor.
Among the many data sources incorporated into the new maps is data from NASA’s Ocean Melting Greenland campaign.

Lead author Mathieu Morlighem of UCI had demonstrated in an earlier study that data from OMG’s survey of the shape and depth, or bathymetry, of the seafloor in Greenland’s fjords improved scientists’ understanding of both the coastline and the inland bedrock beneath glaciers that flow into the ocean.
That’s because the bathymetry at a glacier’s front limits the possibilities for the shape of bedrock farther upstream.

(a) Data coverage, including ice-penetrating radar measurements (Center for Remote Sensing of Ice Sheets, High CApability Radar Sounder, University of Denmark, Uppsala University, Pathfinder Advanced Radar Ice Sounder, Alfred Wegener Institute) and ocean bathymetry (from single-beam data in dark blue),

and (b) BedMachine v3 bed topography sources, which include mass conservation (MC), kriging, Greenland Ice Mapping Project (GIMP) (Howat et al., 2014), RTopo-2/IBCAO v3 (Jakobsson et al., 2012; Schaffer et al., 2016), and bathymetry data from multibeam and gravity inversions acquired after the compilation of IBCAO v3.

The nearer to the shoreline, the more valuable the bathymetry data are for understanding on-shore topography, Morlighem said.
“What made OMG unique compared to other campaigns is that they got right into the fjords, as close as possible to the glacier fronts. That’s a big help for bedrock mapping,” he added.

Additionally, the OMG campaign surveyed large sections of the Greenland coast for the first time ever.
In fjords for which there are no data, it’s difficult to estimate how deep the glaciers extend below sea level.

(a) BedMachine v3 bed topography (m), color coded between −1500 m and +1500 m with respect to mean sea level, with areas below sea level in blue

and (b) regions below sea level (light pink) that are connected to the ocean and maintain a depth below 200 m (dark pink) and that are continuously deeper than 300 m below sea level (dark red).

The thin white line shows the current ice sheet extent.

The OMG data are only one of many datasets Morlighem and his team used in the ice sheet mapper, which is named BedMachine.
Another comprehensive source is NASA’s Operation IceBridge airborne surveys.
IceBridge measures the ice sheet thickness directly along a plane’s flight path.
This creates a set of long, narrow strips of data rather than a complete map of the ice sheet.

Savissuaq Gletscher area in the GeoGarage platform (DGA chart)

Besides NASA, almost 40 other international collaborators also contributed various types of survey data on different parts of Greenland.

No survey, not even OMG, covers every glacier on Greenland’s long, convoluted coastline.
To infer the bed topography in sparsely studied areas, BedMachine averages between existing data points using physical principles such as the conservation of mass.

Bed topography for different sectors of Greenland:

(a) the region of Savissuaq Gletscher, (b) Hayes Gletscher, (c) Illullip Sermia, (d) Mogens Heinesen N, (e) Heimdal Gletscher, and (f) Skinfaxe.

The yellow/red lines indicate the ice front position between 1985 and today from Landsat data, and the white dotted line shows the profile used in Figure 1.

The topography is color coded between −700 m and 800 m, and contours are shown every 200 m from −800 m to 200 m above sea level.

Some glaciers, such as the one 10 km northwest of Heimdal Gletscher, were not mapped using MC.

The new maps reveal that two to four times more oceanfront glaciers extend deeper than 600 feet (200 meters) below sea level than earlier maps showed.
That’s bad news, because the top 600 feet of water around Greenland comes from the Arctic and is relatively cold.
The water below it comes from farther south and is 6 to 8 eight degrees Fahrenheit (3 to 4 degrees Celsius) warmer than the water above.
Deeper-seated glaciers are exposed to this warmer water, which melts them more rapidly.

Surface and bed topography along six profiles (see white dotted lines in Figure 2) from this study (solid black) and bed from B2013 (dotted red, Bamber et al., 2013) and RTopo-2 (dotted yellow, Schaffer et al., 2016). Multibeam bathymetry data (MBES) are shown in blue.

The vertical lines show the ice front position between 1995 and today.

Morlighem’s team used the maps to refine their estimate of Greenland’s total volume of ice and its potential to add to global sea level rise if the ice were to melt completely, which is not expected to occur within the next few hundred years.
The new estimate is higher by 2.76 inches (7 centimeters) for a total of 24.34 feet (7.42 meters).

OMG principal investigator Josh Willis of JPL, who was not involved in producing the maps, said, “These results suggest that Greenland’s ice is more threatened by changing climate than we had anticipated.”

On Oct. 23, the five-year OMG campaign completed its second annual set of airborne surveys to measure for the first time the amount that warm water around the island is contributing to the loss of the Greenland ice sheet.
Besides the one-time bathymetry survey, OMG is collecting annual measurements of the changing height of the ice sheet and the ocean temperature and salinity in more than 200 fjord locations. Morlighem looks forward to improving BedMachine’s maps with data from the airborne surveys.

The maps and related research are in a paper titled “BedMachine v3: Complete bed topography and ocean bathymetry mapping of Greenland from multi-beam echo sounding combined with mass conservation” in Geophysical Research Letters.
This project received support from NASA’s Cryospheric Sciences Program and the National Science Foundation’s ARCSS program.

Links :

• GeoGarage blog : Greenland’s coasts are growing as seas rise / Global warming is melting the Greenland ice ... / Map provides high-resolution look at ... /

How 16th-century European mapmakers described the World’s oceans

A 13th-century depiction of the world as a circle divided by into three continents, Asia, Europe, and Africa.

British Library/ Public Domain

From Atlas Obscura by Genevieve Carlton

For some, they were an obstacle.
For others, they were an opportunity.

According to medieval mapmakers, the world was made up of three continents ringed by narrow bodies of water.
When the voyages of Christopher Columbus, Amerigo Vespucci, and Ferdinand Magellan uncovered continents previously unknown to Europeans, this posed a major problem for those cartographers.
But these explorers did not just stumble upon uncharted land—they also became aware of expansive stretches of ocean around the world.

 Bünting Clover Leaf Map.
A 1581 woodcut, Magdeburg.

Jerusalem is in the center, surrounded by Europe, Asia and Africa.

For the first time, Europeans were confronted with the realization that they lived on a blue planet, with 71 percent of the Earth’s surface covered by water.
The narrow strips of blue on medieval mappae mundi—also known as T-O maps, which showed the earth as a T centered on Jerusalem—were suddenly dwarfed by unimaginably vast oceans.
Stories about the European discovery of the New World are ubiquitous, but stories about the discovery of so much new water are much more rare.

