Tag Archives: Sea levels

Bold pathways point to a low-carbon future

Brighter future? Sunrise over a wind farm in the Cambridgeshire Fens, UK Image: David Clare/Climate News Network
Brighter future? Sunrise over a wind farm in the Cambridgeshire Fens, UK
Image: David Clare/Climate News Network

By Alex Kirby

The positive message from a scientific report for the UN Climate Summit is that the tough task of cutting CO2 emissions to limit global temperature rise to below 2°C is definitely achievable by following a set of bold, practical steps.

LONDON, 11 July 2014 − Scientists often hesitate to give a cut-and-dried, yes-or-no answer when asked how serious climate change is going to be, and whether the world can still escape significant damage.

Surprisingly, perhaps, a report prepared for a UN conference in September is unequivocal. Yes, it says − the worst is not bound to happen.

The good news is that the world can keep climate change within what are thought to be acceptable limits. The less good news is that while it is possible, it certainly won’t be easy.

The report shows how the countries that emit the most greenhouse gases (GHGs) can cut their carbon emissions by mid-century to prevent dangerous climate change. Prepared by independent researchers in 15 countries, it is the first global co-operation to identify practical pathways to a low-carbon economy by 2050.

The Deep Decarbonisation Pathways Project (DDPP) report is an interim version prepared for the UN Climate Summit to be held in New York on 23 September. The full DDPP report will be ready in the spring of 2015.

Dangerous change

The UN Secretary-General, Ban Ki-Moon, said the report tried to show how countries could help to achieve the globally-agreed target of limiting temperature rise to below 2°C. “Ambitious national action is critical to averting dangerous climate change,” he said. “This report shows what is possible.”

The report aims to help countries to set bold targets in the run-up to the UN climate talks to be held in Paris in 2015.

The work is led by the Sustainable Development Solutions Network (SDSN), an initiative of Columbia University’s Earth Institute for the UN, and the Institute for Sustainable Development and International Relations (IDDRI), a policy research institute based in Paris.

Jeffrey Sachs, the director of the SDSN, said the world had committed itself to limit warming to below 2°C, but not to practical ways of achieving that goal.

He said: “This report is all about the practicalities.  Success will be tough – the needed transformation is enormous – but is feasible, and is needed to keep the world safe for us and for future generations.”

“The issue is to convince the world that the future is as important as the present”

Fatih Birol, chief economist of the International Energy Agency, said: “The issue is to convince the world that the future is as important as the present. Paris 2015 may well be our last hope.”

Despite the global agreement to stay below 2°C, the world is on a path that, without action, will lead to an increase of 4°C or more. The Intergovernmental Panel on Climate Change said in its Fifth Assessment Report, known as AR5, that such a rise might exceed the world’s ability to adapt.

It said that a 4°C rise could endanger harvests and cause drastic sea-level rise, spread of diseases, and the extinction of ecosystems.

Some leading climate scientists − including NASA’s former chief climate scientist, Professor James Hansen, who is now at Columbia University − say that even a 2°C rise would be very dangerous. But many politicians regard it as an essential commitment.

The 15 national pathways examined in the report all show the importance of three factors for achieving radically lower carbon emissions.

The first is greatly increased efficiency and conservation in all energy use.

Renewable sources

The second factor is taking the carbon out of electricity by using renewable sources, “such as wind and solar, as well as nuclear power, and/or the capture and sequestration of carbon emissions from fossil-fuel burning”.

Nuclear energy still attracts widespread and determined opposition, and carbon capture and sequestration (trapping CO2 emissions and storing them underground or beneath the sea floor) has not yet proved that it can work on a commercial scale.

The third factor involves replacing fossil fuels in transport, heating and industrial processes with a mix of low-carbon electricity, sustainable biofuels, and hydrogen.

The authors say their interim report shows the critical long-term importance of preparing national deep decarbonisation plans for 2050.

Emmanuel Guerin, the DDPP’s senior project manager, said the pathways were crucial to shaping the expectations of countries, businesses and investors. − Climate News Network

Climate puts US at risk of multi-billion bill

Overheating: US crops such as cotton face a %20 drop in yield Image: Wars via Wikinmedia Commons
Overheated economy: US crops such as cotton face a 20% drop in yield
Image: Wars via Wikimedia Commons

By Alex Kirby

A study of the possible cost of climate change to the US economy warns government and business that billions of dollars could be at risk through damage to property, reduced harvests and workers incapacitated by extreme heat.

LONDON, 29 June, 2014 − The sheer economic cost of climate change to Americans could be far greater than many realise, an influential study says.

