GLOBAL warming is irreversible and billions of people will die over the next century, one of the world's leading climate change scientists claimed yesterday. Professor James Lovelock, the scientist who developed the Gaia principle (that Earth is a self-regulating, interconnected system), claimed that by the year 2100 the only place where humans will be able to survive will be the Arctic.
In a forthcoming book, The Revenge of Gaia, Lovelock warns that attempts to reduce levels of greenhouse gases in the atmosphere may already be too late.
"Our planet has kept itself healthy and fit for life, just like an animal does, for most of the more than three billion years of its existence," he writes.
"It was ill luck that we started polluting at a time when the sun was too hot for comfort. We have given Gaia a fever and soon her condition will worsen to a state like a coma. She has been there before and recovered, but it took more than 100,000 years."
Lovelock, 86, who now lives in Cornwall, reckons temperatures will rise dramatically over the next 100 years: "We are responsible and will suffer the consequences: as the century progresses the temperature will rise eight degrees centigrade in temperate regions and five degrees in the tropics.
"Much of the tropical land mass will become scrub and desert; before this century is over billions of us will die and the few breeding pairs that survive will be in the Arctic, where the climate remains tolerable."
The scientist says he has been loathe to write such a depressing book: "I'm usually a cheerful sod, so I'm not happy about writing doom books. But I don't see any easy way out."
He believes pollution in the northern hemisphere has actually helped reduce global warming by reflecting sunlight.
However "this 'global dimming' is transient and could disappear in a few days like the smoke that it is, leaving us fully exposed to the heat of the global greenhouse". "We are in a fool's climate, accidentally kept cool by smoke," he says.
Climate-change scientists have been warning about the rise in temperatures reaching a "tipping point" when carbon and methane locked up in the Amazon rainforest and Arctic ice would be released into the atmosphere as the climate becomes drier and warmer.
Lovelock says: "We will do our best to survive, but, sadly, I can't see the US or the emerging economies of China and India cutting back in time and they are the main source of emissions. The worst will happen and survivors will have to adapt to a hell of a climate."
'The collapse of the Gulf Stream appears unlikely'
DR RICHARD BETTS
Climate modeller at the Met Office's Hadley Centre, Devon
I'VE always liked Jim Lovelock's holistic approach. He was a pioneer of this kind of thinking, seeing how things interact and the big picture.
That's been more of an inspiration than people would let on in modern climate-change science. We have moved on from not just doing meteorology but also the whole Earth system.
Jim is obviously very concerned about climate change and I think he's taken this opportunity to send out his warning.
I think Jim's sort of going for the worst-case scenario. In terms of billions of dead, I don't know that anyone really knows what the cost of climate change is going to be in terms of lives.
He's thinking of the possibility of very sudden, rapid climate change.
I'm not sure whether he really meant to paint a picture of everyone squashed into the South Pole or something like that. That seems unlikely to me, he's just trying to make the point.
I would agree we are committed to a certain amount of climate change already. We cannot stop what's happening, all we can do is slow it down.
But it's an extremely open question and there are several layers of uncertainty: such as how much the population of the world will increase and how we will develop in terms of economy and technology.
There's also uncertainty as to what these emissions do to the climate itself. There's a whole range of possibilities, really.
I don't think anyone could put any sort of figure on how many people will survive.
There are a lot of physically possible mechanisms for major climate change, but the flip side of that is a lot of these things are unlikely.
The collapse of the Gulf Stream appears to be unlikely to happen at least in the next 100 years, but it's theoretically possible it could happen. It's low probability, but would have a high impact.
'It's likely we'll have to reduce greenhouse gases'
DR MYLES ALLEN
Head of the climate dynamics group at Oxford University's physics department
THERE is no evidence that we have passed any tipping point already.
That said, today's levels of greenhouse gases could already be dangerously high if we kept them at today's level.
But, on the other hand, as the climate changes we'll learn more about the impact and be in a position to do something about it.
I think it is likely that we'll have to reduce greenhouse gases below today's level, in the very long term it is likely to be necessary to do that.
But, if we move beyond fossil fuels, that will eventually happen: we are not doomed to emit greenhouse gases forever.
There's a lot of confusion about whether greenhouse gas levels going above a certain level might result in a dangerous level of warming and if that is "a point of no return".
Of course, it isn't. We could raise carbon dioxide levels to 600 parts per million and we'd have a very dry year, but, providing we brought them down again, as far as temperature is concerned, you would barely notice it.
There's no magic about greenhouse gas levels going above a certain level. It's the amount of time they spend beyond a certain level that is important.
However, if it was to happen on a large scale - and there are worrying trends in methane - that's the sort of thing that could cause problems.
If the Arctic was to start releasing vast amounts of methane, that would be a concern, but, at the same time, methane has a relatively short lifetime. It wouldn't necessarily be a planet-destroying event.
I am less worried by the prospect [of James Lovelock's forecast of billions of deaths by the year 2100] than the prospect of us leaving it so late to do something about climate change that, when we eventually do do something about it, it has to be incredibly traumatic and results in a lot of people suffering completely unnecessarily because we have to turn the world economy around in a hurry when we could have done it in a reasonably calm and orderly manner now.
