David Adam, environment correspondent
Tuesday February 28, 2006
The Guardian (UK)

The Earth's temperature could rise under the impact of global warming to levels far higher than previously predicted, according to the United Nations' team of climate experts.

A draft of the next influential Intergovernmental Panel on Climate Change (IPCC) report will tell politicians that scientists are now unable to place a reliable upper limit on how quickly the atmosphere will warm as carbon dioxide levels increase. The report draws together research over the past five years and will be presented to national governments in April and made public next year. It raises the possibility of the Earth's temperature rising well above the ceiling quoted in earlier accounts.

Such an outcome would have severe consequences, such as the collapse of the Greenland ice sheet and disruption of the Gulf Stream ocean current.

The shift in position comes as Tony Blair is expected to pledge today to work towards a date for stabilising international greenhouse gas emissions when he meets Stop Climate Chaos, the climate change equivalent of Make Poverty History. The group is campaigning for a target date of 2015 for stabilisation, saying a later date would endanger the planet.

The new IPCC report will underpin international talks on how to cut greenhouse gas emissions when the first phase of the Kyoto protocol expires in 2012.

Set up in 1988 by the UN, the IPCC brings together hundreds of experts to summarise the state of climate science for policymakers. It has produced three reports since 1990, each of which has been instrumental in establishing national and international strategies to address global warming. Government officials have until June to comment on the new draft, when scientists will gather in Bergen, Norway, to produce a final version.

For the sake of the world's poor, we must keep the wealthy at home

We all know the damage aviation does, but the government and the airlines want to turn the country into Airstrip One

George Monbiot
Tuesday February 28, 2006
The Guardian (UK)

At last the battlelines have been drawn, and the first major fight over climate change is about to begin. All over the country, a coalition of homeowners and anarchists, of Nimbys and internationalists, is mustering to fight the greatest future cause of global warming: the growth of aviation.

Not all these people care about the biosphere. Some are concerned merely that their homes are due to be bulldozed, or that, living under the new flight paths, they will never get a good night's sleep again. But anyone who has joined a broad-based coalition understands the power of this compound of idealism and dogged self-interest.

The industry has seen it, and is getting its revenge in first. Last week the Guardian obtained a leaked copy of a draft treaty between the European Union and the US that would prevent us from taking any measure to reduce the environmental impact of airlines without the approval of the US government. This, though it might be the widest ranging, is not the first such agreement; the 1944 Chicago convention, now supported by 4,000 bilateral treaties, rules that no government may levy tax on aviation fuel. The airlines have been bottlefed throughout their lives.

The British government admits that the only area in which it is "free to make policy in isolation from other countries" is airport development; it could contain or reverse the growth of flights by restricting airport capacity. Instead, it is softening us up for a third runway at Heathrow, and similar extensions at Stansted, Birmingham, Edinburgh and Glasgow. Twelve other airports have already announced expansion plans. According to the Commons environmental audit committee, the growth the government foresees will require "the equivalent of another Heathrow every five years". Orwell's most accurate prediction in 1984 was the mutation of Britain into Airstrip One.

Already, one fifth of all international air passengers fly to or from an airport in the UK. The numbers have risen fivefold in the past 30 years, and the government envisages that they will more than double by 2030, to 476 million a year. Perhaps "envisages" is the wrong word. By providing the capacity, the government ensures that the growth takes place.

As far as climate change is concerned, this is an utter, unparalleled disaster. It's not just that aviation represents the world's fastest growing source of carbon dioxide emissions. The burning of aircraft fuel has a "radiative forcing ratio" of around 2.7; what this means is that the total warming effect of aircraft emissions is 2.7 times as great as the effect of the carbon dioxide alone. The water vapour they produce forms ice crystals in the upper troposphere (vapour trails and cirrus clouds) that trap the earth's heat. According to calculations by the Tyndall Centre for Climate Change Research, if you added the two effects together (it urges some caution as they are not directly comparable), aviation emissions alone would exceed the government's target for the country's entire output of greenhouse gases in 2050 by around 134%. The government has an effective means of dealing with this. It excludes international aircraft emissions from the target.

It won't engage in honest debate because there is no means of reconciling its plans with its claims about sustainability. In researching my book about how we might achieve a 90% cut in carbon emissions by 2030, I have been discovering, greatly to my surprise, that every other source of global warming can be reduced or replaced to that degree without a serious reduction in our freedoms. But there is no means of sustaining long-distance, high-speed travel.

