- Email: [email protected]
Before it was famous: 150 years of the greenhouse effect
HISTORIES
As an antidote to this year’s Darwin-mania, we celebrate a piece of science from 1859 that wasn’t remotely controversial at the time, but which underpins the hottest political potato of our era: climate change. In May 1859, six months before the publication of On the Origin of Species, Irish physicist John Tyndall proved that some gases have a remarkable capacity to hang onto heat, so demonstrating the physical basis of the greenhouse effect. Charles Darwin had journeyed round the world and ruminated for 20 years before presenting his inflammatory ideas on evolution. Tyndall spent just a few weeks experimenting in a windowless basement lab in London.
THE ROYAL INSTITUTION, LONDON/THE BRIDGEMAN ART LIBRARY
A discovery in need of a controversy “THE scene was one of the most wonderful I had ever witnessed. Along the entire slope of the Glacier des Bois, the ice was cleft and riven into the most striking and fantastic forms. It had not yet suffered much from the warming influence of the summer weather, but its towers and minarets sprang from the general mass with clean chiselled outlines.” John Tyndall was entranced by the Alps, in particular the great glaciers that creaked and groaned as they crept down the mountains. He found the Mer de Glace especially captivating: the largest glacier in France was a deep river of ice that stretched down the north slope of Mont Blanc and spilled out into the Chamonix valley near the hamlet of Les Bois. Tyndall first visited the Alps as a student in 1848 and could hardly stay away. He climbed Mont Blanc several times, made it to the top of Monte Rosa alone with nothing to sustain him but a ham sandwich, and was the first to reach the summit of the magnificent Weisshorn. He would probably have notched up the first ascent of the Matterhorn, too, had 46 | NewScientist | 16 May 2009
his guide not chickened out at the last minute. Between expeditions, Tyndall was busy consolidating his position as one of London’s most energetic experimental scientists. In 1853 he landed the plum job of professor of natural philosophy at the Royal Institution, where he investigated an astonishing number of subjects. Not surprisingly, one of them was glaciers. Tyndall wanted to understand how masses of ice such as the Mer de Glace melted and moved down the mountainside. He was also curious about the conditions that led to their formation, which is how in May 1859 he came to be incarcerated in the basement of the Royal Institution investigating the heatabsorbing properties of gases. The year 1859 was one of those nose-to-thegrindstone years. Tyndall was stuck in London juggling his science, a strenuous round of lectures and writing his first book – on the subject of glaciers. He was familiar with the notion of the “greenhouse effect”, first mooted in the 1770s and developed in the 1820s by Frenchman Joseph Fourier, one-time
secret policeman, governor of Egypt and physicist. Fourier pondered the question of why the Earth was warmer than physics suggested it should be, and concluded that while the light from the sun penetrated the atmosphere easily and heated the Earth, the heat radiated by the Earth couldn’t pass back through the atmosphere quite so easily. He suspected that the atmosphere blocked the
“Thus the bold and beautiful speculation has been made an experimental fact” passage of radiant heat – infrared radiation – from the Earth, preventing its escape into space. A few years later, another Frenchman, Claude Pouillet, speculated that certain gases in the atmosphere were responsible for trapping radiant heat. “This view required experimental verification,” declared Tyndall. Physicists had recently studied the heat-absorbing properties
LIBRARY OF CONGRESS
Explore our histories archive at www.NewScientist.com/histories
The Mer de Glace inspired John Tyndall to carry out the first experiments on greenhouse gases
of liquids and solids, but the general view was that gases were transparent to heat or absorbed imperceptible amounts. The immediate challenge was to devise a means of detecting the undetectable. Tyndall began to work on a piece of apparatus sensitive enough to register the heat absorbed by a slim tube filled with gas. On 9 May, he tested his apparatus and tried it out on some simple gases. “As yet no effect observed,” he wrote in his journal. By 18 May, he had cracked it: “Experimented all day; the subject is completely in my hands.” Now he found that air definitely intercepted some heat. He tried more gases, “and with the most remarkable results”. The main gases in the atmosphere, oxygen and nitrogen, proved virtually transparent to heat, while more complex, compound molecules absorbed heat much more powerfully. Coal gas – a mix of carbon monoxide, methane and other hydrocarbons – turned out to be as much a barrier to radiant heat as a piece of wood. Further experiments showed that carbon
dioxide and water vapour were particularly good at blocking heat radiation, and that it was these gases that were responsible for absorbing most of the heat trapped by the atmosphere. On 10 June, Tyndall demonstrated his experiments before a packed meeting at the Royal Institution, with Albert the prince consort in the chair. “To the eye, the gas within the tube might be as invisible as the air itself, while to the radiant heat it behaved like a cloud which it was almost impossible to penetrate. Thus, the bold and beautiful speculation has been made an experimental fact. The radiant heat of the sun does certainly pass through the atmosphere to the Earth with greater facility than the radiant heat of the Earth can escape into space.” With his mind on his book and half a dozen other projects, Tyndall did not pursue the subject again until late the following year, when he refined his apparatus, tested more gases and produced more accurate measurements. “And that was it,” says Mike Hulme, founding
