The Man Who Saw Global Warming Coming in 1938

In 1938, Guy Stewart Callendar, an English steam engineer published a paper that made a bold claim: burning fossil fuels was warming the planet. At a time when few people believed human activity could affect Earth’s climate, Callendar used basic physics and available temperature data to argue that increasing carbon dioxide from coal and oil combustion was trapping heat in the atmosphere. His paper, titled “The Artificial Production of Carbon Dioxide and Its Influence on Temperature,” pulled together measurements from around the world and suggested that global temperatures had already started to rise. While many scientists ignored or doubted his work at the time, today it stands as an early, clear signal of what we now know as human-caused climate change.

Decades Ahead of His Time 

 Callendar collected temperature readings from 147 weather stations around the world, inputted CO₂ emission data from fossil fuel use, and calculated global temperature trends. His findings? Earth’s atmosphere was warming slowly but steadily, and industrial carbon emissions were to blame. He estimated that global temperatures were increasing by roughly 0.003°C per year, and that CO₂ levels had risen about 10% since the late 1800s. 

Callendar’s paper appeared in the Quarterly Journal of the Royal Meteorological Society, a respected venue but his ideas were largely ignored. At the time, the idea that human activity could influence the vast global climate system was far outside the scientific consensus. But his basic claim that carbon dioxide traps heat and that humans were pumping more and more of it into the atmosphere has since been confirmed by decades of climate research. 

The Legacy That Echoes Through Climate Science 

 Callendar was one of the first to treat climate change as a measurable, physical phenomenon not just a theoretical possibility. His work laid the foundation for the modern understanding of global warming. He did it with limited tools, no funding, and little institutional support. But what he did have was curiosity, precision, and an eye for pattern. Today, his legacy reminds us that climate change science started with a single engineer, a pile of handwritten data, and a very big idea. 

Why This Matters 

 Callendar’s story isn’t just a small detail from the past it’s an example of how science moves forward because people work hard, even when others doubt them. His ideas weren’t just smart they predicted the future. But most people didn’t listen at the time. Today, as climate change becomes a bigger problem, Callendar’s work shows us that having the facts doesn’t always lead to action. It teaches us that we need to take science seriously, and early, before the problems get worse. Callendar’s example reminds us to stay alert, care about the truth, and do something before it’s too late.