Google Analytics Alternative

You are browsing the archive for Glaciers.

Greenland’s icecap loses stability

April 13, 2014 in Arctic, Glaciers, Greenland, Ice Loss, Sea level rise, Warming

FOR IMMEDIATE RELEASE

The calving front of the Jakobshaven Glacier in western Greenland in April 2012 Image: NASA ICE via Wikimedia Commons

The calving front of the Jakobshaven Glacier in western Greenland in April 2012
Image: NASA ICE via Wikimedia Commons

By Tim Radford

Greenland is losing ice from part of its territory at an accelerating rate, suggesting that the edges of the entire ice cap may be unstable.

LONDON, 13 April – Greenland – the largest terrestrial mass of ice in the northern hemisphere – may be melting a little faster than anyone had guessed.

A region of the Greenland ice sheet that had been thought to be stable is undergoing what glaciologists call “dynamic thinning”. That is because the meltwater from the ice sheet is getting into the sea, according to a study in Nature Climate Change.

In short, Greenland’s contribution to sea level rise has been under-estimated, and oceanographers may need to think again about their projections.

Shfaqat Khan from the Technical University of Denmark and colleagues used more than 30 years of surface elevation measurements of the entire ice sheet to discover that overall loss is accelerating. Previous studies had identified melting of glaciers in the island’s south-east and north-west, but the assumption had been that the ice sheet to the north-east was stable.

Four times as fast

It was stable, at least until about 2003. Then higher air temperatures set up the process of so-called dynamic thinning. Ice sheets melt every Arctic summer, under the impact of extended sunshine, but the slush on the glaciers tends to freeze again with the return of the cold and the dark, and since under historic conditions glaciers move at the proverbial glacial pace, the loss of ice is normally very slow.

But global warming, triggered by rising levels of greenhouse gases in the atmosphere, has changed all that. Greenland’s southerly glaciers have been in retreat and one of them, Jakobshavn Isbrae, is now flowing four times faster than it did in 1997.
Now the Danish-led team has examined changes linked to the 600 kilometre-long Zachariae ice stream in the north-east.

This has retreated by about 20 kms in the last decade, whereas Jakobshavn has retreated about 35 kms in 150 years. The Zachariae stream drains around one-sixth of the Greenland ice sheet, and because warmer summers have meant significantly less sea ice in recent years, icebergs have more easily broken off and floated away, which means that the ice stream can move faster. The researchers used satellite studies to measure ice loss.

“North-east Greenland is very cold. It used to be considered the last stable part of the Greenland ice sheet,” said one of the team, Michael Bevis of Ohio State University in the US.

Deep impacts

“This study shows that ice loss in the north-east is now accelerating. So now it seems that all of the margins of the Greenland ice sheet are unstable.”

The scientists used a GPS network to calculate the loss of ice. Glacial ice presses down on the bedrock below it: when the ice melts, the bedrock rises in response to the drop in pressure, and sophisticated satellite measurements can deliver enough information to help scientists put a figure on the loss of ice.

They calculate that between April 2003 and April 2012, the region was losing ice at the rate of 10 billion tons a year.

“This implies that changes at the margin can affect the mass balance deep in the centre of the ice sheet,” said Dr Khan. Sea levels are creeping up at the rate of 3.2 mm a year. Until now, Greenland had been thought to contribute about half a mm. The real figure may be significantly higher. – Climate News Network

Farming on sand

March 10, 2014 in Black Carbon, Deforestation, Development Issues, Flooding, Food security, Glaciers, Himalayas, Land Use, Monsoon, Rainfall, Soil, Water

FOR IMMEDIATE RELEASE

It was once a rice paddy but now it's only sand Image: Kieran Cooke

It was once a rice paddy but now it’s only sand
Image: Kieran Cooke

By Kieran Cooke

The Brahmaputra river is one of the world’s mightiest rivers, with millions dependent on its waters. The river also brings misery, with flooding and erosion major problems: climate change is likely to bring more hardship. Kieran Cooke, one of the editors of the Climate News Network, has been in Assam in northeast India, meeting villagers living on the Brahmaputra’s banks.

Laupani village, Assam, 10 March – The holes are dug laboriously in the dusty, sandy soil. Krishna Maya Sharma stops her work to wipe the sweat from her lined face.

“In the old days we would plant paddy here and have enough to sell at market” says Krishna, a 42 year old mother of six children.

“Now the soil is so bad, sweet potato is the only thing that will grow. The rest of our land is ruined.”

Laupani is a village in the north of the tea state of Assam, spread along the banks of the Brahmaputra river. In the distance, the pink evening light shines on the snow capped ridges of the eastern Himalayas.

The Brahmaputra, its waters rising more than 5,000 metres up on the Tibetan Plateau and flowing for about 3,000 kilometres through China, India and Bangladesh before joining up with the Ganges and out into the Bay of Bengal, is one of the world’s major rivers, 10 kilometres wide in places.

Widespread flooding

According to a recent report by India’s Third Pole organisation, the Brahmaputra carries a volume of water exceeded only by the Amazon and Congo rivers – and greater than the combined flow of Europe’s 20 largest rivers.

The river is a lifeline to millions, delivering vital nutrients to the soils of the plains but its fast flowing waters also cause widespread misery to people like Krishna.

Floods are frequent. There is widespread erosion and massive amounts of sand washed out of the river’s banks are deposited on surrounding fields, making once verdant areas into what looks like an enormous beach. The floods also bring invasive plant species that colonise agricultural lands.

More than 40% of Assam’s geographical area is designated as being flood prone: more than 1.5 million people were displaced by floods in 2012, lives were lost and whole villages were washed away.

Sand accumulations

“The waters were so deep and stayed so long that the grass was destroyed and our cattle died because they had no fodder” says Krishna.

“The sand means our land is no good anymore – my husband has given up being a farmer and is working in construction. Many young men go away to try and find jobs, there is nothing for them here.”

Locals – the majority of whom are poor, subsistence farmers – say river flows are becoming more unpredictable, with erosion and what’s called sandcasting becoming worse.

In part the flooding caused by the Brahmaputra’s waters is a natural phenomenon which has been going on for centuries. As the river’s waters cascade down from the Tibetan Plateau and Himalayas, millions of tons of sediment is washed onto the alluvial plains of Assam and others states in India’s northeast.

Earthquake danger

There are other forces at work: the region is a highly seismic zone. In 1950 the Brahmaputra river basin suffered one of the most violent earthquakes ever recorded. The geology of the area was changed and the river level was raised dramatically, by between eight and 10 metres in places.

Climate change is another factor, with a combination of rising temperatures and accumulations of what’s known as black carbon or soot in the high Himalayas and on the Tibetan Plateau causing glaciers which feed into upper reaches of the Brahmaputra to melt.

Increasingly unpredictable rainfall patterns, with periods of intense downpours, are also contributing to more volatile river flows.

