A billion people will lose their homes due to climate change, says report

British scientists will warn Cancún summit that entire nations could be flooded
Robin McKie The Observer The Guardian 28 Nov 10;

Devastating changes to sea levels, rainfall, water supplies, weather systems and crop yields are increasingly likely before the end of the century, scientists will warn tomorrow.

A special report, to be released at the start of climate negotiations in Cancún, Mexico, will reveal that up to a billion people face losing their homes in the next 90 years because of failures to agree curbs on carbon emissions.

Up to three billion people could lose access to clean water supplies because global temperatures cannot now be stopped from rising by 4C.

"The main message is that the closer we get to a four-degree rise, the harder it will be to deal with the consequences," said Dr Mark New, a climate expert at Oxford University, who organised a recent conference entitled "Four Degrees and Beyond" on behalf of the Tyndall Centre for Climate Change Research. Tomorrow the papers from the meeting will be published to coincide with the start of the Cancún climate talks.

A key feature of these papers is that they assume that even if global carbon emission curbs were to be agreed in the future, these would be insufficient to limit global temperature rises to 2C this century – the maximum temperature rise agreed by politicians as acceptable. "To have a realistic chance of doing that, the world would have to get carbon emissions to peak within 15 years and then follow this up with a massive decarbonisation of society," said Dr Chris Huntingford, of the Centre for Ecology and Hydrology in Oxfordshire.

Few experts believe this is a remotely practical proposition, particularly in the wake of the failure of the Copenhagen climate talks last December – a point stressed by Bob Watson, former head of the Intergovernmental Panel on Climate Change and now chief scientist at the Department for Environment, Food and Rural Affairs. As he put it: "Two degrees is now a wishful dream."

Researchers such as Richard Betts, head of climate impacts at the Met Office, calculate that a 4C rise could occur in less than 50 years, with melting of ice sheets and rising sea levels.

According to François Gemenne, of the Institute for Sustainable Development and International Relations in Paris, this could lead to the creation of "ghost states" whose governments-in-exile would rule over scattered citizens and land lost to rising seas.

Small island states such as Tuvalu and the Maldives are already threatened by inundation. "What would happen if a state was to physically disappear but people want to keep their nationalities?" he asked. "It could continue as a virtual state even though it is a rock under the ocean."

Peter Stott of the Met Office said the most severe effect of all these changes is likely to involve changes to the planet's ability to soak up carbon dioxide. At present, around 50% of man-made carbon emissions are absorbed by the sea and by plants on land.

"However, the amount of carbon dioxide that can be absorbed decreases as temperatures rise. We will reach a tipping point from which temperatures will go up even faster. The world will then start to look very different."

Crop failures and drought within our children's lifetimes
Steve Connor The Independent 29 Nov 10;

Children today are likely to reach old age in a world that is 4C warmer, where the 10,000-year certainties of the global climate can no longer be relied on, and widespread crop failures, drought, flooding and mass migration of the dispossessed become a part of everyday life.

This dire scenario could come as early as the 2060s – well within the lifetime of today's young people. It could mark the point when, for the first time since the end of the Ice Age, human civilisation has to cope with a highly unstable and unpredictable global climate.

A series of detailed scientific assessments of this possible "four-degree world", published today, documents for the first time the immense problems posed if the average global temperature rises by 4C above pre-industrial levels – a possibility that many experts believe is increasingly likely.

The international climate negotiations which resume this week in Cancun, Mexico, are aimed at keeping global temperatures within the "safe" limit of a 2C increase. But many scientists believe that, based on current trends, a rise of 3C or 4C is far more likely.

The greatest concern is that a 4C increase in global average temperatures – a temperature difference as great as that between now and the last Ice Age – would create dramatic transformations in the world, leading to water shortages, the collapse of agriculture in semi-arid regions and triggering a catastrophic rise in sea levels in coastal areas.

