Bonn, Germany - It is that time of year when the annual climate wagon rolls into town, replete with delegates, politicians, scientists and lobbyists.

COP23, the UN Climate Change Conference, begins on Monday in the German city of Bonn.

In theory, the 2017 version should be a wholly uninteresting fortnight of impenetrable text revisions and, to the outsider, unintelligible policy engineering. But then factor in the US president.

In June this year, Donald Trump told the world the US would not be staying in the Paris Agreement, an accord forged in 2015 by all nations bar Nicaragua and Syria. It pledged to hold global warming "well below 2C" and aim for a 1.5C limit.

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Since then Nicaragua has signed up, so the US is now in company only with Syria in its climate vision - a dysfunctional nation ripped apart by war.

There have been concerns as to whether the impending US withdrawal will derail the whole agreement. It certainly has changed the dynamic but perhaps, in a surprising way, it appears to have galvanised the effort to tackle climate change.

Even within the US, cities and states have taken it upon themselves to fight back against the federal scepticism which is reversing President Obama's environmental policies and trying to re-energise coal in the name of jobs.

Take California's governor Jerry Brown, who runs a state which continues to lead in reducing emissions regardless of federal policy. He minimises the negative effects of Trump and is helping fund a US pavilion in Bonn, which will extol the virtues of climate change policy.

On the other hand, it is reported the Trump administration will be promoting coal, natural gas and nuclear energy as an answer to climate change at an event at Bonn. They will argue that no credible projection shows fossil fuels meeting less than 40 percent of global energy demand by 2050. This is likely to be a hugely popular event by virtue of the sheer unpopularity of the concept.

Despite Trump, 'we're still doing this'

Meanwhile, NGOs will be pacing the floors of the conference halls to try and keep up momentum.

The WWF's climate adviser, Dr Stephen Cornelius, says global unity can be maintained without the White House.

"Clearly, America is an important country," said Dr Cornelius. "But you saw when President Trump made his announcement in June, you had a lot of countries standing up saying 'we're still doing this'.

"So even without the federal government stepping up to the plate, you have national actors prepared to do so."

Clearly, America is an important country. But you saw when President Trump made his announcement in June, you had a lot of countries standing up saying 'we're still doing this'. Dr Stephen Cornelius, WWF climate adviser

However you feel about climate change, this has been an extraordinary year of weather.

Warming oceans have fuelled the fury of unprecedented hurricanes and cyclones across the world. There have been raging wildfires, floods and heatwaves.

The science of attribution is still being developed but a trend appears to be emerging of bigger, more destructive events.

'Still emitting far too much'

And that is of particular to concern to low-lying Fiji, which holds this year's presidency of the climate conference.

As sea levels rise, Fiji officials will be pressing for the big emitters to step forward and quite simply offer more in the global effort to tackle climate change.

Ultimately, this conference will try to formulate a rulebook on how to proceed and actually implement the Paris Agreement in the year 2020.

Time is of the essence, say the experts.

Trump may not be listening but let us leave the last word to Erik Solheim, head of the United Nations Environment Programme, who puts it simply.

"The numbers don't lie. We are still emitting far too much and this needs to be reversed."