The long-term stability of the massive ice sheets of Antarctica, which have the potential to raise sea levels by hundreds of metres, has been called into question with the discovery of fast-moving rivers of water sliding beneath their base.

Scientists analysing satellite data were astonished to discover the size of the vast lakes and river systems flowing beneath the Antarctic ice sheets, which may lubricate the movement of these glaciers as they flow into the surrounding sea.

The discovery raises fresh questions about the speed at which sea levels might rise in a warmer world due to the rate at which parts of the ice sheets slide from the land into the ocean, scientists said at the American Association for the Advancement of Science in San Francisco.

"We've found that there are substantial subglacial lakes under ice that's moving a couple of metres per day. It's really ripping along. It's the fast-moving ice that determines how the ice sheet responds to climate change on a short timescale," said Robert Bindschadler, a Nasa scientist at the Goddard Space Flight Centre in Maryland, one of the study's co-authors.

"We aren't yet able to predict what these ice streams are going to do. We're still learning about the controlling processes. Water is critical, because it's essentially the grease on the wheel. But we don't know the details yet," Dr Bindschadler said. "Until now, we've had just a few glimpses into what's going on down there. This is the most complete picture to date about what's going on," he said.

The findings, to be published in the journal Science, came from satellite surveillance of the surface elevation of the ice sheets, which found that they rise or lower depending on the amount of water flowing between the base of the ice sheet and the rock beneath.

The scientists identified many regions of the ice sheet either rose or deflated between 2003 and 2006 as a result of water movements below. Water would be capable of this because it is highly pressurised under the weight of the overlying ice, they said.

Glaciologists have known for some time that water exists under the Antarctic ice sheets - which can be hundreds of metres thick - but they were surprised to find how much water is involved and the speed at which it moves from one subglacial reservoir to another, said Helen Fricker at the Scripps Institution of Oceanography in San Diego.

"We didn't realise that the water under these ice streams was moving in such large quantities, and on such short time scales. We thought these changes took place over years and decades, but we are seeing large changes over months. The detected motions are astonishing in magnitude, dynamic nature and spatial extent," Dr Fricker said.

The West Antarctic ice sheet is the second biggest on the continent, and the rate at which ice flows from it to the Ross ice shelf, and then ultimately into the sea, is critical in assessing the likely impact of climate change on global sea levels.

The study provides evidence that subglacial water is stored in a linked system of reservoirs underneath the ice and can move quickly into and out of those reservoirs. This activity may play a major role in controlling the rate at which ice moves off the continent, Dr Fricker said.

"The links between ice stream activity and the climate are not well understood. To predict how the ice sheets might respond to global warming, this new information is vital as it gives us a more complete picture of what is happening under the ice," she said.

The study was conductedusing the Icesat satellite. It carries a laser altimeter instrument to detect changes as small as 1.5 centimetres in the elevation of the ice sheet's surface, from an orbit of 400 miles above the earth. "From 600 kilometres up in space, we were able to see small portions of the ice sheet rise and sink," Dr Bindschadler said.

Zoologists from around the world were gathering in Atlanta yesterday to plead for a global action plan to save hundreds of species of frogs believed to be on the brink of extinction, because of, in part, a strange and rapidly expanding fungus.

In the past 10 years, the world has lost 170 species of frog to the fungus and other causes. Of the roughly 6,000 varieties of frog and other amphibians still remaining, such as newts and salamanders, almost a third are believed to also be under threat in regions as far apart as Japan, California, Australia and the Andes.

The two-day conference will launch a rescue operation dubbed the "Amphibian Ark". Scores of zoos, botanical gardens and aquariums will create protected habitats for the amphibians and there will also be controlled breeding programmes to save as many species as possible.

In the meantime, research will be stepped up to try to find a remedy to the fungus. Known as a chrytid fungus, it clogs the pores preventing the normal process of breathing through the skin. The condition first makes amphibians drowsy and eventually kills them as skin begins to peel away.

Herpetologists, who specialise in the study of amphibians, suspect that global warming may be partly responsible for the sudden spread of the fungus. Higher temperatures have caused increased daytime cloud cover in high tropical forests, creating perfect conditions for the fungus to thrive on the frogs.

"Something really terrifying is happening to the planet," said Joseph Mandelson, a herpetologist at Zoo Atlanta, and an organiser of this week's conference. "We'd be very stupid if we did not pay very close attention to this."

The plague, now being likened to the HIV-Aids epidemic afflicting humans, is particularly alarming because it is threatening all amphibians, which are a crucial link between water and land animals and a vital part of the ecological food chain in many habitats.

"This is the precedent of a disease working its way across an entire species on the scale of all mammals, all birds or all fish," Mr Mandelson added.

Medical research for humans would also suffer from the disappearance of many kinds of frog that have been found to offer chemicals that contribute to the manufacture of pain relievers. One species had been linked with a chemical that may help in disabling the virus that causes Aids.

Making the Amphibian Ark work, however, will not be cheap. The group organising it aims to create a special endowment next year to help raise the roughly $500m (£256m) that the project will cost.