Professor Jogendra Nath Sarma is a locally based geologist who has been studying the Brahmaputra for years.

“Over time different rivers in the Brahmaputra basin have merged, braiding over a very wide area. Thousands of square kilometres of land has been eaten away. Rampant deforestation is another big contributor to land erosion. “

In the past, says Professor Sarma, people would migrate to higher ground during the flood season but now, due to population growth and large scale immigration, there is nowhere for them to go.

Doubtful future

The future does not look good. According to models produced by scientists at the Indian Institute of Technology in Guwahati, Assam’s capital, climate change will result in the Brahmaputra valley region experiencing more flood events.

The Institute says that not only will river peak flows increase: so will the incidence of pre-monsoon flooding, endangering key phases of the agricultural cycle.

Talk of climate change is not of great interest to Krishna, digging holes for her sweet potato plants. She has more immediate things to worry about.

“Life is getting harder. Every time the floods come, I wonder what will happen. But where else can we go?” – Climate News Network


 

 

 

 

India’s diesel fumes fuel glacier melt

March 6, 2014 in Black Carbon, Climate, Glaciers, Himalayas, Ice Loss, Mountains, Pollution

FOR IMMEDIATE RELEASE

Nanda Devi, one of the highest peaks in the Himalayas: Air pollution from the cities is affecting the mountain glaciers Image: Anirban c* via Wikimedia Commons

Nanda Devi, one of the highest peaks in the Himalayas: Air pollution from the cities is affecting the mountain glaciers
Image: Anirban c8 via Wikimedia Commons

By Kieran Cooke

As India’s economy expands, so does pollution, particularly in the country’s major cities. Kieran Cooke, one of our editors, has recently been in Kolkata, one of the country’s biggest and most polluted population centres: he says increasing pollution is not only harming Kolkata’s citizens – it’s also a likely contributor to climate change taking place in the Himalayan region.

KOLKATA, 6 March – Being a traffic policeman in Kolkata is a life-threatening business. Not only are you at risk of being run over on the traffic-clogged roads and streets of this chaotic city of 14 million – you’re also more than likely to suffer from serious health problems due to some of the worst air pollution not just in India, but in the world.

According to a 2012 report by the New Delhi-based Centre for Science and Environment on air quality in Kolkata, seven out of every ten people in the city suffer from some form of respiratory ailment: not surprisingly, traffic policemen and the city’s thousands of street dwellers are among the high risk groups.

Air pollution, particularly related to diesel-fuelled vehicles that jam Kolkata’s roads, is also linked to the city’s unusually high levels of lung cancer.

Meanwhile the government’s own Central Pollution Control Board gives Kolkata and New Delhi the unenviable status of being joint winners of India’s most polluted city prize.

All this is not just bad news for people living in Kolkata and India’s other major urban conglomerations. The increasing air pollution in India’s cities – particularly those in the northern parts of the country – also has an impact on the degree of melt taking place in glaciers in the Himalayas.

Soaking up the heat

Diesel fumes, along with smoke from coal burning, cooking fires and the burning of waste, are among the main sources of particulate matter called soot or black carbon. Recent studies suggest that funeral pyres and even the burning of incense at temples are also contributors to the accumulation of soot.

This black carbon rises into the atmosphere and is driven by winds on to the snow or ice in the Himalayas, darkening the surface and in the process reducing reflectivity and causing the surface to absorb more heat.

The International Centre for Integrated Mountain Development (ICIMOD), based In Kathmandu, Nepal, is the only transboundary organisation looking at climate developments across the Hindu Kush-Himalayan region.

According to ICIMOD estimates, black carbon is likely responsible for a large part – around 30% by some calculations – of glacial melt in the region. It says most of the black carbon deposited in the Himalayas and in the southern area of the Tibetan Plateau comes from the plains of India, while black carbon on the eastern and northern parts of the Plateau originates in central China.

Bigger harvests

ICIMOD says that while data is limited, studies suggest black carbon may not only be a factor in hastening the melt of mountain glaciers – it could also substantially alter rainfall patters and affect the behaviour of the monsoon.

While many well-organised environmental NGOs and other groups have formed in India in recent years, the environment – and climate change – does not come high on the political agenda.

A late 2013 study by the World Bank and the International Cryosphere Climate Initiative (ICCI) said that up to a million deaths could be avoided each year in the Himalayan region by cutting back on emissions of black carbon and methane. The study also said that regional yields of crops such as rice and wheat could be significantly improved by reducing black carbon.

“The health of people around the world will improve greatly if we reduce emissions of black carbon and methane”, says Jim Yong Kim, the World Bank president.

“Limiting these emissions will also be an important contributor to the fight against climate change.” – Climate News Network

Greenland’s fastest glacier picks up pace

February 6, 2014 in Arctic, European Space Agency, Glaciers, Greenland, Ice Loss, Lakes, Sea level rise

FOR IMMEDIATE RELEASE

An iceberg calved from the rapidly accelerating Jakobshavn Isbræ floats in Greenland's Disko Bay Image: Courtesy of Ian Joughin, PSC/APL/UW

An iceberg calved from the rapidly accelerating Jakobshavn Isbræ floats in Greenland’s Disko Bay
Image: Courtesy of Ian Joughin, PSC/APL/UW

By Tim Radford

Research from the Arctic shows Greenland’s fastest-flowing glacier has doubled its summer flow pace in a decade, and ice cover on Alaskan lakes is declining.

LONDON, 6 February – A fast-moving Arctic glacier which has earned a place in history is now accelerating even more quickly. The Jakobshavn Isbrae (the Danish word for glacier) is a massive river of ice from the Greenland ice sheet to an Atlantic ocean fjord and is thought – there is no way of proving this – to be the source of the giant iceberg that sank the Titanic in 1912.

According to research published in the European Geosciences Union journal The Cryosphere, summer flow speeds have doubled yet again since a Nasa measurement in 2003. And that in turn represented a doubling of flow speeds since 1997.

The Jakobshavn glacier is Greenland’s fastest-flowing glacier. It now moves at 17 kilometres a year. That works out at 46 metres a day. With accelerations like this, phrases like “glacial pace” may no longer serve as clichés of lethargic movement. These speeds are recorded in the summer, when all glaciers are more likely to be a bit friskier. But even when averaged over the whole year, the glacier’s flow has accelerated threefold since the 1990s.

Icebergs “calve” from glaciers – they break off and drift out to sea. The Arctic ice sheet is thinning, and most of the planet’s glaciers are retreating as climates warm, so the Jakobshavn glacier is carrying less ice, at a faster rate, over shorter distances than ever before, and by the end of the century could have shifted 50 kilometres upstream. But right now it is also contributing to sea level rise at a faster rate.

“We know that from 2000 to 2010 this glacier alone increased sea level by about 1mm”, said Ian Joughin, of the Polar Science Centre at the University of Washington, who led the research. “With the additional speed it will likely contribute a bit more than this over the next decade.”

