Welcome Guest [Log In] [Register]
Welcome to Natural Hazards Forum. We hope you enjoy your visit.


You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free.


Join our community!


If you're already a member please log in to your account to access all of our features:

Username:   Password:
Add Reply
Sea level rise
Topic Started: 14 Jan 2018, 01:28 AM (125 Views)
skibboy
Member Avatar

13 January 2018

Sea levels off Dutch coast highest ever recorded in 2017

Posted Image
© ANP/AFP | Sea and water levels are carefully watched in the Netherlands, as much of the country lies below sea-level and is protected by a series of flood defences

THE HAGUE (AFP) - Storm surges and tidal cycles caused record sea levels along the coast of the Netherlands last year, a Dutch marine institute has found.

"The level has been rising gradually since 1890 by about 0.2 cm per year due to the melting of the ice and the warming up of the ocean," expert Fedor Baart, of the research organisation Deltares, said in a statement Friday.

"That means that, as a rule, you expect the sea level to be higher every year."

Sea and water levels are carefully watched in the Netherlands, as much of the country lies below sea-level and is protected from flooding by a series of defences such as dykes, sand dunes, windmills to pump away water and sophisticated barrages.

In 2017, the institute measured the average sea levels along the Dutch coast to be 11 centimetres (over four inches) higher than normal water levels in Amsterdam, a gauge known as the NAP.

The previous highest reading was in 2007 when the water was nine centimetres above the NAP.

The institute said in 2017 "there were several storm surges in a single year for the first time since 2007," which had contributed to the high water levels.

Bad storms can temporarily push water levels up by a meter, which accounts for an average rise of about one centimetre, Baart explained.

The institute also highlighted that every 18.6 years the seas rise and fall by two centimetres on a tidal cycle.

"The last peak was in 2004, and the level is now rising again to the next peak in early 2023," Deltares said in a statement.

It stressed however that "the Dutch coast can cope with extreme water levels" and said "the sea level on the Dutch coast is rising by 20 centimetres every century".

Dutch water defences were completely overhauled and improved after devastating floods in 1953 which left 1,800 people dead.

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
skibboy
Member Avatar

12 February 2018

Sea level rise is accelerating: study

Posted Image
© GETTY IMAGES NORTH AMERICA/AFP/File | Sea ice is viewed aboard NASA's research aircraft in the Antarctic Peninsula region, on November 3, 2017

MIAMI (AFP) - Sea level rise is accelerating and could reach 26 inches (66 centimeters) by century's end, in line with United Nations estimates and enough to cause significant problems for coastal cities, a study said Monday.

The past annual rate of sea level rise -- about three millimeters (0.1 inches) per year -- may more than triple to 10 millimeters per year by 2100, said the report in the Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed US journal.

The findings are "roughly in agreement with the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5) model projections," said the report, based on 25 years of satellite data.

"This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate -- to more than 60 centimeters instead of about 30," said study author Steve Nerem.

"And this is almost certainly a conservative estimate," added Nerem, a professor of aerospace engineering sciences at the University of Colorado Boulder.

Co-authors on the study came from the University of South Florida, NASA Goddard Space Flight Center, Old Dominion University and the National Center for Atmospheric Research.

Climate change leads to rising seas in two ways.

For one, higher concentrations of greenhouse gases in the atmosphere boost the temperature of water and warm water expands.

This so-called "thermal expansion" of the oceans has already contributed about half of the seven centimeters of average global sea level rise in the past quarter century, Nerem said.

Oceans also rise with the increasing flow of water due to rapidly melting ice at the poles.

"This study highlights the important role that can be played by satellite records in validating climate model projections," said co-author John Fasullo, a climate scientist at the National Center for Atmospheric Research.

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
skibboy
Member Avatar

20 February 2018

Coming decades vital for future sea level rise: study

PARIS (AFP) - How quickly humanity draws down the greenhouse gases driving global warming will determine whether sea levels rise half-a-metre or six times that, even if Paris climate pact goals are fully met, researchers reported Tuesday in a study.

