Greenland’s undercut glaciers melting faster than thought

A press release from NASA: Greenland's glaciers flowing into the ocean are grounded deeper below sea level than previously measured, allowing intruding ocean water to badly undercut the glacier faces. That process will raise sea levels around the world much faster than currently estimated, according to a team of researchers led by Eric Rignot of the University of California, Irvine (UCI), and NASA's Jet Propulsion Laboratory, Pasadena, California.

The researchers battled rough waters and an onslaught of icebergs for three summers to map the remote channels below Greenland's marine-terminating glaciers for the first time. Their results have been accepted for publication in the journal Geophysical Research Letters and are now available online.

"Measurements are challenging to obtain beneath hundreds of meters of seawater in poorly charted, ice-infested fjords," Rignot wrote. He and co-authors Ian Fenty of JPL, Cilan Cai and Yun Xu of UCI, and Chris Kemp of Terrasond Ltd., Seattle, obtained and analyzed around-the-clock measurements of the depth, salinity and temperature of channel waters and their intersection with the coastal edge of Greenland's ice sheet.

The team found some glaciers perched on giant earthen sills, protecting them from the punishing salt waters for now, while others were being severely eroded out of sight beneath the surface, meaning they could collapse and melt much sooner.  "Numerical ice sheet models do not take into account these interactions and as a result underestimate how fast the glaciers will respond to climate warming," said Rignot....

Glaciologists from the University of California, Irvine, and JPL mapped remote Greenland fjords by ship in 2014. Their findings show that Greenland's glaciers are likely to be melting faster than previously thought. Credits: UCI/Maria Stenzel

Experts push climate-proof cities, coastal communities

Imelda V. Abano at InterAksyon.com: Experts meeting here say climate-proofing a city or coastline is urgently needed to protect millions of people and key infrastructure. From Manila to New York, cities and coastal areas across the globe are increasingly vulnerable to the impacts of climate change coupled with population growth and poverty.

The adaptations prompted by climate change are meant to minimize risks from extreme weather events, powerful storm surges, sea level rise, droughts, rising temperatures and other effects of a changing climate.

Urban populations, according to the United Nations, is projected to increase from 3.9 billion in 2014 to 6.3 billion in 2050. Asia, the most climate-vulnerable region despite its lower level of urbanization, is home to 53 percent of the world's urban population, followed by Europe with 14 percent and Latin America and the Caribbean with 13 percent.

Smart planning of cities and coastal areas, such as building or planning defenses, securing water supplies or moving people to higher ground, is essential to prepare for the climatic forces, said Steven Wade, head of the Scientific Consultancy at the Met Office, a United Kingdom-based national weather service.

Wade, who presented climate model outputs for climate adaptation in cities at the World Engineers Summit (WES) organized by the Institution of Engineers Singapore, said that adaptation of cities is a significant challenge for planners and engineers, particularly in cities with ageing infrastructure, rapid growth and vulnerable coastal locations....

An aerial night view of Marina Bay, Singapore, shot by Nicolas Lannuzel., Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Reducing vulnerability through a better understanding of migration and adaptation in the Ganges delta in Bangladesh

Jon Lawn and Michele Leone in the Dhaka Tribune (Bangladesh): An abundance of scientific evidence shows that the people living in deltas have an increased vulnerability to sea-level rise and effects of climate change. In 2007, the Intergovernmental Panel on Climate Change (IPCC) reported that low-latitude and less developed areas generally face greater risk, for example in dry areas and mega-deltas. These risks increase vulnerability of specific groups such as the poor.

The poor and vulnerable have migrated in different forms to cope with the disruptions climatic changes has brought upon their lives. Research is crucial to understanding the suitability of migration as an adaptation option to the threats of climate change, and the implications migration has on society and the environment. There is a new project tackling these issues in Bangladesh: a research collaboration between the Bangladesh University of Engineering and Technology (BUET) and the University of Southampton in the UK, which is part of a larger initiative studying migration and adaptation across Africa and South Asia.