There is no definitive word yet on the origin of the deadly fungus but scientists suspect that it may have shown up first in Africa, home to the African clawed frog, which is known to carry the fungus but which appears to be immune to its effects. Other factors in the amphibian deaths include the use of pesticides and the effects of human development.

Last month, Japan for the first time confirmed that it had recorded frog deaths from the fungus. Species known to have been rendered extinct from it have been identified in Australia and Costa Rica. Other regions seeing the impact of the fungus include parts of the Rocky Mountains, all of Mexico, every country in Central America and several in the Andes range.

Faced with the latest, drastic predictions of the effects of climate change, European countries have agreed to a fresh cut in CO2 emissions of one-fifth and to press for a global reduction of 30 per cent.

Environment ministers yesterday dismissed calls to water down EU objectives and approved a binding set of new targets to be fulfilled by 2020, covering the period after the expiry of the Kyoto protocol in 2012. Cuts of 20 per cent on 1990 levels will be implemented unilaterally by the EU but that figure will rise to 30 per cent if it can be agreed internationally.

Although Poland and Hungary had voiced concerns ahead of yesterday's gathering, neither country stood in the way of a deal. However the detail remains to be worked out and European countries will now negotiate a "burden sharing" regime. This will allow the less developed eastern European nations to catch up economically while their wealthier counterparts compensate by cutting emissions more than the average figure.

The accord was hailed as "an historic decision," by Sigmar Gabriel, Environment Minister of Germany which holds the EU presidency. He said targets could be differentiated depending "on the economic situation in the country".

Germany could, he said, attain a 40 per cent cut in CO2 to help bring average reductions down.

In a key concession, some of the EU's newer members can use different starting points for their calculations. That would permit them to take advantage of the drop in CO2 arising from the disappearance of heavy industry following the collapse of Communism.

Poland, which is allowed to calculate from 1988, says that between then and 2004 emissions dropped by 31.6 per cent, making the new, post-2012 targets easily attainable.

Slovenia will be allowed to use 1986 as a base date while Hungary can calculate emissions from a baseline date of 1985-87.

The overall package agreed yesterday will have to be approved by European heads of government at a summit next month.

Environmental groups gave the deal a mixed reaction, welcoming the fact that targets will be binding but calling on EU countries to implement the 30 per cent reduction irrespective of what other nations around the world agree.

Mahi Sideridou of Greenpeace said: "We happily welcome the 30 per cent emission cut proposed for the EU and for developed countries for 2020. Ministers have listened to the science and made a leap forward in addressing the climate crisis. But to then suggest a meagre 20 per cent unilateral EU emissions cut, while admitting this is inadequate and that a 30 per cent cut will be necessary, is a bizarre discrepancy."

David Miliband, the Environment Secretary, said: "The unilateral commitment to cut EU greenhouse gas emissions by 20 per cent by 2020 - the first of its kind - shows we're willing to take concrete action on an issue that citizens care about.

"Action in the EU alone is not enough. Our commitment to a 30 per cent cut in emissions as part of a global agreement strengthens the EU's ability to lead the debate at the G8 and UN climate change talks and to secure an ambitious outcome."

There can be no disguising the fact that the open skies aviation issue poses some rather uncomfortable questions for a newspaper like The Independent, which is serious about protecting the environment and yet also supports the free market. Few would defend the existing restrictions on transatlantic air traffic. There is no reason why a handful of British and American airlines should be the only carriers that can operate freely on this route. The European Union was right to get rid of this piece of shameless protectionism. Doing so will boost competition and should result in a superior service for passengers.

The only economically regrettable aspect about yesterday's agreement by European transport ministers - aside from the fact that it remains somewhat biased towards the US airlines - is that it will not come into effect until next March. A handful of airlines have had an unfair advantage for three decades. Why should they be given an extra year in which to cash in?

Yet this reform will also, by bringing down airfares, eventually increase the volume of transatlantic air traffic. This is what happened when a similar open skies agreement was agreed in Europe 10 years ago. That resulted in the runaway success of the low-cost budget carriers Ryanair and easyJet. This is all bad news from the perspective of the struggle against climate change. Air travel is the fastest-growing source of the UK's greenhouse emissions. If it begins to grow internationally at the same rate, all the world's efforts to reduce emissions in other areas will be cancelled out.

A similar conflict of principle is presented by BA's flights from London to Newquay which began this week. BA has a perfect legal right to enter this market. Other carriers are already shuttling between the two points. But these new flights are clearly detrimental to the environment, as is the rapid expansion of regional UK airports. Though domestic flights are short, they are extremely harmful because they release carbon dioxide at a high altitude. They are also a hugely inefficient method of transport because they use so much energy taking off and landing.

But before we conclude that the two principles held by this newspaper are incompatible, it is worth looking more closely at the issue of aviation. While the monopoly on transatlantic flights is manifestly wrong, that is not to say that the feebleness of the international community in curbing the number of flights being taken is right. In other words, handing a handful of airlines a lucrative monopoly is a very unsatisfactory way of keeping down air traffic volumes.