The study was commissioned by the Risky Business Project, a research organisation chaired by a bi-partisan panel and supported by several former US Treasury Secretaries.

It expects climate change to have varied impacts across different regions and industries. Rising sea levels, it says, could destroy many billion dollars’ worth of coastal properties by 2050, and warming temperatures, especially in the south, south-west and mid-west, could cut the productivity of people working outdoors by 3%.

Without a change in crops, harvests in these regions could fall by 14%. But further north, in states such as North Dakota and Montana, winter temperatures will probably rise, reducing frost and cold-related deaths and lengthening the growing season for some crops.

Kate Gordon, executive director of the Risky Business Project, said : “We still live in a single integrated national economy, so just because it’s not hot where you are doesn’t mean you won’t feel the heat of climate change.”

Michael Bloomberg, a former mayor of New York, said: “Damages from storms, flooding, and heat waves are already costing local economies billions of dollars. We saw that firsthand in New York City with Hurricane Sandy.

Costs of inaction

“With the oceans rising and the climate changing, the Risky Business report details the costs of inaction in ways that are easy to understand in dollars and cents − and impossible to ignore.”

Hank Paulson, a former Treasury Secretary and co-chair of the Risky Business Project, said the report shows us that “our economy is vulnerable to an overwhelming number of risks from climate change.

“But if we act immediately, we can still avoid most of the worst impacts of climate change and significantly reduce the odds of catastrophic outcomes. But the investments we’re making today will determine our economic future.”

In a section on short-term climate threats, the authors say: “The American economy is already beginning to feel the effects of climate change. These impacts will likely grow materially over the next 5 to 25 years…”

“Just because it’s not hot where you are doesn’t mean
you won’t feel the heat of climate change”

They say there is a 1-in-20 chance of yield losses of more than 20% in corn, wheat, soya and cotton crops over that timespan.

On energy, they say changes in temperature driven by greenhouse gases will probably mean a need to build roughly 200 average coal-fired or natural gas-fired power plants between 2020 and 2045, costing up to $12 billion per year.

Climate impacts, the report says, are unusual because future risks are directly tied to present decisions. By failing to lower greenhouse gas emissions today, decision-makers put in place processes that increase overall risks tomorrow.

By 2050, on present trends, $66bn-$106bn worth of existing coastal property will probably be below sea level nationwide, with $238-$507bn worth by 2100.

By mid-century, the average American will probably see 27 to 50 days over 95°F (35°C) each year − two to more than three times the average annual number of such days seen over the last 30 years. By the end of the century, this number will probably average 45 to 96 days over 95°F each year.

But the study says that the south-west, south-east, and upper mid-west will probably see several months of 95°F days annually.

Human threshold

In the longer term, extreme heat during parts of the year could pass the threshold at which the human body can no longer maintain a normal core temperature without air conditioning. At these times, anyone who has to work outdoors, or without access to air conditioning, will face severe health risks and possible death.

The authors say they hope it will become standard practice for the American business and investment community to factor climate change into its decision-making process. They say: “We are already seeing this response from the agricultural and national security sectors; we are starting to see it from the bond markets and utilities as well.

“But business still tends to respond only to the extent that these risks intersect with core short-term financial and planning decisions.”

And the authors warn the government: “We also know that the private sector does not operate in a vacuum, and that the economy runs most smoothly when government sets a consistent policy and a regulatory framework within which business has the freedom to operate.

“Right now, cities and businesses are scrambling to adapt to a changing climate without sufficient federal government support…” − Climate News Network

Underworld threat to melting icecap

 

Concealed beneath the Petermann glacier are towering blocks of ice Image: Michael Studinger/NASA via Wikimedia Commons
Concealed beneath the Petermann glacier are towering blocks of ice
Image: Michael Studinger/NASA via Wikimedia Commons

By Tim Radford

Radar images of Greenland’s glaciers have revealed a spectacular underground landscape of “skyscraper” ice blocks created by a melt-and-freeze cycle that is accelerating the reduction of the icecap

LONDON, 16 June − Researchers in the US have identified a new reason for the acceleration in the melting of Greenland’s icecap − the ice underneath, as it melts and then refreezes, appears to speed up glacial flow.

The melt-and-freeze-again cycle is not itself new, as a similar process has been diagnosed under the ice cap of Antarctica. Nor is the process itself necessarily connected with global warming. Such things must always have happened.