That said, people will be killed by climate change this century. I'd be reasonably confident in that statement.
Arguably, this has started already with the 2003 heatwave in Europe which killed 20,000 to 35,000 people, including 4,000 people in the UK.
'This is meant as a wake-up call'
PROFESSOR JOHN SCHELLNHUBER
Director of the Potsdam Institute for Climate Change Research
I KNOW James Lovelock and respect him tremendously. He's been one of the most influential scientists on the environment for many years now.
Everything he's writing has to be taken very seriously. It's not just some 'Doomsday' prediction.
I think this is really meant as a wake-up call - among the many scenarios about the future of the planet. If we do not really fight global warming, then this is certainly in the upper range of catastrophe, the worst-case scenario.
The probability of the scenario is pretty low, but it cannot be completely ruled out.
Many human lives are at stake if we don't do anything about global warming.
If there was five or six degrees Celsius of warming over the century, that would be a different world.
It is a very extreme scenario he is using, but we are at least on the road towards disaster.
'We have maybe got 20 years'
PROFESSOR JAMES CURRAN
Head of environmental strategy, Scottish Environmental Protection Agency (SEPA)
I'M not as pessimistic as James Lovelock, but I have been sounding these kind of warnings for a few years now.
My own view is we have maybe got 20 years to make drastic cuts to our carbon emissions before the feedback effect on global warming becomes sufficiently strong that it gets out of control.
There are certain global carbon cycles that run the risk of increasing carbon dioxide emissions because of climate change. And one such cycle close to home is that we have enormous peat deposits in Scotland: we have 5,000 million tons of carbon in our peat deposits.
We have peat because we have a cold, wet climate. But, under climate change, Scotland is going to get warmer and drier. The peat begins to crack and air gets inside. In winter, when climate change is going to bring rainstorms, the rain begins to erode the peat and the structure starts to collapse.
There is evidence this is happening and it would only take 0.4 per cent of that peat to erode each year and be released into the atmosphere to double Scotland's total carbon emissions.
'The "tipping point" is probably around 2025'
IT'S too early to start saying 'It's too late...' but it's only just too early.
I am currently working on a book on how we could cut carbon emissions by 90 per cent by 2030.
It is just within the realms of possibility that we could do that. I think that is what we have to do to avoid increasing temperatures by two degrees Celsius above pre-industrial levels [1.3 or 1.4 degrees more than current levels] that would trigger off ecosystem collapses such as the Amazon drying out and releasing its carbon.
That would take you to three degrees, triggering a further collapse that gets you to four or five degrees.
The most painful things we have to do to reduce carbon emissions by 90 per cent include:
A complete moratorium on further flights and a great reduction in the number of current flights.
Much tougher building regulations every time we refurbish our houses, making energy-efficient lights and stuff like that part of the building regulations. It's hopeless leaving it all to the market.
And to start to go up to using the maximum wind resources [for electricity] we can put on the national grid, which is probably about 30 per cent. That could be done very quickly.
The "tipping point" is probably around 2025, but it could happen earlier than that, it depends on feedback responses - there are a lot of unknowns here.
Just last year there was a new study saying British soil has become a source of carbon. Things can happen very quickly and far sooner than we are expecting.
Last year there was a big conference in Exeter and what came out of that is we have only ten years in which we can take some meaningful action.
If we do not do anything in that, we might as well forget about it. Once we get to a certain point with global warming, it's out of our hands.
'Things will get worse'
Worldwide Fund for Nature (WWF), Scotland
IT'S helpful every so often to have a 'Cassandra' who sounds a really extreme warning.
It contributes to the debate about how far climate change will go and how bad it will get. If Lovelock is right and we are too late, then we are in deep trouble. But the middle-ground predictions say it is not too late. Things will get worse, but we can stop it at a stage where human life is still possible, human society continues to exist and life isn't too bad. That's the view most environmental groups take.
There are many people who say this is very, very urgent and we really need to act in 20, ten or five years. I've heard people saying we might be beyond the point of no return. Lovelock could be right, but let's hope not.
There are a series of crucial systems that support life as it is at the moment and if they go wrong they will start very serious changes.
For Scotland, the chief one is the circulation of the oceans. If the Gulf Stream was to shut off, that would reduce the temperature by about 10 per cent.
'It is bad news as it stands'
DR DAVID VINER
Senior research scientist, Climatic Research Unit, University of East Anglia
CLIMATE change poses a big threat. I think Professor Lovelock is over-cooking it slightly, but even if you look at the scientific consensus, the rate of warming is going to cause significant problems. It's bad news as it stands and it is going to cause major problems.
We may get a runaway greenhouse effect, but, at the moment, we just don't know. It would be unwise for governments to throw in the towel now.
We do need to make sure we reduce carbon dioxide emissions. We have a responsibility to stabilise greenhouse gases in the atmosphere and, in the very long term, reduce them.
The scientific community have been telling the government to wake up to this for a while.
We may instigate feedback responses [in the environment] that may enhance the warming, but I'm not a big advocate of the Gulf Stream switching off. That will take a lot more warming than is probably happening. That's way over the top.