In December 2015, the 21st conference of the parties (COP21) of the United Nations Framework Convention on Climate Change (UNFCCC) can mark a decisive turning point in the world’s effort to avert dangerous changes in our climate. This policy memo by Prof Thomas Hale explains five key initiatives that will "ratchet up" climate action and support the outcomes of COP21.

COP21 will make strong progress toward limiting climate change, but countries’ pledges also leave a substantial ‘emissions gap.’ The summit’s success therefore depends in large part on whether it launches a credible basis through which to ratchet up climate action, especially over the next five years.

At COP21 and beyond, countries should strengthen five ‘ratchets’ to increase climate action after 2015: 

1. Agree to raise national contributions in regular, five-year cycles 
2. Agree to practical international review of country pledges that mixes accountability with support for implementation, tailored to countries’ circumstances 
3. Support the groundswell of action from cities, companies, and other actors 
4. Continue diplomatic efforts at the bilateral, mini-lateral, and sectoral levels 
5. Establish a long-term goal and other policy signals that reinforce broader shifts in finance and technology