There is a far more effective and honest way. Measures such as a hefty tax on flights, tax on aviation fuel and restrictions on airport expansion are required. The tax breaks for airlines have been a colossal hidden subsidy over the past five decades. The result is that it makes financial sense for some airlines to fly empty flights from point to point, solely to retain their lucrative airport landing slots. This is the Alice in Wonderland economics that has been created by the world's mollycoddling of the airline industry.

And domestic flights are a very different issue. There is no realistic alternative to at least some transatlantic air travel. But there is a very clear green alternative to most domestic air travel: the railways. Put simply, governments should clamp down on domestic air travel and curtail regional airport expansion because passengers can take the train instead.

Ideally, greater international aviation competition and a new tax regime would have been introduced in tandem. We now have the first. For the sake of the planet, it is incumbent on our leaders to establish the second soon.

The Statoil petrol station in the Stavanger suburb of Forus is on first impressions unremarkable. But if you look carefully, you'll notice that on one side of the forecourt, away from the cars filling up with petrol, is a pump that stands seemingly unnoticed. If the forecasters prove correct, the gas this pump dispenses – hydrogen – is set to take centre stage in the global fight against climate change.

The only emission from the exhaust pipe of a hydrogen-powered car is water. There's no carbon dioxide, no particulates and no sulphur emissions. It's this clean-burn nature that's firing the interest of growing numbers of oil multinationals, car-makers and energy companies.

The hydrogen filling station at Forus, the first in Norway, was opened last August and will be joined by a further four on the main road that hugs the country's southern coast. Eventually these stations will form a 360-mile long "hydrogen highway" stretching from Stavanger to Oslo.

"The goal is that by 2009 it will be possible to drive a hydrogen-powered car along the entire route," says Anders Hermansen from Statoil, Norway's biggest oil company and one of 40 partner organisations involved in the project, called HyNor. "This is very much a 'learning by doing project', as we want to increase our knowledge of hydrogen as well as stimulating wider interest in more environmentally friendly fuels."

Thirteen Toyota Prius hydrogen cars have been acquired for HyNor at an eye-watering cost of £60,000 each. These are the only hydrogen cars in Norway, and are leased out to Statoil and local government groups, which are also partners in the project. The cars are powered by a regular engine that has been adapted to run on hydrogen, with backup being provided by a battery-powered motor. They have a range of around 80 miles before they need to be refuelled. The number of hydrogen cars driving along the highway is expected to steadily increase as the project develops. It's thought that a further 20 cars will be on the streets of Oslo when a hydrogen station opens there later next year.

Bjønar Kruse from the Oslo-based environmental group Zero, another HyNor partner, believes that the growing awareness of climate change in Norway is making people more aware of alternative fuels. "There's been a dramatic change in people's attitude towards climate change in the past 12 months," says Kruse, "and this makes it easier to mainstream hydrogen technology. I'm already receiving inquiries from people wanting to buy hydrogen cars."

But there is some bad news. While hydrogen is the most abundant element in the universe, it rarely exists in its pure form in the environment, preferring instead to bond with other elements such as oxygen to form water and carbon to form hydrocarbons such as oil and gas. To create pure hydrogen, energy is needed to break these bonds.

Because an external energy source is needed to produce it, hydrogen strictly speaking isn't a primary energy source like coal, sunlight or wind, but instead is generally referred to as being an energy carrier like electricity. Hydrogen's critics claim that since its production invariably involves natural gas, hydrogen's energy budget doesn't add up. And with CO2 being produced every step of the way, hydrogen, it's claimed, isn't very green at all.

Ulf Hafseld, HyNor's project manager, accepts that making hydrogen using fossil fuels isn't sustainable. "The answer is to produce hydrogen from water using electricity from renewable energy, which is very easy," he says. "This is already happening in Berlin, where a small electrolysing plant at a filling station is generating the gas from water, using 100 per cent renewable energy from a hydroelectric plant in the Alps. It produces no CO2 emissions at all."

Along with using renewable energy to produce "green hydrogen", Hafseld believes that the increasing use of hydrogen-powered fuel cells in cars are crucial for maximising hydrogen's potential. "Fuel cells are about twice as efficient as internal combustion engines so can help compensate for any energy loss in the gas's production."

Scandinavia is now emerging as a champion of hydrogen technology, following the launch last year of the Scandinavian Hydrogen Highway Partnership. The scheme unites existing hydrogen highway projects in south-west Sweden and Denmark with the project in Norway. "The vision is to make Scandinavia one of the first regions in Europe where hydrogen is used in a network of refuelling stations," says Hafseld. "There are already plans to use surplus electricity from Denmark's wind farms to produce green hydrogen."

After a slow start, the UK is finally getting in on the act with the news that up to 600 hydrogen-powered buses could be serving the streets of London by 2012, after a successful trial earlier this year. There's even greater interest in the US where concerns over the security of oil supplies has seen President Bush recently spend $1.7bn (£845m) turning the States into a world-leader in hydrogen-powered cars. In California, Governor Schwarzenegger has launched a hydrogen highway network and aims to build up to 200 hydrogen-fuelling stations by 2010.

