I would stare at a large monitor and pick out a volcanic plume easily while the city of Quito was not even recognizable. I would really have to hunt for LA or San Francisco in comparison to a giant haboob in the ME. Your standard cold front is more recognizable than any major city from the satellites we used (30m, 15m, 10m mostly).
Pondering how often these volcanoes erupt and send horrific gases aloft, it is hard to say; "Humans are doing it ALL!" Not to mention the thousands (tens, or hundreds of thousands?) of underwater volcanoes that emit all sorts of horribleness.
Then you contemplate that the Earth has been here for 4 billion years + or - a few million... How much hubris do we have to measure for a couple hundred years and say unequivocally; "Humans DID this!!!" It seems a bit...