[cowboysauce]

The authors of the paper estimated that at least 200 times more volcanic activity than what’s present on the Earth would be required to release that much phosphine into the atmosphere. It’s almost certain that there are active volcanos on Venus, but that much activity is unlikely to have gone unnoticed.

[jandrese]

If there was that much volcanic activity we'd expect the atmosphere to be contaminated with ash wouldn't we?