With global interest in hydrogen on the rise and with most car-makers pouring millions into developing hydrogen vehicles, when can we expect to see the mass production of affordable hydrogen cars? "Our target is to produce a hydrogen fuel-cell car for $50,000 by 2015," says Peter Froeschle, a senior manager at DaimlerChrysler, which has already spent more than €1bn (£675m) developing its fleet of prototypes, " though we don't expect the operation to be profitable until 2020."

While nobody is claiming that hydrogen and fuel cells are the solution to our energy needs, there's a growing consensus among oil companies, car manufacturers and environmental groups that it will play a key role in our future mix of low-carbon fuels.

The hard cell

* Fuel cells produce electricity from a chemical reaction involving hydrogen and oxygen. They emit no carbon, although it may be released when producing the hydrogen itself.

* Fuel cells will be at the heart of any future hydrogen economy. Their supporters claim that they potentially offer a carbon-free alternative to fossil fuels.

* While fuel-cell cars are expected to reach mass production by 2025, some believe that we will see widespread use of fuel cells in everyday applications within a few years.

* Anticipated uses of fuel cells include mobile phones, laptops, home heating and power plants.

A survey of British business has delivered a damning verdict on the Government's environmental policies.

The study, carried out by PricewaterhouseCoopers, concludes that "current economic policy instruments to reduce the environmental impact of industry are not encouraging sufficient behavioural change".

Some 71 per cent of respondents said that climate change and environmental issues were affecting the way they conduct business. However, almost half said that Government policy and economic instruments - taxes, duties, the climate-change levy and investment allowances - are "not effective" in encouraging business to "significantly" change its behaviour. Of all the measures at the state's disposal, regulation is seen by business as the most effective, with taxes ranked next and emissions-trading schemes least favoured (though more liked by those involved in them).

The draft Climate Change Bill published in March proposed a legally binding target of a 60 per cent reduction in CO2 emissions by 2050, and a 26-to-32 per cent cut by 2020.

The report suggests that business is content with such aims, but that, in the words of one figure, "Government needs to find a way of getting companies to do the right thing, but in a way that doesn't penalise companies".

Legislation and regulation are the key driver for many, as are fulfilling customers' rising green/organic demands and savings on fuel and energy bills. Most are unhappy with the lack of a stable long-term framework for environmental policy (unlike in economic policy), and are frustrated by the lack of "joined-up thinking" between overlapping responsibilities of officialdom.

Most of those who responded to the survey were "not confident" about making long-term decisions in the current regime and many were sceptical about the link between green taxes and environmental action.

Arrangements such as the EU's Emissions Trading Scheme were markedly more popular with those participating in them, especially in the energy sector, than in the rest of industry. Predictably, companies prefer carrots to sticks, with tax reliefs for using renewable energy and low-emission cars rated highly.

When it comes to going carbon neutral - dismissed by some environmentalists as "greenwashing" - only 3 per cent of companies claim to have achieved it. A majority opposed road charging, with the stiffest resistance coming from the retail sector. Business people owned up to a failure to identify a key individual with responsibility for green issues in their organisations.

John Manning, head of environmental tax and regulation at PricewaterhouseCoopers, said: "The appetite for dealing with the environmental consequences of doing business has never been greater.

"We know that some instruments work more effectively than others. Business needs a clear and meaningful framework if it is to take the important action needed to combat global warming."

Michael Roberts, for the CBI, responded: "It is vital that the Government gives firms a straightforward, long-term, framework to make green decisions in."

Claims that increased solar activity is the cause of global warming - rather than man-made greenhouse gases - have been comprehensively disproved by a detailed study of the Sun.

Scientists have delivered the final blow to the theory that recent global warming can be explained by variations in the natural cycles of the Sun - a favourite refuge for climate sceptics who dismiss the influence of greenhouse-gas emissions.

An analysis of the records of all of the Sun's activities over the past few decades - such as sunspot cycles and magnetic fields - shows that since 1985 solar activity has decreased significantly, while global warming has continued to increase.

Mike Lockwood, of the Rutherford Appleton Laboratory in Chilton, Oxfordshire, said: "In 1985, the Sun did a U-turn in every respect. It no longer went in the right direction to contribute to global warming. We think it's almost completely conclusive proof that the Sun does not account for the recent increases in global warming."

The study, published today in the journal Proceedings of the Royal Society A, shows there is no doubt that solar activity over the past 20 years has run in the opposite direction to global warming, and therefore cannot explain rises in average global temperatures.

Dr Lockwood and his colleague Claus Fröhlich, of the World Radiation Centre in Davos Dorf, Switzerland, have produced the most powerful counter argument to suggestions that current warming is part of the natural cycle of solar activities. "There is considerable evidence for solar influence on Earth's pre-industrial climate, and the Sun may well have been a factor in post-industrial change in the first half of the last century," they write.

However, since about 1940 there has been no evidence to suggest that increases in global average temperatures were caused by solar activity. "Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified," the two scientists said.