The “Deltas, vulnerability and Climate Change: Migration and Adaptation” (DECCMA) project is a five-year long program of applied research which started in early 2014, focusing on the potential and limits of adaptation options in deltaic environments.  The project will analyse the impacts of climate change and changes in other environmental  pressures (such as demand for agriculture or damming rivers) across three contrasting deltas: The Ganges-Brahmaputra-Meghna in both Bangladesh and West Bengal, the Mahanadi delta in India, and the Volta delta in Ghana. The University of Southampton provides the overall leadon the project, partnering with BUET, Jadavpur University in Kolkata, India and the University of Ghana, who lead research in the delta study sites.

We aim to understand the effectiveness of adaptation options for individuals and communities in the coastal zone of the Ganges-Brahmaputra delta, whilst also evaluating the potential for migration to be an active and positive response to climate change. Ultimately, the project team anticipates that the uptake of a robust scientific evidence base for decision-makers and practitioners will lead to improved livelihoods and reductions in poverty in delta regions....

An outline map of the Ganges Delta by John Oldale, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Mangroves help protect coastal areas against sea level rise

Blue & Green Tomorrow: Mangrove forests could play a crucial role in protecting coastal areas from sea level rise caused by climate change, according to new research involving the University of Southampton. A joint study between researchers at the University of Southampton along with colleagues from the Universities of Auckland and Waikato in New Zealand used leading-edge mathematical simulations to study how mangrove forests respond to elevated sea levels.

Taking New Zealand mangrove data as the basis of a new modelling system, the team were able to predict what will happen to different types of estuaries and river deltas when sea levels rise. They found areas without mangroves are likely to widen from erosion and more water will encroach inwards, whereas mangrove regions prevent this effect – which is likely due to soil building up around their mesh-like roots and acting to reduce energy from waves and tidal currents.

Coastal estuaries and recesses in coastlines that form bays receive the run-off from erosion on steep catchments, which give them the tendency to fill in over time. As they infill, the movement of the tidal currents over the shallow areas create networks of sandbanks and channels. The sand banks grow upward to keep pace with water-level changes, while the channels get deeper to efficiently drain the excess water out to sea.

The researchers’ latest work shows that mangroves can facilitate this process, by adding leaf and root structures into the accumulating sediment, which increase the elevation while enhancing the trapping of new sediment arriving from the catchment.

Dr Barend van Maanen from the University of Southampton explains: “As a mangrove forest begins to develop, the creation of a network of channels is relatively fast. Tidal currents, sediment transport and mangroves significantly modify the estuarine environment, creating a dense channel network. Within the mangrove forest, these channels become shallower through organic matter from the trees, reduced sediment resuspensions (caused by the mangroves) and sediment trapping (also caused by the mangroves) and the sea bed begins to rise, with bed elevation increasing a few millimetres per year until the area is no longer inundated by the tide.”...

Mangroves in Zanzibar, shot by Fanny Schertzer, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Evidence from past suggests climate trends could yield 20-foot sea-level rise

University of Florida News: When past temperatures were similar to or slightly higher than the present global average, sea levels rose at least 20 feet, suggesting a similar outcome could be in store if current climate trends continue. Findings published in the journal Science showed that the seas rose in response to melting ice sheets in Greenland and Antarctica, said lead author Andrea Dutton, a University of Florida geochemist.

“This evidence leads us to conclude that the polar ice sheets are out of equilibrium with the present climate,” she said.

Dutton and an international team of scientists assessed evidence of higher sea levels during several periods to understand how polar ice sheets respond to warming. Combining computer models and observations from the geologic record, they found that during past periods with average temperatures 1 to 3 °C (1.8 to 5.4 °F) warmer than preindustrial levels, sea level peaked at least 20 feet higher than today.

“As the planet warms, the poles warm even faster, raising important questions about how ice sheets in Greenland and Antarctica will respond,” she said. “While this amount of sea-level rise will not happen overnight, it is sobering to realize how sensitive the polar ice sheets are to temperatures that we are on path to reach within decades.”

The researchers concluded that sea levels rose 20 to 30 feet higher than present about 125,000 years ago, when global average temperature was 1 °C higher than preindustrial levels (similar to today’s average). Sea level peaked somewhere between 20 and 40 feet above present during an earlier warm period about 400,000 years ago, when global average temperatures are less certain, but estimated to be about 1 to 2 °C warmer than the preindustrial average....