 Map of Borneo by Pigafetta.

For explorers, these oceans were dangerous obstacles.
Attempting to traverse them could quickly turn deadly, as the sailors on Magellan’s expedition learned when only one of their five ships—and 18 of the original 280 crewmen—returned to Spain in 1522.
Antonio Pigafetta, one of Magellan’s surviving men, described this first Pacific Ocean crossing, which took three months and 20 days, in a report.
He wrote, “We only ate old biscuit reduced to powder, and full of grubs, and stinking from the dirt which the rats had made on it when eating the good biscuit, and we drank water that was yellow and stinking.”

 Claudius Ptolemy, 13th Century world map

The oceans also posed a problem for mapmakers.
Reports from explorers deviated wildly from pre-Columbian perceptions of the world’s water, as evidenced in mappae mundi.
The 1475 world map in Lucas Brandis’s Rudimentum novitiorum captures this older outlook on the world.
Asia, at the top of the map, represents one hemisphere, while wedges depicting Europe and Africa sit in the bottom half of the world.
The map was not intended to be representative; instead it focused on a Christian ordering of space with Jerusalem at the world’s center.
The world’s territories appear as hills, and in Europe, rulers sit atop them, with the pope in Rome shown holding a gold cross.
Asia and Africa, less well known to 15th-century Europeans, have more fanciful illustrations, including a pair of dragons, a burning phoenix, and a man-eating demon chasing his victim while clutching his severed arm.
On the map, the Mediterranean separates Europe from Africa and the rivers Don and Nile mark the divide between Asia and its neighbors.
Yet on this particular map, these bodies of water are marked by thin black lines and nothing more.
The only water seems to flow from the four great rivers at the top of the map, which represents the Garden of Eden’s Earthly Paradise.

A 1475 woodcut world map, published in Rudimentum novitiorum.

Public Domain 

The discovery of massive bodies of water forced mapmakers to devise creative solutions.
One of the earliest strategies was to shrink the oceans.
Here, mapmakers borrowed from Columbus himself, who minimized his trans-Atlantic voyage by claiming that the crossing took only 33 days.
However, Columbus only counted from the Canary Islands to the Indies, omitting the 37 days spent traveling from Spain to the Canaries, which included repairs on two of his three ships.

Cantino planisphere (1502)

One of the earliest maps to show the New World, the 1502 Cantino planisphere, shrunk the Atlantic by showing Flores Island, the westernmost of the Azores, just slightly west of the jutting coast of Brazil, when in fact it is several degrees of longitude east of the Brazilian coast.

 Battista Agnese world map (1544)

Battista Agnese, a Genoese mapmaker who produced at least 100 hand-drawn atlases for wealthy patrons, also narrowed the Atlantic in his 1544 world map.
Agnese drew only 10 degrees of longitude between Brazil’s furthest east point and Africa’s furthest west, nearly halving the actual distance of over 3,000 kilometers (1,864 miles).
These cartographic manipulations consistently under-measured the Atlantic, minimizing the distance between the Old World and the New.

From 1570, a world map by Abraham Ortelius. Public Domain

Sixteenth-century mapmakers also invented massive “undiscovered” continents to fill the oceans.
Two of the most famous maps from the 16th century, Abraham Ortelius’s 1570 world map in his atlas Theatrum Orbis Terrarum, and Gerhard Mercator’s 1569 world map, (which introduced the Mercator projection) rely on this approach.
Produced less than a hundred years after the Rudimentum novitiorum, Ortelius’s map shows a completely transformed globe.
The shapes of the world’s continents, recognizable to our contemporary eyes and now divided by the grid of latitude and longitude, are arranged with north at the top, a convention that only emerged in the 16th century.
The least familiar part of the globe is its southern stretches, which Ortelius labels “Terra Australis Nondum Cognita,” or southern land not yet known.

 1604 copy of 1602 Kunyu Wanguo Quantu

Both the Ortelius and Mercator map admitted that the world’s oceans were vastly larger than those shown on any pre-Columbian map, but both also hypothesized a massive southern continent to “balance” the landmasses north of the equator.
Mercator made this explicit in 1595, when he wrote, “it was necessary for such a continent to exist below to Antarctic Pole, which … would balance the other lands.” Europeans were so certain that this continent existed that Australia, first spotted by Europeans in 1606, took its name from the Latin term for Terra Australis.
These imagined continents did not just multiply the Earth’s land—they also limited the disturbing vastness of the world’s oceans.

 Gerard De Jode Universi Orbi seu Terreni Globi (1578)

Other cartographers embraced the ocean’s blank canvas in a different way: by emphasizing just how empty it was.
In addition to minimizing the size of the Atlantic in his beautifully-colored maps, Agnese painted the land a rich green, depicting the mountains, rivers, and lakes that dotted the territory.
On the land, water is drawn in brilliant blue, and the Red Sea and the Gulf of California are colored red, a convention borrowed from mappae mundi.
The ocean, by contrast, was largely blank, the untreated vellum standing in for water.
Agnese did scatter a few islands throughout and used the blank space to highlight Ferdinand Magellan’s route as he circumnavigated the globe.
But his map implies that Magellan did not discover anything notable in the ocean; rather, the ocean was an emptiness between “real” places, defined by the absence of land rather than containing anything worth recording.
Agnese’s unknown land, or terra incognita, which also faded into blank vellum, was visually identical to the explored oceans, perhaps hinting that the ocean was ultimately unknowable.

"A Complete Geographical Map of all the Kingdoms of the World" (坤輿萬國全圖),

the first Chinese world map, 1602

But the seeming blank space of the ocean signified more than peril and emptiness—it also posed an opportunity for enterprising mapmakers.
Blank spaces on the map could be filled with promotions for the map’s creator or his hometown.
The French royal cosmographer and mapmaker André Thévet manufactured not one but two fictional Thevet Islands in the Atlantic in the 1580s.
Similarly, in a 1558 book with an accompanying map, Nicolò Zeno, a Venetian nobleman from a flagging family, alleged that his familial predecessors, Nicolò (his namesake) and Antonio Zeno, had landed on the invented island of Frisland and led voyages in the North Atlantic that discovered the New World in 1380, over a century before Columbus’s Genoa or Vespucci’s Florence could claim the glory.
And on his 1560 world map, Paolo Forlani, one of Venice’s most active mapmakers, used the wide oceans to promote Venice by sprinkling the Atlantic, Pacific, and Indian Oceans with Venetian galleys, clearly not designed for transoceanic voyages.
The ships not only filled the water, but they also proclaimed Venetian dominance in an era when Venice had already lost the race to colonize distant territories.

