I suspect you have been influenced by the steep rises and falls shown on the graph over hundreds of millions of years.
That graph gives the impression that there are immense changes occurring without humans being around.
But the graph is no more than a condensed version of the planets history.
If you allocated 1 cm for every million years, the graph would be at least 5 metres long and all those alarming rises and falls would disappear.
The planet had many different aspects at play over hundreds of millions of years but we need to deal with the next few decades as a matter of urgency as the current situation is changing very fast in relation to the past.
I haven't followed the Barrier reef issues so I can't comment.