The scientists used satellite data to measure the rate of summer change in Greenland. But other satellite radar imagery has begun to reveal an ominous picture of change elsewhere in the Arctic, on the north slope of Alaska. Even during the winter months, ice on the lakes of Alaska has begun to decline. Warmer climate conditions means thinner cover on shallow lakes and a smaller fraction that freeze entirely during the winter months.

“We were stunned to observe such a dramatic ice decline during a period of only 20 years”

Cristina Surdu of the University of Waterloo in Canada and colleagues report in The Cryosphere that there has been a 22% fall in grounded ice – frozen from surface to lakebed – between 1991 and 2011.

They expected to find a decline in ice thickness when they embarked on a study of radar observations of 402 lakes near Barrow in Alaska from the European earth resources satellites ERS-1 and ERS-2. That was because they already had temperature and precipitation records from Barrow dating back five decades.

Freeze dates in the region are now occurring on average six days later than in the past, and the ice is breaking up on average around 18 days earlier.

“At the end of the analysis, when looking at trend analysis results, we were stunned to observe such a dramatic ice decline during a period of only 20 years”, Surdu said. – Climate News Network

Climate imperils Peru’s poverty drive

December 26, 2013 in Amazonia, Climate risk, Development Issues, Drought, Glaciers, South America

FOR IMMEDIATE RELEASE

A garbage picker in Peru: Rising temperatures may endanger the country's anti-poverty policies Image: Alex Proimos from Sydney, Australia, via Wikimedia Commons

A garbage picker in Peru: Rising temperatures may endanger the country’s anti-poverty policies
Image: Alex Proimos from Sydney, Australia, via Wikimedia Commons

By Alex Kirby

Peru’s efforts to reduce poverty are at risk from the effects of climate change, one example of the problems facing the wider Amazonia region in a warming world.

LONDON, 26 December – Peru is the country chosen to host the 2014 UN climate conference, a key meeting for trying to advance an ambitious plan to rein in greenhouse emissions which is planned for agreement in 2015.

But the country has recently earned a rather more dubious distinction. In 2012, for the first time, the Peruvian Amazon became a net emitter of carbon dioxide rather than oxygen, according to the latest human development country report of the UN Development Programme (UNDP).

The Amazon rainforest usually acts as a carbon sink, absorbing atmospheric CO2 rather than releasing it. Scientists think this reversal of its normal behaviour results from the droughts in the western Amazon in 2005 and 2010 and say it shows Peru’s vulnerability to climate change.

Peru has more than halved its poverty rate in the last decade, from 48.5% in 2004 to 25.8% in 2012. But the 2013 UNDP report said its vulnerability to a warming climate could cancel the progress it has made in directing economic growth into sustained poverty reduction.

Glaciers going

One of the UNDP report’s authors, Maria Eugenia Mujica, said: “If we disregard [environmental] sustainability, whatever progress we have made in poverty reduction or improvement of human development will just be erased due to climate change”.

With a temperature rise in the Andes of 0.7°C between 1939 and 2006, Peru has already lost 39% of its tropical glaciers. Temperature rises of up to 6°C are expected in many parts of the Andes by the end of this century.

Peru’s economic success is in some cases directly linked to activities which contribute to climate change, for example illegal gold mining and logging, and the cocaine trade – all of them environmentally destructive, but lucrative.

“The growth does not come from education or health, but from predatory activities, like [resource] extraction and mining”, said Francisco Santa Cruz, another of the report’s authors.

Peru is trying to protect itself against the ravages of a warmer world, but the odds are against it. It recently announced plans to invest US $6 bn in renewable energy projects: around the same time came predictions that climate change could cost between 8% and 34% of its GDP. A report by the Inter-American Development Bank has said the entire Latin American and Caribbean region will face annual damages from global warming of about $100 bn by 2050.

Taken for granted

The Global Canopy Programme and the International Center for Tropical Agriculture, describing climate change as “a threat multiplier”, called in a report this month for a new security agenda for Amazonia and the countries of the region.

Manuel Pulgar, Peru’s environment minister, said at the report’s launch: “Climate change is a global problem, but one that will multiply local and regional problems in unforeseeable ways.

“In Latin America, we have taken Amazonia and its seemingly limitless water and forests as a given. But recent unprecedented droughts have shown us just what happens when that water security falters.

“it impacts food and energy production, it affects the wellbeing of entire populations, and it leaves governments and businesses with a big bill to pay. The science is clear, so we cannot afford to miss the opportunity for positive action now.”  – Climate News Network

 

This report is based on a post on the London Guardian’s Poverty Matters Blog by Dan Collyns on 13 December 2013.

Tree find confirms Italian alpine melt

December 16, 2013 in Europe, Glaciers, Palaeoclimatology

FOR IMMEDIATE RELEASE

The Italian Alps are warming at twice the global rate, and their glaciers are in retreat Image: Ekharlamov via Wikimedia Commons

The Italian Alps are warming at twice the global rate, and their glaciers are in retreat
Image: Ekharlamov via Wikimedia Commons

By Tim Radford

Evidence from high in the Italian Alps confirms that they are warming at twice the global rate, with the region’s glaciers in retreat everywhere.

LONDON, 16 December – It was only a single, withered conifer needle, but it told a dramatic story of climate change. Glaciologists found it in a set of ice cores drilled through a glacier on top of Mount Ortles, in the Italian Alps.

It lay about 80 metres below the glacial surface, encased in solid ice, and carbon dating confirmed that it had blown from the branches of Larix decidua, the European larch, 2,600 years earlier.

It was found about 30 kilometres from a far more dramatic exposure: the body of Ötzi the Iceman, a mummified Bronze Age corpse revealed  by a melting glacier in 1991.

Both finds deliver the same uncompromising message: for at least 5,000 years – because Ötzi perished around that time – the Italian Alps had continued to stay frozen throughout the year.

And now they are melting. Or, to put it the scientific way, in the words of Paolo Gabrielli, of Ohio State University, who led the project: “Our first results indicate that the current atmospheric warming at high elevation in the Alps is outside the normal cold range held for millennia. This is consistent with the rapid, ongoing shrinking of glaciers at high elevation in this area.”

The problem for all climate scientists – and for glaciologists in particular – is that direct measurements are relatively recent: the oldest thermometer readings date back little more than three centuries, and consistent world coverage began only in the 20th century.

Since climates undergo natural cycles of change on a scale of centuries, measurements over a short period are not, in themselves, of much use. Glaciers, in particular, are a problem: retreat or advance would have been  imperceptible to the small populations likely ever to have observed them.

More evidence likely

Visual records – paintings dating from the early 19th century, in most cases – indicate that today’s glaciers are in retreat, but Romantic Age painters weren’t particularly interested in climate or precision topography, so the evidence from paintings is limited.