The industry claims it can reduce its emissions by means of technological developments. But, as the Royal Commission on Environmental Pollution points out, its targets "are clearly aspirations rather than projections". There are some basic technological constraints that make major improvements impossible to envisage.

The first problem is that our planes have a remarkably long design life. The Boeing 747 is still in the air 36 years after it left the drawing board. The Tyndall Centre predicts that the new Airbus A380 will still be flying, "in gradually modified form", in 2070. Switching to more efficient models would mean scrapping the existing fleet.

Some designers have been playing with the idea of "blended wing bodies": planes with hollow wings in which the passengers sit. In principle they could reduce the use of fuel by up to 30%. But the idea, and its safety and stability, is far from proven. Yet this is as good as it gets. As the Advisory Council for Aeronautics Research in Europe says: "The consensus view is that the rate of progress for conventional engines will slow down significantly in the next 10 years." And if the efficiency of engines does improve, this doesn't necessarily solve the problem. More efficient engines tend to be noisier (so even less acceptable to local people), and to produce more water vapour (which means that their total climate impact could in fact be higher). Even if the outermost promise of a 30% cut could be met, it would offset only a fraction of the extra fuel use caused by rising demand.

The airline companies keep talking about hydrogen planes, but if ever the technological problems were overcome they would be an even bigger disaster than current models. "Switching from kerosene to hydrogen," the royal commission says, "would replace carbon dioxide from aircraft with a threefold increase in emissions of water vapour." Biofuels would need more arable land than the planet possesses. The British government admits that "there is no viable alternative currently visible to kerosene as an aviation fuel."

New fuel consumption figures for both fast passenger ships and ultra-high-speed trains suggest that their carbon emissions are comparable to those of planes. What all this means is that if we want to stop the planet from cooking, we will simply have to stop travelling at the kind of speeds that planes permit.

This is now broadly understood by almost everyone I meet. But it has had no impact whatever on their behaviour. When I challenge my friends about their planned weekend in Rome or their holiday in Florida, they respond with a strange, distant smile and avert their eyes. They just want to enjoy themselves. Who am I to spoil their fun? The moral dissonance is deafening.

Despite the claims made for the democratising effects of cheap travel, 75% of those who use budget airlines are in social classes A, B and C. People with second homes abroad average six return flights a year, while people in classes D and E hardly fly; they can't afford the holidays, so are responsible for just 6% of flights. Most of the growth, the government envisages, will take place among the wealthiest 10%. But the people who are being hit first and will be hit hardest by climate change are among the poorest on earth. Already the droughts in Ethiopia, putting millions at risk of starvation, are being linked to the warming of the Indian Ocean. Some 92 million Bangladeshis could be driven out of their homes this century in order that we can still go shopping in New York.

Flying kills. We all know it, and we all do it. And we won't stop doing it until the government reverses its policy and starts closing the runways.

From:

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Public release date: 4-Nov-2005
[ | E-mail Article | ]

Contact: Mariangela D'Acunto
mariangela.dacunto@esa.int
39-069-418-0856
European Space Agency

ERS altimeter survey shows growth of Greenland Ice Sheet interior

Seasonal results from the survey
Click here for a high resolution image.

Researchers have utilised more than a decade's worth of data from radar altimeters on ESA's ERS satellites to produce the most detailed picture yet of thickness changes in the Greenland Ice Sheet.

A Norwegian-led team used the ERS data to measure elevation changes in the Greenland Ice Sheet from 1992 to 2003, finding recent growth in the interior sections estimated at around six centimetres per year during the study period. The research is due to be published by Science Magazine in November, having been published in the online Science Express on 20 October.

Overall elevation changes over 11 years
Click here for a high resolution image.

ERS radar altimeters work by sending 1800 separate radar pulses down to Earth per second then recording how long their echoes take to bounce back 800 kilometres to the satellite platform. The sensor times its pulses' journey down to under a nanosecond to calculate the distance to the planet below to a maximum accuracy of two centimetres.

ESA has had at least one working radar altimeter in polar orbit since July 1991, when ERS-1 was launched. ESA's first Earth Observation spacecraft was joined by ERS-2 in April 1995, then the ten-instrument Envisat satellite in March 2002.

The result is a scientifically valuable long-term dataset covering Earth's oceans and land as well as ice fields – which can be used to reduce uncertainty about whether land ice sheets are growing or shrinking as concern grows about the effects of global warming.

The ice sheet covering Earth's largest island of Greenland has an area of 1 833 900 square kilometres and an average thickness of 2.3 kilometres. It is the second largest concentration of frozen freshwater on Earth and if it were to melt completely global sea level would increase by up to seven metres.

