First the good news. After decades of denial, delay and obfuscation by the fossil fuel industry, an historic agreement on climate change, which was first signed in Paris last year, enters into force today.

We should not underestimate the significance of today – it is the first time that governments have agreed legally binding limits to address climate change.

“This is a moment to celebrate. It is also a moment to look ahead with sober assessment and renewed will over the task ahead,” United Nations’ climate chief, Patricia Espinosa, said in a statement.

All the countries who have ratified the agreement, which includes some of the world’s largest polluters such as the USA, China and India, now have a obligation under a legal framework to limit global warming to 2 degrees C above pre-industrial levels, whilst pursuing a tougher target of 1.5C. Beyond 2C climate change is predicted as being catastrophic.

However that is where the good news runs out.

Already the Republican US Presidential candidate, Donald Trump, has threatened to pull out of the Paris climate agreement, leading to rebukes from France, Brazil and China.

The bigger problem is that, no matter who wins the US election, we are heading for catastrophic climate change.

A new report, published by UNEP, predicts that even if the Paris pledges are fully implemented, we are still on course for a temperature rise of 2.9 to 3.4 degrees this century.

To avoid this, at least a quarter must be cut from emissions by the end of the next decade.

The report argues that the “world must urgently and dramatically increase its ambition to cut roughly a further quarter off predicted 2030 global greenhouse emissions and have any chance of minimizing dangerous climate change”.

The report concludes that 2030 emissions are expected to reach 54 to 56 gigatonnes of carbon dioxide equivalent – far above the level of 42 needed to have a chance of limiting global warming to 2? this century.

“We are moving in the right direction: the Paris Agreement will slow climate change, as will the recent Kigali Amendment to reduce HFCs,” said Erik Solheim, head of UN Environment. “They both show strong commitment, but it’s still not good enough if we are to stand a chance of avoiding serious climate change.

Solheim added that “If we don’t start taking additional action now … we will grieve over the avoidable human tragedy. The growing numbers of climate refugees hit by hunger, poverty, illness and conflict will be a constant reminder of our failure to deliver. The science shows that we need to move much faster.”

Others agree. Harjeet Singh, who leads on climate change for the charity ActionAid, says: “The Paris agreement sends a much-needed signal to politicians and industry that we have to build a new world, and this has to start now. However, the deal is not enough to keep people and the planet safe.”

Asad Rehman, international climate campaigner at Friends of the Earth, added: “The Paris agreement is a major step in the right direction, but it falls a long way short of the giant leap needed to tackle climate change. Far tougher action is needed to rapidly slash emissions.”

Next week, governments will meet in Morocco to continue discussing how to put implement the Paris accord.