One of the studies, led by scientists from the Met Office's Hadley Centre, predicts that, unless there is a concerted international agreement to curb dramatically the burning of fossil fuels such as coal, oil and gas, a 4C warmer world is virtually inevitable by the end of this century. This critical threshold could, however, be reached within just 50 or 60 years based on other factors, such as human interference with natural feedback cycles that accelerate global warming, and the sensitivity of the climate to man-made carbon-dioxide emissions.

"Most emissions scenarios have a chance that take us past the four-degree point by the end of the 21st century, but it is down to the strength of the feedbacks and the sensitivity of the climate as to when this actually happens. It's certainly not outrageous to say it could happen in the 2060s," said Richard Betts, the lead author of the Hadley Centre study, published in the Philosophical Transactions of the Royal Society.

Of equal concern to scientists is the speed of climate change. A second study in the series found that a global temperature rise of between 2C and 4C could be so rapid that it would coincide with the expected peak in global population, which is expected to reach nine billion by 2050 before it begins to fall.

This would mean that the problems of water shortages and food production caused by climate change will occur at precisely the same time as the world is having to cope with feeding the greatest number of people in its history. A slower rate of climate change, on the other hand, will see the highest temperature increases occurring after the global population has peaked.

Niel Bowerman of Oxford University, who led the study into the rate of climate change, said it highlighted the urgency of having emissions peak in coming years. "Our study shows we need to start cutting emissions soon to avoid potentially dangerous rates of warming within our lifetimes, and to avoid committing ourselves to potentially unfeasible rates of emissions reduction in a couple of decades time," he added.

Climate change scientists warn of 4C global temperature rise
Team of experts say such an increase would cause severe droughts and see millions of migrants seeking refuge
Damian Carrington The Guardian 29 Nov 10;

The hellish vision of a world warmed by 4C within a lifetime has been set out by an international team of scientists, who say the glacial progress of the global climate change talks that restart in Mexico today makes the so-called safe limit of 2C impossible to keep. A 4C rise in the planet's temperature would see severe droughts across the world and millions of migrants seeking refuge as their food supplies collapse.

"There is now little to no chance of maintaining the rise in global surface temperature at below 2C, despite repeated high-level statements to the contrary," said Kevin Anderson, at the University of Manchester, who with colleague Alice Bows contributed research to a special collection of Royal Society journal papers published tomorrowtoday. "Moreover, the impacts associated with 2C have been revised upwards so that 2C now represents the threshold [of] extremely dangerous climate change."

The new analysis by Anderson and Bows takes account of the non-binding pledges made by countries in the Copenhagen Accord, the compromise document that emerged from the last major UN climate summit, and the slight dip in greenhouse gas emissions caused by the economic recession. The scientists' modelling is based on actual tonnes of emissions, not percentage reductions, and separates the predicted emissions of rich and fast-industrialising nations such as China. "2010 represents a political tipping point," said Anderson, but added in the report: "This paper is not intended as a message of futility, but rather a bare and perhaps brutal assessment of where our 'rose-tinted' and well-intentioned approach to climate change has brought us. Real hope and opportunity, if it is to arise at all, will do so from a raw and dispassionate assessment of the scale of the challenge faced by the global community."

A rise of 4C could be seen as soon as 2060 in a worst case scenario, according to research in the same journal, led by the Met Office's Richard Betts and first revealed in the Guardian last year. Betts accepts the scenario is extreme but argues it is also plausible given the rapidly rising trend in emissions.

Rachel Warren, at the University of East Anglia, described a 4C world in her research paper: "Drought and desertification would be widespread ... There would be a need to shift agricultural cropping to new areas, impinging on [wild] ecosystems. Large-scale adaptation to sea-level rise would be necessary. Human and natural systems would be subject to increasing levels of agricultural pests and diseases, and increases in the frequency and intensity of extreme weather events."

Warren added: "This world would also rapidly be losing its ecosystem services, owing to large losses in biodiversity, forests, coastal wetlands, mangroves and saltmarshes [and] an acidified and potentially dysfunctional marine ecosystem. In such a 4C world, the limits for human adaptation are likely to be exceeded in many parts of the world."