The theory that past changes in solar activity may have explained some changes in the climate before the industrial revolution is not in dispute. In previous centuries, for instance, notably between about 1420 and 1570, when the Vikings had to abandon their Greenland settlements, solar minima corresponded with unusually cool weather, such as the "little ice age" of the 17th century.

But climate sceptics have exploited this to dispute the idea that man-made emissions are responsible for global warming. In the recent Channel 4 programme The Great Global Warming Swindle, the rise in solar activity over the latter half of the 20th century was erroneously presented as perfectly matching the rise in global average temperatures.

Dr Lockwood said he was outraged when he saw the documentary, because of the way the programme-makers used graphs of temperature rises and sunspot cycles that were cut off in the 1980s, when the two trends went in the opposite direction.

"The trouble is that the theory of solar activity and climate was being misappropriated to apply to modern-day warming. The sceptics were taking perfectly good science and bringing it into disrespect," Dr Lockwood said.

The Royal Society said yesterday: "There is a small minority which is seeking to confuse the public on the causes of climate change. They are often misrepresenting the science, when the reality is that the evidence is getting stronger every day."

First, what is a carbon footprint?

Think of it as a way of measuring how heavily we all tread on the planet. It's a colourful way of expressing the amount of carbon dioxide, the main cause of global warming, we each emit each year. And this is serious stuff ­ it's measured in tonnes.

How many tonnes?

It depends on who you are and where ­ and above all ­ how you live. On average each of us in Britain has a carbon footprint of about nine tonnes. That compares with about 20 tonnes for each American and around 18 tonnes for each Australian. But the Swiss and the Swedes ­ with higher standards of living than us ­ manage to keep theirs down to about six tonnes.And the big difference,of course, is with the Third World. The average Chinese carbon footprint is about three tonnes, the average Indian one about one tonne and the average Ethiopian about a tenth of a tonne. Lightest of all in their impact are the people of Chad, contributing just one hundredth of a tonne of carbon dioxide each ­ that's 900 times less than us.

Does that matter?

Yes. It matters in rich countries like ours because our profligancy is helping to drive climate change: 44 per cent of all Britain's emissions of carbon dioxide come as a result of the choices we each make in our daily lives ­ such as how we use transport and heat and light our homes. And it matters in poor ones, because they will have to use more energy ­ much of it from the fossil fuels that emit the greenhouse gas ­ if they are to develop. Their need to grow means that we will have to cut our carbon footprints even more if we are to avert global warming running out of control. Science suggests that people in rich counties will have to shrink theirs by 80 per cent by the middle of the century.

Can it be done?

Absolutely. Really simple things like installing energy-efficient light bulbs, improving the insulation of our homes, and not leaving appliances on standby can do a lot. Investments such as getting a hybrid car, or installing solar panels on the roof, can do a great deal more. And new technologies and techniques will keep coming onstream. But human nature being what it is, it would be a great help if Governments took measures to encourage ­ or push ­ us to save energy.

What sort of measures?

Those most mentioned are "economic instruments" ­ which often boils down to a fancy way of describing taxes. Green taxes are becoming ever more popular: opinion polls suggest that Britons back them by a 2 to 1 majority. All the main political parties support them, if to differing extents ­ and several have been introduced by successive Governments, mainly on industry, over the past 15 years. Other countries, particularly Scandinavian ones, have done more. But nowhere has even begun to tap their full potential.

Won't that mean paying even more tax?

Not if it's done properly, as part of what has come to be called " ecological tax reform". That involves reducing taxes like income tax and national insurance by the same amount as green ones are increased, so that the Government's total "take" remains the same. We would therefore be paying more for electricity and petrol, but out of a bigger pay packet. In fact, this could create many more jobs as well as cutting pollution.

How so?

Income tax and national insurance effectively penalise work and employment, things we ought to be promoting, whereas green taxes bear down on things like pollution, which we should be curbing. Ecological tax reform would therefore switch the burden from "goods" to "bads", giving companies a greater incentive to lay off kilowatt hours than to sack people. Indeed a big EU study concluded that it would create at least 2.7 million jobs across Europe, while tackling global warming. Taxes on labour have helped cause employers to use labour 20 times more productively over the last 150 years. Increasing energy costs, partly through taxation, could cause firms to make similar improvements in efficiency, greatly reducing pollution.

But won't this just disappear into the Treasury's coffers?

It could do, but it would be much better ­ at least at first ­ to spend the money on things that will help tackle global warming. People are suspicious: two thirds of Britons believe that governments use climate change as a way of increasing revenue. Making sure that money from green taxes was spent on green projects ­ like improving the infrastructure for public transport ­ would help allay this concern and achieve a double whammy for the environment.

Surely there are drawbacks?

Indeed there are. Perhaps the biggest is that, while income tax is " progressive", hitting richer people harder, taxes on energy could be " regressive", disproportionately hurting the poor, who tend to spend a greater part of their income on keeping warm or getting around. But the Netherlands has shown that these can be tweaked so that they actually benefit the poor, by providing cheap energy to meet basic needs while charging more for luxury use.

So is tax always best?