But Robin Bell, a geophysicist at Columbia University’s Lamont Doherty Earth Observatory, reports with colleagues in Nature Geoscience that they used ice-penetrating radar to identify ragged blocks of ice as tall as skyscrapers and as wide as the island of Manhattan at the very bottom of the ice sheet. These structures cover about a tenth of the island and seem to form as melted water below the ice freezes again. They then warp the ice around and above them.

Easier to flow

“We see more of these features where the ice sheet starts to go fast,” Professor Bell said. “We think the refreezing process uplifts, distorts and warms the ice above, making it softer and easier to flow.”

Bell and her colleagues looked at the Petermann Glacier in Greenland’s north, which in 2010 pushed a huge chunk of ice into the sea. Observations suggest that the glacier is moving twice as fast as the surrounding ice, and the hypothesis is that the melt-and-freeze-again process is contributing to this acceleration.

Researchers have been troubled for a decade or more by the apparent increase in ice loss from Greenland. Were the whole island to melt, sea levels worldwide would rise by more than seven metres, so the concern is practical.

Recently, researchers have found that the bedrock beneath many glaciers is actually below sea level, making the glaciers vulnerable from ocean inflow. They have identified a process called “dynamic thinning”, triggered by warmer air temperatures, and they know anyway that natural geothermal heat flow mis likely to melt the base of the ice and lubricate any acceleration.

They have measured a fourfold increase since 1997 in summer flow speeds in the island’s Jakobshavn glacier. And they have indicated that the Greenland icecap each summer becomes more vulnerable to melting because the snows themselves are becoming darker, as more dust blows in from areas that are increasingly ice free.

Ice slide

So the discovery of a process that will make the ice slide to the sea more efficiently is not of itself more sinister. The meltwater could come from a number of sources. The friction created by a glacier as it moves must contribute. So could natural heat flow from the bedrock. Surface ice could melt in the summer sun and drain through crevasses to the base.

However, what the discovery helps to offer, literally and metaphorically, is a deeper understanding of the processes at work below the ice.

What is not clear is whether the melt-and-freeze cycle will influence the rate at which ice is lost in future. Nor does anyone yet know what triggers the cycle.

“The conditions under which such switches occur should be investigated, as they directly affect the ability of an ice sheet to slide over its bed,” advises Joseph A. McGregor, of the University of Texas at Austin, writing in the same issue of Nature Geoscience. − Climate News Network

Dark shadow falls on melting icecap

 

Signs of melting as darkness falls on the Greenland icecap Image: Matthew Hoffmann/NASA ICE via Wikimedia Commons
Signs of melting can be seen as darkness descends on the Greenland icecap
Image: Matthew Hoffmann/NASA ICE via Wikimedia Commons

By Tim Radford

Dust blowing in from warming areas of the Arctic is causing the Greenland icecap to melt faster by reducing the whiteness that reflects light and keeps it cool 

LONDON, 13 June − French scientists have identified a new mechanism that could cause the Greenland icecap to melt even faster – because dust is making its surface darker.

Marie Dumont, of the French national meteorological service, Météo-France, reports with colleagues in Nature Geoscience that, since 2009, the snows of the Arctic region’s biggest single permanent white space have been steadily darkened by “light-absorbing impurities” − known to the rest of the world simply as dust.

The Arctic has always been cold and white, simply because it is not just cold but is also white. The phenomenon is called albedo. Regions with a high albedo reflect light and stay cooler, so ice is a form of self-insulation.

Conversely, things that absorb light become warmer − and satellite data analysed by Dr Dumont and her fellow researchers shows that the Greenland ice is getting darker in the springtime.

They think the dust is blowing in from areas of the Arctic that are losing snow cover much earlier in the season as the climate warms. And, they calculate, this steady darkening alone has led to “significant” melting of the icecap.

This finding is ominous. What the researchers have identified is yet another case of what engineers call positive feedback. In the last 30 years, the Arctic sea ice has been in retreat, and researchers expect that, later in the century, the Arctic ocean will be entirely free of ice most summers.

Insulating layers

That means that there will be more atmospheric dust each spring, landing on the snows of Greenland and lowering its albedo even more, so the insulating layers of ice on the huge island will continue to retreat.

Researchers have twice in the last few months had to revise their predictions for the melting of the Greenland glaciers. The continued melting of the ice sheet is expected to raise global sea levels by 20cm by 2100, and since the whole ice sheet – which would take much longer to melt − holds enough frozen water to raise sea levels by more than seven metres, what happens in Greenland matters very much to maritime cities as far apart as Miami and Mumbai.

