Why the Paris summit worked

Here are the eight lessons the UN and key delegates involved in brokering the Paris deal learnt from Copenhagen that led to the success this year:

1 Make it voluntary

The 1997 Kyoto Protocol was a legally binding treaty setting limits for emissions of greenhouse gases — but only for industrial nations. After signing the deal, the US backed out because developing nations had no obligations, leaving Kyoto covering just 37 mostly European nations and 12 per cent of global emissions. The Paris deal reaped pledges from 186 nations by making the system essentially voluntary.

2 Prepare the ground

French Foreign Minister Laurent Fabius and his team made more than 100 official visits and held more than 400 bilateral meetings with 140 different countries over the past two years. Half of those meetings were at the level of presidents and prime ministers.

3 The big players need to agree

It’s a deal uniting 195 countries, but the US and China are the most important since they account for 35 per cent of emissions. The two countries didn’t coordinate positions in Copenhagen, where China stood with Brazil, India and South Africa in wanting to preserve distinctions in the way the talks deal with rich and poor nations. In 2009, President Barack Obama had to force his way into a meeting