Not necessarily. People do not always respond to price signals as neatly as economists like to think. Look at how many people still use old incandescent light bulbs even though they cost much more in electricity bills than new energy-efficient ones. It's unfashionable to say so, but regulation can work best. Australia for example has announced it is banning sale of the old style bulbs by 2010.

What about the future?

The really radical idea, increasingly supported by some leading politicians, is to introduce 'personal carbon allowances'. These would give everyone a set allowance of carbon dioxide each year ­ but allow these to be bought and sold. Thus those who wanted to emit more ­ for example by frequent flying - could buy some of the allowance of those who lived more modestly. It would not exactly be a tax - but, one way or another, people who want to have big carbon footprints in future are likely to have to pay heavily.

What is HSBC doing to help? Find out more at www.hsbc.com/cr

For HSBC, carbon matters. The energy we use to heat, light and cool our buildings and power our IT equipment emits large amounts of CO2. So does our business travel. Increasing levels of CO2, caused by human activity, contribute to climate change and HSBC believes that climate change is the greatest environmental challenge we face this century. As a result, we:

* Measure our carbon footprint and report annually on how much carbon dioxide we emit;

* Manage our carbon footprint to reduce the amount of energy we consume. HSBC has recently committed a further £45 million over the next five years to reduce the bank's carbon footprint. The Global Environmental Efficiency Programme will enable HSBC offices worldwide to showcase environmental innovation and share best practice through a series of initiatives, involving renewable energy technologies, waste reduction programmes and employee engagement to help the bank achieve its environmental reduction targets;

* Buy green electricity. In many parts of the world, including the UK, HSBC buys electricity from renewable sources ­ generated from wind, water, the sun or biogas ­ which produces fewer or no CO2 emissions;

* Offset the remaining CO2 emissions we produce.

HSBC believes accounting for the CO2 we emit is the right thing to do. In 2005, HSBC was the first major bank ­ and the first FTSE 100 company ­ to become carbon neutral. Going carbon neutral reflects our desire to act responsibly and reduce our carbon footprint. As a carbon neutral company, HSBC will incur the additional costs that arise from buying carbon offsets to neutralise the remaining CO2 emissions we produce from our operations.

Rich and poor nations yesterday agreed, for the first time, to make big cuts in pollution in order to fight global warming. And the Bush administration, which has consistently sought to sabotage international action to combat climate change, helped to lead the way.

Governments and environmentalists are hoping this weekend that the apparently incredible breakthrough will set the stage for a new onslaught on the heating-up of the planet.

On Tuesday, the new UN Secretary-General, Ban Ki-moon, is hosting a meeting of 70 government heads to try to kick-start an international treaty to replace the Kyoto Protocol when its present provisions expire in 2012. On Thursday and Friday President George Bush will hold his own international meeting on the issue.

Yesterday's little-expected breakthrough, which was foreshadowed in last week's Independent on Sunday, is expected to do more than the Kyoto agreement to slow down global warming. It came after negotiations – under the auspices of the United Nations Environment Programme (Unep) – on strengthening another treaty, the Montreal Protocol on the ozone layer, first agreed exactly 20 years ago.

Negotiators from 190 countries agreed to accelerate the banning of hydrochlorofluorocarbons (HCFCs), used in refrigeration and air-conditioning. These damage the Earth's ozone layer, which shields the planet from the sun's harmful ultra-violet rays. But HCFCs are even more dangerous as greenhouse gases, up to 1,700 times more powerful than carbon dioxide in warming up the planet.

Under the protocol's existing provisions, the HCFCs were due to be phased out by 2030 in rich countries, and by 2040 in poor ones, but at last week's meeting negotiators accepted a proposal – put forward by the Bush administration – to bring both deadlines forward by a decade.

Although the measure will help to heal the ozone layer faster, its main intention is to combat global warming.

The accelerated phase-out is estimated to be the equivalent of cutting carbon-dioxide emissions by up to 25 billion tonnes over the coming decades. This compares with the two million tonnes a year due to be saved by the Kyoto Protocol between 2008 and 2012 if, as seems unlikely, its targets are met.

It also involves both rich and poor countries agreeing targets to cut emissions, something that has not yet happened under any other climate-change agreement – and is one of the main bones of contention over Kyoto. China, which produces most HCFCs, has had to make particular sacrifices.

The breakthrough is a triumph for Achim Steiner, Unep's executive director, who did much to bring it about. He said yesterday: "Historic is an often over-used word, but not in the case of this agreement. Governments had a golden opportunity to deal with the twin challenges of climate change and protecting the ozone layer – and governments took it."

Even before yesterday's breakthrough, the Montreal Protocol was seen as the most effective environmental treaty. Agreed shortly after the discovery of the ozone hole above Antarctica, it has already phased out almost all of the chemicals primarily responsible – the chlorofluorocarbons or CFCs once used in aerosol sprays and refrigeration.

This is expected to prevent 6.3 million deaths from skin cancer in the United States alone. But the biggest benefit has been an unintended one, in combating global warming, since the CFCs are also powerful greenhouse gases.

