Scientists have been aware of climate change and the dangers it poses for some time. But when did they first warn humanity about it? The work of Svante Arrhenius A few months ago, an analysis effort incorporating a range of over 88,000 studies confirmed and extended similar results obtained in 2019: the consensus on the human origin of climate change was evaluated at over 99.9%. While some of the general public and policymakers still believe that a debate continues within the scientific community, the issue of the human origin of climate change is now closed among climate experts. We know that humans have been questioning the subject for a long time, but specifically, when did we first become aware of climate change? According to historian Spencer Weart of the Center for History of Physics at the American Institute of Physics in College Park, Maryland, the first documented debates on climate change date back to ancient Greece (1200 BC to 323 BC). However, these inquiries focused only on local regions. “People wondered if draining marshes or cutting down forests could bring more or less rain to the region,” details the researcher at LiveScience. It was only much later, in 1896, that the question was truly raised. According to Weart, Swedish scientist Svante Arrhenius (1859-1927) was the first person to imagine that humanity could change the climate on a global scale. The researcher then published his calculations, pointing out that adding CO2 to the atmosphere could warm the planet. For these works, Arrhenius relied on the research of Joseph Fourier (1768-1830), who at his time hypothesized that the Earth would be much colder without an atmosphere. He was also inspired by John Tyndall (1820-1893) and Eunice Newton Foote (1819-1888). Both had separately shown that carbon dioxide and water vapor trapped heat, suggesting that an atmosphere could act as a blanket. Arrhenius’s predictions about climate change were largely accurate, but according to the historian, his work was not widely accepted. At the time, the idea that humans could influence global climate was simply acknowledged. Many also considered this warming beneficial. The phenomenon later gradually became a concern Everything then came together from the 1950s, about sixty years after Arrhenius’ work. At the time, a study by Roger Revelle (1909-1991) published in the journal Tellus in 1957 revealed that the ocean would not absorb all the carbon dioxide released in human industrial fuel emissions. In fact, the researcher pointed out that carbon dioxide levels in the atmosphere could consequently increase significantly. Three years later, Charles Keeling (1928-2005) published a separate study that revealed, with supporting evidence, an annual increase in carbon dioxide levels in the Earth’s atmosphere. From then on, scientists began to worry about the impact that human-origin emissions could have on the climate, and many called for action from the late 1970s onwards. This led to the first global climate conference in 1979. A little later, in 1987, twenty-four countries signed the Montreal Protocol on the protection of the ozone layer. The following year was marked by the establishment of the Intergovernmental Panel on Climate Change (IPCC), which has been regularly publishing reports ever since. Finally, in the same year, the G7 countries recognized the need to develop strategies in the field of climate change at the Toronto conference. Meanwhile, other studies began to highlight climate change as a potential threat to species and ecosystems worldwide. Warnings continued in the 1990s and 2000s, despite opposition from fossil fuel companies and other ideologues opposed to any government action.