Forlani’s map of North America from 1566. Public Domain

Mapmakers also explored a range of design techniques to fill the oceans.
Giovanni Lorenzo D’Anania’s 1582 map of the North Atlantic not only populated the waters with imaginary islands, but also filled the sea with dark dots and large labels for the land, minimizing the impression of blankness.
In his 1566 map of North America, Forlani similarly peppered the Atlantic with islands both real and invented, expanded the size of North America, and dotted the waters on his engraving to avoid the impression that the oceans were simply blank.
He also made the Pacific much smaller than the Atlantic, placing the island of Japan halfway between North America and Asia.

Map of the Southern hemisphere, 1593 by Gerard de Jode

These mapmakers and the explorers who crossed the newly found oceans saw the water both as an obstacle, separating Europeans from their destination and posing countless dangers, and as an opportunity.
A blank space on a map let a mapmaker reinvent himself, much like pirates who roamed the seas, by manufacturing islands or adding flourishes to promote his city.
And when mapmakers signed their works, they almost always did so in the ocean.

Links :

• GeoGarage blog : Ancient nautical maps' surprising accuracy ... / From Ptolemy to GPS, the brief history of maps / The greatest maps in history, collected in ... / Maps have ‘north’ at the top, but it could’ve ... /  Portolan charts 'too accurate' to be medieval / The golden age of nautical charts - When ... / The making of a mysterious Renaissance map / Venetian navigators : the voyages of the ... / The end of the map : why the World looks ...
• LOC : Portolan atlas of the Mediterranean Sea, western Europe, and the northwest coast of Africa
• Avan Stallar : maps gallery

Bird vs fish

Giant trevallies launch themselves out of the water to catch fledgling terns.

 

Links :

• The Conversation : Blue Planet academic consultants on the message that humanity cannot afford to ignore
• GeoGarage blog : David Attenborough on the scourge of the oceans: 'I remember being told plastic doesn't decay, it's wonderful'

BP and Shell planning for catastrophic 5°C global warming despite publicly backing Paris climate agreement

Neither company sets targets to reduce emissions and
BP’s total investment in renewable and clean technologies has actually shrunk since 2005, 
the report said 

From The Independant by Ben Chapman

Companies are trying to 'have their oil and drink it' by committing to 2°C in public while planning for much higher temperature rises, says shareholder campaign group, ShareAction

Oil giants Shell and BP are planning for global temperatures to rise as much as 5°C by the middle of the century.
The level is more than double the upper limit committed to by most countries in the world under the Paris Climate Agreement, which both companies publicly support.

The discrepancy demonstrates that the companies are keeping shareholders in the dark about the risks posed to their businesses by climate change, according to two new reports published by investment campaign group Share Action.
Many climate scientists say that a temperature rise of 5°C would be catastrophic for the planet.

ShareAction claims that the companies’ actions put the value of millions of people's pensions at risk.
Two years after BP and Shell shareholders voted resoundingly in favour of forcing the companies to make detailed disclosures about climate risks, the companies have made unconvincing steps forward, according to the reports.
ShareAction said that Shell and BP are meeting their legal requirements, but are putting shareholders’ capital at risk because of numerous failings in their plans for the future.

Neither company sets targets to reduce emissions and BP’s total investment in renewable and clean technologies has actually shrunk since 2005, the reports said.
That’s despite the company’s public-facing image of being “beyond petroleum”.

BP invests just 1.3 per cent of its total capital expenditure in low-carbon projects while Shell has pledged to invest 3 per cent of its annual spend on low-carbon by 2020.

Both companies assess the resilience of their businesses against climate models in which temperatures warm by between 3°C and 5°C.
A maximum warming of 2°C beyond pre-industrial levels is the central aim of the landmark Paris climate agreement, which both firms say they support.
It is widely believed that any warming beyond 2°C could cause serious and potentially irreversible changes to the climate.
Shell reaffirmed its commitment to the Paris Agreement in a statement publicising its most recent AGM.
“Shell has a clear strategy, resilient in a 2°C world,” the company said, but its change modelling document states that “the emissions pathways until the middle of the century overshoots the trajectory of a 2°C goal”.

ShareAction’s report also found that top executives at both Shell and BP are still given incentives to pursue strategies centred on oil and gas and are paid bonuses over three to six years for fossil fuel projects that could have damaging effects for shareholders decades later.
Michael Chaitow, senior campaigns officer at ShareAction, said the report revealed an “uncomfortable discrepancy” between Shell and BP’s public support for a low-carbon economy and their actual business planning.
“Shell and BP want to have their oil and drink it too, by advocating for the landmark Paris Agreement to limit global temperature rises to below 2°C degrees, while planning for scenarios that would violate it,” he said.

The group called on Shell and BP shareholders, which include powerful institutional investors, to demand that the two oil companies do more to tackle climate change.

In 2015, more than 98 per cent of shareholders in both Shell and BP voted for resolutions that require the companies to regularly report on their emissions, resilience to climate change, investment in low-carbon technology and executive incentives.
The resolutions helped pave the way for subsequent shareholder resolutions on climate-related disclosure at oil and gas companies including Exxon and Occidental Petroleum.

Following the Shell and BP resolutions, billionaire businessman and former New York Mayor, Michael Bloomberg, founded a task force to press companies to properly disclose to the world the risks that climate change presents.

Catherine Howarth, chief executive of ShareAction, said the chief executives of both Shell and BP are running companies that look “poorly prepared for the speed of technological and economic change now underway in the global energy market”.
She added: “Millions of pension savers are exposed to Shell and BP’s shares. These reports challenge the professional investors looking after our pension savings to manage the growing financial risks facing BP and Shell more actively in the coming year.”

Neither BP nor Shell would comment on the report directly.
BP said it “anticipates a range of scenarios to give us flexibility in our approach".