"The trajectory of emissions in the next few decades will shape our coastlines in the centuries to come," lead author Matthias Mengel, a scientist at the Potsdam Institute for Climate Impact Research in Germany, told AFP.

Every five years that elapse before carbon pollution peaks will add 20 centimetres to sea level rise in 2300, the study found.

"This is the same amount we have experienced so far since the beginning of the fossil fuel economy," Mengel said by email.

The world collectively spews about 40 billion tonnes of CO2 into the atmosphere every year.

After stalling for three years, emissions rose by two percent in 2017, dashing hopes they had peaked.

On current trends, emissions could increase for at least another decade.

The 197-nation Paris Agreement calls for capping global warming at "well below" two degrees Celsius (3.6 degrees Fahrenheit), and pursuing efforts to hold the line at 1.5 C.

Average global temperatures have already gone up by 1 C since the industrial revolution began.

The treaty also sets a less talked about but equally crucial goal: ensuring that, by the end of this century, our species stops adding CO2 to the atmosphere, a threshold known as "net zero emissions".

Mengel and colleagues asked a deceptively simple question: by how much will the world's oceans rise over the next two centuries if both these targets are achieved?

The most likely outcome, they found, was an increase of 70 to 120 centimetres (27.5 to 47 inches) by 2300, depending on when CO2 pollution peaks, how quickly it drops, and the date net zero emissions is achieved.

That's probably enough to doom some low-lying island states and wreak havoc in the populated mega-deltas of Bangladesh, Vietnam, India and Egypt, but would at least leave more time to adapt.

- Redrawing coastlines -

Currently, some 100 million people live within a metre (three feet) of the high-tide level, leaving them vulnerable not only to sea level rise but evermore powerful storm surges.

The study also showed, however, that fulfilling the Paris mandate does not necessarily avert catastrophic change.

If carbon emissions don't peak until 2035 and CO2 continues to leech into the atmosphere until 2090, for example, the ocean watermark could go up three metres by 2300, rendering continental coastlines unrecognisable.

And if the Paris temperature goal is not met, there is a small chance oceans would rise five metres.

The biggest wild card in predicting future sea levels is the Antarctic ice sheet, which contains enough frozen water to lift oceans several dozen metres.

Its western peninsula is especially sensitive to climate change.

"Large ice loss seems possible even under modest warming in line with the Paris agreement," said Mengel. "A sea level rise of up to three meters by 2300 cannot be ruled out."

Ocean uplift is also driven by the expansion of water as it warms, and runoff from melting glaciers.

Earth's atmosphere responds far more quickly to cuts in greenhouse gas emissions than oceans.

Indeed, scientists estimate that there is at least half-a-metre of "committed" sea level rise already in the pipeline, perhaps more.

"Even if we stop emitting today, the effects of our past emissions will be felt for centuries to come," said Pete Strutton, an oceanographer at the University of Tasmania.

"Every year that we delay action has consequences for the future."

Matthias Mengel acknowledged that the best-case projections in the study are "really optimistic".

Despite voluntary, carbon-cutting pledges by virtually all the world's nations, global temperatures are on track to rise 3 C above pre-industrial levels by 2100.

"In the end, the Paris Agreement will not be evaluated on what it promised or aspires to do, but on the change it managed to catalyse and the emissions reductions achieved in the real world," said co-author Joeri Rogelj, a climate modeller at the International Institute for Applied Systems Analysis in Austria.

by Marlowe HOOD

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
skibboy
Member Avatar

NASA Study Clarifies Antarctic Ice-Sheet Motion

Posted Image
The flow of Antarctic ice, derived from feature tracking of Landsat imagery. Credit: NASA Earth Observatory

2018-02-21

A NASA study has provided the clearest picture yet of changes in Antarctic ice flow into the ocean.

