Premier Jay Weatherill overnight joined leaders from seven other jurisdictions throughout the world at a signing ceremony held at the US Ambassador’s residence in Paris, as the international climate summit continues this week.

South Australia has become the first Australian state to sign up to an initiative spearheaded by California Governor Jerry Brown, known colloquially as the ‘Under2MOU’.

Signatories commit to keeping the increase in global average temperature below 2C.

Weatherill told InDaily this morning the target was identified by scientists as a threshold “to give us a chance of avoiding dangerous climate change”.

“It’s by no means a guarantee,” he said.

He said the ceremony, conspicuously held during the Paris talks, was both practical and symbolic.

“It’s about sub-national governments taking action to get on with the business of acting on climate change, and also putting pressure on national governments,” he said.

“We obviously want to encourage more people to join, to try and garner momentum (and) to ensure the Paris agreement is a more substantial one.”

The project’s official site contains a quote from Ban Ki-moon, describing it as “the most ambitious commitment made to date by states and provinces world-wide”.

“It could be a game changer,” he said.

A glut of jurisdictions have signed on after Governor Brown spruiked the initiative at the Paris talks: there are now 80 signatories hailing from 22 countries and representing 614 million people. Weatherill says they collectively represent more than $18.6 trillion in GDP – a quarter of the world’s economy.

“While national governments are working towards an agreement on limiting global emissions, it will be the cities and states that will need to do the heavy lifting,” Weatherill said.

“We are the ones who have control of the policy levers, and here in Paris, we have been held up as an example of a jurisdiction that has put its plans into action.”

Weatherill revealed his recent commitment to achieving carbon neutrality in Adelaide was prompted by the impending agreement.

Signatories to the Memorandum of Understanding aim to limit greenhouse gas emissions to two tons per capita by 2050 – 80 to 95 per cent below the 1990 level.

“To sign on we had to change our existing objective,” he said.

“SA is already 9 per cent below 1990 levels (and) we need to be able to commit to 80 to 90 per cent … we referred it off to a three-person expert panel and they prepared a report that demonstrated we could achieve carbon neutrality.”

Jerry Brown addresses the international media contingent, as Weatherill (left) looks on.

He said the findings of the panel demonstrated the goal was “realistic”, and insisted it needn’t come at the expense of SA’s embattled manufacturing sector.

“Not necessarily … it could be completely the opposite,” he said.

“In the long-term, our supply of renewable energy resources has the capacity to produce low cost power, and SA will have a relative advantage in the manufacturing of goods which are energy intensive.

“We want to export our transportable fuel like oil, gas and uranium … and use for domestic purposes fixed energy resources like solar and wind.”

The other signatories to the agreement overnight were the cities of Austin, Oakland and Seattle, Italy’s Basilicata Region, Mato Grosso in Brazil, Spain’s Navarra Government and the province of South Holland.

Brown said in a statement: “Make no mistake, as leaders of the world’s cities, states and regions, we are on the front lines in the battle to combat climate change.”

US Ambassador to France Jane D. Hartley said the signatories recognized that “we are waging a fight to save our planet, and we have recognized that we must take action at all levels – as individuals, cities, states, and regions – to combat the very real threat of climate change”.