David Evans was a "carbon accountant" for six years for the Australian government.
Recent progress in scientific knowledge has weakened his confidence in C02 global warming. (In other words, Al Gore's slides are seven years old/out of date, and need updating.)
He has broken ranks with the climate change community.
"At what stage of the weakening [of scientific certainty] should the science community alert the political system that carbon emissions might not be the main cause of global warming?"
An interesting question.
The answer would probably be "not until the present funding cycle has run its course and the effects of C02 reduction strategies have worked their way through society. (And socialists have made their dishonest fortunes through their funny-money carbon offsets.)
Then the scientists can step in and explain why the earlier projections were wrong, and present a new theory and a new catastrophic threat that warrants continued generous funding. It's a strategy corporations use -- having 1st, 2nd, and 3rd generation productions in the pipeline to ensure continued revenue streams.
The trick, of course, is that the cause of climate peril must be man -- it's no good if it's just the sun having a bad hair day. There has to be a man-made cause that supports leftist moralizing and interventionist strategies.
The advantage to socialist-minded governments is that a good climate scare can justify socialist levels of government control and taxation. So liberal governments will be happy to continue to fund scare-based science.
In Canada, even the nominally Conservative government has joined the bandwagon, not, alas, sufficiently to avoid the wrath of Canada's answer to Al Gore -- David Suzuki.
A very readable article by Mr. Evans may be found at:
And that's the way the Ball bounces.