Links :

• The Independant : Gas companies spend €104m lobbying to ensure Europe remains 'locked in' to fossil fuels for decades, report finds
• Desmog : Shell, BP Climate Disclosures 'Just a Marketing Tool' — Report
• LATimes :  What Exxon knew about the Earth's melting Arctic
• Investors : Royal Dutch Shell charges into a future beyond oil
• NYTimes : Saudi Arabia’s Grand plan to move beyond oil: Big goals, bigger hurdles 
• Wired : Could San Francisco get the oil industry to pay for Climate change ? 
• OilPrice : Big Oil Sinks $1 Billion into climate fund
• UN : Carbon dioxide levels surge to new high in 2016, UN weather agency reports 
• The Guardian : Global atmospheric CO2 levels hit record high
• GeoGarage blog : In a 1991 film, Shell Oil issued a stark warning about climate change risks, and much of it has proved to be true

New science suggests the ocean could rise more — and faster — than we thought

Shot just off the coast of Ilulissat , the best western Greenland has to offer, covering vast glaciers, icebergs and Icefjords melting away.

Rising air and sea temperatures is causing the massive Greenland ice sheet to shed 300 gigatons of ice a year into the ocean, the single largest source of sea level rise from melting ice!

From Washington Post by Chris Mooney

Climate change could lead to sea level rises that are larger, and happen more rapidly, than previously thought, according to a trio of new studies that reflect mounting concerns about the stability of polar ice.

In one case, the research suggests that previous high end projections for sea level rise by the year 2100 — a little over three feet — could be too low, substituting numbers as high as six feet at the extreme if the world continues to burn large volumes of fossil fuels throughout the century.

“We have the potential to have much more sea level rise under high emissions scenarios,” said Alexander Nauels, a researcher at the University of Melbourne in Australia who led one of the three studies.
His work, co-authored with researchers at institutions in Austria, Switzerland, and Germany, was published Thursday in Environmental Research Letters.

The results comprise both novel scientific observations — based on high resolution seafloor imaging techniques that give a new window on past sea level events — and new modeling techniques based on a better understanding of Antarctic ice.

The observational results, from Texas and Antarctica, examine a similar time period — the close of the last Ice Age a little over 10,000 years ago, when seas are believed to have risen very rapidly at times, as northern hemisphere ice sheets collapsed.

Off the Texas coast, this would have inundated ancient coral reefs. Usually, these reefs can grow upward to keep pace with sea level rise, but there’s a limit — one observed by a team of scientists aboard a vessel called the Falcor in 200 foot deep waters off the coast of Corpus Christi.

These so-called drowned reefs showed features that the researchers called “terraces,” an indicator of how the corals would have tried to respond to fast rising sea levels.
Because the organisms must maintain access to a certain amount of sunlight, they would have tried to grow higher to keep up with fast rising seas — but they wouldn’t have been able to do so over a very large area.
And so their growth became concentrated in progressively smaller, stepped regions:

A 3-D representation of Dream Bank, a long-dead reef offshore South Texas.

The vertical scale of the image has been increased to clearly illustrate the terrace structures that form due to rising sea levels via a process known as backstepping.

(Image courtesy of P. Khanna/Rice University)

“The reef under stress often has a tendency to kind of shrink to this higher elevated area,” said André Droxler, one of the authors of the study in Nature Communications and a researcher at Rice University.
“It creates this pyramid-like system.” (Droxler completed the research with colleagues from Rice and Texas A&M University, Corpus Christi.)

The youngest drowned corals date to the end of the last ice age, around 11,500 years ago — corresponding to what scientists believe were large warming events in the northern hemisphere and so-called meltwater pulses from now melted ice sheets.
And multiple drowned reefs off Texas show a similar pattern — and terminate in similar water depths.
“Over 120 kilometers, the reefs behaved the same way. It’s difficult to find any other reason why they would do this,” Droxler said.

Droxler thinks the reef structures suggest eras when sea level was rising by tens of millimeters annually, far beyond the current, roughly 3 millimeters per year.
(A 50 millimeter annual sea level rise would produce a meter, or over 3 feet, of rise every 20 years.)
The new study therefore concludes that during the last ice age, there were multiple bursts of fast sea level rise — and implies that our future could hold something similar.
“The steady and gradual sea-level rise, observed over the past two centuries [may] not be a complete characterization of how sea level would rise in the future,” the study concludes.

Meanwhile, far away in the Southern hemisphere, a team of scientists used a very similar seafloor mapping technology to detect ancient iceberg “plough marks” etched deep into the seafloor of Pine Island Bay, an ocean body that currently sits in front of one of West Antarctica’s most worrying glaciers, Pine Island.
The results were published in the journal Nature on Wednesday by researchers at the University of Cambridge, the British Antarctic Survey, and the Bolin Center for Climate Research in Stockholm.

The seafloor grooves, the researchers believe, were made during a similar era to the Texas coral steppes (the close of the last ice age), and signal a very rapid retreat of Pine Island over roughly a thousand years.

Here’s what they looked like in the seafloor imagery the study produced:

Linear-curvilinear iceberg-keel ploughmarks on the surface of a large grounding-zone wedge located in the mid-shelf Pine Island Trough, West Antarctica. (Martin Jakobsson)

What’s critical about the markings, explains lead study author Matthew Wise of the University of Cambridge, is their maximum depth — 848 meters, or around 2,800 feet.
Because ice floats with 10 percent of its mass above the surface and the remaining 90 percent below it, this suggests that when the ice broke from the glacier, close to 100 meters (over 3oo feet) of it was extending above the water surface.

That’s a key number, because scientists are converging on the belief that ice cliffs of about this height above the water level are no longer sustainable and collapse under their own weight — meaning that when you get a glacier this tall up against the ocean, it tends to crumble and crumble, leading to fast retreat and potentially fast sea level rise.
“If we think about how thick these icebergs would have needed to be considering these float with 90 percent of their mass and thickness beneath the sea,” Wise said, “we think of an ice cliff that was at the maximum thickness implied by the physics of the ice.”

 NASA

The problem is that if it happened then, well, it could happen again.
Both Pine Island glacier and its next door neighbor, Thwaites, are known to get thicker as one travels inland away from the sea, which means they are capable of once again generating ice cliffs taller than the critical size detected by the current study.
“If a cliff even higher than the ~100 m subaerial/900 m submarine cliffs were to form, as might occur with retreat of Thwaites Glacier in West Antarctica, it might break repeatedly with much shorter pauses than now observed, causing very fast grounding line retreat and sea level rise,” explained Richard Alley, a glaciologist at Penn State University, by email after reviewing the current study for the Post.