The findings uses satellite data to confirm accelerating ice losses from the West Antarctic Ice Sheet and also reveal surprisingly steady rates of flow from its much larger neighbor to the east.

The computer-vision technique used data from hundreds of thousands of NASA-U.S. Geological Survey Landsat satellite images to produce a high-precision picture of changes in ice-sheet motion.

The new work provides a baseline for future measurement of Antarctic ice changes and can be used to validate numerical ice sheet models that are necessary to make projections of sea level.

It also opens the door to faster processing of massive amounts of data.

“We’re entering a new age,” said the study’s lead author, Alex Gardner of NASA’s Jet Propulsion Laboratory in Pasadena, California.
“When I began working on this project three years ago, there was a single map of ice sheet flow that was made using data collected over 10 years, and it was revolutionary when it was published back in 2011. Now we can map ice flow over nearly the entire continent, every year. With these new data, we can begin to unravel the mechanisms by which the ice flow is speeding up or slowing down in response to changing environmental conditions.”

The approach taken by Gardner and his team largely confirms earlier findings, though with a few unexpected twists.

Among the most significant: a previously unmeasured acceleration of glacier flow into Antarctica’s Getz Ice Shelf, on the southwestern part of the continent - likely a result of ice-shelf thinning.

The research, published in the journal The Cryosphere, also identified the fastest speed-up of Antarctic glaciers during the seven-year study period.

The glaciers feeding Marguerite Bay, on the western Antarctic Peninsula, increased their rate of flow by 1,300 to 2,600 feet (400 to 800 meters) per year, probably in response to ocean warming.

Perhaps the research team’s biggest discovery, however, was the steady flow of the East Antarctic Ice Sheet.

During the study period, from 2008 to 2015, the sheet had essentially no change in its rate of ice discharge - ice flow into the ocean. While previous research inferred a high level of stability for the ice sheet based on measurements of volume and gravitational change, the lack of any significant change in ice discharge had never been measured directly.

The study also confirmed that the flow of West Antarctica’s Thwaites and Pine Island glaciers into the ocean continues to accelerate, though the rate of acceleration is slowing.

In all, the study found an overall ice discharge for the Antarctic continent of 1,929 gigatons per year in 2015, with an uncertainty of plus or minus 40 gigatons.

That represents an increase of 36 gigatons per year, plus or minus 15, since 2008.

A gigaton is one billion tons.

The study found that ice flow from West Antarctica - the Amundsen Sea sector, the Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula - accounted for 89 percent of the increase.

The Computer-Vision Technique

The team developed software that processed hundreds of thousands of pairs of images of Antarctic glacier movement from Landsats 7 and 8, captured from 2013 to 2015.

These were compared to earlier radar satellite measurements of ice flow to reveal changes since 2008.

“We’re applying computer vision techniques that allow us to rapidly search for matching features between two images, revealing complex patterns of surface motion,” Gardner said.

Instead of researchers comparing small sets of very high-quality images from a limited region to look for subtle changes, the novelty of the new software is that it can track features across hundreds of thousands of images per year - even those of varying quality or obscured by clouds - over an entire continent.

“We can now automatically generate maps of ice flow annually - a whole year - to see what the whole continent is doing,” Gardner said.

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
skibboy
Member Avatar

Rising Seas Lead to Shifting Alliances

Posted Image
File image courtesy of The Maldives

BY THE LOWY INTERPRETER 2018-04-27

[By Dr. Kumuda Simpson]

In 2009 the first democratically elected President of the Maldives, Mohamed Nasheed, held an underwater cabinet meeting.

The stunt was crafted to draw international attention to the plight of many low-lying island nations as climate change causes sea levels to rise, threatening their continued existence.

Nasheed used the moment to call on world leaders to act to confront climate change, stating that unless they were successful, nations such as the Maldives would disappear.

Discussions around climate change and its security implications usually focus on rising sea levels, extreme weather, and issues of food and water scarcity.