But direct measurement of surviving ice really can tell a story, and Gabrielli’s team produced a fragment of this narrative in San Francisco at a meeting of the American Geophysical Union.

The Alps are warming at twice the global rate, and the glaciers are everywhere in retreat. Alto dell’Ortles is the highest glacier in the eastern Alps, at 3,900 metres: its ice is likely to hold much more evidence of climate change and human impact.

As they drilled into the glacier, the research scientists from six nations found that the first 30 metre layer was composed of grainy compacted snow that had partly melted. Below that was nothing but solid, enduring ice all the way down to frozen bedrock.

They could be sure that nothing had changed in this permanent layer of ice for at least 2,600 years, because it had preserved a larch needle from a tree that must have grown at least 2,000 years after Ötzi had perished in the same complex of Alpine glaciers.

“The leaf supports the idea that prehistoric ice is still present at the highest elevations of the region,” Gabrielli said. – Climate News Network

Warsaw – Day 2: Extreme weather – who suffers most?

November 12, 2013 in Climate, Climate risk, Extreme weather

FOR IMMEDIATE RELEASE

Image: © Marek and Ewa Wojciechowscy/Trips over Poland via Wikimedia Commons

Image: © Marek and Ewa Wojciechowscy/Trips over Poland via Wikimedia Commons

By Paul Brown in Warsaw

One of the Climate News Network editors, Paul Brown, is in the Polish capital, host of the UN climate talks – the 19th Conference of the Parties (COP 19) of the United Nations Framework Convention on Climate Change. He reports that developing countries have been hit hardest in the last 20 years as climate change takes hold.

Haiti topped the chart as the country most at risk from extreme weather events in this year’s Global Climate Risk Index, because of the devastation caused by Hurricane Sandy in 2012 that left 200,000 people homeless and destroyed many crops.

The Index, released on the second day of the UN climate conference here, noted that while the damage in New York made all the headlines it was in Haiti that losses were greatest.

All ten of the countries most at risk from extreme events in the 1993 to 2012 period were developing countries, emphasising the message in Warsaw that poor countries cannot cope with the increasing number of catastrophes by themselves.

The major issue at the conference in the wake of the current Philippine disaster is how to finance “loss and damage” caused by an increasingly unstable climate.

The index, compiled by a think tank called Germanwatch from figures supplied by the giant re-insurance company Munich Re, lists ten countries most affected in 2012 and the long-term climate risk from loss of life and damage from 1993 to 2012.

The Philippines came second in the 2012 list because of a devastating cyclone in that year and is almost certain to come number one in next year’s table because of the current crisis caused by super-typhoon Haiyan, which has killed more than 10,000 people.

“…the self-help capacity of countries is being overwhelmed by the scale of the climate disasters they are facing.”

Pakistan came third in both this year’s list and the 2011 table, showing its increasing vulnerability to floods and droughts.

In the 20-year long-term risk list Honduras was first, Myanmar (Burma) second and Haiti third, reflecting a constant battering of these countries by extreme weather events.

Christoph Bals, policy director of Germanwatch, said: “The report illustrates that the self-help capacity of countries is being overwhelmed by the scale of the climate disasters they are facing.

“These are the countries that have contributed least to climate change because they have tiny emissions, yet they are the countries that are suffering most from it. Developed countries that have caused the problem have a moral responsibility to help.”

Bals admitted that the list had flaws, in that it did not include the gradual effects of sea level rise and melting glaciers, but said there were no data for the losses caused in this way, only by more sudden disasters. Africa was also under-represented because losses from drought were hard to evaluate.

“Our people have contributed least to climate change, yet they are enduring great suffering.”

Muhammad Irfan Tariq, director general of the Climate Change Division of the Pakistan Government, who helped launch the report in Warsaw, said: “The report makes clear that my country is already adversely affected by climate change. Loss of glaciers, floods and droughts are causing suffering and loss of life, not to mention the economic losses in a mainly agricultural economy.

“In 1950 we had 5,000 litres of fresh water available for each person in the country. Now it is less than 1,000. As a result we are suffering loss of energy from hydro-electricity, shortages of food, and general water scarcity. We need more reservoirs to capture the snowmelt in the spring to last us for the year.

“Our people have contributed least to climate change, yet they are enduring great suffering. We have had disastrous floods followed by three years of droughts; we have not the resources to deal with this on our own.”

Unusually several European countries, including Serbia and Bosnia/Herzegovina, made the 2012 list. The report says that after experiencing the hottest summer in 40 years the Balkan countries suffered from extensive droughts that destroyed most of their crops.

The ten most-affected countries in 2012, in order of seriousness, are Haiti, the Philippines, Pakistan, Madagascar, Fiji, Serbia, Samoa, Bosnia/Herzegovina, Russia and Nigeria.

The top ten for 1993 to 2012 are Honduras, Myanmar, Haiti, Nicaragua, Bangladesh, Vietnam, the Philippines, the Dominican Republic and Mongolia (equal 8th), and Thailand and Guatemala (equal 10th). – Climate News Network

Shock outlook for local weather

October 9, 2013 in Climate, Extreme weather, Forecasting, Greenhouse Gases, Policy, Pollution, Warming, Weather

FOR IMMEDIATE RELEASE

A global map of when cities can expect climate change to affect local climates drastically Image: Mora et al, University of Hawaii
A world map of when cities can expect global warming to have a drastic effect on local climates
Image: Mora et al, University of Hawaii

 By Tim Radford

Detailed new research into when global warming will start to have a serious effect on local climates has produced the shock finding that it could happen much sooner than scientists have previously predicted

London, 9 October – Catastrophic climate change may begin sooner than anyone expected ­­– and the first place to feel the heat could be a small but important city in Indonesia. By 2020, oceanographers and climate scientists warn, rising air temperatures around Manokwari in West Papua could trigger a new climate regime.

Dr Camilo Mora and research colleagues at the University of Hawaii report today in Nature that they looked at the question of when global warming would begin to alter local climates. And they admit that they were shocked by the results of their calculations.

Weather is what happens every day – gentle rain, torrential rain, heat waves, cold snaps, and so on. Climate is the range and pattern of these turbulent events over a generation or so.

For more than two decades, climate scientists have been warning that increasing greenhouse gas emissions will change climate inexorably. Increasingly – one of the most recent cases reported was in August this year – researchers have warned that, by mid-century, the world could move into a regime in which, in some continental locations, even the coolest summer days will be hotter than the hottest days experienced now.

Future warming

Such warnings are general: they define what will happen on average. But Mora and colleagues were concerned with specifics. So they used 39 climate models or computer simulations of climate change, plus climate records of observed change from 1860 to 2005, to compose a new map of future warming around the planet.

They considered variables such as precipitation, evaporation, ocean surface temperature and the chemistry (the pH) of the seas.  And they made assumptions – one of which was that the world would go on burning natural gas, coal and oil, manufacturing cement, clearing forests and so on at an increasing rate.