Scientists in the Netherlands and in the US concluded earlier this year that, by the end of this decade, the Montreal treaty will have done more than five times more to counteract climate change than Kyoto.

Professor Mario Molina, one of the first scientists to discover the threat to the ozone layer, says this has delayed warming by 12 years, and may have kept the world from "passing the 'tipping point' for abrupt and irreversible climate change".

Yesterday's agreement on HCFCs, which replaced CFCs, will do even more – but governments and environmentalists caution that it will be no substitute for tough action over the next two years to cut emissions of carbon dioxide, primarily from the burning of oil, gas and coal. This remains the main cause of climate change, but Mr Bush is still resisting growing pressure for action both in the US and from overseas.

David Doniger, of the Natural Resources Defense Council, said yesterday that "the Bush administration deserves credit for working with other countries to push for faster cuts in HCFCs". But he added: "This is the tail. Cutting carbon dioxide emissions is the dog."

Further reading: 'Action on Ozone', published by the United Nations Environment Programme (Unep)

A landmark assessment by the UN of the state of the world's environment paints the bleakest picture yet of our planet's well-being. The warning is stark: humanity's future is at risk unless urgent action is taken. Over the past 20 years, almost every index of the planet's health has worsened. At the same time, personal wealth in the richest countries has grown by a third.

The report, by the United Nations Environment Programme (Unep), warns that the vital natural resources which support life on Earth have suffered significantly since the first such report, published in 1987. However, this gradual depletion of the world's natural "capital" has coincided with unprecedented economic gains for developed nations, which, for many people, have masked the growing crisis.

Nearly 400 experts from around the world contributed to the report, which warns that humanity itself could be at risk if nothing is done to address the three major environmental problems of a growing human population, climate change and the mass extinction of animals and plants.

The report is the fruit of five years' work by leading scientists and is the fourth in a series since the publication in 1987 of Our Common Future by an international commission into the state of the global environment chaired by the former Norwegian prime minister Gro Harlem Brundtland.

Achim Steiner, the executive director of Unep, said that the objective of the latest report was not to present a "dark and gloomy scenario" but to make the case for an urgent call to action. However, the dire state of almost every aspect of the planet's wellbeing points to 20 years of missed opportunities.

Mr Steiner said yesterday at the launch of the report that it was illuminating how over the past 20 years the financial wealth of the planet has soared by around a third. "But at the same time it is sobering: much of the 'natural' capital upon which so much of human well-being and economic activity depends – water, land, the air and atmosphere, biodiversity and marine resources – continue their seemingly inexorable decline," he said.

Meanwhile, the political response to the growing emergency has been limited. "Without an accelerated effort to reform the way we collectively do business on planet Earth, we will shortly be in trouble if indeed we are not already," Mr Steiner said.

"There have been enough wake-up calls. I sincerely hope this is the final one. The systematic destruction of the Earth's natural and nature-based resources has reached a point where the economic viability of economies is being challenged – and the bill we hand on to our children may prove impossible to pay," he said.

The fourth Unep report since the seminal 1987 report of the Brundtland Commission reveals a stark continuation in the environment's decline. The environmental "footprint" of humanity has increased dramatically in 20 years, with a rising population and increased use of energy, land and other natural resources.

Unep's Global Environment Outlook (GEO-4) states that the human demand on the planet now means we are living beyond our means. The present footprint is equivalent to 22 hectares per person, whereas the natural carrying capacity of the Earth is less than 16 hectares per person, the report says.

The world economy has at the same time boomed, with the global GDP per capita rising from about $6,000 (£2,920) to just over $8,000. But this increased wealth has been geared towards the developed world and has come at an enormous cost to the environment. Available freshwater stocks have declined dramatically since the 1980s, in west Asia, for instance, from 1,700 cubic metres per person per year, to 907 cubic metres today. By the middle of the century, this is likely to fall still further to 420 cubic metres per person per year. Over the past 20 years, the proportion of fish stocks in the world that have collapsed has doubled from 15 per cent to 30 per cent. At the same time the proportion of fish stocks that are deemed to be overexploited has risen from 20 per cent to 40 per cent.

The intensity with which agricultural land is farmed has also increased, and with it the burden of soil erosion, water scarcity, nutrient depletion and pollution. In 1987, a hectare of cropland yielded 1.8 tons of produce, but due to intensification this has now risen to 2.5 tons.

Energy consumption in developed nations has risen significantly. In Canada and the US, for instance, the demand for energy has grown by 19 per cent since 1987. Concentrations of carbon dioxide, a principal greenhouse gas, are about a third higher than they were 20 years ago.

Species of animals and plants are estimated to be going extinct at a rate that is about 100 times faster than the historical record, largely as a result of human activities. Biologists have now classified 30 per cent of amphibians, 23 per cent of mammals and 12 per cent of birds as threatened.

A growing human population, which is expected to reach nine billion by the mid-century, will place increasing pressure on land, water and biodiversity. Land will have to be more intensively farmed, or more land will have be cultivated. "Either way, biodiversity suffers," the report says.