NOAA image of the Ross Ice Shelf in Antarctica

Risk of major sea level rise in Northern Europe

A press release from Niels Bohr Institute: Global warming leads to the ice sheets on land melting and flowing into the sea, which consequently rises. New calculations by researchers from the Niels Bohr Institute show that the sea level in Northern Europe may rise more than previously thought. There is a significant risk that the seas around Scandinavia, England, the Netherlands and northern Germany will rise by up to about 1½ meters in this century. The results are published in a special issue of the scientific journal Climate Research.

Sea level rise is a significant threat to the world’s coastal areas, but the threat is not the same everywhere on Earth – it depends on many regional factors. “Even though the oceans are rising, they do not rise evenly across the globe. This is partly due to regional changes in the gravitational field and land uplift,” explains Aslak Grinsted, associate professor at the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen.

He explains that gravity over the surface of the land and sea varies due to differences in the subsurface and surroundings – the greater the mass, the greater the gravity. The enormous ice sheet on Greenland attracts the sea, which consequently becomes higher around Greenland. When the ice sheet melts and flows out to sea as water, this attraction is reduced and even though more water has entered the sea, the sea level around Greenland would fall.

...Another very important effect for Northern Europe is that during the ice age we had a thick ice sheet that weighted down the land. When the weight disappears, then the land rises and even though it has been more than 10,000 years since the ice disappeared, the land is still rising. The calculations show that in the Gulf of Bothnia the land is still rising faster than the expected sea level rise....

...“Based on the UN climate panel’s report on sea level rise, supplemented with an expert elicitation about the melting of the ice sheets, for example,how fast the ice on Greenland and Antarctica will melt while considering the regional changes in the gravitational field and land uplift, we have calculated how much the sea will rise in Northern Europe,” explains Aslak Grinsted.

,,,The calculations show that there is a real risk that what have been regarded as high scenarios in the Netherlands and England will be surpassed....

Lemvig on the Danish coast, shot by Anigif, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Dutch sea level rise expert: Miami will be "the new Atlantis," a city in the sea

Jessica Weiss in Miami New Times: A few months after Hurricane Sandy bared down on New York, killing over 150 people and wreaking $65 billion in damage, federal leaders cried for help to make the Northeast more flood-proof. Dutch expert Henk Ovink answered. Ovink had helped make his homeland, where 55 percent of the country is extremely flood-prone, a world pioneer in preparing for sea level rise. ... So there's good cause to be worried when the Dutch expert says there’s no place in worse shape today than Miami. He’s begun calling the city “the new Atlantis,” after the legendary and beautiful island subcontinent that was submerged by the sea in one night.

“If we look around the world and take into account sea level rise and the increase of water related disasters, among the places in the world that have the most assets and investments at risk, Miami is leading that list,” Ovink tells New Times. “Miami will no longer be a land city, but a city in the sea.”

In recent years, scientists have repeatedly warned that South Florida’s coastal communities and barrier islands could be completely underwater in 100 years. Earlier this year, National Geographic published research on the projected cost of an extreme weather event in 2050. With so many buildings, roads and other infrastructure so close to sea level, Miami was number one on the list, with a projected loss of $278 billion dollars, followed by Guangzhou, China ($268 billion), and New York-Newark ($209 billion).

A first step is for leaders to recognize and talk about climate change.  “It’s scary that the state of Florida briefed staff not to talk about climate change,” Ovink says. “When you think about future risks and how to deal with them, that is not right approach. You have to address those issues and come up with a strategy. It's an opportunity.”

The problem, Ovink says, is that dozens of individual cities, like Miami Beach, are pursuing their own balkanized strategies rather than making a unified effort to find creative solutions. Government, businesses, NGOs and residents should plan together, Ovink says, and do more than just stop-gap efforts. In the very short term, ideas might include raising buildings, preventing ocean water from flooding freshwater aquifers, and installing pumps to stop city flooding. But long term efforts need to be more comprehensive....

