Swedish climate activist Greta Thunberg is very much the modern face of environmentalism, but she has plenty of forerunners.
The death of Prince Philip last week at the age of 99 saw the Duke of Edinburgh remembered for his vital role in promoting conservation issues long before the threat posed by industrialisation, pollution and climate change to the natural world received widespread acceptance.
Beloved BBC naturalist Sir David Attenborough, who worked with his majesty, is another leading environmentalist who understood the extinction threat long before there was broad consensus about the need for urgent action.
But before any of them, one pioneering scientist after another in Europe and the United States made visionary discoveries that shaped our understanding of the predicament facing our planet.
Here’s an introduction.
Relatively late into his distinguished career, the French Enlightenment mathematician (1768-1830) considered the idea that our planet, if heated solely by the sun, should be much colder than it is.
In seeking out possible sources of the additional warmth, Fourier realised that the earth’s atmosphere must be capable of insulation, taking inspiration from Swiss meteorologist Horace Benedict de Sassure’s experiments with solar ovens, therein outlining the principle of the greenhouse effect.
Claude Servais Mathais Pouillet (1790-1868) and William Hopkins (1793-1866) would further develop his ideas.
Eunice Newton Foote
The American scientist and suffragette (1819-88) from Seneca Falls, New York, would pick up Pouillet’s investigations into the role of carbon dioxide (CO2) in trapping heat in her pioneering work studying the warming effect of sunlight on gases, realising that changing the amount of CO2 in the atmosphere would raise the temperature of the earth.
Experimenting with glass bell jars filled with different fumes, she discovered that CO2 was particularly conducive to warming, therein observing the phenomenon that came to be known as the “greenhouse effect”, writing: “An atmosphere of that gas would give to our earth a high temperature; and if, as some suppose, at one period of its history, the air had mixed with it a larger proportion than at present, an increased temperature from its own action, as well as from increased weight, must have necessarily resulted.”
Her paper, “Circumstances Affecting the Heat of the Sun’s Rays”, based on these experiments, was delivered on her behalf by Professor John Henry of the Smithsonian Institution to the American Association for the Advancement of Science at its annual gathering in Albany in August 1856.
Her observations were rediscovered in 2010, prompting her to belatedly receive in death the recognition she deserved in life.
The Irish physicist (1820-93) advanced Foote’s findings – whether knowingly or not is unclear – through his own experiments into infrared radiation’s impact on the retention of heat in the air.
Beginning in May 1859, Tyndall began to study the impact of thermal radiation on different gases and aerosols using a ratio spectrophotometer to see which played a role in trapping heat.
Just a month later he was demonstrating his findings before the Royal Society in London, reporting that coal, gas and ether strongly absorbed radiant heat and therein proved the greenhouse effect first theorised by Fourier.
“When heat is absorbed by the planet, it is so changed in quality that the rays emanating from the planet cannot get with the same freedom back into space,” he told his peers. “Thus the atmosphere admits of the entrance of solar heat; but checks its exit, and the result is a tendency to accumulate heat at the surface of the planet.”
The Swedish chemist and Nobel prize-winner (1859-1927) is credited with making the first explicit connection between a hypothetical doubling of atmospheric CO2 levels and a rise in the surface temperature of the earth, which he proposed in 1896, a notion arising from his quest for an explanation for what brought about the prehistoric ice ages.
His calculations led him to conclude that CO2 emissions from man’s fossil-fuel burning industries and other combustion processes were large enough to cause global warming.
But it was his colleague, Nils Gustaf Ekholm (1848-1923), who first used the phrase “greenhouse effect”, arguing that humans should be able to “regulate the future climate of the earth and consequently prevent the arrival of a new ice age” by taking control of its CO2 emissions.
Guy Stewart Callendar
The British steam engineer (1898-1964) was a keen weather watcher and recorded historic temperature readings from 147 different stations dating back to the 19th century, eventually spotting a clear correlation between CO2 levels in the atmosphere and the global temperature.
By 1938, he was able to demonstrate with confidence before the Royal Meteorological Society that the earth’s temperature had risen over the past 50 years, apparently in tandem with industrial emissions.
Despite the society’s director, Sir George Simpson, dismissing his findings as a coincidence, the phenomenon, which supported Arrhenius’s earlier contentions, came to be known as the Callendar Effect.
Also working to prove Arrhenius’s theory was the American scientist (1928-2005), who began recording CO2 levels at the Mauna Loa Observatory in Hawaii on behalf of the Scripps Institute of Oceanography in 1958.
Three years later, Keeling produced a warning that CO2 levels were rapidly increasing, which became known as the Keeling Curve but which was rubbished at the time by the US National Science Foundation, the institution dismissing his work as “routine” and pulling his funding.
But the truth was becoming unavoidable, with even Lyndon Johnson’s Science Advisory Committee warning of global warming by greenhouse gas emissions by 1965.
The panel’s report “Restoring the Quality of Our Environment” warned that fossil fuel emissions “may have a significant effect on climate; carbon dioxide is nearly transparent to visible light, but it is a strong absorber and back radiator of infrared radiation… consequently, an increase of atmospheric carbon dioxide could act, much like the glass in a greenhouse, to raise the temperature of the lower air.”
Climate change would gradually come to be more widely understood as the 1970s and 1980s progressed, overcoming the reluctance of industry to face up to the necessity for change and benefitting from forward-thinking public figures like Prince Philip, Sir David and later US vice president Al Gore bringing the issues to the attention of the public.