The Paris agreement on climate change entered into force on 4 November, the first agreement by governments on legally binding limits to global temperature rises. Under the agreement, all nations have agreed to combat climate change and to “unleash actions and investment towards a low carbon, resilient and sustainable future that will keep a global average temperature rise well below 2 degrees Celsius with the accepted international aim of working to limit it to 1.5 degrees Celsius”, the UN said.

The agreement was approved by 197 countries at COP21 in Paris in December 2015. It entered into force 30 days after an agreed threshold was reached with ratification by at least 55 parties, accounting for at least 55% of total global greenhouse gas emissions. The threshold was reached on 5 October when the European Parliament approved its ratification by the European Union. The United Nations said that 97 parties have now ratified the agreement. China and the US ratified it on 3 September.

International Atomic Energy Agency (IAEA) director-general Yukiya Amano said the entry into force of the Paris agreement marks an important milestone in global efforts to combat climate change.  However, he added that a key challenge facing all countries is how to secure sufficient energy to power economic growth, while working to mitigate the effects of climate change. “Nuclear power is one of the lowest-carbon technologies for generating electricity. Some 30 countries are already using nuclear power and another 30 are considering introducing it,” he said. He added that nuclear power has already made a significant contribution to avoiding carbon dioxide emissions and it will continue to do so.

The IAEA told journalists that it is starting to "coordinate research efforts of member states on the assessment of the potential role of nuclear in their climate change mitigation strategies”. It will cover various analytical methods, frameworks and strategies.

Loreta Stankeviciute of the IAEA's Planning and Economic Studies Section will oversee the work. She said research "would include aspects such as energy planning but also focus on the assessment and effectiveness of support mechanisms that were mentioned under the Paris Agreement such as domestic policies and carbon prices in order to identify key barriers and develop approaches to address those investments in low carbon technologies."

The head of the Planning and Economic Studies Section, David Shropshire, said IAEA tools were generalised enough to be used for any kind of energy development, not just nuclear power. To make best use of the tools, it has recently signed a practical arrangement with the International Renewable Energy Agency (Irena). The focus of cooperation between the two UN agencies has been Africa, but could be expanded anywhere, said Shropshire.

"Somehow we have to stop emissions," said Shropshire, "We have to replace a lot of infrastructure that is carbon-based with low-carbon. And nuclear, as you know, is already low carbon so we are already part of that infrastructure – that's the good news."

The previous day, the UN Environment Programme (Unep) said in its annual Emissions Gap report that the world must “urgently and dramatically” increase its ambition to cut roughly a further quarter off predicted 2030 global greenhouse emissions to have any chance of minimising dangerous climate change. The report found 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 degrees celsius this century. The report said the world is still heading for temperature rise of 2.9 to 3.4 degrees celsius this century, even with Paris pledges.

According to the report, scientists agree that limiting global warming to under 2 degrees celsius this century, compared to pre-industrial levels, will reduce the likelihood of more-intense storms, longer droughts, sea-level rises and other severe climate impacts. However, even meeting the lower target of 1.5 degrees celsius will only reduce, rather than eliminate, those impacts.