What is being hailed as ‘a historic new global climate agreement’ has been struck at the United Nations conference (COP21) on climate change in Paris.
The deal undoubtedly takes a significant step forward to reducing emissions, although some reservations have been expressed over the shortage of binding targets. But for the first time ever 195 countries, including the world’s largest emitters, have now committed to act together to combat climate change and have agreed a mechanism that will ensure they are held equally accountable. The agreement has the primary aim of driving the world’s economies forward on a path to limiting global temperature rises to below 2°C, or even 1.5 if action is taken quickly enough. The central pillar of the agreement, which will commit all parties to cutting emissions, will come into effect in 2020.
US president Barack Obama called the agreement "ambitious" and "historic", but also warned against complacency. "Together, we’ve shown what’s possible when the world stands as one," he said. And although admitting that the deal was not "perfect", he said it was "the best chance to save the one planet we have".
China’s chief negotiator Xie Zhenhua also said that the deal was not perfect. But he commented that "this does not prevent us from marching historical steps forward".
Nearly 200 countries took part in the negotiations to strike the first climate deal to commit all countries to cut emissions, which would come into being in 2020. In that year, all parties will be expected to update their plans to cut emissions by 2030. These plans will be put forward by each party to the agreement in the form of Intended Nationally Determined Contributions, a mechanism developed in advance of COP21, with an updated version to be assessed in 2018.

The key measures in the agreement include:
-To peak greenhouse gas emissions as soon as possible and achieve a balance between sources and sinks of greenhouse gases in the second half of this century;
– To keep global temperature increase "well below" 2°C (3.6°F) and to pursue efforts to limit it to 1.5°C;
– To review progress every five years;
– $100 billion a year in climate finance for developing countries by 2020, with a commitment to further finance in the future.

Countries will now have to come together regularly to review their climate plans and collectively ensure that the necessary action is being taken to tackle climate change.
The agreement sets out a clear long-term goal of net zero emissions by the end of the century, indicating a degree of commitment to decarbonising. Progress against this goal will be independently assessed in 2018 and every five years thereafter.
This long-term goal is intended to send a strong signal to investors, businesses, and policy-makers about the shift to a low carbon economy and provides confidence that will help drive the scale of investment needed.
Countries will also be legally obliged to make new post-2030 commitments to reduce emissions every 5 years, from 2025. For the first time, all countries will be held accountable by independent review for acting according to their pledges.
And all developed countries will collectively mobilise $100 billion per year from both the public and private sector to help the poorest and most vulnerable countries to protect themselves from the effects of climate change and support low carbon development. The agreement now recognises the role of emerging economies in mobilising resources and contributing finance over time as well.

However, not all observers were impressed. Nick Dearden, director of campaign group Global Justice Now, said: "It’s outrageous that the deal that’s on the table is being spun as a success when it undermines the rights of the world’s most vulnerable communities and has almost nothing binding to ensure a safe and liveable climate for future generations."
Some aspects of the agreement will be legally binding, such as submitting an emissions reduction target and the regular review of that goal. However, the targets set by nations will not be binding under the deal struck in Paris. In the past the imposition of such targets has been resisted by countries such as China, India and South Africa which feel they could hamper economic growth and development. The latest negotiations attempted to avoid such an impasse by developing the system of Intended Nationally Determined Contributions.