Six kilograms of carbon dioxide a day. If that sounds like little more than an obscure scientific measurement, think again. In the years to come it’s a figure we may have to get used to. Why? Because, say climate scientists, that’s the maximum daily amount of carbon dioxide each of us can generate if humanity is to have a chance of keeping the rise in global temperature below 2C.

That figure, endorsed by Lord Stern, then the government’s chief economist, in his 2006 report on the economics of climate change, is one of the best illustrations of the scale of the challenge of powering our world without endangering the planet.

Compare it with the amount we emit now. Britain generates about 10 tonnes per person each year - about 27kg a day. America generates about 60kg of CO2 a day, according to the Atlas of Climate Change, and China about 9kg, a figure rising as the country develops.

How, then, can humankind cut those emissions to 6kg by 2050, as Stern and like-minded climate scientists say we must? It adds up to about two tonnes a year, roughly equal to the amount emitted by a person in Mozambique.

Power generation lies at the heart of the debate. Around the world there are about 5,000 large power stations that burn fossil fuels, mostly coal or gas. They emit the equivalent of about 11 billion tonnes of CO2 a year - a huge chunk of the 49 billion tonnes generated globally by human activities, according to figures from the Intergovernmental Panel on Climate Change.

The panel says energy supply is responsible for 26% of global greenhouse gas emissions. Transport accounts for about 13% and buildings about 8%. Stern’s latest report, Key Elements of a Global Deal on Climate Change, states: “The importance of technological innovation in delivering this transformation can hardly be overstated.” In other words, technology is the best hope we have of cutting emissions.

According to a report from the consultancy McKinsey & Company, each unit generated will have to be made to produce 10 times more of everything - of CO2 power, food, consumer goods and so on - than today. And we have just 40 years to achieve that if the global temperature rise is to be kept below 2C.

John Pothecary is a divisional managing director at RPS, an international con-sultancy specialising in the development of energy resources and environmental management. He believes that global leadership is one of the biggest issues. “There are all kinds of technologies we can use to cut carbon emissions, but first we need the political and financial systems that will ensure they are adopted,” he says.

Pothecary is partly referring to the negotiations under way to draw up a replacement for the Kyoto Protocol, which will set emissions reduction targets. The negotiations will culminate in a United Nations conference in Copenhagen in December 2009, which will, hopefully, produce a new protocol.

It will have to set global targets for cutting carbon emissions that are perceived as fair and achievable. For the energy industry, Copenhagen is a giant fork in the road, the outcome of which will influence its actions for decades. A successful protocol could lead to a system of carbon quotas whereby each country would have a ceiling placed on its CO2 emissions. Any excess emissions would have to be covered by buying quotas from other countries, otherwise the country would face a fine.

If it worked, such a system could transform the relative costs of different fuels. Coal, for example, whose abundance makes it the cheapest bulk source of energy, could become the most expensive because it generates the greatest emissions. Nuclear and wind power, which currently cost two to threeCO2 times more than energy from coal, could become far cheaper in a low-car-bon world, and oil and gas may lie somewhere in between.

Such shifts would create a powerful incentive to develop the new technologies Stern refers to. Perhaps the most important is carbon capture and seques-tration, a system of stripping CO2 from power station emissions and storing it underground. In theory this could be adopted by most coal and gas power stations, turning them from polluting monsters into low-carbon paragons.

What happens if Copenhagen fails to create a workable protocol? The stresses on the process are showing. Even Britain, which likes to portray itself as setting a lead on green issues, is already lobbying for aviation to be excluded from the EU’s target of getting 20% of energy from renewable sources by 2020.

David Eyton, research and technology vice-president at global energy giant BP, says: “It’s cheaper to produce energy from fossil fuels than from renewables, and there are plenty of them, so we will keep producing them and people will keep using them. That is our primary business for now.

“The policymakers at Copenhagen have to bridge that gap in costs and address greenhouse gas emissions. The decisions they make will determine our investment portfolio and the products we offer people for decades to come.”

Goodwill in short supply

Can global treaties on our climate lead to real cuts in carbon emissions? History suggests not. Lawrence Susskind, professor of urban and environmental planning at the Massachusetts Institute of Technology, has looked at the achievements of other global treaties on the environment and found them sadly wanting.