Their calculations told them that, if that was so, then air temperatures worldwide would rise to force a new climate regime – that is, the climate pattern would shift continuously beyond the most extreme records experienced in the past 150 years. And the date for this tipping point would be 2047.

However, 2047 represents a mean – a date arrived at by defining the average. So some places will feel the big heat well ahead of 2047, while many others will be affected decades later.

The scientists therefore went for greater detail. Which is why Manokwari, a metropolitan area of fewer than 300,000 people, and home to 24 distinct tribal groups, each with its own language and culture, looks set to make history.

It will, according to the scientists’ calculations, start to experience climate change in just seven years from now. By 2020, the local climate will be consistently hotter, and the local rainfall patterns could alter.

“The results shocked us . . . Within my generation, whatever climate we were used to will be a thing of the past.”

Dr Mora admitted: “The results shocked us. Regardless of the scenario, changes will be coming soon. Within my generation, whatever climate we were used to will be a thing of the past.”

Other tropical and subtropical cities will start to share the Manokwari experience a little later. Things will become increasingly uncomfortable in Lagos by 2029, in Mexico City by 2031, and Cairo by 2036.  Moscow, which has already recorded unprecedented heat waves this century, will experience permanent change in 2063. Reykjavik will remain relatively untroubled until 2066.

The finding, to an extent, upsets some expectations about the impact of global warming. For a quarter of a century, climate scientists have warned that the fastest changes will be in the Arctic, and the loss of sea ice has been dramatic.

But the tropics are home to the greatest concentrations of biodiversity – the coral reefs, rain forests and savannas – and also to the greatest numbers of the poorest people.

Vulnerable to change

Tropical plants and animals are finely adapted to environmental conditions, and vulnerable to change; coral reefs and plants in particular can hardly migrate. Crop plants, too, are sensitive to extremes of heat, and so are water supplies. The implications are that at least a billion people – and possibly very many more – could find themselves increasingly short of food and water, and with ever greater strains on sanitation and health systems.

Swift and determined action to stabilise emissions could delay the tipping point and give more nations time to adapt, but the bad news is that such action could now only delay the mean date to 2069 – and the developing nations in the tropics would still be first in the firing line.

“Our results suggest that countries first impacted by unprecedented climates are the ones with the least capacity to respond,” said Ryan Longman, one of the co-authors of the study. “Ironically, these are countries that are least responsible for climate change in the first place.”Climate News  Network

Projected Year of Climate Departure from Historical Variability

Multi-model averages showing the projected year of climate departure from historical variability for cities around the world using two Representative Concentration Pathway (RCP) scenarios. RCP4.5 represents a CO2 concentration of 538 ppm by 2100. RCP8.5 represents 936 ppm CO2 by  2100.