However, we should think more broadly about how climate change will create conditions in which the vulnerability of some states could be manipulated in ways that destabilise global security.

In the Maldives, which comprises 1200 islands in the Indian Ocean and was once a strategic ally of India, the growing influence of China and climate adaptation strategies interact in ways that are certain to exacerbate the geostrategic rivalry between the two Indo-Pacific powers.

As tensions play out in island countries, we are seeing significant geopolitical implications emerge alongside the obvious human security consequences of climate change.

Under Nasheed, the Maldives planned to mitigate the effects of climate change by relocating residents of the islands most vulnerable to sea-level rise.

In the intervening years since the President’s PR stunt, the country has experienced a significant backsliding of democracy, with Nasheed ousted from power during a police mutiny in 2012.

The current President, Abdulla Yameen Abdul Gayoom, has abandoned the relocation plans and instead pursued a policy of land reclamation intended to build up the islands to above sea level.

The plan depends on vast amounts of foreign investment and development projects.

Concerns about climate change and rising sea levels were at the heart of Yameen’s decision to amend the country’s constitution to allow foreign ownership of land.

To buy land, foreigners will have to invest at least $1 billion, and show that 70% of their project site will be made up of land reclaimed from the sea.

India has long viewed China’s increasing influence in the Maldives with concern.

The new investment rule, when assessed alongside the free trade agreement between China and the Maldives, and Maldivian participation in the Asian Infrastructure Investment Bank (AIIB) and Maritime Silk Road initiative, seems to open space for China to add another strategic pearl to its string in the Indian Ocean.

The proxy battle between India and China for influence in the Maldives is a worrying example of the way in which climate adaptation support, delivered through infrastructure development and land reclamation, could in future be manipulated for political leverage.

A similar scenario triggered alarm bells for some Australian and New Zealand policymakers last week as rumours spread that China was in discussions to build a military base in Vanuatu.

While those rumours were later denied by Vanuatu, the long-term implications of China’s vast regional project of infrastructure investment through development loans, the Belt and Road Initiative, and deepening economic relationships with states spanning the Indian and Pacific oceans are causing concern among many countries, including Australia.

China could use climate change as a key element of its geo-economic strategy, through development aid and infrastructure loans tied to climate adaptation projects, to deepen its influence in the Indo-Pacific.

This in itself is not necessarily problematic. The key concern is that as developing states take on unsustainable debt to China through these initiatives, their ability to exercise independence in foreign policymaking becomes compromised.

Australia and New Zealand should think carefully about this as they develop climate security policies and look at the long-term implications of development assistance within the Indo-Pacific region.

Climate change should not be thought of as a separate category of risk, but rather as the backdrop upon which future geopolitical developments in the Indo-Pacific will unfold.


Dr. Kumuda Simpson is a lecturer in International Relations in the Department of Politics and Philosophy at La Trobe University, Melbourne.

She has published on a range of issues, including American politics and regional security issues in the Middle East.

Her book America’s Nuclear Diplomacy with Iran was published in 2015.

She is currently working on a second book, which looks at the security implications of global climate change.

She is a regular commentator on ABC Radio and local radio stations, and a regular columnist for The Conversation.

This article appears courtesy of the Lowy Interpreter and may be found in its original form here: https://www.lowyinstitute.org/the-interpreter/climate-change-and-shifting-alliances-maldives


The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
skibboy
Member Avatar

Scientists Study Antarctic Glacier, Hoping to Crack Sea Level Risks

April 30, 2018 by Reuters

Posted Image
The surface of the Thwaites Glacier, photographed from a 2017 reconnaissance flight. Credit: NSF photo

OSLO, April 30 (Reuters) – Britain and the United States launched a $25 million project on Monday to study the risks of a collapse of a giant glacier in Antarctica that is already shrinking and nudging up global sea levels.

The five-year research, involving 100 scientists, would be the two nations’ biggest joint scientific project in Antarctica since the 1940s.