The French researchers have backed up their observations with a computer model of potential surface melt in Greenland. If a perfect reflecting surface would have a value of one, then meteorologists allot a value of 0.9 to the albedo of fresh snow. They calculate that a decrease in the albedo of even a very small ratio, such as 0.01, could lead to the melting of 27 billion tons of ice every year.

They are not saying that this is already happening, but they do argue that “future trends in light-absorbing impurities should therefore be considered in projections of Greenland’s mass loss”.

Accelerating warming

This is not the only newly-identified potential mechanism for positive feedback. A report by Laetitia Pichevin, of the University of Edinburgh’s School of GeoSciences, Scotland, and fellow researchers, was published in the same issue of Nature Geoscience. It says that rising global temperatures could decrease the amount of carbon dioxide naturally taken up by the world’s oceans, thus also accelerating global warming. This, too, is another process that could go on accelerating.

The researchers analysed sediments laid down 26,000 years ago in the Gulf of California and measured the abundance of silicon and iron in tiny marine fossils. They found that those periods when silicon was least abundant in ocean waters coincide with relatively warmer climates, low levels of atmospheric iron, and reduced carbon dioxide uptake by the plankton in the oceans.

“We were surprised by the many ways in which iron affects the CO2 given off by the oceans,” Dr Pichevin said. “If warming climates lower iron levels at the sea surface, as occurred in the past, this is bad news for the environment.” – Climate News Network

Help needed now for climate refugees

 

Somalis displaced by drought in 2011 queue to register at a refugee camp in Ethiopia Image: Cate Turton/DFID via Wikimedia Commons
Somalis displaced by drought in 2011 queue at a refugee camp in Ethiopia
Image: Cate Turton/DFID via Wikimedia Commons

By Paul Brown

Governments worldwide are warned of the need to draw up plans urgently to avoid conflict and insecurity by helping populations who are being forced to move because of climate change

 

LONDON, 11 June − Hundreds of thousands of people are already migrating because of climate change, and countries urgently need adaption plans to resettle populations and avoid conflict.

Sea level rise, violent storms and more gradual disasters such as droughts will cause more unplanned mass population movements − either temporary or permanent − and governments need to manage this by planning in advance to protect vulnerable people, says a new report.

The report, by the United Nations University’s Institute for Environment and Human Security, warns that unplanned movements will lead to conflict and insecurity. Governments need to act regionally to anticipate and facilitate the movement of people.

Ideally, for the displaced families, this would mean providing access to land and housing. They would need financial services, health, education, water and sanitation. They would also need jobs and the ability to cover the costs of living and food security.

Move to survive

Economic and environmental factors sometimes combine to cause migration, with people anticipating that they may have to move to survive. This can lead to people moving individually to seek a new life − like many of those currently crossing the Mediterranean to Europe from North Africa − or to whole family groups looking for new lands.

Some countries already faced with voluntary or forced migration because of climate change are involved in relocating populations and are working internationally to find new homes in other countries for their people. This planning allows displaced people to live and work abroad with dignity, rather than be refugees.

An example is Kiribati in the Pacific, where displaced islanders have been trained for new jobs – for example, nursing − in countries such as Australia. Other new jobs include seafaring, teaching and policing. This enables family members to work abroad and support those relatives still at home who want to remain in their islands for as long as possible.

The report studied the national adaption programmes of 50 countries affected by climate change, and which fear that populations will have to move because of climate change. They include low-lying countries such as Bangladesh, a number of Pacific and Caribbean island nations, and dry African countries. The adaptation programmes are available from the UN Framework Convention on Climate Change.

The Nansen Initiative, launched in 2012 by the governments of Norway and Switzerland, is a project designed to study how to help people who are displaced across international borders by the effects of climate change.

The Initiative is in the process of looking at regions particularly affected by climate change that already have problems with migration. These are the Pacific, Central America, the “Greater Horn of Africa”, and South-East Asia and South Asia. The report concludes that all of the Pacific region island countries are already affected by slow and sudden-onset natural hazards, including cyclones, floods and drought.

Dry Corridor

A recent meeting held in Costa Rica heard that, as well as sudden natural disasters, changes in the rainfall pattern have led to what is known as the “Dry Corridor”. Participants discussed the plight of the indigenous people of Kuna, in Panama, where 65,000 individuals were relocated from their low-lying islands to higher ground.

In the Greater Horn of Africa region, climate change is expected to increase the already significant migration of populations caused by droughts and floods. Hundreds of thousands of people were displaced within Somalia or across the borders to Kenya, Ethiopia and Djibouti during the 2010-2011 droughts.