The final study, released Thursday morning in Environmental Research Letters, takes a different approach but provides perhaps the most sweeping verdict.

The study used five “shared socioeconomic pathways” that analyze possible futures for global society and its energy system, and resulting climate change, over the course of this century.
These scenarios will feed into the next report of the United Nations Intergovernmental Panel on Climate Change, the most influential scientific body that assesses climate change, according to the University of Melbourne’s Alexander Nauels, the lead author of the current study

The research combined these scenarios with tools to project future sea level rise in light of recent science suggesting that Antarctic ice in key regions could collapse relatively rapidly.
That includes possible fast retreat at Pine Island and Thwaites glaciers due, in part, to the problem of ice cliff instability.

The result was that in one scenario assuming high fossil fuel use and strong economic growth during the century, the study predicted that seas could rise by as much as 4.33 feet on average — with a high end possibility of as much as 6.2 feet — by 2100.
That includes possibly rapid sea level rise as high as 19 millimeters per year by the end of the century.

These numbers are considerably higher than high end projections released in 2013 by the Intergovernmental Panel on Climate Change.
(It is important to emphasize that the highest sea level numbers presented in the new study would result from human choices to pursue large fossil fuel exploitation and economic growth with little attempt to slow climate change. It is far from clear that this is the path the world will actually take.)

On the other hand, if the world limits global warming to the Paris climate agreement emissions target, the study finds that sea level rise might be held as low as 1.7 feet by 2100, on average.
Here’s an image illustrating the results:

21st century global mean sea level rise projections with median and shaded 66 percent model ranges under a baseline high warming scenario and low warming scenario.

The dashed lines represent scenarios consistent with the United Nations’ Intergovernmental Panel on Climate Change’s (IPCC) findings in 2013, while the solid lines present revised sea level rise modeling results based on Antarctic ice sheet contributions suggested by DeConto and Pollard (2016).

The IPCC consistent sea level rise likely ranges are based on Nauels et al. (2017).

Global mean sea level rise is provided in centimeters relative to the 1986-2005 mean.

(Nauels et al.)

When the IPCC undertakes a similar analysis, Nauels said, it could produce results like these.
“I think the numbers will go up,” he said of the body’s report, which is expected in 2021.

So in sum — new research is affirming that seas have risen quite rapidly in the planet’s past, and that major glaciers have retreated quickly because their enormous size makes them potentially unstable.
Meanwhile, additional modeling projects these kinds of observations forward and suggests that the century in which we are now living could — could — see similar changes, at least in more severe global warming scenarios in which the world continues to burn high volumes of fossil fuels.

But unlike those submerged corals off the coast of Texas, the difference is that we know this could be coming — which gives us a chance to stop it.

Links :

• The Guardian : Sea levels to rise 1.3m unless coal power ends by 2050, report says
• Inside Climate news : Are Antarctica's Ice Sheets Near a Climate Tipping Point?

Home

Home from Frost Films
A Cinematic Short Film celebrating the life of a man called Bob.
Throughout his entire life he's always put the ocean first,
which has lead to him being homeless and living in a van.
But he loves the ocean and his life as much as ever, and of course, still surfs every day.
"Your happiness comes within yourself"

Links :

• HackSpirit : A scientist reveals what being near the ocean actually does to your brain

How did early sailors navigate the Oceans ?

Do you know how the early sailors navigate the oceans?

The technology today makes it real easy to navigate the oceans.

But it's very interesting to know how the early sailors managed to navigate without it.

There's a lot of history on it.
I tried my best to compile some important and interesting parts of it into this video.

How did Polynesian wayfinders navigate the Pacific Ocean ?
by Alan Tamayose and Shantell De Silva

A spacecraft graveyard exists in the middle of the ocean — here's what's down there

Point Nemo on Google Earth

From Business Insider by Dave Mosher

• Large satellites, space stations, and other objects can pose a threat when they fall to the ground.
• As a result, many nations de-orbit old spacecraft over the most remote place on Earth, called Point Nemo.
• This "spacecraft cemetery" is about 1,450 miles away from any piece of land and home to hundreds of dead satellites.
• Space agencies and companies are concerned about space junk and working on ways to prevent its formation and clean it up.

The most remote location on Earth has many names:
It's called Point Nemo (Latin for "no one") and the Oceanic Pole of Inaccessibility.
Most precisely, its exact coordinates are 48 degrees 52.6 minutes south latitude and 123 degrees 23.6 minutes west longitude.

The spot is about 1,450 nautical miles from any spot of land — and the perfect place to dump dead or dying spacecraft, which is why its home to what NASA calls its "spacecraft cemetery."
"It's in the Pacific Ocean and is pretty much the farthest place from any human civilization you can find," NASA said.
Bill Ailor, an aerospace engineer and atmospheric reentry specialist, put it another way: "It's a great place you can put things down without hitting anything," he said.

To "bury" something in the cemetery, space agencies have to time a crash over that spot.
Smaller satellites don't generally end up at Point Nemo, since, as NASA explains, "the heat from the friction of the air burns up the satellite as it falls toward Earth at thousands of miles per hour. Ta-da! No more satellite."

The problem is larger objects, like Tiangong-1: the first Chinese space station, which launched in September 2011 and weighs about 8.5 tons.

A scale model of China's Tiangong-1 space station.

Jason Lee/Reuters

China lost control of the 34-foot-long orbital laboratory in March 2016, and it is now doomed to crash by early 2018.

Where, exactly?
No one yet knows.
Ailor, who works for the nonprofit Aerospace Corporation, said his company likely won't generate a forecast until five days before the space station is expected to break apart in Earth's atmosphere.

When it does, hundreds of pounds of the spacecraft — like titanium scaffolding and glass-fiber-wrapped fuel tanks — could be falling at more than 180 miles per hour just before slamming into the ground (and thousands of miles per hour faster in the upper atmosphere).

Since China doesn't have control of Tiangong-1, it can't assure the space station will disintegrate over Point Nemo.

Footage courtesy of NASA

The dead-spacecraft dumping zone

Astronauts living aboard the International Space Station actually live closer to the graveyard of spacecraft than anyone else.
This is because the ISS orbits about 250 miles above Earth — and Point Nemo, when the orbital laboratory flies overhead. (The nearest island, meanwhile, is much farther away.)

