The Paris climate agreement has come into legal force, bringing together parties accounting for at least 55 per cent of global greenhouse gas emissions.

The deal seeks to keep global warming below 2℃, and as close as possible to 1.5℃ above pre-industrial levels.

It has been celebrated for the speed at which it came into effect, just 11 months after negotiations concluded and 30 days after it met its ratification threshold.

The Paris deal is a fairly flexible one, mixing both binding and voluntary elements in a way that was attractive and accommodating for all nations, and specifically to enable US President Barack Obama to bring it in without the need for the obstructive US Congress to support it.

The legal aspects oblige parties to provide climate finance to developing countries, and abide by processes, mechanisms and timetables for setting and reviewing their own national climate targets.

It wants to peak global emissions as soon as possible, and push for zero net global emissions from 2050.

The United Nations Framework Convention on Climate Change has hailed the move as 'a turning point in the history of common human endeavour'.

But one expert says the formal ratification “means few legal obligations for participating countries”.

“The Paris Agreement is a legal ribbon around existing practices and actions”, according to researcher in international climate change negotiations and lecturer at ANU, Dr Luke Kemp.

“Paris entering into force has more symbolic rather than legal strength. The speed of entry into force is mainly indicative of its weak substance,” he said.

“But what does entry into force mean for those which do not join? Not a great deal for now.

“In the longer term a lack of ratification would likely lead to exclusion from discussion under the Paris negotiations, as well as an inability to use elements such as market based mechanisms under the agreement.

“Non-ratifying countries will likely become international pariahs.

“However aside from social pressure, the Paris Agreement is extremely weak against countries who choose not to join, or to withdraw. It contains no ‘non-party’ measures to entice participation or punish non-ratifying countries.”

Professor Roger Jones, research fellow in the Victorian Institute of Strategic Economic Studies, says it is a good start.

“The press release announcing that the Paris Agreement has come into force said that humanity would look back on today as ‘the day that countries of the world shut the door on inevitable climate disaster’... this clearly wasn’t written by a scientist,” he said.

“What the Agreement is doing is reducing the likelihood of disaster by opening a door to a world that will take more concerted and direct action to reduce disaster – disaster that was never inevitable but is still possible.

“Australia in its current position is between a rock and a hard place. We will continue to have to deal with the impacts of climate change – that affect us more than most developed countries, while clinging to old technologies and industries that soon will be almost worthless. The economy is showing all the signs of being on the path to transformation – it will be unforgiving to those countries and regions that fail to harness those changes for their own, and the world’s, benefit.

“This task is not trivial – the leeway in terms of change for some of our most threatened regions and ecosystems is wafer thin. We have to step through that door, because it will close, and sooner than some of our governments seem to think.”

Foreign Minister Julie Bishop and Environment Minister Josh Frydenberg are attending a conference in Marrakech this week, marking the first official meeting of parties to the Paris agreement.

Greenpeace, The Climate Institute and Oxfam have called for the historic milestone to be backed up with real and decisive action from leaders.

University of Melbourne Associate Professor Peter Christoff reflects on what the deal will mean for Australia’s future in an article for The Conversation, here.