The report concludes that in addition to finding land, homes and jobs for the newcomers so they can support their families, they need to be made part of the community. Planned relocation efforts should be aimed at integration of the newcomers into existing political structures and giving them some participation in decision making about their own futures. The plight of the old and vulnerable, children and women must be considered.

The need is to avoid conflict within families, with authorities and host communities. Efforts should be made to avoid loss of cultural and spiritual identity and traditional knowledge. This will avoid the need for further migration and displacements.− Climate News Network

No way back for West Antarctic glaciers

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Birth of an iceberg: a massive crack appears in the Pine Island glacier in West Antarctica Image: Nasa Earth Observatory via Wikimedia Commons

Birth of an iceberg: a massive crack in West Antarctica’s Pine Island glacier
Image: Nasa Earth Observatory via Wikimedia Commons

By Tim Radford

Satellite data analysis reveals the ominous news that the melting glaciers of West Antarctica have passed the ‘point of no return’ as the southern hemisphere gets warmer

LONDON, 22 May – The glaciers of the West Antarctic may be in irreversible retreat, according to the evidence of satellite data analysed by scientists at the US space agency Nasa.

The study of 19 years of data, due to be reported in the journal Geophysical Research Letters, confirms the ominous news that the southern hemisphere is not just warming − it is that it is warming in a way that speeds up the melting of the West Antarctic glaciers.

Long ago, glaciologists began to wonder whether the West Antarctic ice sheet was inherently unstable. The water locked in the ice sheet in the Amundsen Sea region – the area the Nasa researchers examined − is enough to raise global sea levels by more than a metre. If the whole West Antarctic ice sheet turned to water, sea levels would rise by at least five metres.

Steady change

What the latest research has revealed is a steady change in the glacial grounding line, which is the point in a glacier’s progress towards the sea where its bottom no longer scrapes on rock but starts to float on water. It is in the nature of a glacier to flow towards the sea, and at intervals to calve an iceberg that will then float away and melt. The puzzle for scientists has been to work out whether this process has begun to accelerate.

Eric Rignot, a glaciologist at the Nasa Jet Propulsion Laboratory and the University of California, Irvine, thinks it has. He and his research partners believe that European Space Agency satellite data has recorded the points at which the grounding lines can be identified in a series of West Antarctic glaciers monitored between 1992 and 2011, as the glaciers flexed in response to the movement of tides.

All the grounding lines had retreated upstream, away from the sea − some by more than 30 kilometres. The grounding lines are all buried under hundreds of metres of ice, and are difficult to identify.

The shift of ice in response to tidal ebb and flow provides an important clue. It also signals an acceleration of melting, because it is the glacier’s slowness that keeps the sea levels static. As it inches towards the sea, there is time for more snow and ice to pile up behind it.

Speeds up

But if the water gets under the ice sheet, it reduces friction and accelerates the passage of frozen water downstream. So the whole glacier speeds up, and the grounding line moves yet further upstream.

Something similar has been reported from the glaciers of Greenland. And once the process starts, there is no obvious reason why it would stop. The melting will still be slow, but the latest evidence indicates that it seems to be inexorable.

“We’ve passed the point of no return,” Prof Rignot says. “At current melt rates, these glaciers will be history within a few hundred years.

“The collapse of this sector of West Antarctica appears to be unstoppable. The fact that the retreat is happening simultaneously over a large sector suggests it was triggered by a common cause, such as an increase in the amount of ocean heat beneath the floating sections of the glaciers. At this point, the end of this sector appears to be inevitable.” – Climate News Network

Reefs merit protection money

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Waves crash ashore on the Southern Pacific island of Niue Image: Gadfium via Wikimedia Commons

Waves sweep in across coral reefs surrounding the Southern Pacific island of Niue
Image: Gadfium via Wikimedia Commons

By Tim Radford

The great natural protective barriers that coral reefs provide for millions of people in coastal communities are seriously threatened, but scientists calculate that restoration projects would cost 20 times less than building artificial breakwaters to keep pounding waves at bay

LONDON, 19 May − Coral reefs, under threat around the tropics from the double menace of global warming and ocean acidification, are also natural protection systems for million people. And the importance of that protection is shown in a new scientific study confirming that a coral reef can reduce the energy of a pounding wave by up to 97%.

It is widely known that reef systems offer a natural barrier. But Filippo Ferrario, from the University of Bologna in Italy, and an international team of researchers report in Nature Communications that they decided to try to put a figure on the effectiveness of a living limestone rampart maintained by a tiny animal that is the basis for a rich submarine ecosystem.