COUNTRY CITY

RCP8.5

RCP4.5

Afghanistan Kabul

2045

2071

Albania Tirana

2046

2070

Algeria Algiers

2041

2063

Andorra Andorra la Vella

2044

2070

Angola Luanda

2035

2052

Antigua and Barbuda St. John’s

2033

2047

Argentina Buenos Aires

2066

2094

Armenia Yerevan

2045

2076

Australia Perth

2042

2072

Australia Canberra

2045

2072

Australia Sydney

2038

2052

Australia Melbourne

2045

2073

Australia Brisbane

2042

2070

Austria Vienna

2055

2084

Azerbaijan Baku

2047

2072

Bahamas Nassau

2029

2041

Bahrain Manama

2032

2054

Bangladesh Dhaka

2054

2082

Barbados Bridgetown

2034

2046

Belarus Minsk

2065

2091

Belgium Brussels

2056

2086

Belize Belmopan

2034

2048

Benin Porto-Novo

2029

2043

Bhutan Thimphu

2035

2052

Bolivia La Paz

2028

2037

Bosnia and Herzegovina Sarajevo

2051

2079

Botswana Gaborone

2050

2083

Brazil Rio de Janeiro

2050

2079

Brazil São Paulo

2051

2083

Brazil Brasília

2047

2072

Brunei Bandar Seri Begawan

2027

2035

Bulgaria Sofia

2051

2082

Burkina Faso Ouagadougou

2036

2053

Burundi Bujumbura

2035

2049

Cambodia Phnom Penh

2043

2068

Cameroon Yaoundé

2025

2032

Canada Ottawa

2047

2072

Canada Toronto

2049

2074

Canada Montreal

2046

2072

Canada Vancouver

2056

2083

Cape Verde Praia

2042

2066

Central African Republic Bangui

2028

2036

Chad N’Djamena

2045

2075

Chile Santiago

2043

2071

China Beijing

2046

2078

China Shanghai

2045

2070

China Tianjin

2050

2080

China Guangzhou

2046

2072

China Shenzhen

2043

2065

China Dongguan

2044

2071

China Hong Kong

2043

2065

China Wuhan

2045

2070

China Chongqing

2046

2075

China Shenyang

2048

2080

Colombia Bogotá

2033

2047

Comoros Moroni

2031

2048

Costa Rica San José

2037

2058

Cote d’Ivoire Abidjan

2026

2034

Cote d’Ivoire Abidjan

2026

2034

Croatia Zagreb

2053

2085

Cuba Havana

2031

2045

Cyprus Nicosia

2039

2059

Czech Republic Prague

2056

2085

Denmark Copenhagen

2060

2089

Djibouti Djibouti

2034

2048

Dominica Roseau

2034

2048

Dominican Republic Santo Domingo

2026

2033

DR Congo Kinshasa

2028

2038

Ecuador Quito

2034

2050

Egypt Cairo

2036

2057

Egypt Alexandria

2036

2054

El Salvador San Salvador

2033

2049

Equatorial Guinea Malabo

2024

2030

Eritrea Asmara

2035

2053

Estonia Tallinn

2065

2091

Ethiopia Addis Ababa

2036

2054

Fiji Suva

2038

2065

Finland Helsinki

2063

2091

France Paris

2054

2084

Gabon Libreville

2024

2028

Georgia Tbilisi

2046

2077

Germany Berlin

2061

2090

Ghana Accra

2027

2034

Greece Athens

2041

2064

Grenada St. George’s

2032

2042

Guatemala Guatemala City

2038

2054

Guinea Conakry

2027

2036

Guinea-Bissau Bissau

2032

2045

Guyana Georgetown

2029

2039

Haiti Port-au-Prince

2025

2030

Honduras Tegucigalpa

2040

2055

Hungary Budapest

2056

2085

Iceland Reykjavik

2066

2084

India Mumbai

2034

2051

India Delhi

2050

2081

India Bangalore

2046

2069

India Hyderabad

2057

2085

India Ahmedabad

2046

2075

India Chennai

2034

2052

India Kolkata

2053

2081

India Surat

2045

2066

India Pune

2037

2055

India Jaipur

2045

2074

India New Delhi

2050

2081

Indonesia Jakarta

2029

2042

Indonesia Manokwari

2020

2025

Iran Tehran

2045

2068

Iraq Baghdad

2036

2055

Ireland Dublin

2059

2083

Israel Jerusalem

2038

2061

Italy Rome

2044

2067

Italy Milan

2048

2073

Italy Naples

2044

2065

Jamaica Kingston

2023

2028

Japan Tokyo

2041

2067

Japan Yokohama

2041

2067

Japan Kyoto

2040

2065

Jordan Amman

2040

2063

Kazakhstan Astana

2058

2091

Kazakhstan Almaty

2047

2075

Kenya Nairobi

2036

2058

Kiribati Tarawa

2049

2074

Kuwait Kuwait City

2036

2054

Kyrgyzstan Bishkek

2048

2077

Laos Vientiane

2056

2085

Latvia Riga

2064

2091

Lebanon Beirut

2040

2063

Lesotho Maseru

2038

2057

Liberia Monrovia

2025

2032

Libya Tripoli

2038

2059

Liechtenstein Vaduz

2051

2076

Lithuania Vilnius

2067

2091

Luxembourg Luxembourg City

2056

2083

Macedonia Skopje

2049

2080

Madagascar Antananarivo

2032

2047

Malawi Lilongwe

2036

2053

Malaysia Kuala Lumpur

2029

2039

Maldives Malé

2025

2027

Mali Bamako

2034

2051

Malta Valletta

2038

2054

Marshall Islands Majuro

2027

2036

Mauritania Nouakchott

2040

2069

Mauritius Port Louis

2037

2059

Mexico Mexico City

2031

2050

Micronesia Palikir

2024

2031

Moldova Chisinau

2058

2092

Monaco Monaco

2044

2066

Mongolia Ulan Bator

2054

2087

Montenegro Podgorica

2048

2075

Morocco Casablanca

2048

2080

Morocco Rabat

2046

2076

Mozambique Maputo

2038

2060

Myanmar Yangon

2036

2055

Myanmar Mandalay

2045

2072

Myanmar Yangon

2036

2055

Myanmar Naypyidaw

2041

2069

Namibia Windhoek

2044

2067

Nepal Kathmandu

2041

2063

Netherlands Amsterdam

2058

2086

New Zealand Wellington

2041

2070

Nicaragua Managua

2037

2052

Niger Niamey

2039

2060

Nigeria Lagos

2029

2043

Nigeria Abuja

2034

2047

North Korea Pyongyang

2042

2068

Norway Oslo

2061

2088

Oman Muscat

2032

2049

Pakistan Karachi

2035

2055

Pakistan Lahore

2049

2073

Pakistan Islamabad

2042

2064

Palau Ngerulmud

2023

2025

Panama Panama City

2031

2045

Papua New Guinea Port Moresby

2033

2043

Paraguay Asunción

2059

2086

Peru Lima

2038

2057

Peru Lima

2038

2057

Philippines Manila

2038

2055

Poland Warsaw

2063

2090

Portugal Lisbon

2052

2084

Qatar Doha

2033

2052

Republic of the Congo Brazzaville

2028

2038

Romania Bucharest

2054

2085

Russia Moscow

2063

2092

Russia Saint Petersburg

2064

2093

Rwanda Kigali

2031

2042

Saint Kitts and Nevis Basseterre

2033

2047

Saint Lucia Castries

2034

2047

Saint Vincent and the   Grenadines Kingstown

2033

2046

Samoa Apia

2028

2039

San Marino San Marino

2047

2072

Sao Tome and Principe São Tomé

2025

2028

Saudi Arabia Riyadh

2032

2050

Saudi Arabia Jeddah

2034

2050

Senegal Dakar

2044

2073

Serbia Belgrade

2054

2081

Seychelles Victoria

2027

2039

Sierra Leone Freetown

2028

2037

Singapore Singapore

2028

2037

Slovakia Bratislava

2055

2082

Slovenia Ljubljana

2051

2075

Solomon Islands Honiara

2024

2026

Somalia Mogadishu

2030

2040

South Africa Pretoria

2043

2068

South Africa Johannesburg

2043

2068

South Africa Cape Town

2038

2060

South Africa Durban

2035

2053

South Africa Bloemfontein

2043

2067

South Korea Seoul

2042

2067

South Korea Busan

2044

2068

South Sudan Juba

2041

2056

Spain Madrid

2046

2076

Spain Barcelona

2043

2065

Sri Lanka Colombo

2029

2037

Sudan Khartoum

2038

2062

Suriname Paramaribo

2028

2040

Swaziland Mbabane

2041

2067

Sweden Stockholm

2060

2089

Switzerland Bern

2050

2080

Switzerland Zurich

2050

2077

Switzerland Geneva

2048

2076

Syria Damascus

2041

2068

Taiwan Taipei

2042

2066

Tajikistan Dushanbe

2045

2071

Tanzania Dodoma

2040

2063

Tanzania Dar es Salaam

2034

2053

Thailand Bangkok

2046

2070

The Gambia Banjul

2037

2062

Timor-Leste Dili

2030

2040

Togo Lomé

2031

2046

Tonga Nukualofa

2043

2075

Trinidad and Tobago Port of Spain

2032

2044

Tunisia Tunis

2038

2060

Turkey Istanbul

2046

2075

Turkey Ankara

2047

2080

Turkmenistan Ashgabat

2046

2072

Tuvalu Funafuti

2029

2040

Uganda Kampala

2047

2064

UK London

2056

2088

Ukraine Kiev

2063

2090

United Arab Emirates Abu Dhabi

2033

2047

Uruguay Montevideo

2056

2084

USA Orlando

2046

2074

USA New York City

2047

2072

USA Washington DC

2047

2071

USA San Francisco

2049

2074

USA Anchorage

2071

2095

USA Honolulu

2043

2067

USA Los Angeles

2048

2079

USA Chicago

2052

2081

USA Houston

2050

2081

USA Philadelphia

2047

2072

USA Phoenix

2043

2073

USA San Diego

2046

2075

USA Dallas

2063

2093

USA Austin

2058

2090

USA Detroit

2051

2076

USA Seattle

2055

2082

USA Denver

2048

2079

Uzbekistan Tashkent

2046

2072

Vanuatu Port Vila

2038

2065

Venezuela Caracas

2034

2052

Vietnam Ho Chi Minh City

2039

2062

Vietnam Hanoi

2055

2085

Yemen Sanaa

2039

2060

Zambia Lusaka

2041

2067

Zimbabwe Harare

2044

2070

The IPCC’s Fifth Assessment Report

September 27, 2013 in Antarctic, Arctic, Climate, Extreme weather, Greenhouse Gases, Greenland, Permafrost, Polar ice, Science, Sea level rise, Warming

FOR IMMEDIATE RELEASE

Vatnajökull in Iceland: The IPCC says humans are the main cause of recent warming Image: Andreas Tille via Wikimedia Commons

Vatnajökull in Iceland: The IPCC says humans are the main cause of recent warming
Image: Andreas Tille via Wikimedia Commons

By the editors

Summary for Policymakers of the Working Group I contribution to the Fifth Assessment Report

A note from the Climate News Network editors: we have prepared this very abbreviated version of the first instalment of the IPCC’s Fifth Assessment Report (AR5) to serve as an objective guide to some of the headline issues it covers. It is in no sense an evaluation of what the Summary says: the wording is that of the IPCC authors themselves, except for a few cases where we have added headings. The AR5 uses a different basis as input to models from that used in its 2007 predecessor, AR4: instead of emissions scenarios, it speaks of RCPs, representative concentration pathways. So it is not possible everywhere to make a direct comparison between AR4 and AR5, though the text does so in some cases, and at the end we provide a very short list of the two reports’ conclusions on several key issues. The language of science can be complex. What follows is the IPCC scientists’ language. In the following days and weeks we will be reporting in more detail on some of their findings.

