Among the natural disasters that have marked the history of our planet, the spectacular eruption of Mount Tambora in 1815 remains forever etched in our memories. This Indonesian volcano unleashed the most violent eruption ever recorded, sending a plume of reflective particles into the sky and plunging the world into chaos.
The year that followed this cataclysm was dubbed “the year without a summer”: global temperatures plummeted, crops failed, famine struck, a cholera pandemic spread and tens of thousands of people died. It is even said that this eruption inspired Mary Shelley to write Frankenstein, while she was taking refuge from unusually cold weather in Switzerland in 1816.
Today, scientists warn that the world could face another major eruption. Markus Stoffel, a professor of climatology at the University of Geneva, emphasizes that it is not a question of if, but when. Geological data suggests a probability of a massive eruption this century, with an estimated risk of 1 in 6, he told CNN.
However, it is important to note that this phenomenon would occur in a profoundly changed world, not only more populated, but also impacted by the climate crisis. This future major eruption will inevitably lead to “climate chaos,” Stoffel warns, adding that “humanity has no plan.”
Volcanoes have always shaped our world, contributing to the formation of continents, the building of the atmosphere and climate change. When they erupt, they release a mixture of lava, ash and gases, including greenhouse gas carbon dioxide, although in much smaller quantities than those produced by the burning of fossil fuels.
When it comes to climate impacts, scientists focus more on another gas: sulfur dioxide. A major volcanic eruption can send sulfur dioxide into the stratosphere, where it turns into tiny aerosol particles that reflect sunlight, cooling the planet below.
Satellite data can track how much sulfur dioxide is released by modern volcanic eruptions. When Mount Pinatubo in the Philippines erupted in 1991, about 15 million tons of sulfur dioxide flew into the stratosphere, cooling the world by about 0.5 degrees Celsius for several years.
For ancient eruptions, data is more limited. Scientists are trying to reconstruct these events using information from ice cores and tree rings, time capsules that hold the secrets of the past atmosphere. These investigations have found that massive eruptions in recent millennia have temporarily cooled the planet by 1 to 1.5 degrees Celsius.
Mount Tambora, for example, has lowered global temperatures by nearly 1 degree Celsius. There is evidence that the massive eruption of Samalas in Indonesia in 1257 may have helped trigger the “Little Ice Age,” a period of cold that lasted for hundreds of years.
These historical events suggest that massive eruptions can also affect rainfall, disrupting monsoon systems in Africa and Asia. Understanding the impacts of these past eruptions is crucial, but the next one will occur in a world that is considerably warmer than the one before the age of fossil fuels.
In an already unstable world, the effects of a major volcanic eruption could be even more devastating than in 1815, says Michael Rampino, a professor at New York University. Global warming could also exacerbate the impact of these eruptions by altering the formation and dispersion of aerosol particles, potentially amplifying the cooling effect.
Thus, as the threat of a major volcanic eruption looms over our changing world, it is imperative that humanity prepares for the consequences of such an event. Lessons from the past and understanding current geoclimatic dynamics are essential to anticipate and mitigate the effects of another major natural upheaval.