Made this post on a different forum, wanted to repost it here too (made other posts too, but i wanted to share this one
Just to put things in perspective, especially given we recently saw a study suggest that it even erupted around 5500 cu km of volcanic material (almost double the size of it, and almost three times that of Yellowstone's largest eruption) 75.000 years ago.
There is no strong evidence of cooling, but it likely might explain the bottleneck theory in that humans actually show little DNA variation, suggesting that around 1000 humans survived this disaster. In ice cores, there's no strong evidence of very strong cooling, there is some evidence but not strongly, you would think there was more cooling. The effects weren't as severe as models suggest, however much more prolonged which could be explained by 1. ice cores going so far not accurately showing temperature variation by decade but more by thousands of years 2. the volcano cooling the climate so much that it triggered feedback mechanisms like advancing glaciers, increasing albedo effects so that there was no point of return possible.
There is however a vegetation model that suggests that most of the Northern Hemisphere vegetation by that point simply was dead, and never grew back in it's original form until the major ice age was over. Temperatures in ice cores suggest that the climate never returned to pre-Toba levels, so while the climate was already cooling, it probably increased the speed of cooling for a bit, and was a trigger to a more colder climate and for the strengthening of the major Ice Age. It also coincides with the disappearance of an African Humid Period which usually happens in interglacials, but also confirms the disappearance of vegetation observed in models.
That being said, volcanoes are not the cause of changing the climate, it's part of the climate cycle. It's not like volcanoes were never been around, and life still exists. It's find a way to adapt. Especially given the current distribution of continents is there for a long time as well as plate tectonics, it probably happens quite regularly on a geological scale, even eruptions of that size.
(You can make a case of less volcanic activity in supercontinent phases, but the most massive basalt flood eruptions happened around than, and that actually makes sense, since more magma gets trapped in the mantle when less volcano erupts regularly, which might explain those basalt floods, as well as the breaking up of a supercontinent again, and the formation of new tectonic fault lines and perhaps hot spots), again suggesting a cyclus in that (as well as explanation for it).