“More than 400 multilateral agreements such as the Kyoto protocol on climate change now exist, addressing problems including the loss of endangered species and habitats, ocean dumping, the shipping of hazardous substances, and desertification,” he says. “Yet there is no evidence to suggest that any of these are working with perhaps the one exception of the Montreal protocol on ozone-depleting chemicals.”

What all these treaties have in common is that they are administered by ad hoc secretariats, depend for funding donated by the very countries they are supposed to be regulating and are highly politicised - so the science gets distorted.

Even when they are agreed there is no central agency, no United Nations Environmental Treaty-making and Enforcement body with the means to enforce them. It means any successor to Kyoto is likely to prove just as pointless and ineffective as the rest.

Gas flow improved

Natalie Davies, 26, joined Shell in March last year and now works as a project services engineer based in Assen, northeast Holland. She is part of an extensive project to renovate and update the facilities and equipment used in processing gas from the huge Groningen field to make them more efficient and environmentally friendly.

Davies is Shell’s on-site representative, monitoring contractors that install ultrasonic gas-flow meters, which measure the gas before it is sent to the supplier. This includes filling the plant with nitrogen and helium to make sure connections don’t leak.

The hands-on role complements her theoretical experience, and she will eventually become a cost and planning engineer. Her work also counts towards chartership with the Institution of Mechanical Engineers. Away from the spanners and slide rule, she is enjoying learning Dutch.

Davies joined Shell after gaining a masters of engineering from Cambridge University. After two years of general engineering courses, she specialised in manufacturing and took an internship one summer with a manufacturing company. Her time there led to a job offer, but she preferred the variety of options on offer at Shell.

“I wanted to join the energy sector because we are going to face huge challenges and I’ve always thought it’s better to be part of it and make a difference,” she says. “Being on the inside, I feel I can do that. It’s great to be on site and see in practice how everything works. It makes a lot more sense to see it yourself.

“It’s also a great learning opportunity and has flexibility and freedom too. If I see something interesting, I can speak with the contractor and find out what they are doing.

“I’m confident that schemes in the company are such that I will be challenged in whatever position I want to do. I’m quite ambitious and see myself moving to technical project management. There is flexibility and if I don’t like something, I can move, as it’s such a huge company.”

Dangers ahead

Greenhouse gases increase the atmosphere’s ability to trap , of which humanity releases heat. The best known is CO2 about 50 billion tonnes a year. Some is used by plants or absorbed in the sea but the rest stays in the atmosphere for decades. Levels have risen from about 280 parts per million before the industrial revolution to the equivalent of 430ppm.

This has helped warm the world by about 0.7C, with another 0.5C expected from gases already in the atmosphere. The Intergovernmental Panel on Climate Change says that if greenhouse gas emissions rise at present rates, levels will reach 550ppm by 2035 - with temperature rises of 3C-4C.

Brown’s balancing act Follow the money

The International Energy Agency recently published a study on the cost of low-carbon technologies aimed at keeping global temperature rises below 2.4C. It found that the world needed to spend an extra £23 trillion from 2010 to 2050 to decarbonise power generation and promote energy efficiency measures that would stabilise the climate.

“The average year-by-year investments needed to achieve a virtual decarbonisation of the power sector include: 55 fossil-fuelled power plants with carbon capture; 32 nuclear plants; 17,500 large wind turbines and 215 square metres of solar panels,” said the report. “It also requires widespread adoption of near-zero emission buildings and deployment of nearly a billion electric or hydrogen fuel-cell vehicles. In the coming decade we need a global revolution in the way we produce and use energy.” Gordon Brown has already pledged the nation to cutting its emissions by 60% by 2050 compared with 1990 levels, and is likely to raise that to the 80% cut expected to be recommended by his new Climate Change Committee in its first report next month. Brown, however, has made it clear he also wants Britain to build more airports, roads and coal-fired power stations, and to expand its economy.

Defra, the environment ministry, has indicated that it expects Britain to meet up to a third of any future carbon emission reduction targets by purchasing carbon credits from developing countries, through an international trading system.

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