Unruly Antarctica could change sea-level outlook without much warning

Researchers from several institutions, including Rutgers University, Princeton and Harvard, worked with Climate Central to create an interactive map which illustrates sea level projections in cities across the globe.

The map provides projections that both include and exclude the new Antarctic research.
Local rises would vary from region to region under the same scenario and would exceed the global average for all US Gulf and Atlantic coast locations, according to the report.
The study ‘Evolving Understanding of Antarctic Ice-Sheet Physics and Ambiguity in Probabilistic Sea-Level Projections’ is the first to integrate Antarctic models into sea-level projections.

From Ars Technica by Scott K. Johnson

These sea-level rise scenarios aren’t new, but they are food for thought. 

Sea-level rise is one of the more challenging effects of climate change to project.

It’s not that the direction of the change is unclear—sea level will rise as the planet warms—but it’s extraordinarily difficult to know when which sections of which glaciers will slide into the sea.

Many factors are involved besides temperatures, including ocean currents and the topography of the bedrock below ice sheets.

The flow of glaciers into the sea has accelerated in this vulnerable area of the West Antarctic Ice Sheet along the Amundsen Sea.

As a result, the projections of sea-level rise presented to entities like the Intergovernmental Panel on Climate Change (IPCC) have been heavily caveated and have changed significantly over time.
The 2013 IPCC report, for example, projected considerably higher sea-level rise than the 2007 report, which explained that it was leaving out important ice-sheet processes that needed more research.
And the recent 2017 US National Climate Assessment again increased projections of sea-level rise based on the current state of the science.

A new study from a group of researchers led by Rutgers’ Bob Kopp has made for splashy headlines in recent days, some of which claimed the study showed that sea-level rise will be “worse than thought” or that the study confidently predicted how many people would be inundated by rising seas this century.
Neither description is really true, as there is nothing new about the sea-level rise scenarios shown.
In fact, Kopp also helped put together the sea-level chapter of the US National Climate Assessment, and the numbers in the new study obviously match those in the report.

That doesn’t mean the study from Kopp et al. isn’t notable and interesting.
It relates to something the scientific community has been wrestling with for the last couple of years—a pair of studies using an improved ice-sheet model that simulated much faster ice loss from the vulnerable West Antarctic Ice Sheet.
While this simulation was more compatible with recent research in Antarctica, it’s not easy to fold the model’s alarming first results—which are not the final word—into the existing outlook.

Partly because ice-sheet models have not reached the point where researchers feel they accurately represent everything we know, several past efforts have produced a hybrid sort of projection incorporating detailed surveys of experts in the field.
This new study takes a hybrid projection like that from 2014 and replaces the Antarctic ice-loss estimates with the alarming model simulations to find out what the implications would be.
The answers are more interesting (and wonky) than “sea-level rise goes higher.”
But yes, the new study definitely does increase the estimated future sea-level rise.

The top two graphs show sea-level projections for three emissions scenarios from a 2014 study.

The bottom two graphs update those projections with recent model simulations of vulnerable Antarctic glaciers.

In the high greenhouse-gas emissions scenario, the 2014 projection estimated about 0.5 to 1.25 meters of sea-level rise by 2100, whereas this new version shows 0.9 to almost 2.5 meters.
(For reference, the 2013 IPCC report projected about 0.5 to 1 meter, and the new 2017 US National Climate Assessment put it in the neighborhood of 1 to 2.5 meters using a different scenario scheme.)

Once you move past 2100, the scenarios diverge in a big way. By 2300, the difference in sea level between the low and high emissions scenarios grows to more than 10 meters.
Once ice sheets become destabilized, they keep raising sea levels for a long, long time—our actions this century can shape the world for many centuries to come.

Beyond that, here’s what the study really reveals: in this century, the biggest variable controlling how much sea-level rise we get is the behavior of Antarctic ice.
We don’t know whether to expect the high end or the low end of the range of projections, even assuming we follow the high emissions path.

And because the situation can change in Antarctica in a matter of decades, we can’t really know what will happen in the second half of the 21st century based on what we see in the first half.
The model simulations with the highest rate of sea-level rise in 2100 weren’t necessarily those with the highest rate in the 2020s.
The lesson, the researchers write, is that “this means that ‘extreme’ future scenarios need to be considered even if they overestimate current rates of sea-level rise.”

Again, the researchers emphasize that these model simulations of higher sea-level rise provide a realistic “worst-case scenario” more than they predict the most likely outcome.
But because the real possibility of a worst-case scenario isn’t likely to be ruled out any time soon, planning should account for an uncertain future.