Medieval manuscript of Calcidius' Latin translation of Plato's Timaeus, one of the main sources for the Atlantis legend. In the late sixteenth century, this manuscript belonged to Leiden University professor Daniel Heinsius who gave it to his son Nicholas. Nicholas, whose signature appears on the manuscript, was the librarian of Queen Christina of Sweden, whose collection came to the Vatican Library after her death.

NASA study shows Antarctica’s Larsen B ice shelf nearing its final act

NASA: A new NASA study finds the last remaining section of Antarctica's Larsen B Ice Shelf, which partially collapsed in 2002, is quickly weakening and likely to disintegrate completely before the end of the decade.

A team led by Ala Khazendar of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, found the remnant of the Larsen B Ice Shelf is flowing faster, becoming increasingly fragmented and developing large cracks. Two of its tributary glaciers also are flowing faster and thinning rapidly.

"These are warning signs that the remnant is disintegrating," Khazendar said. "Although it’s fascinating scientifically to have a front-row seat to watch the ice shelf becoming unstable and breaking up, it’s bad news for our planet. This ice shelf has existed for at least 10,000 years, and soon it will be gone."

Ice shelves are the gatekeepers for glaciers flowing from Antarctica toward the ocean. Without them, glacial ice enters the ocean faster and accelerates the pace of global sea level rise. This study, the first to look comprehensively at the health of the Larsen B remnant and the glaciers that flow into it, has been published online in the journal Earth and Planetary Science Letters.

...NASA research has found that the last section of Antarctica's Larsen B Ice Shelf is likely to disintegrate before the end of the decade. Khazendar noted his estimate of the remnant's remaining life span was based on the likely scenario th
at a huge, widening rift that has formed near the ice shelf's grounding line will eventually crack all the way across. The free-floating remnant will shatter into hundreds of icebergs that will drift away, and the glaciers will rev up for their unhindered move to the sea.

Located on the coast of the Antarctic Peninsula, the Larsen B remnant is about 625 square miles (1,600 square kilometers) in area and about 1,640 feet (500 meters) thick at its thickest point. Its three major tributary glaciers are fed by their own tributaries farther inland. "What is really surprising about Larsen B is how quickly the changes are taking place," Khazendar said. "Change has been relentless." ...

The polar research ship Nathaniel B. Palmer in Barilari Bay, Antarctic Peninsula being a part of the U.S. Antarctic Program (USAP). The icebreaker was on a two-month science expedition to the Larsen B. Embayment, which was occupied for 10,000 years until 2002 by an ice shelf, 23 January 2010.

Flood risk to nuclear reactors raises meltdown fears

Paul Brown in the Ecologist: ...All nuclear plants need large quantities of water for cooling so all must be built close to the sea, large rivers or lakes. This makes them vulnerable to sea level rise, storm surges and to the possible collapse of large dams upstream from poor construction, floodwater or seismic activity.

Since nuclear plants are designed to operate for as long as 60 years and need around a further century to decommission, accelerating sea level rise and more intense rainfall may present serious problems. There are currently 435 operating nuclear reactors in the world, many of them potentially vulnerable to flooding because of natural disasters. Examples from the UK, Finland and the US show that the extent of the danger is not always being disclosed.

... The same fears [of flooding] were raised in the US by the Union of Concerned Scientists after a report was leaked about the danger to nuclear reactors from dams bursting. According to a report by the US Nuclear Regulatory Authority (NRC), which had been withheld, more than 30 nuclear installations were in danger from flooding. The Commission was later accused of using security concerns to mask embarrassing information.

Among many revelations in the report was the fact that the authorities had known for a decade or more that the failure of a dam upstream from the Oconee nuclear plant in South Carolina would cause floodwater to overwhelm its three reactors, possibly causing a catastrophic meltdown The odds of the dam bursting were far higher than thechances of the accident that devastated Fukushima.

Oconee is one of the largest nuclear plants in America and has been operating since 1983. Its owner, Duke Energy, remains confident that it could shut the plant down safely in an hour, before floodwaters from upstream could reach the reactors. The NRC has decided that this is sufficient safeguard....

A 1974 image of the control room at the Oconee nuclear plant in South Carolina

That sinking feeling: Developing nations speak out on climate change

Thom Mitchell in New Matilda: Developing nations around the world - rarely big emitters of carbon emissions - are ramping up their calls for radical global action to tackle the climate threat that is already looming large for low-lying countries.