Between 1971 and mid-2016, space agencies all over the world dumped at least 260 spacecraft into the region, according to Popular Science.
That tally has risen significantly since the year 2015, when the total was just 161, per Gizmodo.

Buried under more than two miles of water is the Soviet-era MIR space station, more than 140 Russian resupply vehicles, several of the European Space Agency's cargo ships (like the Jules Verne ATV), and even a SpaceX rocket, according to Smithsonian.com.

These dead spacecraft aren't neatly tucked together, though.

Ailor said a large object like Tiangong-1 can break apart into an oval-shaped footprint of debris that extends 1,000 miles long and dozens of miles wide.
Meanwhile, the land-free zone around Point Nemo stretches more than 6.6 million square miles — so paying your respects to a specific item isn't easy.

While not all spacecraft wind up in the cemetery, the chances are extremely slim that anyone would get hit by debris regardless of where the spacecraft break up on Earth, Ailor said.

"It's not impossible, but since the beginning of the space age .... a woman who was brushed on the shoulder in Oklahoma is the only one we're aware of who's been touched by a piece of space debris," he said.

A bigger risk is leaving dead spacecraft in orbit.

An illustration of space junk. Satellites and debris are not to scale.

ESA

The pernicious threat of space junk

Some 4,000 satellites currently orbit Earth at various altitudes.
There's space for more — even the 4,425 new internet-providing satellites that Elon Musk and SpaceX wish to launch in the near future.

But it's getting crowded up there when considering the threat of space junk.

In addition to all those satellites, there are thousands of uncontrolled rocket bodies orbiting earth, along with more than 12,000 artificial objects larger than a fist, according to Space-Track.org.
That's not to mention countless screws, bolts, flecks of paint, and bits of metal.

"Countries have learned over the years that when they create debris, it presents a risk to their own systems just as it does for everybody else," Ailor said.

The worst kind of risk, according to the European Space Agency, is when a piece of space junk accidentally hits another piece, especially if the objects are large.

Such satellite collisions are rare but do happen; one occurred in 1996, another in 2009, and two in 2013.
These accidents — along with the intentional destruction of space satellites — have generated countless pieces of space debris that can threaten satellites in nearby orbits years later, leading to a kind of runaway effect.

"We've figured out that this debris can stay up there for hundreds of years," Ailor said, later clarifying that some objects in higher orbits, like geosynchronous satellites, can stay in orbit for thousands of years.

Getting old spacecraft out of orbit is a key to preventing the formation of space junk, and many space agencies and corporations now build spacecraft with systems to de-orbit them (and land them in the spacecraft cemetery).

But Ailor and others are pushing for the development of new technologies and methods that can lasso, bag, tug, and otherwise remove the old, uncontrolled stuff that's already up there and continues to pose a threat.
"I've proposed something like an XPRIZE or a Grand Challenge, where would you identify three spacecraft and give a prize to an entity to remove those things," he said.

The most important hurdle to clear, though, may be politics on Earth.
"It's not just a technical issue. This idea of ownership gets to be a real player here," Ailor said.
"No other nation has permission to touch a US satellite, for instance. And if we went after a satellite ... it could even be deemed an act of war."

Ailor said someone needs to get nations together to agree on a treaty that spells out laws-of-the-sea-like salvage rights to dead or uncontrollable objects in space.
"There needs to be something where nations and commercial [companies] have some authority to go after something," he said.

Links :

• DailyMail : Where spaceships go to die: Nasa's watery graveyard in the South Pacific 1,600 miles from land is now the resting place for 260 sunken craft
• Gizmodo : This Watery Graveyard Is the Resting Place for 161 Sunken Spaceships
• GeoGarage blog : Where is Point Nemo? / The place furthest from land is known as Point Nemo

Map provides high-resolution look at nearly entire Arctic region

A color-shaded relief image made from the 5-meter mosaic of ArcticDEM shows a portion of the Brooks Range on the North Slope of Alaska.

Colors suggest elevation, from lower (green) to higher (brown).

Credit: Paul Morin, PGC

From EOS by Randy Showstack

Researchers highlight the value of the time element incorporated into imagery and having a baseline for revisiting and comparing topography.

“The Arctic, before we started, was one of the most poorly mapped places on Earth.
It’s not anymore,” said Paul Morin, co–principal investigator of the ArcticDEM initiative, which has now released high-resolution digital elevation models (DEM) of 97.4% of the region.
With this latest release, “we have a uniform product at 2-meter [resolution]” for all the land area north of 60°N latitude, plus those parts of Alaska, Greenland, and Russia’s Kamchatka Peninsula that are south of that point.

ArcticDEM Explorer produces digital elevation models to show change over time

The public-private initiative plans to fill in the gaps with a final release in May 2018, according to Morin, director of the Polar Geospatial Center (PGC) at the University of Minnesota.

The initiative, which has produced a 3-D digital representation of terrain surface, is an important tool for studying, understanding, and making decisions about the Arctic, including resources, natural hazards, and infrastructure, scientists and environmental managers told Eos. It is “a game changer for high-latitude science and modeling,” said Laurence Smith, professor of geography at the University of California, Los Angeles.

Released on 6 September, the publicly available ArcticDEM incorporates satellite-acquired imagery, high-performance computing, and open-source photogrammetry software to stitch together a terrain model that governments, commercial entities, and the academic community could find useful for many applications.

The ArcticDEM release consists of two products, Morin told Eos. One is a time-stamped, 2-meter-resolution collection of overlapping DEMs of the Arctic, with each DEM having the date and time associated with it.
The other is a 5-meter-resolution DEM product, which is not time stamped, of the entire region.
The products build on earlier ArcticDEM versions by adding 32% more terrain data, including sizable portions of Russia and Scandinavia.

(top) The newly released Arctic digital elevation model, or DEM, depicts 97.4% of the region’s terrain.

Colors show elevation: green for near sea level, brown for higher topography such as mountains, and white for the highest-altitude areas, such as the Greenland ice sheet. 

(bottom) A silhouette of the full ArcticDEM shows the 32% additional Arctic terrain (orange) included in the DEM since its last release.
Credit: Paul Morin, PGC

Temporal Aspect of Topography

The products provide two significant advances, according to Morin.
The first is that the resolution for just about the entire Arctic is much higher than in other models.
For instance, compared with the U.S.-Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer’s (ASTER) Global Digital Elevation Model (GDEM), which came out with updated versions in 2011 and 2016, the 5-meter ArcticDEM has 36 times the resolution of ASTER’s GDEM, which has 30-meter pixels, whereas the 2-meter ArcticDEM has 225 times greater resolution.