In this Summary for Policymakers, the following summary terms are used to describe the available evidence: limited, medium, or robust; and for the degree of agreement: low, medium, or high. A level of confidence is expressed using five qualifiers: very low, low, medium, high, and very high, and typeset in italics, e.g., medium confidence. For a given evidence and agreement statement, different confidence levels can be assigned, but increasing levels of evidence and degrees of agreement are correlated with increasing confidence. In this Summary the following terms have been used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% probability, very likely 90–100%, likely 66–100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely: 95–100%, more likely than not >50–100%, and extremely unlikely 0–5%) may also be used when appropriate.

Observed Changes in the Climate System

 

Atmosphere

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased

Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.

For the longest period when calculation of regional trends is sufficiently complete (1901–2012), almost the entire globe has experienced surface warming.

In addition to robust multi-decadal warming, global mean surface temperature exhibits substantial decadal and interannual variability. Due to natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends.

As one example, the rate of warming over the past 15 years, which begins with a strong El Niño, is smaller than the rate calculated since 1951.

Changes in many extreme weather and climate events have been observed since about 1950. It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale

Ocean

Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence ). It is virtually certain that the upper ocean (0−700 m) warmed from 1971 to 2010, and it likely warmed between the 1870s and 1971.

On a global scale, the ocean warming is largest near the surface, and the upper 75 m warmed by 0.11 [0.09 to 0.13] °C per decade over the period 1971–2010. Since AR4, instrumental biases in upper-ocean temperature records have been identified and reduced, enhancing confidence in the assessment of change.

It is likely that the ocean warmed between 700 and 2000 m from 1957 to 2009. Sufficient observations are available for the period 1992 to 2005 for a global assessment of temperature change below 2000 m. There were likely no significant observed temperature trends between 2000 and 3000 m for this period. It is likely that the ocean warmed from 3000 m to the bottom for this period, with the largest warming observed in the Southern Ocean.

More than 60% of the net energy increase in the climate system is stored in the upper ocean (0–700 m) during the relatively well-sampled 40-year period from 1971 to 2010, and about 30% is stored in the ocean below 700 m. The increase in upper ocean heat content during this time period estimated from a linear trend is likely.

Cryosphere

Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence).

The average rate of ice loss from the Greenland ice sheet has very likely substantially increased … over the period 1992–2001. The average rate of ice loss from the Antarctic ice sheet has likely increased … over the period 1992–2001. There is very high confidence that these losses are mainly from the northern Antarctic Peninsula and the Amundsen Sea sector of West Antarctica.

There is high confidence that permafrost temperatures have increased in most regions since the early 1980s. Observed warming was up to 3°C in parts of Northern Alaska (early 1980s to mid-2000s) and up to 2°C in parts of the Russian European North (1971–2010). In the latter region, a considerable reduction in permafrost thickness and areal extent has been observed over the period 1975–2005 (medium confidence).

Multiple lines of evidence support very substantial Arctic warming since the mid-20th century.

Sea Level

The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m.

Since the early 1970s, glacier mass loss and ocean thermal expansion from warming together explain about 75% of the observed global mean sea level rise (high confidence). Over the period 1993–2010, global mean sea level rise is, with high confidence, consistent with the sum of the observed contributions from ocean thermal expansion due to warming, from changes in glaciers, Greenland ice sheet, Antarctic ice sheet, and land water storage.

Carbon and Other Biogeochemical Cycles

The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification

From 1750 to 2011, CO2 emissions from fossil fuel combustion and cement production have released 365 [335 to 395] GtC [gigatonnes - one gigatonne equals 1,000,000,000 metric tonnes] to the atmosphere, while deforestation and other land use change are estimated to have released 180 [100 to 260] GtC.

Of these cumulative anthropogenic CO2 emissions, 240 [230 to 250] GtC have accumulated in the atmosphere, 155 [125 to 185] GtC have been taken up by the ocean and 150 [60 to 240] GtC have accumulated in natural terrestrial ecosystems.

Drivers of Climate Change

The total natural RF [radiative forcing - the difference between the energy received by the Earth and that which it radiates back into space] from solar irradiance changes and stratospheric volcanic aerosols made only a small contribution to the net radiative forcing throughout the last century, except for brief periods after large volcanic eruptions.

Understanding the Climate System and its Recent Changes

Compared to AR4, more detailed and longer observations and improved climate models now enable the attribution of a human contribution to detected changes in more climate system components.

Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system.

Evaluation of Climate Models

Climate models have improved since the AR4. Models reproduce observed continental-scale surface temperature patterns and trends over many decades, including the more rapid warming since the mid-20th century and the cooling immediately following large volcanic eruptions (very high confidence).

The long-term climate model simulations show a trend in global-mean surface temperature
from 1951 to 2012 that agrees with the observed trend (very high confidence). There are, however, differences between simulated and observed trends over periods as short as 10 to 15 years (e.g., 1998 to 2012).

The observed reduction in surface warming trend over the period 1998–2012 as compared to the period 1951–2012, is due in roughly equal measure to a reduced trend in radiative forcing and a cooling contribution from internal variability, which includes a possible redistribution of heat within the ocean (medium confidence). The reduced trend in radiative forcing is primarily due to volcanic eruptions and the timing of the downward phase of the 11-year solar cycle.

Climate models now include more cloud and aerosol processes, and their interactions, than at the time of the AR4, but there remains low confidence in the representation and quantification of these processes in models.

The equilibrium climate sensitivity quantifies the response of the climate system to constant radiative forcing on multi-century time scales. It is defined as the change in global mean surface temperature at equilibrium that is caused by a doubling of the atmospheric CO2 concentration.

Equilibrium climate sensitivity is likely in the range 1.5°C to 4.5°C (high confidence), extremely unlikely less than 1°C (high confidence), and very unlikely greater than 6°C (medium confidence). The lower temperature limit of the assessed likely range is thus less than the 2°C in the AR4, but the upper limit is the same. This assessment reflects improved understanding, the extended temperature record in the atmosphere and ocean, and
new estimates of radiative forcing.