As Vanuatu grapples with the fall out of category five Tropical Cyclone Pam which struck the Pacific nation on March 15, developing nations’ calls for action from high-emitting nations like Australia are being amplified.

At the United Nations Third World Disaster Risk Reduction conference in Sendai, Japan, calls to action from Vanuatu’s President and other highly exposed nations came at a grimly ironic time - March 14 to 18 - as Pam bore down on, then battered, the Pacific.

“Overnight a devastating disaster can wipe out years of development and reduce people [to] a state of increased poverty,” Baldwin Lonsdale, the President of Vanuatu, said at the conference.

"According to the World Bank report of 2012 it places Vanuatu on the map as the most prone country in the South Pacific region in all natural hazards such as earthquakes, volcanic eruptions, tsunami, drought, floods, landslides, tropical cyclones and impacts of climate change and rising sea level,” he said....

Hideaway Island on Vanuatu, shot by Graham Crumb, Wikimedia Commons, under the Creative Commons Atribution-Share Alike 3.0 Unported license 

As sea level rise accelerates, buying shorefront property becomes a game of musical chairs

Ivy Main at the Energy Collective: Thank God for climate change deniers. They may eventually be the only buyers for shorefront real estate.

Sea level rise may not cause widespread flooding until later in this century or into the next one, but real estate deals involve long timelines: the useful life of a new house or a commercial building can be at least fifty years, while an infrastructure project might last a hundred years or more.

And of course, it’s one thing to lose your house, and another to lose the ground beneath it. Sea level rise means low-lying real estate now comes with an expiration date.

So smart buyers—and landowners—have to consider not just today’s flood maps, but also ones that haven’t been drawn yet. If a rising sea will threaten property some decades from now, it will depreciate over time, like a car. At some point only chumps and climate deniers will buy.

Head-in-the-sand posturing still dominates the headlines, like Florida Governor Rick Scott’s alleged ban on the use of the term “climate change,” or the North Carolina legislature’s silly (and costly) attempt to legislate sea level rise out of existence. Now the Federal Emergency Management Agency (FEMA) hopes to force states to get serious about climate change by requiring states to do a better job planning for natural disasters caused in part by global warming. FEMA’s goal is to save money through better planning, but conservatives have attacked the requirement as politically motivated....

FEMA photo of beach houses in Pensecola, Florida, damaged by Hurricane Ivan in 2004

Antarctic ice shelves are melting dramatically

Karl Mathiesen in the Guardian (UK): The ice around the edge of Antarctica is melting faster than previously thought, potentially unlocking metres of sea-level rise in the long-term, researchers have warned. A team of US scientists looked at 18 years’ worth of satellite data and found the floating ice shelves that skirt the continent are losing 310km3 of ice every year. One shelf lost 18% of its thickness during the period.

The loss of ice shelves does not contribute much directly to sea level rise. But they act like a cork in a bottle at the point where glaciers meet the sea – jamming the flow of ice from the massive ice sheets of east and west Antarctica.

Professor Andrew Shepherd, director of the Centre for Polar Observation and Modelling at the University of Leeds, said the rates of ice loss were unsustainable and could cause a major collapse. This is already occurring at the massive Pine Island glacier, where ice loss has doubled in speed over the last 20 years as its blocking ice shelf has melted.

“This is a real concern, because such high rates of thinning cannot be sustained for much longer, and because in the places where Antarctic ice shelves have already collapsed this has triggered rapid increases in the rate of ice loss from glaciers above ground, causing global sea levels to rise,” he said.

The new research, published in the journal Science on Thursday, discovered for the first time that ice shelf melt is accelerating.

Dr Paul Holland, a climate scientist at the British Antarctic Survey (BAS), said the loss of the shelves would speed the complete collapse of the west Antarctic ice sheet, which would eventually cause up to 3.5m of sea level rise. But he said it was highly unlikely this would occur this century. He said the “worst case scenario” for 2100 was that ice sheets would contribute an additional 70cm to the sea level rise caused by the warming of the ocean....

