By day, he worked on fossil fuels, by night, he discovered climate change.

There is something poetic about the life of Guy Callender. By day, he worked on fossil fuels, by night, he discovered climate change. 

Guy’s dad, Hugh, was a physicist. He was English, but in 1893, he got a job as Professor of Physics at McGill University in Montreal and moved there with his wife, Victoria. Guy and his three siblings were born there, though the family soon moved back to the UK in 1898, when Hugh got a flashy new job at the Royal College of Science (better known as Imperial College today).

As you might have spotted from the dates already, Guy was in his mid-late teens when World War One broke out. That could well have been the end of our story. A lot of British men Guy’s age died in that war.

But Guy had lost an eye as a child, so couldn’t join the army. Instead, he went to work in his Dad’s lab x-raying airplanes and using special new electrical equipment to detect submarines.

Guy's WW1 also helps us reflect on an important side point. War is often wrapped up in technologies, but this link was particularly obvious when it came to this war. The machines of battle got bigger and louder. It was remarked upon in papers back in Britain and one of the things that made people uneasy about the war - it felt different (as well as the fact that transport technologies meant they had closer reporting of events). And all these tanks, planes and ships had to be powered by something - petrol. Today, we’re pretty used to the connection between oil and war, but WW1 was one of the points in history where this relationship really congealed. The chap who founded Shell was made a baron for his contribution to the war, for example (though that’s another story…).

Something else we should note about Guy joining daddy’s lab to do exciting war work - he was pretty lucky, and he came from not just a reasonably privileged background, but one steeped in science. Today some educationalists talk about ‘science capital’ - analogous to cultural capital (which itself is analogous to actual money), the sort of knowledge and connections some kids get at home which means they can talk about theatre or art or stories in New Scientist and so fit in with elites and do well in uni interviews and networking around work, and generally impress people. Guy had bucketloads of this sort of symbolic science coin. The Callendar homelife was rich with scientific discussion, with famous scientists dropping by and exciting new research and technologies discussed around the dinner table.

When the war ended, Guy joined Imperial to formally train in mechanics and mathematics, before rejoining his Dad’s lab. He ended up pretty well respected in his own right, one of Britain’s leading engineers and author of the standard reference book of tables and charts on the properties of steam at high temperatures and pressures.

He got married, had twins and moved to Sussex near a secret defense research lab, which is where he worked till he retired in the late 1950s.

During World War Two, he worked on the petroleum warfare department, sharing a patent for something called FIDO which would disperse fog so aircraft could take off and land even in bad weather conditions. It worked by burning massive quantities of petrol (3000-5000 gallons to land just one aircraft) but it was deemed worth the cost during wartime. He also had a project analysing fuels from captured aircraft - the idea was to work out where the fuel had come from from chemical traces, but the science he developed also gave them new insights into water vapor, carbon dioxide and ozone and low concentration and low temperatures in the atmosphere, which apparently up being really useful to understanding the Earth's heat budget too.

Around all that, his hobbies included gardening, tennis, cycling and BEING A MASSIVE WEATHER NERD.

And this is where, finally, we get to the really important contribution to climate science.

Back in the 1890s, the decade Guy was born in, Swedish scientist Svante Arrhenius had run some maths on how adding or subtracting carbon dioxide to the atmosphere might alter the climate. By his calculations, doubling carbon dioxide emissions could raise the Earth’s temperature by five or even six degrees Celsius. These figures were largely ignored though. Arrhenius himself didn’t believe humans were likely to create enough carbon dioxide to cause problems, and even if they did, he expected them to dream up some clever ways out of it.

Guy thought the theory and calculations were interesting, but he wanted more, and went digging for evidence in the temperature records.

He used data collected by the Smithsonian to work out a global increase in land temperature of about 0.3 degree C between 1880 to the mid 1930s. The available data on carbon dioxide wasn’t quite so good, but selecting evidence from areas he felt might be representative of clean air (i.e. not inner cities) he worked out a 6% rise in atmospheric carbon dioxide for the same period. Modern research suggests Callendar was pretty much spot-on with his calculations.

He also pointed out that humans had long been able to play a role in natural processes, and that humanity was now heavily accelerating the otherwise quite slow-moving carbon cycle by “throwing some 9,000 tons of carbon dioxide into the air each minute.”

In April 1938 he presented it to the Royal Meteorological Society in London and… they largely dismissed him.

It’s tempting to write up his story as a sort of steampunkish, plucky ametaur taking on the stuffed shirt scientists - his prophetic insights dismissed by their overly professional, blinkered view. Could they not see the truth of climate change staring them in right in the eyes?! But that’d be wrong. He wasn’t really an outsider. He was a Fellow of the Royal Meteorological Society and served on its council. He was also a Fellow of the Glaciological Society. And he’d grown up surrounded by professional science.

Moreover, even Callendar himself wasn’t too fussed about the whole thing – even if global warming was happening, he thought it wouldn’t end up as much more than a degree, and that might be nice, offering more CO2 for plants and delaying a "return of the deadly glaciers." Like a lot of the early climate change researchers, Callendar was worried about a new ice age, and knew greenhouse gases were part of what was keeping us warm. The idea that humans would over-egg enough to cause dangerous global warming just didn’t seem so likely back then.

He published the research still, and these papers were slowly picked up by others. He died reasonably young - aged 67 - by then people were already starting to cite him, but he never really got to see the full impact of his work. In recent years, some climate scientists have celebrated Callendar’s contribution, you can even follow him on Twitter