To add some more meaning to these numbers, the researchers calculated the present population living in areas that could become inundated by sea-level rise in 2100.
Even in the lowest emissions scenario (where global warming is limited to about 1 degree Celsius beyond current temperatures), that includes at least 75 million people worldwide.
In the high emissions scenario, the “worst-case” pushes that number as high as 235 million.
The difference between these two future worlds is far from academic.

Links :

• ArsTechnica (2016) : New model shows Antarctica alone could raise sea level a meter by 2100
• Eco Watch : New Research Confirms 'Catastrophic' Climate Threat: Global Sea Levels could rise 174 feet from melting East Antarctic Ice sheet 
• National Geographic : East Antarctic Ice Has a Wild Past. It May Be a Harbinger
• DailyMail : Climate change activists used 'arbitrary' adjustments to exaggerate sea level rise, scientists claim
• Wired : Sea Level Rise Will Imperil Humanity's Future and Its Past
• GeoGarage blog : Antarctica's warm underbelly revealed / Scientists warn of 'giant leap backward' at climate talks /From Miami to Shanghai : 3C of warming will leave world cities below sea level /New Greenland maps show more glaciers at risk /New science suggests the ocean could rise more — and faster — than we thought /Greenland’s coasts are growing as seas rise /

 

Nautical maps no safeguard against subsea cable breakages

Submarine cable on a UKHO map in Cape Town (Marine GeoGarage)

From WebAfrica

International maritime law and nautical maps have failed to prevent instances of ship captains dropping anchors on key undersea broadband cables.

This is according to Didier Mainguy (pictured), who is chief mission for Cape Town docked cable repair ship CS Leon Thevenin.
The CS Leon Thevenin consists of a sixty‐man team and is on standby in Cape Town to respond to broadband subsea cable damage along African shores.
The ship, in turn, is owned by a subsidiary of French telecoms giant Orange.
Mainguy has told ITWeb Africa that his ship conducts up to three major subsea cable repairs per year, with the latest being a fix on an undersea network at Mtunzini, near Durban, South Africa.
Cable cuts by ship anchors, such as those on the South East Asia-Middle East-Western Europe 4 (SEA-ME-WE 4) cable near Egypt last year, have proven to be highly disruptive for internet services in Africa, resulting in little to no online access in affected areas.

TeleGeography cable map

But the problem is exacerbated by ship captains who either deliberately, or accidentally, fail to follow international maritime laws stipulating that vessels must take note of nautical charts, which are regularly updated with the position of all submarine cables.
The likes of the ‘United Nations Convention on the Law of the Sea’ requires that seafarers avoid conduct likely to damage cables or pipes. Meanwhile, several countries have national legislation to regulate their territorial waters.
“We are not living in a perfect world where 100% of driving licence holders stop at the red traffic light. It’s unfortunate but that’s the way it is,” Mainguy told ITWeb Africa.
“At sea it is the same, not 100% of the masters ticket holders, or ship captains, always comply with the laws,” Mainguy said.
Mainguy explained to ITWeb Africa that there have been instances of trawlers intentionally fishing “very close to the cables and pipes” because there are more fish around those vicinities.
These ships have then dropped their anchors dangerously close to the cables.
Cables, particularly in shallow waters, are also placed within a “protection zone” where activities harmful to this infrastructure is typically banned, Mainguy told ITWeb Africa.
Meanwhile, Mainguy said there have been other instances of ship captains who drop their anchors at a “safe distance from the cable but strong winds come or stormy weather, and the anchor is dragged onto the seafloor towards the cable.”
In other emergency cases, such as engine failure, the only option to save a vessel and the crew is to drop an anchor to stop the ship drifting towards shore, Mainguy said.



Overall; though, the dropping of anchors on subsea broadband cables is among the biggest cause of damage to this infrastructure.
Mainguy told ITWeb Africa that other causes of cable damage include fishing activity, climatic events such as tropical storms or cyclones, submarine tectonic or volcanic activity, strong currents and even shark bites.
More measures needed to halt damage
Cost of repairs for subsea cable damages range from $500,000 to $3 million per repair, excluding the price of alternative solutions that may need to be purchased by subsea cable operators, according to Byron Clatterbuck, chief commercial officer for pan-African broadband company SEACOM.
Clatterbuck further told ITWeb Africa that information regarding the position of subsea cables “is often not widely and actively communicated to relevant shipping and fishing organisations” for various reasons.
Clatterbuck noted that more clear and comprehensive communication regarding the position of these cables then is key to preventing this problem.
But he added that another key solution to mitigating the problem of cable cuts by anchors is the actual positioning of the cables along the seabed.
SEACOM itself operates a 17,000 km subsea network connecting Africa to Europe and Asia.
“The first and most important way to prevent ship anchors from dragging up and damaging subsea cables is for the cables to be laid in areas where there is little shipping activity or at least little chance of anchoring activity,” Clatterbuck told ITWeb Africa.
“Although this is an important element, it is unfortunately not always practical or possible to take it into consideration when choosing the subsea cable route,” he said.

