Has global warming stopped?

'The global temperature of 2007 is statistically the same as 2006 and every year since"

'The fact is that the global temperature of 2007 is statistically the same as 2006 and every year since 2001'. Plus read Mark Lynas's response

Global warming stopped? Surely not. What heresy is this? Haven’t we been told that the science of global warming is settled beyond doubt and that all that’s left to the so-called sceptics is the odd errant glacier that refuses to melt?

Aren’t we told that if we don’t act now rising temperatures will render most of the surface of the Earth uninhabitable within our lifetimes? But as we digest these apocalyptic comments, read the recent IPCC’s Synthesis report that says climate change could become irreversible. Witness the drama at Bali as news emerges that something is not quite right in the global warming camp.

With only few days remaining in 2007, the indications are the global temperature for this year is the same as that for 2006 – there has been no warming over the 12 months.

But is this just a blip in the ever upward trend you may ask? No.

The fact is that the global temperature of 2007 is statistically the same as 2006 as well as every year since 2001. Global warming has, temporarily or permanently, ceased. Temperatures across the world are not increasing as they should according to the fundamental theory behind global warming – the greenhouse effect. Something else is happening and it is vital that we find out what or else we may spend hundreds of billions of pounds needlessly.

In principle the greenhouse effect is simple. Gases like carbon dioxide present in the atmosphere absorb outgoing infrared radiation from the earth’s surface causing some heat to be retained.

Consequently an increase in the atmospheric concentration of greenhouse gases from human activities such as burning fossil fuels leads to an enhanced greenhouse effect. Thus the world warms, the climate changes and we are in trouble.

The evidence for this hypothesis is the well established physics of the greenhouse effect itself and the correlation of increasing global carbon dioxide concentration with rising global temperature. Carbon dioxide is clearly increasing in the Earth’s atmosphere. It’s a straight line upward. It is currently about 390 parts per million. Pre-industrial levels were about 285 ppm. Since 1960 when accurate annual measurements became more reliable it has increased steadily from about 315 ppm. If the greenhouse effect is working as we think then the Earth’s temperature will rise as the carbon dioxide levels increase.

But here it starts getting messy and, perhaps, a little inconvenient for some. Looking at the global temperatures as used by the US National Oceanic and Atmospheric Administration, the UK’s Met Office and the IPCC (and indeed Al Gore) it’s apparent that there has been a sharp rise since about 1980.

The period 1980-98 was one of rapid warming – a temperature increase of about 0.5 degrees C (CO2 rose from 340ppm to 370ppm). But since then the global temperature has been flat (whilst the CO2 has relentlessly risen from 370ppm to 380ppm). This means that the global temperature today is about 0.3 deg less than it would have been had the rapid increase continued.

For the past decade the world has not warmed. Global warming has stopped. It’s not a viewpoint or a sceptic’s inaccuracy. It’s an observational fact. Clearly the world of the past 30 years is warmer than the previous decades and there is abundant evidence (in the northern hemisphere at least) that the world is responding to those elevated temperatures. But the evidence shows that global warming as such has ceased.

The explanation for the standstill has been attributed to aerosols in the atmosphere produced as a by-product of greenhouse gas emission and volcanic activity. They would have the effect of reflecting some of the incidental sunlight into space thereby reducing the greenhouse effect. Such an explanation was proposed to account for the global cooling observed between 1940 and 1978.

But things cannot be that simple. The fact that the global temperature has remained unchanged for a decade requires that the quantity of reflecting aerosols dumped put in our atmosphere must be increasing year on year at precisely the exact rate needed to offset the accumulating carbon dioxide that wants to drive the temperature higher. This precise balance seems highly unlikely. Other explanations have been proposed such as the ocean cooling effect of the Interdecadal Pacific Oscillation or the Atlantic Multidecadal Oscillation.

But they are also difficult to adjust so that they exactly compensate for the increasing upward temperature drag of rising CO2. So we are led to the conclusion that either the hypothesis of carbon dioxide induced global warming holds but its effects are being modified in what seems to be an improbable though not impossible way, or, and this really is heresy according to some, the working hypothesis does not stand the test of data.

It was a pity that the delegates at Bali didn’t discuss this or that the recent IPCC Synthesis report did not look in more detail at this recent warming standstill. Had it not occurred, or if the flatlining of temperature had occurred just five years earlier we would have no talk of global warming and perhaps, as happened in the 1970’s, we would fear a new Ice Age! Scientists and politicians talk of future projected temperature increases. But if the world has stopped warming what use these projections then?

