He would become a renowned scientist during his life. But the unclassifiable Arrhenius, who always investigated at the boundary between physics and chemistry, was also a man ahead of his time: some of his works foresaw the influence of human activity on climate change or supported the hypothesis of the extraterrestrial origin of life on our planet. Many of these theories, discoveries and predictions—for which he would also be recognised, though long after his death—were very controversial in his time.
Svante Arrhenius (19 February 1859 – 2 October 1927) referenced these controversies when he received the 1903 Nobel Prize for Chemistry for his work that helped us to understand electricity from a chemical point of view, and that had initially been disdained by his professors. The first Swede to achieve the prestigious award from the Swedish Academy recalled in his speech that: “These new theories also suffered from the misfortune that nobody really knew where to place them. Chemists would not recognize them as chemistry, nor physicists as physics. They have in fact built a bridge between the two.” By enunciating his electrochemical theory, Arrhenius had founded a new field of research: physical chemistry, in which the phenomena of two sciences overlapped.
Throughout his career, Arrhenius followed this interdisciplinary approach, also becoming interested in different questions and phenomena in fields as diverse as meteorology, climatology and cosmology. One of the problems then in vogue in the scientific community that especially caught his interest was to find the cause of the different glaciations that the planet had gone through throughout its history. Arrhenius wanted to find out if the determining factor for these climatic events could be the concentration of CO2 in the Earth’s atmosphere. John Tyndall had already focused on this, identifying methane, water vapour and CO2 as atmospheric gases that cause the greenhouse effect.
In 1895 Arrhenius wanted to quantify this influence of CO2 on the greenhouse effect, which involved doing endless, complex and tedious calculations by hand—an activity that, apparently, served as a therapy to help him overcome his separation from his first wife. The results he obtained finally came to light in an article published in 1896. In it, Arrhenius concluded that a reduction in the atmospheric CO2 levels to half the then existing ones would result in a drop in the temperature of the planet of between 4 and 5°C, which could lead to a massive cooling like the one that takes place during glaciations.
The risks of emissions a century before
But he also warned that if those same levels increased by 50%, the planet would experience a warming of between 5 and 6°C, which, as Arrhenius pointed out, meant, among other things, that Scandinavia would enjoy a more benign and pleasant climate. In addition, the article also identified human industrial activity as the main source of new CO2 into the atmosphere. Although he estimated that, at the rate of emissions at that moment, this concentration would take about 3,000 years to reach, we now know that this forecast was very moderate and optimistic.
Arrhenius warned of the risks of the growing CO2 emissions by man and the consequent climate change, almost a century before the world decided to fight global warming. Despite all its serious implications, his study was largely ignored at the time. It was not until the 1970s, when the greenhouse effect began to emerge as a real and imminent concern, that the work of the Swedish scientist was given the value that it deserved.
Arrhenius was also a pioneer of the now popular Theory of Panspermia, which hypothesises about the possible extraterrestrial origin of life on Earth. In 1905 he applied the newly discovered phenomenon of radiation pressure to assert that seeds, spores and other forms of life could have travelled through space to reach our planet driven by this radiation pressure from stars. His hypothesis would only gain prominence many decades later, eventually confirming Arrhenius as much more than a great chemist: he was a visionary of science.