Another Met Office study analyses how a 4C rise would differ from a 2C rise, concluding that threats to water supplies are far worse, in particular in southern Europe and north Africa, where regional temperatures would rise 6-8C. The 4C world would also see enhanced warming over most of the US, Canada and northern Asia.

In sub-Saharan Africa (SSA), "the prognosis for agriculture and food security in a 4C world is bleak", according Philip Thornton, of Kenya's International Livestock Research Institute, who led another research team. He notes there will be an extra billion people populating Africacontinent by 2050.

"Croppers and livestock keepers in SSA have in the past shown themselves to be highly adaptable to short- and long-term variations in climate. But the kind of changes that would occur in a 4C+ world would be way beyond anything experienced in recent times. It is not difficult to envisage a situation where the adaptive capacity and resilience of hundreds of millions of people could simply be overwhelmed by events," Thornton's team concludes.

over scattered citizens and land that has been abandoned to rising seas, an expert said yesterday.

Another team tackled another complex question: what would happen to humid tropical forests in a 4C world? There was the risk of forest die-off in the Amazon, central America and parts of Africa, but some regions, e.g. around the Congo basin, would have the potential for forest expansion. The scientist noted, however, that in practice deforestation might be the most important factor.

The speed – as well as the size – of the temperature rise is crucial too, warned scientists from Oxford University, as faster rates of global warming could outpace the ability of human civilisation and the natural world to adapt. "Dangerous climate change depends on how fast the planet is warming up, not just how hot it gets," said Myles Allen of Oxford University's department of Pphysics. "It's not just how much we emit, but how fast we do so."

Worst case study: global temp up 4 degrees C by 2060s
* Temperatures might, in worst case, rise 4 C by 2060s
* Rising seas could bring $270 bln annual containment bill
* Four degree C rise would disrupt food, water supplies
Alister Doyle, Reuters 29 Nov 10;

CANCUN, Mexico, Nov 28 (Reuters) - World temperatures could soar by 4 degrees Celsius (7.2 degrees Fahrenheit) by the 2060s in the worst case of global climate change and require an annual investment of $270 billion just to contain rising sea levels, studies suggested on Sunday.

Such a rapid rise, within the lifetimes of many young people today, is double the 2 degrees C (3.6 degrees Fahrenheit) ceiling set by 140 governments at a U.N. climate summit in Copenhagen last year and would disrupt food and water supplies in many parts of the globe.

Rising greenhouse gas emissions this decade meant the 2 degree goal was "extremely difficult, arguably impossible, raising the likelihood of global temperature rises of 3 or 4 degrees C within this century," an international team wrote.

The studies, published to coincide with annual U.N. climate talks in Mexico starting on Monday, said few researchers had examined in detail the possible impact of a 4 degrees C rise above pre-industrial levels.

"Across many sectors -- coastal cities, farming, water stress, ecosystems or migration, the impacts will be greater," than at 2 degrees, wrote Mark New of Oxford University in England, who led the international team.

One study, published in the British journal Philosophical Transactions of the Royal Society A, said temperatures could rise by 4 degrees C in the worst case by the early 2060s.

Other scenarios showed the threshold breached later in the century or not at all by 2100, raising risks of abrupt changes such as a loss of Arctic sea ice in summer, a thaw in permafrost or a drying out of the Amazon rainforest.

MIGRATION

One of the papers gave what it called a "pragmatic estimate" that sea levels might rise by between 0.5 and 2 meters (1.64 to 6.56 feet) by 2100 if temperatures rose 4 degrees Celsius.

Containing a sea level rise of 2 meters, mostly building Dutch-style sea walls, would require annual investments of up to $270 billion a year by 2100.

That sum might limit migration to perhaps 305,000 people from the most vulnerable areas, wrote Robert Nicholls of the University of Southampton. Lack of protective measures could mean the forced resettlement of 187 million people.

People living on small islands, in Asia, Africa or river deltas were most at risk.

The studies concluded that governments should do more both to cut greenhouse gas emissions and research back-up methods such as "geo-engineering" programs that could dim sunlight or seek to suck greenhouse gases from the air. (Editing by Todd Eastham)