The second major advance, Morin said, is the time element incorporated into the 2-meter-resolution DEMs obtained from multiple satellite passes over regions.
This allows for a comparison of topography over time in the rapidly changing Arctic region, including changes in glaciers and permafrost, he said.
The difference between the 5- and 2-meter-resolution products is “the difference between a map and a time series of measurements,” he said.
Morin added that the 5-meter-resolution product is beneficial for providing a view of an entire watershed or other large region, whereas the time-stamped 2-meter-resolution product is more useful for studies of smaller areas over time.

  Scientists are using data of the Lena Delta at the end of a remote river in Siberia

to study river systems that are otherwise inaccessible.
see on ArcticDEM explorer

“Probably the biggest leap forward here for science is that we’ve proven that topography can be produced continuously,” Morin said.
This means that whenever the Sun is at least 7° above the horizon, satellites are gathering stereo imagery that then gets processed and released in short order, he explained. Every year, about 75% of the entire Arctic gets reimaged, he said.
For some high-priority areas, such as outlet glaciers in Greenland, the reimaging happens more frequently.
Satellites collect each stereo image as a pair of mono images taken at specific, known angles.

Previous DEM production projects were “one-offs,” Morin noted.
A large mapping effort would produce a DEM of a region like Alaska with the intention of not repeating the mapping for an extended period of time, he noted.

Ragnar Heidar Thrastarson, geographic information system coordinator for the Icelandic Meteorological Office, said, “Previously, we thought of DEMs as a fixed spatial entity that needed to be collected once and then maybe again in 20 years or so. But there are a lot of natural phenomena that change faster than that,” he told Eos.

The new temporal aspect of ArcticDEM “is a huge benefit” for modeling those and following changes in glaciated areas, he said.

A time series (left to right) of images of the West Branch of the Columbia Glacier in Alaska, showing the glacier’s retreat from 2010 to 2015.

Credit: Paul Morin, PGC

Public-Private Partnership

The U.S. National Geospatial-Intelligence Agency (NGA) and the National Science Foundation (NSF) have supported the initiative, which grew out of a January 2015 executive order from then president Barack Obama. The four satellites used for collecting imagery—Worldview-1, -2, and -3 as well as GeoEye-1—are all owned by DigitalGlobe and licensed by NGA, which provides the imagery for the initiative.

NSF is providing $2.5 million through its Directorate for Geosciences. In addition, the NSF-funded Blue Waters petascale supercomputer at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign processes the stereo imagery into elevation models. The products, which are produced on a supercomputer, are distributed through arcticdem.org and are also available through Amazon Web Services.

The project also has involved other academic partners and Esri, a mapping company based in Redlands, Calif., that developed an online application, ArcticDEM Explorer, to analyze data.

Visible as a darker gray region in the center of this image made from ArcticDEM, the remote Siberian city of Yakutsk stretches between wilderness (green, yellow, and orange areas to the left) and the Lena River (blue) in northern Russia.

Credit: Paul Morin, PGC

An Important Tool for Arctic Science and Modeling Hazards

Scientists and environmental managers told Eos that ArcticDEM is an important tool for Arctic science and other applications.
“It’s a tremendous baseline of information for basic research related to land surface processes,” said Scott Borg, acting deputy assistant director for geosciences at NSF.

Eric Rignot of the University of California, Irvine, and NASA’s Jet Propulsion Laboratory in Pasadena, Calif., told Eos that he will use ArcticDEM to process ice velocity on glaciers and ice sheets and said it will also help clarify drainage boundaries between glaciers.
It “will finally provide a useful reference in time from which we can measure changes in ice volume,” he said.

The Asiaq Greenland Survey used ArcticDEM to make a detailed topographic map and a tsunami model after an 18 June landslide and tsunami at Karrat Fjord.
One motivation was “to look for other areas in the same region that could fail in the same way,” Morin said.

“Earth science is about change,” he noted.
“The surface is key to the past, and being able to measure changes in the surface is going to enable all different kinds of science, from coastal erosion and landslides, to forest management and civil engineering. Because we now have created a baseline for topography for about 10% of the land surface of the Earth, measurements in the future of topography can be measured against this data set.”

Links :

• NGA :  NGA completes Arctic DEM project, producing elevation model maps of entire Arctic / NGA Arctic website
• UMN : ArcticDEM / news

Astrolabe: Shipwreck find 'earliest navigation tool'

The instrument was once used by mariners to measure the altitude of the Sun during their voyages

photo : Philip Koch

From BBC by Rebecca Morelle

An artefact excavated from a shipwreck off the coast of Oman has been found to be the oldest known example of a type of navigational tool.

Ghubbat ar Rahib bay where the wreck is being excavated

with the GeoGarage platform (UKHO chart)

This copper-alloy disc, bearing the Royal coat of arms and the armillary sphere of Dom Manuel I is an important object although its precise identity & function is still unknown.
It does have features suggesting it could be an astrolabe, or part thereof. 
The item was found in 2014 in a shipwreck in the Indian Ocean as one of nearly 3,000 objects recovered from the wreck, but it had no visible signs of navigational markings - until now.Esmeralda Shipwreck - The Official Vasco da Gama Expedition

Marine archaeologists say the object is an astrolabe, an instrument once used by mariners to measure the altitude of the Sun during their voyages.

It is believed to date from between 1495 and 1500.
The item was recovered from a Portuguese explorer which sank during a storm in the Indian Ocean in 1503.
The boat was called the Esmeralda and was part of a fleet led by Portuguese explorer Vasco da Gama, the first person to sail directly from Europe to India.

Using an astrolabe

David Mearns, from Blue Water Recovery, who led the excavation and is the author of The Shipwreck Hunter, told the BBC: "It's a great privilege to find something so rare, something so historically important, something that will be studied by the archaeological community and fills in a gap."

The astrolabe was discovered by Mr Mearns in 2014, and was one of nearly 3,000 artefacts recovered during a series of dives.
The bronze disc measures 17.5cm in diameter and is less than 2mm thick.
"It was like nothing else we had seen and I immediately knew it was something very important because you could see it had these two emblems on it," said Mr Mearns.
"One I recognised immediately as a Portuguese coat of arms... and another which we later discovered was the personal emblem of Don Manuel I, the King of Portugal at the time."

