It takes an enormous leap of faith to believe that all the major developed countries represented at the Paris climate talks will forge a new agreement, then stay the course without reneging on their commitments once the domestic cost of driving down greenhouse gases hits home.

For some the notion that the developing world can be paid off with billions of dollars in financial aid to help overcome their own reliance on fossil fuels will seem more palatable than maintaining efforts to seriously reduce their greenhouse gas levels.

But it's really not so simple.

US Secretary of State John Kerry - who has been a key influencer in persuading other developed nations including New Zealand to change their tune in Paris - illustrates the climate conundrum this way.

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"The fact is that even if every single American citizen biked to work, carpooled to school, used only solar panels to power their homes, if we each planted a dozen trees, if we somehow eliminated all of our domestic greenhouse gas emissions, guess what - that still wouldn't be enough to offset the carbon pollution coming from the rest of the world. All nations would need to be united together for it to be effective."

But says Kerry: "If all the industrial nations went down to zero emissions - it still wouldn't be enough - not when more than 65 per cent of the world's carbon pollution comes from the developing world. It's just plain physically impossible to do so."

New Zealand's own position has been relatively muddled.

But it became untenable when the Pacific Island countries which stand to be inundated by rising sea levels lifted the bargaining tempo.

Yesterday, it appeared that John Key had given Climate Issues Minister Tim Groser a strong nudge to swing in behind the "high ambition" target to limit global temperature rises to 1.5C instead of the 2C goal which Groser had earlier supported.

Laurent Fabius - the French politician who is chairing the summit - has worked out a sophisticated two-tier negotiating strategy.

Fabius has reached out beyond and above the diplomatic representatives in Paris and their more entrenched positions to political leaders in capitals.

In Australia, Malcolm Turnbull had publicly let it be known he stood ready to lobby other political leaders to help forge an agreement.

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Turnbull had already accepted the 1.5C target ahead of New Zealand's shift. It is unclear what role Australia's own diplomats played in shifting New Zealand's stance. Fabius had released three draft agreements by the time this column was written.

A general consensus had built around the long-term goal of keeping global warming well below 2C (3.6 degrees F), while pursuing efforts to limit the temperature rise.

What wasn't clear yesterday was how strong the signals would be to investors to eschew fossil fuels for clean renewable energy sources including wind and solar power. Or as in New Zealand, hydro power and in Australia, the growing consensus towards nuclear power investment.

Unless that occurs it will be tough to halt the global warming trajectory.

The Fabius draft requires developed countries to help poorer countries adapt to the "loss and damage" sustained by climate change and also to assist their transition from fossil fuels to clean energy.

It has been suggested the developed countries set aside $100 billion annually for the developing countries. The world's energy mix underlines the complexities involved in making a shift. Right now fossil fuels, including coal, oil and gas, comprise about 80 per cent.

Instead, the new draft also talks about a goal of achieving "greenhouse gas emission neutrality in the second half of the century". But unless their emissions reduction plans are made mandatory the goal will prove illusory.