They found that the shallowest part of a reef – the crest where the waves break first – dissipates 86% of the wave’s energy, while the whole reef can reduce the sea’s impact by 97%.

And the cost of maintaining a reef − that is, the cost of a reef restoration project − is US$1,290 per metre, compared with an average $19,791 per metre to build an artificial breakwater. That’s almost 20 times cheaper.

First line of defence

“Coral reefs serve as an effective first line of defence to incoming waves, storms and rising seas,” says study co-author Michael Beck, lead marine scientist of the US Nature Conservancy. “Two hundred million people across more than 80 nations are at risk if coral reefs are not protected and restored.”

Dr Ferrario adds “The study illustrates that the restoration of coral reefs is an important and cost-effective solution to reduce risks from coastal hazards and climate change.”

Marine scientists have argued for decades that natural systems such as mangrove forests, sandspits, water meadows and reefs offer protection for coastal cities. A huge proportion of humanity now lives in cities, and many cities have grown up on estuaries, around natural harbours, or on beach fronts − that is, at or near sea level.

Extreme weather

Sea levels will rise inexorably with global warming, and climate change threatens to increase the frequency and the magnitude of extreme weather events. There have been warnings that, by the end of the century, coastal flooding could cost up to a trillion dollars a year.

But the natural reefs that have offered shelter for so many people – for example, an estimated 41 million in Indonesia, 36 million in India, and 23 million in the Philippines – are under stress from pollution and overfishing.

Corals are also sensitive to rising water temperatures. And, although there is some evidence that some corals can adapt, there are serious concerns about the consequences of change in water chemistry as more and more atmospheric carbon dioxide dissolves in the oceans. – Climate News Network

Climate worries insurers and military

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US Navy personnel help with the clean-up in Staten Island, New York, after Superstorm Sandy hit in 2012 Image: US Navy via Wikimedia Commons

The US Navy helps with the clean-up in New York state after Superstorm Sandy in 2012
Image: US Navy via Wikimedia Commons

By Alex Kirby

Powerful voices in finance and the armed forces raise concerns about the risks of increasingly extreme weather events causing billions of dollars of damage and potentially igniting humanitarian disasters and regional conflicts

LONDON, 15 May − The risks associated with climate change have got some very important people worried − the people who pick up the bills, and those who clear up the mess or try to prevent it happening.

The world’s biggest and oldest insurance market, Lloyd’s of London, has published a report that urges insurers to include climate risks in their models. It says: “Scientific research points conclusively to the existence of climate change driven by human activity.

“Nevertheless, significant uncertainty remains on the nature and extent of the changes to our climate and the specific impacts this will generate. Many of the effects will become apparent over the coming decades and anticipating them will require forward projections, not solely historical data.”

Quoting the Munich Re insurance group , the World Bank says damage and weather-related losses around the world have increased from an annual average of $50bn in the 1980s to nearly $200bn over the last decade.

Causing havoc

The Lloyd’s report was published the day after the US National Climate Assessment (NCA) warned Americans that climate change is already causing havoc across the country. John Holdren, the White House science adviser, said the NCA was the “loudest and clearest alarm bell to date signalling the need to take urgent action to combat the threats to Americans from climate change”.

The most expensive year on record for natural disasters was 2011, when insured losses cost the industry more than $126bn. In 2012, Superstorm Sandy caused $35bn of insured losses, making it the most expensive hurricane in US history after Hurricane Katrina in 2005.

The Lloyd’s report says a 20cm rise in sea level at the southern tip of Manhattan Island increased Sandy’s surge losses by 30% (up to $8bn) in New York alone.

John Nelson, chairman of Lloyd’s, told the Guardian newspaper in London: “The destruction Sandy brought to the eastern US seaboard was responsible for claims of up to $300m in lost fine art, a consequence of the many expensive US beachfront homes damaged.”

Typhoon Haiyan, which devastated much of the Philippines and other parts of south-east Asia in November 2013, was one of the strongest tropical cyclones on record.

Trevor Maynard, head of exposure management and reinsurance at Lloyd’s, said: “Climate change is very much here to stay. Hurricanes are getting stronger worldwide, and especially over the north Atlantic. . .  At the moment we are heading for a rise of four degrees by the end of the century.”

Mission reality

IT’S NOT ONLY the insurers who believe that climate change is a real and growing risk. Increasingly, the prospect is preoccupying military planners.