director of the Tyndall Centre for Climate Change Research at the University of East Anglia, UK. “But he had done enough to be able to envisage the idea that this was a mechanism that could regulate global climate.” One of the hotly debated topics of the day was Louis Agassiz’s theory that northern Europe had at times been covered by a thick layer of ice. Tyndall was convinced, and his own results suggested that changes in the various components of the atmosphere could have produced “all the mutations of climate which the researches of geologists reveal”. “Many people think the greenhouse effect is a late 20th-century invention. Yet the physical basis for anthropogenic global warming was established six months before Darwin published On the Origin of Species,” says Hulme. “Unlike Darwin, Tyndall’s findings didn’t cause a revolution in thinking. It was a long, slow process before people recognised the implications.” Tyndall was keenly aware of the output from Victorian England’s coal fires and factory chimneys, yet he didn’t join the dots and suggest that all the extra CO2 might alter the Earth’s climate. “Perhaps if he had been more reflective like Darwin he would have made the connection,” says Hulme. “But Tyndall was very different from the near-reclusive Darwin. He was energetic, sociable and enjoyed the limelight, and he was always frantically busy.” Even if he had made the link, it may not have made much difference. “Tyndall’s results were so far ahead of the time when they were needed that they sat there unexploited for another 40 years,” says Hulme. What would Tyndall think if he could see how the climate is changing today? He would find it hard to grasp the fact that humans are responsible, says Hulme. “The idea that humans could change something on a planetary scale would have been revolutionary then. Even today, some people can’t accept that humans can have such influence on the planet. They have an innate resistance to the idea that humanity can have such an effect.” One thing is certain: Tyndall would mourn the melting glaciers. The rumpled Glacier des Bois that he admired has vanished. In the past 130 years, the Mer de Glace has receded more than a kilometre and is no longer visible from the valley below. Stephanie Pain ■ Further reading: “On the origin of ‘the greenhouse effect’: John Tyndall’s 1859 interrogation of nature” by Mike Hulme (Weather, vol 64, p 121). Mike Hulme’s new book Why We Disagree About Climate Change is published this week by Cambridge University Press 16 May 2009 | NewScientist | 47
As an antidote to this year’s Darwin-mania, we celebrate a piece of science from 1859 that wasn’t remotely controversial at the time, but which underpins the hottest political potato of our era: climate change. In May 1859, six months before the publication of On the Origin of Species, Irish physicist John Tyndall proved that some gases have a remarkable capacity to hang onto heat, so demonstrating the physical basis of the greenhouse effect. Charles Darwin had journeyed round the world and ruminated for 20 years before presenting his inflammatory ideas on evolution. Tyndall spent just a few weeks experimenting in a windowless basement lab in London.
THE ROYAL INSTITUTION, LONDON/THE BRIDGEMAN ART LIBRARY
A discovery in need of a controversy “THE scene was one of the most wonderful I had ever witnessed. Along the entire slope of the Glacier des Bois, the ice was cleft and riven into the most striking and fantastic forms. It had not yet suffered much from the warming influence of the summer weather, but its towers and minarets sprang from the general mass with clean chiselled outlines.” John Tyndall was entranced by the Alps, in particular the great glaciers that creaked and groaned as they crept down the mountains. He found the Mer de Glace especially captivating: the largest glacier in France was a deep river of ice that stretched down the north slope of Mont Blanc and spilled out into the Chamonix valley near the hamlet of Les Bois. Tyndall first visited the Alps as a student in 1848 and could hardly stay away. He climbed Mont Blanc several times, made it to the top of Monte Rosa alone with nothing to sustain him but a ham sandwich, and was the first to reach the summit of the magnificent Weisshorn. He would probably have notched up the first ascent of the Matterhorn, too, had 46 | NewScientist | 16 May 2009
his guide not chickened out at the last minute. Between expeditions, Tyndall was busy consolidating his position as one of London’s most energetic experimental scientists. In 1853 he landed the plum job of professor of natural philosophy at the Royal Institution, where he investigated an astonishing number of subjects. Not surprisingly, one of them was glaciers. Tyndall wanted to understand how masses of ice such as the Mer de Glace melted and moved down the mountainside. He was also curious about the conditions that led to their formation, which is how in May 1859 he came to be incarcerated in the basement of the Royal Institution investigating the heatabsorbing properties of gases. The year 1859 was one of those nose-to-thegrindstone years. Tyndall was stuck in London juggling his science, a strenuous round of lectures and writing his first book – on the subject of glaciers. He was familiar with the notion of the “greenhouse effect”, first mooted in the 1770s and developed in the 1820s by Frenchman Joseph Fourier, one-time
