Climate catastrophe isn't so certain

[Anomalocaris]

Atmospheric changes have a long-lasting affect. Krakatoa was the last but was actually almost a century past the worst of the volcanic eruption cycle. The worst is believed to have come from Iceland, the worst eruptions seen in several million years. These were not your typical volcanic eruptions you think about, but created mass magma fields which were much more devastating to the climate (it's these that are also believed to have lead to the end of the Cretaceous.

They ended near the beginning of the early 19th century...I had always assumed that the Industrial Revolution with its CO2 emissions had curtailed the affect of the SO2 until it was revealed in new data that there was a rebound effect from volcanic activity of this magnitude. Venus is the best example of this. It just does not end when you cut off the switch...that's why it's called a runaway greenhouse effect.

I think you really need to familarize yourself with some concrete numbers regarding volcanic eruption before sprouting off figures like "worst in several million years". Lakagígar eruption in Iceland in 1783 is a very modest eruption by the standards of what is seen on earth on a time scale of just several hundred years, much less millions of years. It erupted <5 cubic miles of lava and a few tens of millions of tons of SO2. It was soundly beaten in 1812 in both volume of magma involved in eruption and SO2 emission by Tambora eruption in Indonesia. An earlier eruption off the coast of Eastern Australia iaround 1450 is thought to have emitted 3-4 times more SO2 than the Lakagígar.

Lakagígar's claim to record was it may have involved more lava flowing on the ground than other historic eruptions. But many historic eruptions involved more magma that were shot out as tephra instead of flowing out as lava. So hardly does the size of lava flow make Lakagígar particular big in the overall scheme of historic volcanos.

For a large resurgent caldera eruption of the sort that happen once every roughly 100,000 years or so, you will be looking at about 200 times more lava and SO2 than Lakagígar. Last eruption of this magnitude happened about 80,000 years. At least 3 more of them happened just within the borders of the lower 48 states within the last 1.3 million years.

For a truly large eruption like the sort that form large basalt igneous provinces, you will be looking at single eruptions spewing out about 20,000 times more lava and SO2 than Lakagígar. You find this type of eruption about 15 million years ago in Oregon.

The key is even the columbia river basalt province that featured multiple eruptions that may have individually been been up to 20,000 times the size of Lakagígar eruption in 1783 did not seem to cause a global extinction event.

So hardly can we blame a mere sliver of a volcano in Iceland for major climate change with fairly severe extinction implications.

BTW, an asteriod ended the cretaceous. The big basalt province in India, it may have stressed the ecosystem, but there seems to be no evidence that it killed it.