Detection and Attribution of Climate Change

Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.

It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.

Future Global and Regional Climate Change

Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.

The global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation.

It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease.

Global mean sea level will continue to rise during the 21st century. Under all RCP scenarios the rate of sea level rise will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets.

Sea level rise will not be uniform. By the end of the 21st century, it is very likely that sea level will rise in more than about 95% of the ocean area. About 70% of the coastlines worldwide are projected to experience sea level change within 20% of the global mean sea level change.

Climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence). Further uptake of carbon by the ocean will increase ocean acidification.

Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.

A large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible on a multi-century to millennial time scale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period.

Surface temperatures will remain approximately constant at elevated levels for many centuries after a complete cessation of net anthropogenic CO2 emissions. Due to the long time scales of heat transfer from the ocean surface to depth, ocean warming will continue for centuries. Depending on the scenario, about 15 to 40% of emitted CO2 will remain in the atmosphere longer than 1,000 years.

Sustained mass loss by ice sheets would cause larger sea level rise, and some part of the mass loss might be irreversible. There is high confidence that sustained warming greater than some threshold would lead to the near-complete loss of the Greenland ice sheet over a millennium or more, causing a global mean sea level rise of up to 7 m.

Current estimates indicate that the threshold is greater than about 1°C (low confidence) but less than about 4°C (medium confidence) global mean warming with respect to pre-industrial. Abrupt and irreversible ice loss from a potential instability of marine-based sectors of the Antarctic Ice Sheet in response to climate forcing is possible, but current evidence and understanding is insufficient to make a quantitative assessment.

Methods that aim to deliberately alter the climate system to counter climate change, termed geoengineering, have been proposed. Limited evidence precludes a comprehensive quantitative assessment of both Solar Radiation Management (SRM) and Carbon Dioxide Removal (CDR) and their impact on the climate system.

CDR methods have biogeochemical and technological limitations to their potential on a global scale. There is insufficient knowledge to quantify how much CO2 emissions could be partially offset by CDR on a century timescale.

Modelling indicates that SRM methods, if realizable, have the potential to substantially offset a global temperature rise, but they would also modify the global water cycle, and would not reduce ocean acidification.

If SRM were terminated for any reason, there is high confidence that global surface temperatures would rise very rapidly to values consistent with the greenhouse gas forcing. CDR and SRM methods carry side effects and long-term consequences on a global scale.

Then and Now

For comparison, here are the IPCC’s projections in four key areas: from the 2013 AR5, in bold – from the 2007 AR4, in regular type

Probable temperature rise by 2100: 1.5-4°C under most scenarios – from 1.8-4°C
Sea level rise: very likely faster than between 1971 and 2010 – by 28-43 cm
Arctic summer sea ice disappears: very likely it will continue to shrink and thin – in second half of century
Increase in heat waves: very likely to occur more frequently and last longer – increase very likely

Climate case overwhelming – scientists

September 16, 2013 in Adaptation, Arctic, Climate, Extreme weather, Glaciers, Greenhouse Gases, Polar ice, Sea level rise, Sustainable Development, Warming

FOR IMMEDIATE RELEASE

The Arctic is melting, and temperatures nearby could reach 8°C, the scientists say Image: Patrick Kelley via Wikimedia

The Arctic is melting, and temperatures nearby could reach 8°C, the scientists say
Image: Patrick Kelley via Wikimedia

By Alex Kirby

Eleven days before the Intergovernmental Panel on Climate Change publishes its latest report, a group of eminent scientists says there is massive evidence of human responsibility.

LONDON, 16 September – With the IPCC report not yet published, there is already heated debate about what it will say, and about the implications of its findings for human development.

The scientists’ statement is unequivocal, and is not based on whatever the IPCC may publish. They  say: “The body of evidence indicating that our civilisation has already caused significant global warming is overwhelming.”

The statement comes from 12 members of the recently established Earth League, which describes itself as “a voluntary alliance of leading scientists and institutions dealing with planetary processes and sustainability issues”.

They say that if humans continue with business as usual, using fossil fuels and pumping out excessive amounts of greenhouse gases, the world will be on track for a planet that is 4°C warmer by the end of this century, or even earlier.

The group says assertions that there has been no warming this century are simply wrong. “Regardless of the…  (erroneous) claim that global warming has already stopped, evidence is that once well-known impacts from El Niño, volcanic aerosols and solar variability are removed from the observations, the warming trend of the ocean-atmosphere system is unbroken; and that it will continue (potentially towards 4°C) unless serious mitigation action is taken.

“That global warming continues unabated over the last decade is confirmed by ocean measurements. Ninety per cent of the additional heat that the Earth system absorbs due to the increase in greenhouse gases is stored in the oceans, and the global array of thousands of scientific measurement robots in the oceans proves that they keep heating up at a steady pace. Meanwhile satellites show that sea levels also keep rising steadily.”

The statement says a 4°C rise would drastically change the Earth. Some coastlines and entire islands would be submerged by rising sea levels, and more extreme heat waves would cause crop failures and loss of life.

It says powerful feedback processes that would very probably raise the warming even higher could be triggered, and might prove irreversible: “Four degrees of planetary warming means some 8°C change close to the Arctic, which will cause even larger impacts on the Eurasian and North American land mass and the surrounding seas.”

“…our societies seem to be willing to impose immense risks on future generations.”

Already, it says, there is persuasive evidence that immense changes may be under way: “The last two decades were… punctuated by devastating floods (like the Pakistan deluge in 2010) that may be related to an incipient restructuring of the atmospheric circulation.

“The signs on the climate wall as expressed by the accelerated melting of Arctic sea ice and by the retreat of the overwhelming majority of glaciers worldwide are there for all to see. Yet this is just the beginning.”

The scientists say: “Although climate science only tells us what might happen and not what to do about it, we feel that inaction is an unacceptable prospect.

“Nations go to war, implement mass vaccinations of their populations and organise expensive insurance and security systems (such as anti-terror measures) to address much fainter threats. However, our societies seem to be willing to impose immense risks on future generations.”

The 12 signatories recognise that some people believe it is impossible for human activities to produce a 4°C temperature rise.  Others, they say, are already acknowledging defeat by maintaining that the international policy goal of limiting warming to less than 2°C is a lost case.

They write that there is “ample evidence” that the world can hold a 2°C line, and say technology shows that global sustainability is attainable. But they add: “… the evidence demonstrates that the time frame to achieve this is rapidly shrinking.”

The signatories of the statement include Professor Hans Joachim Schellnhuber, of the Potsdam Institute for Climate Impact Research, Germany, and Professor Sir Brian Hoskins, Director of the Grantham Institute for Climate Change at Imperial College London. The link above lists all 12 signatories. – Climate News Network