As with any multinational showcase meeting, delegates at each COP (and especially its host) want the meeting to be seen as a success. As the 26th COP approaches, it is in some ways salutary to look back at previous COPs and identify those outcomes which made them a hallmark meeting and the failures which made others less memorable. In recent years, COP15 in Copenhagen was regarded as a failure because despite high hopes and great hoopla it failed to gain agreement by the UNFCCC signatories on taking action to reduce carbon emissions and ended with the weak “agreement to agree” known as the Copenhagen Accord. The COP21 in Paris is regarded as a success in that 196 countries agreed to take action to slow and eventually reduce carbon emissions (“Paris Agreement”). Furthermore, the Paris Agreement aspired to limit global warming to 1.5 degrees above pre-industrial levels, adding to the 2 degree limit from 1970 temperatures. Of course, there was much else that was positive to come out of Paris, including a commitment by developed nations to deliver $100 billion a year for five years from 2020 to help poorer countries address climate change. There were a number of other significant agreements which we have considered previously.

However, as a delayed COP26 is about to start, the world in which the Paris Agreement was fashioned looks markedly different to the world today. In 2015 relations between the major industrial nations were more cordial (or at least not as fractious) as they are today. Heads of governments and business leaders were both present and committed. Climate change featured large on political and social agendas; the Pope issued his encyclical ‘Laudato si’, calling for human action to combat global warming; the host country generated over 90% of its electricity from zero carbon sources (including nuclear), and, whilst the issues were pressing, they still seemed solvable, provided countries delivered on their Nationally Determined Contributions (NDCs).