Ice is thawing from Greenland to Antarctica and man-made global warming is accelerating the trend.

The scientists would study the Thwaites Glacier, which is roughly the size of Florida or Britain, in West Antarctica, the UK Natural Environment Research Council and U.S. National Science Foundation said in a joint statement.

“Rising sea levels are a globally important issue which cannot be tackled by one country alone,” UK science minister Sam Gyimah said.

Thwaites and the nearby Pine Island Glacier are two of the biggest and fastest-retreating glaciers in Antarctica.

If both abruptly collapsed, allowing ice far inland to flow faster into the oceans, world sea levels could rise by more than a meter (3 feet), threatening cities from Shanghai to San Francisco and low-lying coastal regions.

The scientists would deploy planes, hot water drills, satellite measurements, ships and robot submarines to one of the remotest parts of the planet to see “whether the glacier’s collapse could begin in the next few decades or centuries,” the statement said.

Despite satellites, “there are still many aspects of the ice and ocean that cannot be determined from space,” said Ted Scambos, of the National Snow and Ice Data Center and the lead U.S. scientific coordinator.

Other scientists from South Korea, Germany, Sweden, New Zealand and Finland would also contribute.

The United States is keeping up research even though U.S. President Donald Trump doubts mainstream scientific findings that human activities, led by the burning of fossil fuels, are the main cause of global warming.

(Reporting By Alister Doyle Editing by Edmund Blair)

(c) Copyright Thomson Reuters 2018. Posted Image

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
skibboy
Member Avatar

Watch: Four-Mile Iceberg Calving

Video: https://www.youtube.com/watch?time_continue=100&v=7tyfSlnMe8E

BY MAREX 2018-07-09 20:06:54

New York University scientists have captured a four-mile iceberg breaking away from a glacier in eastern Greenland on video.

The resulting iceberg, broken off from Greenland’s Helheim Glacier, would stretch from lower Manhattan up to Midtown in New York City.

Witnessing the phenomenon, also known as calving (the breaking off of large blocks of ice from a glacier), could help create more accurate simulations to help predict and plan for climate change, say the researchers.

“Global sea-level rise is both undeniable and consequential,” said David Holland, a mathematics professor at New York University. “By capturing how it unfolds, we can see, first-hand, its breath-taking significance.”

The video shows a range of different iceberg formation styles captured during the calving event which began on June 22 at 11:30 p.m. local time and took place over approximately 30 minutes (the video has condensed the time of this occurrence to approximately 90 seconds).

The video depicts a tabular, or wide and flat, iceberg calve off and move away from the glacier.

As it does so, thin and tall icebergs, also known as pinnacle bergs, calve off and flip over.

The camera angle then shifts to show movement further down the fjord, where one tabular iceberg crashes into a second, causing the first to split into two and flip over.

In April this year, New York University received a $2.1 million, five-year grant from the National Science Foundation to better understand Antarctic glaciers and the forces behind sea-level rise.

The grant is part of the newly announced $25-million International Thwaites Glacier Collaboration, headed by the U.K.'s Natural Environment Research Council and the National Science Foundation, which will deploy scientists to gather the data needed to understand whether the glacier’s collapse could begin in the next few decades or next few centuries.

A 2017 estimate suggested that a collapse of the entire the Western Antarctic Ice Sheet would result in a 10-foot-rise in sea level - enough to overwhelm coastal areas around the globe, including New York City.

So far, the Thwaites Glacier, a part of the Western Antarctic Ice Sheet that has already drained a mass of water that is roughly the size of Great Britain or the state of Florida, has accounted for approximately four percent of global sea-level rise.

“Rising sea levels are a globally important issue which cannot be tackled by one country alone,” says U.K. Science Minister, Sam Gyimah.

Source: Posted Image.com
Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
ZetaBoards - Free Forum Hosting
Create a free forum in seconds.
Learn More · Register for Free
« Previous Topic · Climate change · Next Topic »
Add Reply

Skin by OverTheBelow