Via NASA, a satellite image of Schokalsky Bay, Antarctica

Rapid coastal population growth may leave many exposed to sea-level rise

Science Daily: The number of people potentially exposed to future sea level rise and associated storm surge flooding may be highest in low-elevation coastal zones in Asia and Africa, according to new projections published March 11, 2015 in the open-access journal PLOS ONE by Barbara Neumann from Kiel University, Germany, and colleagues.

Many coastal areas are densely populated and exposed to a range of coastal hazards, including sea level rise. As coastal population density and urbanization continue to increase, researchers are investigating how coastal populations may be affected by potential environmental impacts at global and regional scales in the future. Based on four different sea-level and socioeconomic scenarios, the authors of this study assessed future population changes by the years 2030 and 2060 in the low-elevation coastal zone and estimated trends in exposure to 100-year coastal floods.

From the scenario-based projections, the researchers estimated that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 100-year storm surge events, was highest in Asia
. China, India, Bangladesh, Indonesia, and Viet Nam had the largest numbers of coastal population per country and accounted for more than half of the total number of people living in low-elevation coastal zones, both now and in the future scenarios. However, Africa was estimated to experience the highest future rates of population growth and urbanization in the coastal zone, particularly in Egypt and sub-Saharan countries in West and East Africa. While the authors' research method does not explicitly consider possible population displacement or out-migration due to factors such as sea level rise, the results highlight countries and regions with a high degree of potential exposure to coastal flooding, and also help to identify regions where policies and adaptive planning for building resilient coastal communities are essential....

NASA image of Haiphong

Greenland Ice: The warmer it gets the faster it melts

Space Daily via SPX: Melting of glacial ice will probably raise sea level around the globe, but how fast this melting will happen is uncertain. In the case of the Greenland Ice Sheet, the more temperatures increase, the faster the ice will melt, according to computer model experiments by Penn State geoscientists.

"Although lots of people have thought about sea level rise from the ice sheets, we don't really know how fast that will happen," said Patrick Applegate, research associate, Penn State's Earth and Environmental Systems Institute.

If all the ice in the Greenland Ice Sheet melts, global sea level would rise by about 24 feet. In the last 100 years, sea level in the New York City area has only increased by about one foot. However, storm surges from hurricanes stack on top of this long-term increase, so sea level rise will allow future hurricanes to flood places where people are not ready for or used to flooding. A vivid example occurred during Hurricane Sandy when parts of the New York City subway tunnel system flooded.

Greenland might be especially vulnerable to melting because that area of the Earth sees about 50 percent more warming than the global average. Arctic sea ice, when it exists, reflects the sun's energy back through the atmosphere, but when the sea ice melts and there is open water, the water absorbs the sun's energy and reradiates it back into the air as heat.

Arctic sea ice coverage has decreased over the last few decades, and that decrease will probably continue in the future, leading to accelerated temperature rise over Greenland. Floating ice does not add to sea level, but the Greenland Ice Sheet rests on bedrock that is above sea level.

Feedbacks in the climate system cause accelerated temperature rise over the Arctic. Other feedbacks in the Greenland Ice Sheet that contribute to melting include height-melting feedback. A warm year in Greenland causes more melt around the edges of the ice sheet, lowering the surface. The atmosphere is warmer at lower altitudes, so the now lower surface experiences even more melting. This process can lead to accelerated ice melt and sea level rise....

A glacier seen from offshore near Amassalik, Greenland, shot by Christine Zenino Christine Zenino ,Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Pakistan's coastal villagers retreat as seas gobble land

Rina Saeed Khan in Reuters via the Thomson Reuters Foundation: For fisherman Sammar Dablo, it was as if "the seawater stole our homes" when land erosion forced his village to relocate further inland on Pakistan's south coast.

The people of the fan-shaped Indus Delta, where the Indus River meets the Arabian Sea, are among the poorest of the poor, mostly illiterate and living in wooden shacks on the mud flats. As seawater has washed into the delta, destroying thousands of hectares of fertile land and contaminating underground water channels, they survive by fishing in the saltwater creeks where dolphins are a common sight.

...The move was not easy, as households had to spend 15,000 rupees ($149) each to build new huts for themselves, he added. The story of Phirt village is not an isolated case. According to Dablo, many other communities in the delta are also shifting as their land disappears.

