(author here) No, we don't need humans to record something in writing. But the point I was trying to make, is that maybe there are climate change sceptics out

(author here) No, we don't need humans to record something in writing. But the point I was trying to make, is that maybe there are climate change sceptics out there who will discard any and all evidence that wasn't recorded in writing by humans, as "unreliable scientific mumbo jumbo". But they can't discard this particular evidence for having that particular fault (although such folk will no doubt still end up denying this particular evidence, on account of its other faults, of which I admit there are a number).