On a different thread, Richard asked what drove each of us to become
sceptics mutant variants.
I thought the best way to reply was to include in my comment the graph that first made me question how serious climate change was likely to be.
The backstory: I was an alarmist. Like John in another thread, I had too much trust in science. Wrong things could arise, but they could never thrive in the cauldron of ideas. A friend was an avowed sceptic, and peppered me with reasons why there was no danger from carbon dioxide, many of them spurious. The atmosphere was already opaque to infra-red photons, so adding carbon dioxide would have no effect. You know the kind of thing. One assertion must have been about carbon dioxide levels being very high at some point in prehistory. I did not believe what I was told, and looked for the true figure. Then I happened upon a graph at Wiki, and the rest is history.
This did not show the monotonic decline of carbon dioxide that I had imagined occurred after the evolution of photosynthesis. My naïve idea was that plants would have exploded across the planet quite rapidly. From that point, bathing in carbon dioxide as they were, they would have stripped more and more of it from the atmosphere faster and faster until they soon ended up at starvation point – at the level at which production of carbon dioxide from decay balanced that fixed by photosynthesis. It seemed a rational idea. If you go back to the Carboniferous, the reason that trees did not decay was because there were no fungi that could do the job. The dead trees piled up, got buried, compressed, and slowly turned to coal: it couldn’t happen today because there are plenty of fungi that can decompose wood.
Anyway, photosynthesis scavenged carbon dioxide until it became limiting at “pre-industrial” levels. In my mind carbon dioxide levels had been at low levels for a couple of hundred million years until Homo sapiens upset the balance by digging up all those Carboniferous fossil trees.
Except it didn’t happen that way. This was the graph that I saw:
(Not exactly this. Someone reversed the direction of time after I first saw it.) I knew which page it was on at Wiki so I went back there to cut and paste it into a comment on Richard’s thread.
But it wasn’t there. First I wondered whether I had a faulty memory and had landed on the wrong page. Then I wondered whether some nefarious memory-holing had gone on.
Luckily if Wiki deletes something, it is not memory-holed in the 1984 sense. The old version is still there in the history; if you rummage at the back of the cupboard, you’ll find it in the end. Back and back I went, until sure enough there was my graph. The last version of the page in which it was included was dated 28th August 2018. On that day it got flushed.
Earlier version, 28 August 2018:
Current version, 13 August 2021:
As to the reason for the deletion? I cannot ascribe a motive to the Wiki editor who binned the graph for sure, but it would be natural for a typical mutant variant to regard the move as an effort to erase a fact that was both inconvenient and popular with denialists. The figure provides context to today’s carbon dioxide level of a bit over 400 ppm. It also calls into question the use of terms like “unprecedented” and “irreversible”. Any reference made to “saving the Earth” or of impending cataclysm should take note that as far as Earth is concerned, it’s a case of been there, done that.