The Toba “super volcanic” eruption 74,000 years ago had a massive impact on human evolution. In size it dwarfed Krakatoa and Tambora emitting 2,800 cubic km (about 670 cubic miles) of ash and lava or about about 200 times larger than Krakatoa. It cooled the earth by ~3 C for a period of about 10 years. Parts of Indonesia, India and the Indian Ocean were covered by 15 centimeters of volcanic debris. Human populations outside Africa suffered severely in the short term due to food shortages. Some have estimated that just a few thousands individuals survived this period. Our DNA today is all derived from this small pool.
Volcanoes cool the planet by increasing global albedo and cutting out sunlight. Their imprint can be seen in the current global temperature data.
The severn largest volcanic eruptions in the last 270 years compared to Global Temperatures. The 3 largest eruptions all occurred before 1850. CRUTEM4 is shown in Green.
Luckily Toba is not due to erupt again for another 600,000 years!
Not long ago we learned that 19,000 undersea volcanoes were recently discovered. While the ash will not get into the atmosphere is their output of CO2 accounted for?
earthsky.org/earth/19000-un
I doubt it.
Another interesting question is why the bottom of the ocean is not covered in ice – not even in the Arctic !
This implies a heat source coming from the earth itself.
“Human populations outside Africa suffered severely in the short term due to food shortages. Some have estimated that just a few thousands individuals survived this period. Our DNA today is all derived from this small pool.”
This is most likely wrong. There is no evidence that any other animal species or even the ecosystems in the volcano region suffered any kind of catastrophe. A human-only volcanic catastrophe is extremely unlikely.
And volcanoes, even the biggest ones, have an acute and short effect. For a real catastrophe you need something like an igneous province, like the Deccans.
Do we know there were no species extinctions following Toba ?
Of course. People should not pay credit to all those catasthropic tales from the past or in the future. How many Asian species show a genetic bottleneck at the time of the Toba supereruption?
Singh, A. and Srivastava, A.K., 2022. Had youngest Toba tuff (YTT, ca. 75 ka) eruption really destroyed living media explicitly in entire Southeast Asia or just a theoretical debate? An extensive review of its catastrophic event. Journal of Asian Earth Sciences: X, p.100083.
Smith, E.I., Jacobs, Z., Johnsen, R., Ren, M., Fisher, E.C., Oestmo, S., Wilkins, J., Harris, J.A., Karkanas, P., Fitch, S. and Ciravolo, A., 2018. Humans thrived in South Africa through the Toba eruption about 74,000 years ago. Nature, 555(7697), pp.511-515.
Lane, C.S., Chorn, B.T. and Johnson, T.C., 2013. Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka. Proceedings of the National Academy of Sciences, 110(20), pp.8025-8029.
Volcanoes have very little effect on climate despite contrary popular and scientific beliefs.
You may well be right !
Ice Ages do though 😉