 Telegraph and cable lines (1914)

Other solutions could be more costly as well, according to Clatterbuck.
“Most subsea cables are buried deeply close to the shore end or are housed in rock trenches to protect them from inadvertent damage. While this can be done in greater depths and increase distance between the cable and the shore end, it is a more costly procedure and is not always a guarantee of security.
“In some cases the seabed is shallow and it is not possible for a subsea cable to be buried deeply for many kilometers from shore and many sea anchors, particularly from large ships, can drag up a subsea cable even if it is deeply buried in a soft seabed,” Clatterbuck told ITWeb Africa.

courtesy of GeoData

Are African nations taking subsea cable protection seriously?
African nations such as South Africa and Nigeria have companies such as Telkom and Main One that are members of the International Cable Protection Committee (ICPC).
The ICPC looks to enforce protection of all subsea cables, but, in particular, emphasis has been placed on broadband infrastructure owing to the global economy’s increased dependence on telecommunications technology.
“Most African countries understand the importance of reliable subsea cable infrastructure to the economic development of the continent, and are aware of the importance of protecting them from accidental damage,” Clatterbuck told ITWeb Africa.

Undersea cable repairing

But Clatterbuck added that more could be done to safeguard subsea cables along African shores.
In particular, he said stiff penalties for ship operators are key to curbing the problem.
ITWeb Africa reported earlier this year that representatives of a ship that damaged two submarine internet cables near Egypt in March 2013 had to pay $12.535 million in damages.
Telecom Egypt inked a settlement with lawyers representing the ‘B-Elephant’ tanker ship that damaged and cut two submarine cables, Europe India Gateway (EIG) and Telecom Egypt (TE) North, last March.
The ship’s anchor dragged through the cables on 22 March 2013, resulting in widespread internet disruptions.
“It is a positive thing to see ships -- and the companies or organisations that manage them -- being penalised for ignoring maritime laws and regulations and damaging subsea cables.
“This tends to help educate other ship captains about the importance of abiding by these regulations to avoid damaging these vital economic assets,” Clatterbuck said.

Links :

• BBC : Russia a 'risk' to undersea cables, defence chief warns / Ship's anchor severs Jersey's undersea internet cables
• Hydro : Subsea Cable Route Surveying
• GeoGarage blog : Undersea cables are actually more vulnerable than you might think / Here’s how the Internet’s arteries travel across the world's oceans in 2014

François Gabart smashes new record for solo sailing around the world

For his first attempt, François Gabart the skipper of trimaran MACIF set a new solo round the world record in 42 days 16 hours 40 minutes and 35 seconds, he improved by 6 days 10 hours 23 minutes and 53 seconds the time set on 25 December 2016 by Thomas Coville (49 days 3 hours 4 minutes 4 minutes 28 seconds).

His time is the second best overall, crew and solo sailor in the round the world race, with only IDEC Sport (Francis Joyon) having done better on 26 January 2017 on the Trophée Jules-Verne (40 days 23 hours 30 minutes and 30 seconds).

Ultim moments

François Gabart left Ouessant at 10:05 a. m. on Saturday, November 4 and crossed the finish line for his solo round-the-world race between Cap Lizard and Ouessant at 2:45 a. m. (French time) on Sunday, December 17.
The MACIF trimaran will have actually covered 27,859.7 miles, her actual average on this course is 27.2 knots.

 Evolution of a record :
French sailor Francois Gabart has taken just 42 days to circumnavigate the globe single-handed non stop.
How sailing has developed in the last 50 year.
The first person to do it, Sir Robin Knox-Johnston, took 313 days in 1969
and in 1988 Philippe Monnet more of 129 days.

At some Nm of the arrival

 First contact with sailing for François on an Optimist in the 90's (with the same sponsor)

Links :

• GeoGarage blog : Joyon completes round-the-world boat race in record 40 days / Man on the moon : Thomas Coville slashes solo yachting round the world record

Tides breathing



Tides from Dunkerque to Saint Jean de Luz from December 14 to December 20, 2017

Clocks indicate the time and height of water.