Some media commentators say that the science of global warming is now beyond doubt and those who advocate alternative approaches or indeed modifications to the carbon dioxide greenhouse warming effect had lost the scientific argument. Not so.

Certainly the working hypothesis of CO2 induced global warming is a good one that stands on good physical principles but let us not pretend our understanding extends too far or that the working hypothesis is a sufficient explanation for what is going on.

I have heard it said, by scientists, journalists and politicians, that the time for argument is over and that further scientific debate only causes delay in action. But the wish to know exactly what is going on is independent of politics and scientists must never bend their desire for knowledge to any political cause, however noble.

The science is fascinating, the ramifications profound, but we are fools if we think we have a sufficient understanding of such a complicated system as the Earth’s atmosphere’s interaction with sunlight to decide. We know far less than many think we do or would like you to think we do. We must explain why global warming has stopped.

David Whitehosue was BBC Science Correspondent 1988–1998, Science Editor BBC News Online 1998–2006 and the 2004 European Internet Journalist of the Year. He has a doctorate in astrophysics and is the author of The Sun: A Biography (John Wiley, 2005).] His website is

Hawking in 1991. Photo: Rex/Tom Pilston/The Independent
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Stephen Hawking’s life is a triumph of intellect over adversity

Stephen Hawking received his "death sentence" more than 50 years ago. The Astronomer Royal pays tribute to him.

Soon after I enrolled as a graduate student at the University of Cambridge in 1964, I encountered a fellow student, two years ahead of me in his studies; he was unsteady on his feet and spoke with great difficulty. This was Stephen Hawking. I learned that he had a degenerative disease – amyotrophic lateral sclerosis – and might not live long enough even to finish his PhD degree. But, amazingly, he has lived on for 50 years longer. Mere survival would have been a medical marvel, but of course he hasn’t merely survived. He has become the most famous scientist in the world – acclaimed for his brilliant researches, for his bestselling books about space, time and the cosmos and, above all, for his astonishing triumph over adversity.

The Theory of Everything, the film currently in cinemas, portrays the human story behind this struggle. And it surpasses most biopics in representing the main characters so well that they themselves are happy with the portrayal.

Astronomers are used to large numbers. But few numbers could be as large as the odds I’d have given back in 1963, when Stephen received his “death sentence”, against ever celebrating this uniquely inspiring crescendo of achievement, sustained now for more than 50 years.

Stephen went to school in St Albans and then to university at Oxford. He was, by all accounts, a “laid-back” undergraduate, but his brilliance nonetheless earned him a first-class degree, and an “entry ticket” to a research career in Cambridge. Within a few years of the onset of his disease he was wheelchair-bound and his speech became an indistinct croak that only those who knew him could interpret. But in other respects fortune had favoured him. He married a college friend, Jane Wilde, who provided a supportive home life for him and their three children.

His scientific work went from strength to strength: he quickly came up with a succession of insights into the nature of black holes (then a very new idea) and how our universe began. In 1974 he was elected to the Royal Society, Britain’s main scientific academy, at the exceptionally early age of 32.

He was by then so frail that most of us suspected he could scale no further heights. But, for Stephen, this was still just the beginning. He worked in the same building as I did. I would often push his wheelchair into his office, and he would ask me to open an abstruse book on quantum theory – the science of atoms, not a subject that had hitherto much interested him. He would sit hunched motionless for hours; he couldn’t even turn the pages without help. I wondered what was going through his mind, and if his powers were failing. But within a year he came up with his best ever idea, encapsulated in an equation that he says he wants on his gravestone.

The great advances in science generally involve discovering a link between phenomena that seemed hitherto conceptually unconnected: for instance, Isaac Newton realised that the force making an apple fall was the same as the force that held the moon and planets in their orbits. Stephen’s “eureka moment” revealed a profound and unexpected link between gravity and quantum theory which predicted that black holes would not be completely black, but would radiate in a characteristic way. This radiation is significant only for black holes much less massive than stars – and none of these has been found. However, “Hawking radiation” became a hugely influential concept in mathematical physics; indeed, one of the main achievements of string theory has been to firm up and build on his idea. It is remarkable that it is still the focus of theoretical interest, a topic of debate and controversy even 40 years after discovery. He has not been awarded the Nobel Prize because his idea is not confirmed by experiment. But in 2012 he was one of the first winners of the Milner Prize, worth $3m, intended to recognise theoretical work.