Mark Wright, a Pentagon spokesman, said: “This is a mission reality, not a political debate. The scientific forecast is for more Arctic ice melt, more sea-level rise, more intense storms, more flooding from storm surge, and more drought.”

A former US Navy officer, retired Vice-Admiral Lee Gunn, is reported by NBC News as saying that the 2011 Arab Spring uprising could in part be traced to a winter drought in China, plus record heat waves and flooding in several other countries, including Russia.

Gunn concluded: “There was a drought and a wheat shortage that resulted in an increase in wheat prices and, therefore, an increase in bread prices − a staple in North Africa.”

NBC says US security experts are also concerned by possible threats to the rice harvest in south-east Asia, and specifically in Vietnam. They say the melting of the Himalayan glaciers would add to sea-level rise, ruining rice production and ravaging Bangladesh. If it did, they believe, that could create a flow of refugees into India, and also threaten fresh water resources in India and Pakistan.

Dennis McGinn, the US Navy assistant secretary for energy, installations and environment, told NBC that there were also worries in military circles about unstable governments and fragile societies.

“The last thing in the world these nations need are the severe and more frequent effects of bad weather, including crop failures,” McGinn said. “Therein is a recipe for the kind of instability that will inevitably involve the United States in humanitarian assistance, disaster relief or, indeed, in a regional conflict.”

A further report, by 16 retired generals and admirals, says climate change is a direct threat to national security and the US economy. The authors, members of the Military Advisory Board of the not-for-profit CNA Corporation, blame rising temperatures for, in part, worsening international tension. 

Their study says that the impacts of climate change are already intensifying instability in vulnerable regions, especially the resource-rich and rapidly changing Arctic. It says the projected impacts within the US will threaten its homeland security and major sectors of its economy. − Climate News Network

Glacier tracing goes digital

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The Aletsch glacier, Switzerland, a country where the health of glaciers is vital for tourism  IMAGE: Didier Baertschiger via Wikimedia Commons

The Aletsch glacier in Switzerland, where the health of glaciers is vital for tourism
Image: Didier Baertschiger via Wikimedia Commons

By Paul Brown

Detailed new maps of all the world’s glaciers have been produced to provide vital data that will help plan for the effects of climate change

LONDON, May 10 – Scientists have for the first time compiled a complete map of all the glaciers on Earth, providing extensive data that will help calculate sea level rise caused by global warming and the threats to communities that rely on melt water for agriculture and water supply.

The data, including length and volume, is contained in a collection of digital outlines of the world’s 200,000 glaciers − excluding the Greenland and Antarctica ice sheets.

It has been named the Randolph Glacier Inventory, after the US town of Richmond, New Hampshire, which was one of the meeting places for the group of international scientists who carried out the study as part of the fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC). The study has been published in the Journal of Glaciology.

Many glaciers are in extremely remote regions, such as the Himalayas and Greenland, which has made them hard to reach − let alone measure their length and thickness. A combination of large-scale efforts by volunteers on the ground and satellite technology has overcome these difficulties, enabling 70 scientists from 18 countries to compile the maps.

Overall, the glaciers cover 730,000 square km − an area the size of Germany, Poland and Switzerland combined. The volume of ice is about 170,000 cubic km, which is less than previously thought, but still enough to raise global sea levels between 35cm and 47cm if they all melted.

Sea level rise

Although this is less than 1% of the amount of water stored in the Greenland and Antarctica icecaps, it matters because most of the glaciers are melting now, actively adding to sea level rise. The two big icecaps are so cold inside that it will be thousands of years before the ice temperature rises enough to reach melting point.

Some of the most populous areas on earth, such as China, India and Pakistan, rely on melt water from glaciers for agriculture. At present, glaciers still provide plenty of summer water, but in many cases they are melting faster than winter snows are replenishing them. If this continues, the summer water flow will eventually cease, leading to calamity for the human populations that rely on them.

This is already happening in some parts of the Andes in South America, with some smaller glaciers having disappeared. The impact affects, for example, some wine-growing regions that rely on melt water for their vines.

There are still uncertainties about some of the measurements because, in some cases, glaciers are covered in debris as they move down mountains, while others are obscured by snow, making measurements of thickness more difficult.

Each glacier in the new inventory is represented by a computer-readable outline, making precise modelling of glacier-climate interactions much easier.

Glaciers currently add about one-third to existing sea level rise − about the same amount as the two giant ice sheets. The remaining third is the result of thermal expansion of the oceans as they warm.