secret policeman, governor of Egypt and physicist. Fourier pondered the question of why the Earth was warmer than physics suggested it should be, and concluded that while the light from the sun penetrated the atmosphere easily and heated the Earth, the heat radiated by the Earth couldn’t pass back through the atmosphere quite so easily. He suspected that the atmosphere blocked the
“Thus the bold and beautiful speculation has been made an experimental fact” passage of radiant heat – infrared radiation – from the Earth, preventing its escape into space. A few years later, another Frenchman, Claude Pouillet, speculated that certain gases in the atmosphere were responsible for trapping radiant heat. “This view required experimental verification,” declared Tyndall. Physicists had recently studied the heat-absorbing properties
LIBRARY OF CONGRESS
Explore our histories archive at www.NewScientist.com/histories
The Mer de Glace inspired John Tyndall to carry out the first experiments on greenhouse gases
of liquids and solids, but the general view was that gases were transparent to heat or absorbed imperceptible amounts. The immediate challenge was to devise a means of detecting the undetectable. Tyndall began to work on a piece of apparatus sensitive enough to register the heat absorbed by a slim tube filled with gas. On 9 May, he tested his apparatus and tried it out on some simple gases. “As yet no effect observed,” he wrote in his journal. By 18 May, he had cracked it: “Experimented all day; the subject is completely in my hands.” Now he found that air definitely intercepted some heat. He tried more gases, “and with the most remarkable results”. The main gases in the atmosphere, oxygen and nitrogen, proved virtually transparent to heat, while more complex, compound molecules absorbed heat much more powerfully. Coal gas – a mix of carbon monoxide, methane and other hydrocarbons – turned out to be as much a barrier to radiant heat as a piece of wood. Further experiments showed that carbon
dioxide and water vapour were particularly good at blocking heat radiation, and that it was these gases that were responsible for absorbing most of the heat trapped by the atmosphere. On 10 June, Tyndall demonstrated his experiments before a packed meeting at the Royal Institution, with Albert the prince consort in the chair. “To the eye, the gas within the tube might be as invisible as the air itself, while to the radiant heat it behaved like a cloud which it was almost impossible to penetrate. Thus, the bold and beautiful speculation has been made an experimental fact. The radiant heat of the sun does certainly pass through the atmosphere to the Earth with greater facility than the radiant heat of the Earth can escape into space.” With his mind on his book and half a dozen other projects, Tyndall did not pursue the subject again until late the following year, when he refined his apparatus, tested more gases and produced more accurate measurements. “And that was it,” says Mike Hulme, founding
director of the Tyndall Centre for Climate Change Research at the University of East Anglia, UK. “But he had done enough to be able to envisage the idea that this was a mechanism that could regulate global climate.” One of the hotly debated topics of the day was Louis Agassiz’s theory that northern Europe had at times been covered by a thick layer of ice. Tyndall was convinced, and his own results suggested that changes in the various components of the atmosphere could have produced “all the mutations of climate which the researches of geologists reveal”. “Many people think the greenhouse effect is a late 20th-century invention. Yet the physical basis for anthropogenic global warming was established six months before Darwin published On the Origin of Species,” says Hulme. “Unlike Darwin, Tyndall’s findings didn’t cause a revolution in thinking. It was a long, slow process before people recognised the implications.” Tyndall was keenly aware of the output from Victorian England’s coal fires and factory chimneys, yet he didn’t join the dots and suggest that all the extra CO2 might alter the Earth’s climate. “Perhaps if he had been more reflective like Darwin he would have made the connection,” says Hulme. “But Tyndall was very different from the near-reclusive Darwin. He was energetic, sociable and enjoyed the limelight, and he was always frantically busy.” Even if he had made the link, it may not have made much difference. “Tyndall’s results were so far ahead of the time when they were needed that they sat there unexploited for another 40 years,” says Hulme. What would Tyndall think if he could see how the climate is changing today? He would find it hard to grasp the fact that humans are responsible, says Hulme. “The idea that humans could change something on a planetary scale would have been revolutionary then. Even today, some people can’t accept that humans can have such influence on the planet. They have an innate resistance to the idea that humanity can have such an effect.” One thing is certain: Tyndall would mourn the melting glaciers. The rumpled Glacier des Bois that he admired has vanished. In the past 130 years, the Mer de Glace has receded more than a kilometre and is no longer visible from the valley below. Stephanie Pain ■ Further reading: “On the origin of ‘the greenhouse effect’: John Tyndall’s 1859 interrogation of nature” by Mike Hulme (Weather, vol 64, p 121). Mike Hulme’s new book Why We Disagree About Climate Change is published this week by Cambridge University Press 16 May 2009 | NewScientist | 47