Cambridge has been Stephen’s base throughout his career and he became a familiar figure in the city, navigating his wheelchair around the streets. By the end of the 1970s he had advanced to one of the most distinguished posts at the university – the Lucasian Professorship of Mathematics, once held by Newton. Stephen held the chair with distinction for 30 years but reached the retiring age in 2009, and since then has held a special research professorship. He has continued to seek new links between the very large (the cosmos) and the very small (atoms and quantum theory) and to gain deeper insights into the very beginning of our universe, addressing such questions as: “Was our Big Bang the only one?” He always had an amazing ability to figure things out in his head but generally he worked with colleagues who would write a formula on a blackboard; he would stare at it, and say what should come next.

In 1987 Stephen contracted pneumonia. He had to undergo a tracheotomy, which removed even the limited powers of speech he then possessed. It had been more than ten years since he could write, or use a keyboard. Without speech, the only way he could communicate was by directing his eye towards one of the letters of the alphabet on a big board in front of him.

But he was saved by technology. He still had the use of one hand; and a computer, controlled by a single lever, allowed him to spell out sentences. These were then declaimed by a speech synthesiser with the androidal American accent that has since become his trademark. His lectures were, of course, pre-prepared, but conversation remained a struggle. Each word involved several presses of the lever, so a single sentence took several minutes. He has learned to economise with words. His comments are aphoristic or oracular, but often infused with wit. In recent years he has become too weak to control this machine effectively, even with facial muscles or eye movements, and his communication – to his immense frustration – has become still slower. Let’s hope that his new Intel predictive software speeds things up, though he will not modify his “trademark” voice.

At the time of his tracheotomy operation, he had a rough draft of a book that he hoped would describe his ideas to a wide readership and earn something for his two eldest children, Robert and Lucy, who were then of college age. On recovering from pneumonia, he resumed work with the help of an editor. When the US edition of A Brief History of Time appeared, the printers had made errors (one picture was upside down), and the publishers tried to recall the stock. To their amazement, all copies had already been sold. It was the first inkling that the book was destined to have huge success – four years on bestseller lists around the world.

Stephen became an international celebrity. His later ideas appear, beautifully illustrated, in other books such as The Universe in a Nutshell and The Grand Design. These were not bought by quite as many people as his first book, but they are more clearly written, and probably more people got to the end of them. He has featured in numerous television programmes; his lectures have filled the Royal Albert Hall in London, and similar venues in the United States and Japan. (In principle, machine translation could now give him an advantage over the rest of us by converting his speech into Japanese, Korean, or other languages.) He lectured at Bill Clinton’s White House; he was back there again more recently when President Obama presented him with the Presidential Medal of Freedom, a very rare honour for any foreigner. He has featured in Star Trek and The Simpsons, as well as in numerous TV advertisements. Even before the present film, his life and work had featured in movies. In an excellent TV docudrama, he was played by Benedict Cumberbatch. (And in 2012 Cumberbatch spoke his words in a three-part documentary, The Grand Design, made for the Discovery Channel.)

The Theory of Everything conveys with sensitivity how the pressure of his celebrity, and the need for round-the-clock care by a team of nurses, strained his marriage to breaking point. Jane’s book on which the film is based chronicles the 25 years during which, with amazing dedication, she underpinned his family life and his career.

This is where the film ends. But it leaves us only halfway through Stephen’s adult life. After the split with Jane, he married Elaine Mason, who had been one of his nurses, and whose former husband had designed his speech synthesiser. However, this partnership broke up after a few years. He has been sustained, then and thereafter, by a team of helpers and personal assistants, as well as his family. His daughter, Lucy, has written books for children with her father listed as co-author.

His 60th-birthday celebrations in January 2002 were a memorable occasion for all of us. Hundreds of leading scientists came from all over the world to honour and celebrate Stephen’s discoveries, and to spend a week discussing the latest theories on space, time and the cosmos. But the celebrations weren’t just scientific – that wouldn’t have been Stephen’s style. There were parties and dinners each evening. He was surrounded by his children and grandchildren. A Marilyn Monroe lookalike cut a huge birthday cake; a troupe of cancan dancers performed; there was music and singing. And when the week’s events were all over, he celebrated with a trip in a hot-air balloon.