The latest scientific report from the Intergovernmental Panel on Climate Change pointed out that at the same time as sea levels are rising, most Asian deltas are sinking due to groundwater extraction, floodplain engineering and the trapping of sediment by dams.

The Indus Delta has seen an 80 percent reduction in sediment since the early 20th century, according to a 2009 paper published in Nature Geoscience. Around 20 dams and a large number of canals divert the waters of the Indus River, depriving the delta of fresh water.

Some inhabitants have moved to inland mud flats, where they do not have to buy the land they occupy. Others are decamping to Karachi’s coastal villages where relatives have settled. ... Climate change is clearly increasing vulnerabilities in the delta area. Sea-level rise is contributing to higher storm surges, erosion, flooding and salinity, according to WWF-Pakistan...

NASA view of the Indus River delta

In Jakarta, that sinking feeling is all too real

Bill Tarrant at the Thomson Reuters Foundation via Reuters: …"Jakarta is a bowl, and the bowl is sinking," said Fook Chuan Eng, senior water and sanitation specialist with the World Bank, who oversees a $189 million flood mitigation project for the city.

The channels of the Ciliwung and other rivers are sinking. The entire sprawl of Jakarta's north coast - fishing ports, boatyards, markets, warehouses, fish farms, crowded slums and exclusive gated communities - it's all sinking. Even the 40-year-old seawall that is supposed to keep the Java Sea from inundating the Indonesian capital is sinking.

…Flooding from overflowing rivers and canals in the area is at least an annual event that forces Rahmawati and the rest of the kampong to evacuate to public buildings nearby. High-water marks from the last big flood, in 2013, are still visible on the walls of the kampong.

Jakarta is sinking because of a phenomenon called subsidence. This happens when extraction of groundwater causes layers of rock and sediment to slowly pancake on top of each other.

The problem is particularly acute in Jakarta because most of its millions of residents suck water through wells that tap shallow underground aquifers. Wells also provide about a third of the needs of business and industry, according to city data….

Jakarta's skyline, shot by Vian kadal, Wikimedia Commons,  under the Creative Commons Attribution-Share Alike 3.0 Unported license

Mumbai, Kolkata most vulnerable to climate change

The Financial Express (India): India’s populous coastal cities Mumbai and Kolkata are most vulnerable to loss of life and properties due to coastal flooding in the second half of the century, the government has said quoting a UN report ahead of a key global climate conference in Peruvian capital Lima.

The UN’s Intergovernmental Panel on Climate Change (IPCC) has warned against extreme weather events like occurrence of heatwave, heavy precipitation, droughts, floods, cyclones and wildfire that cause damage to ecosystems and human systems in various regions, Environment Minister Prakash Javadekar said.

“… India is among the top 20 countries and regions most at risk based on analysis of climate risk and coping ability. Mumbai and Kolkata will have the greatest population and assets exposure to coastal flooding in 2070,” he said.

The minister’s statement assumes significance at a time when representatives of governments are scheduled to meet in Lima from tomorrow for the Climate Change Conference to lay the foundation for an effective, new and universal climate change agreement in Paris in 2015.

Mumbai' sea-face at night

Sea level rise won’t only affect infrastructure

Scoop via Forest & Bird (New Zealand): The independent conservation organisation Forest & Bird is asking the Parliamentary Commissioner for the Environment (PCE) to widen the focus of her next report on climate change-driven sea level rise.

A preliminary report on sea level rise was released by the PCE today. The PCE will release another report next year on the impacts of sea level rise on the most vulnerable areas of coastline around the country, and the risks to infrastructure in those areas.

Forest & Bird Group Manager Campaigns and Advocacy Kevin Hackwell says the next report should also take into account the impacts of sea level rise on our natural coastal ecosystems, and recommend the best ways to deal with sea level rise.

He says some critical natural features could be changed forever by sea level rise. “For example the huge Kaipara Harbour north of Auckland covers 947 square kilometres at high tide, with nearly half of that area exposed as mudflats and sandflats at low tide,” Kevin Hackwell says.