The excavation team believed the object was an astrolabe, but they could not see any navigational markings on it.

However, a later analysis uncovered its hidden details.
Laser scanning work carried out by scientists at the University of Warwick revealed etches around the edge of the disc, each separated by five degrees.

The University of Warwick used laser scans to uncover etches on the astrolabe,
which helped navigators work out the height of the sun

This would have allowed mariners to measure the height of the sun above the horizon at noon to determine their location so they could find their way on the high seas.
Mariners' astrolabes are relatively rare, and this is only the 108th to be confirmed catalogued. It is also the earliest known example by several decades.

Mr Mearns said: "We know it had to have been made before 1502, because that's when the ship left Lisbon and Dom Manuel didn't become King until 1495, and this astrolabe wouldn't have carried the emblem of the King unless he was King.
"I believe it's probably fair to say it dates roughly to between 1495 to 1500. Exactly what year we don't know - but it is in that narrow period."
He added: "It rolls back this history by at least 30 years - it adds to evolution, it adds to the history, and hopefully astrolabes from this period can be found."

Links :

• NPR : Left By Explorer's Armada, Shipwreck Yields 'Earliest Known' Marine Astrolabe
• DailyMail : 'Earliest known marine navigation tool' is uncovered on the shipwrecked Esmeralda that sank off the Oman coast during a violent storm 500 years ago
• National Geographic : Rare Solar Navigation Tool Found in Ancient Shipwreck
• GeoGarage blog : The great explorers of Islam

Ocean acidification is deadly threat to marine life, finds eight-year study

Scientists haul in samples of seawater in Svalbard, Norway.

Greenpeace is working with the German marine research institute to investigate ocean acidification.

Photograph: Nick Cobbing/Greenpeace

From The Guardian by Fiona Harvey

Plastic pollution, overfishing, global warming and increased acidification from burning fossil fuels means oceans are increasingly hostile to marine life

If the outlook for marine life was already looking bleak – torrents of plastic that can suffocate and starve fish, overfishing, diverse forms of human pollution that create dead zones, the effects of global warming which is bleaching coral reefs and threatening coldwater species – another threat is quietly adding to the toxic soup.

Ocean acidification is progressing rapidly around the world, new research has found, and its combination with the other threats to marine life is proving deadly.
Many organisms that could withstand a certain amount of acidification are at risk of losing this adaptive ability owing to pollution from plastics, and the extra stress from global warming.

 Satellite animation of ocean salinity made using one of the same satellites

used to create the new estimates of ocean acidification.

Credit: ESA

The conclusions come from an eight-year study into the effects of ocean acidification which found our increasingly acid seas – a byproduct of burning fossil fuels – are becoming more hostile to vital marine life.

“Since ocean acidification happens extremely fast compared to natural processes, only organisms with short generation times, such as micro-organisms, are able to keep up,” the authors of the study Exploring Ocean Change: Biological Impacts of Ocean Acidification found.

Marine life such as crustaceans and organisms that create calcified shelters for themselves in the oceans were thought to be most at risk, because acid seas would hinder them forming shells. However, the research shows that while these are in danger, perhaps surprisingly, some – such as barnacles – are often unaffected, while the damage from acidification is also felt much higher up the food chain, into big food fish species.

An unhealthy pteropod shows the effects of ocean acidification, including dissolving shell ridges on its upper surface, a cloudy shell, and severe abrasions.

Photograph: Courtesy of NOAA

Ocean acidification can reduce the survival prospects of some species early in their lives, with knock-on effects.
For instance, the scientists found that by the end of the century, the size of Atlantic cod in the Baltic and Barents Sea might be reduced to only a quarter of the size they are today, because of acidification.

Peter Thomson, UN ambassador for the oceans and a diplomat from Fiji, which is hosting this year’s UN climate change conference in Bonn, urged people to think of the oceans in the same terms as they do the climate.
“We are all aware of climate change, but we need to talk more about ocean change, and the effects of acidification, warming, plastic pollution, dead zones and so on,” he said.
“The world must know that we have a plan to save the ocean. What is required over the next three years is concerted action.”

credit : WHOI

 

The eight-year study was carried out by the Biological Impacts of Ocean Acidification group (known as Bioacid), a German network of researchers, with the support of the German government, and involved more than 250 scientists investigating how marine life is responding to acidification, and examining research from around the world.
The study was initiated well before governments signed a global agreement on climate change at Paris in 2015, and highlights how the Paris agreement to hold warming to no more than 2C may not be enough to prevent further acidification of the world’s seas.

Governments will meet in Bonn in November to discuss the next steps on the road to fulfilling the requirements of the Paris agreement, and the researchers are hoping to persuade attendees to take action on ocean acidification as well.

courtesy of NOAA

Ocean acidification is another effect of pouring carbon dioxide into the atmosphere, as the gas dissolves in seawater to produce weak carbonic acid.
Since the industrial revolution, the average pH of the ocean has been found to have fallen from 8.2 to 8.1, which may seem small but corresponds to an increase in acidity of about 26%.
Measures to reduce the amount of carbon dioxide reaching the atmosphere can help to slow down this process, but only measures that actively remove carbon already in the atmosphere will halt it, because of the huge stock of carbon already in the air from the burning of fossil fuels.

Worse still, the effects of acidification can intensify the effects of global warming, in a dangerous feedback loop.
The researchers pointed to a form of planktonic alga known as Emiliania huxleyi, which in laboratory experiments was able to adapt to some extent to counter the negative effects acidification had upon it.
But in a field experiment, the results were quite different as the extra stresses present at sea meant it was not able to form the extensive blooms it naturally develops.
As these blooms help to transport carbon dioxide from the surface to the deep ocean, and produce the gas dimethyl sulfide that can help suppress global warming, a downturn in this species “will therefore severely feed back on the climate system”.

Links :

• The Guardian : Deep sea life faces dark future due to warming and food shortage / Finding Nemo? We may be losing him, says climate study 
• BBC : More acidic oceans 'will affect all sea life
• News Deeply : What Scientists Are Learning About the Impact of an Acidifying Ocean
• Climate Central : Ocean Acidification, Now Watchable in Real Time 
• GeoGarage blog : Satellite images to monitor ocean acidification in remote ... / 'The other CO2 problem': How acidic oceans will ... / Study: our oceans are so acidic they're dissolving ... / An acid test for policy / Ocean acidification : the other CO2 issue