Stephen continued, even in his sixties, to write technical papers and to speak at premier international conferences – doubly remarkable in a subject such as maths, where even most healthy researchers peak at an early age. He reminded us that he was not another Einstein; nonetheless few, if any, have done more to deepen our knowledge of gravity, space and time.

He remains an inveterate traveller despite attempts to curb this as his respiration weakens. All his trips involve an entourage of assistants and nurses. His fame, and the allure of his public appearances, have given him the resources for nursing care, even private jets, and protected him against the “Does he take sugar?” type of indignity that the disabled often suffer.

Why has he become such a “cult figure”? The notion of an imprisoned mind roaming the cosmos plainly grabbed people’s imagination. If he had achieved equal distinction in (say) genetics, rather than cosmology, his triumph of intellect against adversity probably would not have had the same resonance with a worldwide public.

It was amazing enough that Stephen reached the age of 60; few of us then thought that he would survive to another milestone – his 70th birthday. But he did, and this was again marked by an international gathering of scientists, and also with some razzmatazz: Richard Branson, Daniel Craig and other celebrities attended. Yet plainly he was then weakening; he had to watch most of the events by video while in hospital on a respirator.

But once again he recovered, and was soon back at work. Within three months he was off on another transatlantic trip. This was not just to lecture: he was determined to visit an underground laboratory in Canada where landmark and delicate experiments had been done. He was undeterred by having to descend two miles down a mineshaft. On a later trip only a last-minute health setback prevented him from travelling onwards to the Galapagos. In April 2013, he gave lectures to huge audiences in California. And just four months ago he was the “star” attraction (along with Brian May) at Starmus, a “cosmos and music” festival in the Canary Islands.

Stephen is far from being the archetypal unworldly or nerdish scientist – his personality has remained remarkably unwarped by his frustrations and handicaps. As well as his inveterate scientific travels, he enjoys trips to the theatre or the opera. He has robust common sense, and forceful political opinions that he is ready to express. However, a downside of his celebrity is that his comments attract exaggerated attention even when he speaks about topics in which he has no special expertise – philosophy, for instance, or the dangers posed by aliens or intelligent machines.

Despite the pressures and difficulties, he is a determined campaigner for the disabled. He has also always been, at a personal level, sensitive to the misfortunes of others. He records that, in hospital soon after his illness was first diagnosed, he felt his depression lift when he compared his lot with that of a boy in the next bed who was dying of leukaemia. In later life, he went to great efforts to visit a terminally ill colleague. And he has been happy to align himself with other campaigns and causes. When he visited Israel, he insisted on going also to the West Bank. Newspapers in 2006 showed remarkable pictures of him in his wheelchair, surrounded by fascinated and curious crowds in Ramallah. And in 2013 he accepted the advice of Palestinian colleagues to decline an invitation to a major conference in Israel. But by the time the ensuing (and entirely predictable) controversy broke, he was in intensive care with a collapsed lung. Last month he hit headlines again with his claims that computers may become so powerful that it will be the end for humanity.

Even more astonishing are the photographs of him “floating” in the Nasa aircraft (the “Vomit Comet”) that allows passengers to experience weightlessness. He was manifestly overjoyed at escaping, albeit briefly, the clutches of the gravitational force he has studied for decades and that has so cruelly imprisoned his body. He says he would still like to be a “space tourist”. In London in the summer of 2012, he reached perhaps his largest ever audience when he played a star role in the opening ceremony for the Paralympics. He is probably, at least since the death of the actor Christopher Reeve, the best-known disabled person in the world – and, unlike Reeve, he achieved his fame while already disabled.

Tragedy struck Stephen Hawking when he was only 21. He was diagnosed with a deadly disease and his expectations dropped to zero. He has said that everything that has happened since then is a bonus. And what a triumph his life has been. His name will live in the annals of science; millions have had their cosmic horizons widened by his bestselling books; and even more, around the world, have been inspired by a unique example of achievement against all the odds – a manifestation of astonishing willpower and determination.

It is a great thing that some phases and facets of Stephen’s life have been so well portrayed in The Theory of Everything. Let’s hope that some time there will be another film that depicts his later life, and his scientific achievements.

This article is an updated and expanded version of a tribute to Stephen Hawking published in 2007

Martin Rees is a fellow of Trinity College and Emeritus Professor of Cosmology and Astrophysics at the University of Cambridge

This article first appeared in the 16 January 2015 issue of the New Statesman, The Jihadis Among Us