A catastrophic drop in ozone levels in the Earth’s atmosphere due to the super-eruption of Toba probably contributed to a dramatic reduction in the human population about 60,000 to 100,000 years ago. The result was the so-called bottle-neck effect, which is expressed in the reduction of the gene pool of mankind. This conclusion was reached by an international group of scientists, which published an article in the journal Nature Communications Earth & Environment.
The scientists used the ModelE climate model developed by NASA’s Goddard Institute for Space Studies to calculate the level of ultraviolet radiation after the ancient eruption of the Toba supervolcano in Indonesia. Although the volcano was previously thought to be responsible for the decline of the human gene pool, no concrete evidence of the devastating effects on humanity has yet been presented. At the same time, large eruptions release huge amounts of sulfur dioxide into the atmosphere, limiting the formation of ozone.
Modeling has revealed that the volcanic plume from Toba could reduce ozone levels globally by 50 percent. Even assuming that the eruption was not as severe, the impact on ozone would still be significant. The increased intensity of ultraviolet radiation due to the ozone holes could have significantly affected human survival.
According to the researchers, the effects of increased UV radiation could be similar to the effects of nuclear war. For example, crop yields and marine productivity would then fall due to the sterilizing effects of radiation. Going outside without protection will cause eye damage and sunburn in less than 15 minutes. Long-term exposure contributes to DNA damage and skin cancer.