He's indicated strongly that he would reverse President Trump's departure from the Paris Agreement under which 195 countries, including Australia, agreed to reduce the amount of global warming carbon dioxide they emit.

The aim of the Paris Agreement is to limit emissions to net zero globally in the second half of the century, but many countries, including China, Japan, South Korea and those in the European Union, have gone further by saying they will get to net zero by 2050. Mr Biden is expected to make the same commitment.

The issue will no doubt go up the agenda with the approach of the UN climate talks in Glasgow at the end of 2021.

The coming change in Washington has fired up the debate in Canberra.

According to the Climate Council, which "supports Australia's shift to a prosperous, renewably powered economy", "net zero emissions refers to achieving an overall balance between greenhouse gas emissions produced and greenhouse gas emissions taken out of the atmosphere.

"Think of it like a set of scales: producing greenhouse gas emissions tips the scales, and we want to get those scales back into balance with no new greenhouse gas being added to the atmosphere in any given year.

"Eventually, we will probably need to tip them the other way to repair past harm. Once we stop emitting greenhouse gases from fossil fuels, we still need to deal with all the emissions we've already pumped into the atmosphere over the years. That's the difference between zero and net zero."

It does not.

Again according to the Climate Council, "getting to net zero means we can still produce some emissions, as long as they are offset by processes that reduce greenhouse gases already in the atmosphere."

This could mean planting new forests, for example. Forests suck carbon dioxide out of the air so they offset the emissions which come from coal-fired power stations and cars.

Broadly, it would be good to get to "net zero" emissions by 2050 but it isn't absolutely committed to it.

Prime Minister Scott Morrison told Parliament that improvements in technology might well deliver the target but that a firm commitment to reach it wasn't sensible.

"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 until such time as we can be very clear with the Australian people about what the cost of that is and how that plan can deliver on that commitment, it would be very deceptive on the Australian people and not honest with them to make such commitments without being able to spell that out to Australians.''

As you would expect, the Greens are utterly committed to net-zero emissions by 2050.

Labor, however, is keeping its powder dry on the way it might get there.

It went into the last election saying that if it won it would commit to:

After the defeat, the party reviewed its polices but the new Opposition Leader Anthony Albanese re-adopted the 2050 commitment.

But its interim policy is not so clear. There is a split between those in the green-tinged wing of the party and those who fear alienating traditional working-class voters, particularly in areas dependent on coal for jobs. According to the Australian Financial Review, "Monday night's shadow cabinet meeting was the most explosive many have witnessed.

"Anthony Albanese and now-backbencher Joel Fitzgibbon were 'going hammer and tongs' over climate change policy, so much so that everyone else 'was looking for a hole to climb in', said one.

"'It was f---ing big,' said another. 'The worst I've ever seen'.

"At one stage, shadow Attorney-General Mark Dreyfus interjected, calling Fitzgibbon a disgrace, to which Fitzgibbon responded: "Shut up idiot, the more you talk, the more I'm on the right track."

Some Labor people conclude that Mr Biden's victory was, at least partly, because of his strong position on the environment.

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Others argue that this would be a misreading, and that if Labor goes into the next election with a strong commitment to radical action, defeat looms. It would (rightly or wrongly) be depicted as resulting in higher fuel bills.

The Organisation for Economic Cooperation and Development which represents the 37 main industrial countries apart from China said: "Australia needs to develop a long-term strategy that integrates energy and climate policies to support progress towards its commitment to reduce greenhouse emissions (including land use change and forestry) to 26 to 28 per cent below 2005 levels by 2030.

"Australia should consider pricing carbon emissions more effectively and doing more to integrate renewables into the electricity sector."