US President Joe Biden moved decisively, rejoining the Paris Agreement on day 1, and appointing former secretary of state John Kerry as his climate envoy, and with cabinet status.

Kerry, in turn, called on countries to "treat the crisis as the emergency that it is" by reducing greenhouse gas emissions as a matter of urgency.

He warned that the costs of coping with climate change were escalating, with the US spending some $A350 billion in one year after three storms.

"We've reached a point where it is an absolute fact that it's cheaper to invest in preventing damage or minimising it at least than cleaning up."

A similar message came from our Climate Council, warning of the looming $100 billion annual cost of natural disasters for which we are not prepared.

Kerry also emphasised that climate is a top priority for Biden.

"We have a president now, thank God, who leads and tells the truth ... and he knows that we have to mobilise in unprecedented ways to meet the challenge that is fast accelerating, and we have limited time to get it under control."

Kerry called for all countries to come to COP26 in Glasgow in November with commitments to meet net zero emissions by mid-century and national plans to reduce greenhouse gases in the next decade.

What a sharp contrast with the lack of truth and leadership on climate coming from Morrison.

This week he claimed that: "The political debate about reaching a carbon neutral future is over," but he will not take a new 2030 or 2035 emissions reduction target to that UN meeting.

Morrison rejects that it is an emergency and he rests on his assertion that he will meet his Paris commitment to reduce emissions by 26-28 per cent by 2030 "in a canter".

Where's the truth in his claim that the politics is settled, when his Coalition partner was lobbying again this week for new coal-fired power plants, which in turn has seen several key city-based Liberal MPs reject the proposal.

Morrison now faces the prospect of significant disunity on the climate issue in what will be an election year.

The Opposition is also dividing seriously on the issue, which has culminated, so far, in the removal of the Opposition climate spokesman.

Both the LNP and the Opposition now seem committed to selling out to the fossil fuel lobby, clearly against our national interest, at a time when a majority of voters, households, leading mining and other businesses, investors, financial institutions, regulators.

Many across civil society are calling on the government to lead decisively.

This will only compound our global ranking as a laggard on climate. Morrison is also being misleading about the nature and significance of our 2030 Paris target.

The government's own Climate Change Authority recommended a target of 45-65 per cent. The decision to announce the lesser target of 26-28 per cent was purely a political decision, not based on science or policy.

Our 2030 target is not consistent with the Paris objective of keeping the increase in global average temperature to well below 2 degrees above pre-industrial levels, and pursuing efforts to limit the temperature increase to 1.5 degrees.

Indeed, our 2030 target is consistent with global warming of about 3 degrees and much more in Australia.

Recently, our Bureau of Meteorology told the Senate that current targets have us on track to warm by a catastrophic 4.4 degrees by the end of the century.

As a member of the Climate Targets Panel, we released a report yesterday - based on the CCA "carbon budget" methodology and government data - that suggests that to be consistent with the 2 degree objective, our 2030 target should be at least 50 per cent, 67 per cent by 2035 and net zero by 2045.

To be consistent with 1.5 degrees, our 2030 target would need to be 74 per cent, achieving net zero by 2035.

The government has plundered much of the carbon budget since 2014: ignoring CCA advice, trying to close it down, repealing the carbon price - and emissions have risen.

Against this hard evidence, Morrison is denying reality, fostering the illusion that he is addressing the climate challenge by sticking with the 2030 target, doing all he can to get to net zero by mid-century, while point-scoring against the Opposition.

The planet is not swayed by politics. There is no vaccine for climate.

The imperative for Morrison is to lead our nation on a genuine and fair transition to a low carbon society.

John Hewson is a professor at the Crawford School of Public Policy, ANU, and a former Liberal opposition leader.