The lack of an Australian commitment to net-zero carbon emissions by 2050 will be the question that follows Prime Minister Scott Morrison both internationally and at home, for as long as the pledge remains unmade.
The proposition is again front of mind, after the election of former Vice-President Joe Biden in the United States, who had made the commitment, and looks set to completely reverse the country's position on climate change from that held by Donald Trump.
And on Monday independent MP Zali Steggall introduced a private member's bill including the net-zero pledge among a series of measures to prevent and adapt to a changing climate.
But Mr Morrison was bullish on Monday when asked in Question Time why his government was leaving Australia behind by not committing to a net-zero emissions by 2050 policy.
Would Australia be left behind? Not according to the Prime Minister.
"When it comes to the matter of net zero by 2050, Australia would like to meet that as quickly as possible, as quickly as it's able," he said.
But there's a catch, of course. Mr Morrison said he won't make such a commitment until he can tell Australians how much it would cost.
Later this week the Bureau of Meteorology and CSIRO will release their sixth State of the Climate report, which comes out every two years.
It's likely to show just what the cost is, and will continue to be, of not acting.