The high and low seas follow one another on the Atlantic, Channel and North Sea coasts.
 -see other video -
courtesy of maree.info (see iOS mobile app)

Breathing with the tides 

Links :

• GeoGarage blog : A breathing Earth / High tide in Saint Malo / Saint Malo Live webcam / 'Tides of the century' in France / The science of tides / Sea change: a tidal journey around Britain - interactive /Ancient tides different from today : some dramatically ... / Big spring tide extremes in time-lapse

Down the Drain: How 'Pulling the Plug' on Earth's oceans would look

A simulation of draining the world's oceans by pulling a hypothetical "plug" in the Marianas Trench, inspired by the work of Randall Munroe of XKCD
Other oceans aren't necessarily deeper than the Pacific, they just get landlocked and stop draining
Many lakes will likely stick around since they are fed from rivers and direct rainfall.
The continents drift, but not that much, over this time span.
The plug is 10m in diameter (that's metres, for the Americans).
No, there's not actually a plug...

From LiveScience by Mindy Weisberger

What might it look like if you "pulled the plug" in the Mariana Trench — the planet's deepest spot — and drained the water from all the oceans in the world?

A recent time-lapse video portrays that speculative scenario using real data, shown in an animation by Ryan Brideau, a masters candidate in geospatial visualization and analysis at the University of New Brunswick in Canada.

In the animation, posted to Reddit, a flat map of Earth reveals coastlines expanding and land bridges appearing between continents and former islands as the seas shrink. Meanwhile, islands and land masses emerge from the oceans as the water drains away, over a period of nearly 3 million years.

Drainage in the Pacific Ocean where the trench is located continues to the end of the animation — which lasts about 30 seconds — while other large bodies of water quickly become landlocked and cease to drain at all, Brideau wrote on Reddit.

 Drain the Oceans by Randall Munroe

He explained that he first encountered the idea of an imaginary giant "plug" in the deepest part of the ocean — and what might happen if that plug were removed — in the book "What If? Serious Scientific Answers to Absurd Hypothetical Questions" (Houghton Mifflin Harcourt, 2014) by Randall Munroe, the writer and illustrator behind the exquisitely nerdy (and humorous) science comic xkcd.

Munroe, who also wrote about the intriguing question in a blog post, envisioned a plug measuring about 33 feet (10 meters) in diameter, with the water somehow vanishing at the drainage point and materializing on Mars (in case you were wondering where all that liquid would end up).
He estimated in the post that it would take hundreds of thousands of years for significant drainage to happen, with sea levels dropping at "less than a centimeter a day," he wrote.

Brideau was intrigued by the challenge of re-creating an animated version of the model that Munroe used for that scenario, the researcher told Live Science in an email.
He located a visualization of draining oceans created by NASA scientists in 2008, but those researchers took "a major shortcut" by not factoring in the connections between oceans, Brideau explained.
"That makes a big difference in terms of difficulty, and I wanted to see how close I could get to Randall's result myself," Brideau said in the email.

In this draining scenario, California surfers would have to travel a lot farther to catch those gnarly waves.

Credit: Ryan Brideau

Creating a visualization like this requires high-resolution elevation maps of land structures above and below sea level, along with location data for all the major water bodies on Earth, Brideau explained.
"These need to be in 'raster' form, which is simply an image, but instead of each pixel recording color, they record elevation or the presence/absence of water," he said.
The model then estimated drainage in the oceans, adjusting for changes in connections between bodies of water as they become isolated by emerging seafloor structures and cease to drain, Brideau explained.

"The hard part is calculating the remaining water at each iteration," he said.
"You have to figure out which areas of water in the previous step were 'drainable' and subtract them from the remaining water, but leave the water bodies that were untouched in place. You also have to subtract any landforms that have started sticking out of the water.
"The big variable that I didn't take into account is the weather, which might cause some water bodies to start to dry out if their primary source of incoming water is currently the ocean," Brideau told Live Science.
"But in reality, the weather would also be changing, so it's hard to predict," he said.

His model visualized dramatic changes to the continental coastlines in the first 200,000 years.
Toward the end of the animation — nearly 3 million years after the plug was pulled — only the Pacific Ocean is still flowing into the drainage hole in the trench.
At this point, every frame in the animation represents a drop in ocean depths of about 33 feet (10 m) Brideau wrote on Reddit.
"I think the visualization is captivating because it plays out a doomsday scenario at a massive scale, and yet is still relatable. Everyone has drained a bathtub and knows how long that takes, and so it's fun to think of doing that for something the size of the ocean," he told Live Science in an email.
"I distinctly remember as a kid my brother and I pulling on a rope at the beach that we were convinced was connected to a giant plug at the bottom. It's just a fun thing to think about," Brideau said.