...“Quite a few of our shore birds breed just above the current high tide level on our open coasts or at the head of estuaries. For instance the four remaining nesting sites of New Zealand’s Seabird of the Year, the fairy tern, could be wiped out by storm surges,” Kevin Hackwell says.

“We would also like to see the PCE make recommendations on how sea level rise should be dealt with. Building extensive sea walls is likely to be very expensive, in many places unrealistic, and in the long run may create more problems than they would solve....

Sphinx Rock in Marie's Leg Cove, New Zealand, shot by Pseudopanax, Wikimedia Commons, under the Creative Commons 3.0 license 

Salinity matters when it comes to sea level changes

A press release from Lawrence Livermore National Laboratory: Using ocean observations and a large suite of climate models, Lawrence Livermore National Laboratory scientists have found that long-term salinity changes have a stronger influence on regional sea level changes than previously thought.

“By using long-term observed estimates of ocean salinity and temperature changes across the globe, and contrasting these with model simulations, we have uncovered the unexpectedly large influence of salinity changes on ocean basin-scale sea level patterns,” said LLNL oceanographer Paul Durack, lead author of a paper appearing in the November issue of the journal Environmental Research Letters (link is external).

Sea level changes are one of the most pronounced effects of climate change impacts on the Earth and are primarily driven by warming of the global ocean along with added water from melting land-based glaciers and ice sheets. In addition to these effects, changes in ocean salinity also can affect the height of the sea, by changing its density structure from the surface to the bottom of the ocean.

The team found that there was a long-term (1950-2008) pattern in halosteric (salinity-driven) sea level changes in the global ocean, with sea level increases occurring in the Pacific Ocean and sea level decreases in the Atlantic. These salinity-driven sea level changes have not been thoroughly investigated in previous long-term estimates of sea level change. When the scientists contrasted these results with models, the team found that models also simulated these basin-scale patterns, and that the magnitude of these changes was surpri
singly large, making up about 25 percent of the total sea level change.

“By contrasting two long-term estimates of sea level change to simulations provided from a large suite of climate model simulations, our results suggest that salinity has a profound effect on regional sea level change,” Durack said. “This conclusion suggests that future sea level change assessments must consider the regional impacts of salinity-driven changes; this effect is too large to continue to ignore.”...

Lined with bottles triggered at different levels of the ocean, this conductivity, temperature and depth profiler bearing a suite of sampling bottles is a mainstay of oceanography. It can be deployed to depths of 6,000 meters to study changes in ocean temperature and salinity. Photo courtesy of Ann Thresher/CSIRO

Worst case scenarios of sea level rise, and why scientists and policymakers consider them

Robert McSweeney in the Carbon Brief: Sea levels could rise by a maximum of 190 centimetres by the end of the century, according to a new study, which examines a worst case scenario for sea level rise. In reality, the amount of sea level rise we get is likely to be less than that. But scientists and policymakers examine such 'worst case' scenarios to safeguard against climate risks.

With 10 per cent of the world's population living less than 10 metres above sea level, the threat of  coastal flooding is significant. The Intergovernmental Panel on Climate Change (IPCC) expects sea level rise to cause a ' significant increase' in sea levels extremes and the risk of coastal flooding.

The new study, published in  Environmental Research Letters, considers the assessment of 13 ice sheet experts. They conclude that the contribution from ice sheets is likely to be greater than projected by the IPCC. The paper suggests that sea levels could rise by as much as 190 cm this century.

Projections of sea level rise are typically constructed by working out the contribution to sea level rise from different  factors. The biggest contribution is from water expanding as it warms, followed by melting glaciers, then melting ice sheets on Greenland and Antarctica.

The crucial question for sea level rise this century is how much ice will be lost from the ice sheets, the authors argue. But it remains one of the largest uncertainties. In its Fifth Assessment Report (AR5), the IPCC  says there isn't sufficient evidence for them to give probabilities of large-scale losses of ice sheets.

The new study uses expert judgement to consider areas of ice sheet loss that are often not included in the sea level  models that the IPCC bases its assessment on. They then combine these judgements with the methods used in AR5 to produce their upper-limit figure of 190 cm....

A 2008 FEMA photo by Patsy Lynch of Hurricane Ike debris in Port Arthur, Texas