Speed of retreat

In countries such as Switzerland, where the health of glaciers is vital for tourism, the speed of their retreat has been closely monitored. The melting is also important because it causes landslides, as well as impacting on water supply.

“The rapid shrinking of glaciers during the past 20 years is well recognisable in the Alps and other parts of the world,” said Frank Paul, a senior researcher in the University of Zurich’s Department of Geography and a co-author of the study.

Tobias Bolch, a researcher at the Institute for Cartography at the Technische Universität Dresden, Germany, is another co-author of the study. He said: “Here and in other parts of the world glaciers also impact on the regional to local-scale hydrology, natural hazards, and livelihoods in otherwise dry mountain regions.

“Accurate knowledge of water reserves and their future evolution is thus key for local authorities for early implementation of mitigation measures.” – Climate News Network

E. Antarctic ice basin ‘may be at risk’

FOR IMMEDIATE RELEASE

The German researchers say they have found a so far unknown source of sea level rise in East Antarctica Image: euphro via Wikimedia Commons

The German researchers say they have found a so far unknown source of sea level rise in East Antarctica
Image: euphro via Wikimedia Commons

By Alex Kirby

The East Antarctic ice sheet is thought by most scientists to be stable. But a German team says it has found how part of it could in time melt unstoppably.

LONDON, 4 May – Part of the East Antarctic ice sheet may be less stable than anyone had realised, researchers based in Germany have found.

Writing in Nature Climate Change, two scientists from the Potsdam Institute for Climate Impact Research (PIK) say the melting of quite a small volume of ice on the East Antarctic shore could ultimately trigger a discharge of ice into the ocean which would result in unstoppable sea-level rise for thousands of years ahead. www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2226.html

Their findings, which they say amount to the discovery of a hitherto overlooked source of sea level rise, appear unlikely to happen any time soon. They are based on computer simulations of the Antarctic ice flow using improved data of the ground profile beneath the ice sheet.

“East Antarctica’s Wilkes Basin is like a bottle on a slant,” said Matthias Mengel, the lead author of the study. “Once uncorked, it empties out.” The basin is the largest region of marine ice on rocky ground in East Antarctica.

At the moment a rim of ice at the coast holds the ice behind it in place, like a cork holding back the contents of a bottle. The air over Antarctica remains cold, but oceanic warming can cause the ice on the coast to melt. This could make the relatively small “cork” disappear.

Once it had gone, the result would be a long-term sea level rise of three to four metres. “The full sea-level rise would ultimately be up to 80 times bigger than the initial melting of the ice cork,” says the study’s co-author, Anders Levermann. “Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk.”

Stability ‘over-estimated’

Levermann is a lead author of the sea-level change chapter of the most recent scientific assessment report by the Intergovernmental Panel on Climate Change, the IPCC. Its report, published in September 2013, says Antarctica’s total sea level contribution could be up to 16 centimetres during this century.

“If half of that ice loss occurred in the ice-cork region, then the discharge would begin. We have probably overestimated the stability of East Antarctica so far,” says Levermann.

Melting would cause the retreat of the grounding line, where the ice on the solid continental landmass meets the sea and starts to float. The rocky ground beneath the ice in the Wilkes Basin forms a huge valley below sea-level which slopes downwards as it heads inland.

When the grounding line retreats from its current position on a ridge into the valley, the rim of the ice facing the ocean becomes higher than before. More ice is then pushed into the sea, eventually breaking off and melting. And the warmer it gets, the faster this happens.

For all the ice in the Wilkes Basin to be lost in this way would take 5,000-10,000 years, the simulations showed. But once it had started, the discharge of ice would slowly but relentlessly continue until the whole basin was empty, even if the climate ceased to warm.

Unavoidable consequences

“This is the underlying issue here”, said Matthias Mengel. “By emitting more and more greenhouse gases we might trigger responses now that we may not be able to stop in the future.”

He told the Climate News Network: “While the sparse existing observations do not indicate warmer water inflow towards the Wilkes ice sheet margin at present, there is no reason why changes similar to those in West Antarctica could not also occur here.”

The possibility remains a distant prospect. Mengel said some simulations produced the warm ocean conditions needed to remove the ice cork within the next 200 years, but It would take around 2,000 years to raise global sea levels by one metre.

He added: “The issue is that this would then be unstoppable…We have detected a new and previously overlooked source of sea level rise, therefore these numbers have to be added to the present sea level rise projections of the IPCC.

“Sea level as projected for the forthcoming centuries is already potentially devastating for many coastal areas around the globe. Every centimetre of sea level rise on top of these projections is even more significant.” – Climate News Network