Prime Minister Tony Abbott's apparent, if modest, conversion to the idea that climate change was an "important subject" following talks with French president Francois Hollande on Wednesday was greeted with no small measure of cynicism.

This was, after all, a politician who had built a political career on climate scepticism, with his famous remark in 2010 that it was "absolute crap" to assert the science was settled.

"Conversion" runs aground: Prime Minister Tony Abbott. Credit:Andrew Meares

It took only two days, but the doubters can claim vindication after revelations that the government sent a briefing note to Barack Obama to dissuade him that the Great Barrier Reef was under threat by climate change.

In an interview with Fairfax Media's Latika Bourke in New York, Minister for Foreign Affairs Julie Bishop said the Reef was "not under threat from climate change because its biggest threat is the nutrient runoffs agricultural land, the second biggest threat is natural disasters, but this has been for 200 years".