Against a background of continued degradation of the land and oceans, of population increases and of species extinctions, lies the spectre of climate change – one the biggest threats facing humanity in the 21st century. There is now "visible and unequivocal" evidence that global warming is causing further impacts on the global environment, the GEO-4 report says.

Mike Childs, the campaigns director at Friends of the Earth, said the report made it clear we need concerted international political action to reduce greenhouse gas emissions and halt the loss of wildlife and ecosystems. "This report clearly demonstrates that we also need a step change in understanding that the steady degradation of the world's environment threatens the well-being of everybody on the planet," he said.

"Our response to this planetary emergency must be to harness humankind's amazing ingenuity to make the next two decades a time of innovation and determination to create a fairer and greener world."

Twenty years of environmental failure

Since 1987, when the landmark UN report Our Common Future (overseen by Gro Harlem Brundtland, right) warned of the need for concerted action to secure humanity's future, the state of the global environment has declined in numerous ways.

* The availability of fresh water had declined dramatically. In west Asia, for instance, available fresh water has fallen from 1,700 cubic metres per person per year to 907 cubic metres, largely due to pollution and demand.

* Levels of carbon dioxide have risen by a third and energy demands of countries such as the United States and Canada are nearly a fifth higher than in 1987.

* In 1987, about 15 per cent of global fish stocks were classified as collapsed, and 20 per cent were overexploited. Now 30 per cent have collapsed and a further 40 per cent are overexploited.

* The number of species which is threatened with extinction has increased. Since 1987, there has been a 50 per cent decline in the populations of some freshwater animals and a 30 per cent fall among terrestrial and marine species.

* The agricultural intensification of cultivated land has risen, with greater impact on pollution, nutrient depletion and water use. A hectare of farmland in 1987 produced an average yield of 1.8 tons, but now it produces 2.5 tons.

* Human population has increased by a third since 1987. At the same time there has been a threefold increase in global trade and average income per head has increased by a third, with global GDP per capita rising from $6,000 in 1987 to a total of $8,000 today.

The sprawling forests of the northern hemisphere which extend from China and Siberia to Canada and Alaska are in danger of becoming a gigantic source of carbon dioxide rather than being a major "sink" that helps to offset man-made emissions of the greenhouse gas.

Studies show the risk of fires in the boreal forests of the north has increased in recent years because of climate change. It shows that the world's temperate woodlands are beginning to lose their ability to be an overall absorber of carbon dioxide.

Scientists fear there may soon come a point when the amount of carbon dioxide released from the northern forests as a result of forest fires and the drying out of the soil will exceed the amount that is absorbed during the annual growth of the trees. Such a prospect would make it more difficult to control global warming because northern forests are seen as a key element in the overall equations to mitigate the effect of man-made CO2 emissions.

Two studies published today show that the increase in forest fires in the boreal forests – the second largest forests after tropical rainforests – have weakened one of the earth's greatest terrestrial sinks of carbon dioxide.

One of the studies showed that in some years, forest fires in the US result in more carbon dioxide being pumped into the atmosphere over the space of a couple of months than the entire annual emissions coming from cars and energy production of a typical US state.

A second study found that, over a 60-year period, the risk of forest fires in 1 million sq kms of Canadian wilderness had increased significantly, largely as a result of drier conditions caused by global warming and climate change. Tom Gower, professor of forest ecology at the University of Wisconsin-Madison, said his study showed that fires had a greater impact on overall carbon emissions from boreal forests during the 60-year period than other factors such as rainfall, yet climate was at the heart of the issue.

The intensity and frequency of forest fires are influenced by climate change because heatwaves and drier undergrowth trigger the fires. "Climate change is what's causing the fire changes. They're very tightly coupled systems," Professor Gower said.

"All it takes is a low snowpack year and a dry summer. With a few lightning strikes, it's a tinderbox," he said.

Historically, the boreal forests have been a powerful carbon sink, with more carbon dioxide being absorbed by the forests than being released. However, the latest study, published in the journal Nature, suggests the sink has become smaller in recent decades, and it may actually be shifting towards becoming a carbon source, Professor Gower said.

"The soil is the major source, the plants are the major sink, and how those two interplay over the life of a stand [of trees] really determines whether the boreal forest is a sink or a source of carbon," he said.

"Based on our current understanding, fire was a more important driver of the carbon balance than climate was in the past 50 years. But if carbon dioxide concentration really doubles in the next 50 years and the temperature increases 4C to 8C, all bets may be off."

The second study, published in Carbon Balance and Management, found carbon dioxide emissions from some forest fires exceeded the annual car and energy emissions from individual US states.

Christine Wiedinmyer of the US National Centre for Atmospheric Research in Boulder, Colorado, used satellite imaging datato estimate CO2 output based on the degree of forest cover in a particular area.

In some years, the amount of CO2 released from forest fires was equivalent to about 5 per cent of the man-made total. But in other years, more widespread and intense forest fires resulted in massively increased emissions.

"There is a significant potential for additional net release of carbon from forests of the United States due to changing fire dynamics in the coming decades," Dr Wiedinmyer said.