MohammedY, Twitter asked:
Can volcanic eruption substantially change the climate more so for instance than man-made activities?
We posed this question to Hazel Rymer from the Open University...
Hazel - It does depend on what you mean by substantially change and what sort of eruption, but yes, some of the largest volcanic eruptions have profoundly affected the climate, and could do so again in the future.
Chris - Thank you. I think there’s evidence that the legacy of Krakatoa from 1880 is still there in the sea. The ocean level is still a bit lower than it would otherwise have been because the Earth cooled because of the stuff ejected into the atmosphere. I think there was a paper published in Nature a few years ago on that.
Hazel - Yup. You can see these effects for an extraordinarily long period of time.