The influx of freshwater into the North Atlantic from any increase in melting from the Greenland Ice Sheet could also weaken the Gulf Stream, potentially seriously impacting the climate of northern Europe and the wider world.

Efforts to measure changes in the Greenland Ice Sheet using field observations, aircraft and satellites have improved scientific knowledge during the last decade, but there is still no consensus assessment of the ice sheet's overall mass balance. There is however evidence of melting and thinning in the coastal marginal areas in recent years, as well as indications that large Greenland outlet glaciers can surge, possibly in response to climate variations.

Much less known are changes occurring in the vast elevated interior area of the ice sheet. Therefore an international team of scientists - from Norway's Nansen Environmental and Remote Sensing Center (NERSC), Mohn-Sverdrup Center for Global Ocean Studies and Operational Oceanography and the Bjerknes Centre for Climate Research, Russia's Nansen International Environmental and Remote Sensing Center and the United States' Environmental Systems Analysis Research Center – were compelled to derive and analyse the longest continuous dataset of satellite altimeter observations of Greenland Ice Sheet elevations.

Greenland's east coast seen by Envisat
Click here for a high resolution image.

By combining tens of millions of data points from ERS-1 and ERS-2, the team determined spatial patterns of surface elevation variations and changes over an 11-year period.

The result is a mixed picture, with a net increase of 6.4 centimetres per year in the interior area above 1500 metres elevation. Below that altitude, the elevation-change rate is minus 2.0 cm per year, broadly matching reported thinning in the ice-sheet margins. The trend below 1500 metres however does not include the steeply-sloping marginal areas where current altimeter data are unusable.

The spatially averaged increase is 5.4 cm per year over the study area, when corrected for post-Ice Age uplift of the bedrock beneath the ice sheet. These results are remarkable because they are in contrast to previous scientific findings of balance in Greenland's high-elevation ice.

The team, led by Professor Ola M. Johannessen of NERSC, ascribe this interior growth of the Greenland Ice Sheet to increased snowfall linked to variability in regional atmospheric circulation known as the North Atlantic Oscillation (NAO). First discovered in the 1920s, the NAO acts in a similar way to the El Niño phenomenon in the Pacific, contributing to climate fluctuations across the North Atlantic and Europe.

Comparing their data to an index of the NAO, the researchers established a direct relationship between Greenland Ice Sheet elevation change and strong positive and negative phases of the NAO during winter, which largely control temperature and precipitation patterns over Greenland.

Professor Johannessen commented: "This strong negative correlation between winter elevation changes and the NAO index, suggests an underappreciated role of the winter season and the NAO for elevation changes – a wildcard in Greenland Ice Sheet mass balance scenarios under global warming."

He cautioned that the recent growth found by the radar altimetry survey does not necessarily reflect a long-term or future trend. With natural variability in the high-latitude climate cycle that includes the NAO being very large, even an 11-year long dataset remains short.

"There is clearly a need for continued monitoring using new satellite altimeters and other observations, together with numerical models to calculate the Greenland Ice Sheet mass budget," Johannessen added.

Modelling studies of the Greenland Ice Sheet mass balance under greenhouse global warming have shown that temperature increases up to about 3ºC lead to positive mass balance changes at high elevations – due to snow accumulation – and negative at low elevations – due to snow melt exceeding accumulation.

Such models agree with the new observational results. However after that threshold is reached, potentially within the next hundred years, losses from melting would exceed accumulation from increases in snowfall – then the meltdown of the Greenland Ice Sheet would be on.

A paper published in Science in June this year detailed the results of a similar analysis of the Antarctic Ice Sheet based on ERS radar altimeter data, carried out by a team led by Professor Curt Davis of the University of Missouri-Columbia.

The results showed thickening in East Antarctica on the order of 1.8 cm per year, but thinning across a substantial part of West Antarctica. Data were unavailable for much of the Antarctic Peninsula, subject to recent ice sheet thinning due to regional climate warming, again because of limitations in current radar altimeter performance.

ESA's CryoSat mission, lost during launch on 8 October, carried the world's first radar altimeter purpose-built for use over both land and sea ice. In the context of land ice sheets, CryoSat would have been capable of acquiring data over steeply-sloping ice margins which remain invisible to current radar altimeters - these being the very regions where the greatest loss is taking place.

Efforts are currently underway to investigate the possibility of building and flying a CryoSat-2, with a decision to be taken by the end of the year. In the meantime, the valuable climatological record of ice sheet change established by ERS and Envisat will continue to be extended.

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