Five years ago, I had barely slept for 2 weeks. Now I've recovered, and with the #Parisversaire today, I've been thinking about how we designed the #ParisAgreement – and how it is working today. A thread 1/16

We knew how big the task would be. We were all veterans of the UN negotiation process, and had lived through the trauma of #COP15 in Copenhagen. We knew we needed to take a new approach, one built on an integrated theory of human, organizational, and state behavior 2/16

The fundamental premise of the #ParisAgreement: it had to be a flexible legal framework, that could over time accommodate the changes in technologies, economies, & societies that would need to happen over the long-run for us to succeed & limit temperature rise 3/16

The other important philosophy I worked from was that the real enforcement mechanism couldn't be a punishment or sanctions- based one : the enforcement mechanism was changing expectations. The belief that the transition is inevitable is the mechanism itself 4/16

This expectation mechanism applies to all actors: cities, states, companies, financial investors. They need to believe the transition is inevitable. We need all actors for the transition to be successful. This was a safety net: we knew national political winds could change 5/16

This safety net was tested early on, when President Trump withdrew the US, and it worked. Citizens rose up to declare We Are Still In. They felt they had a moral obligation to a global agreement. And now, the US national government is coming back too 6/16

Of course, those expectations need to be translated into concrete commitments and plans. One of the most important points in the Agreement is the requirement for countries to set mid-century goals and Long-Term Strategies to get there 7/ 16

These 2050 strategies are the missing link: they connect the bottom-up self-determined national plans with the requirement to reduce GHG emissions.
This point was discussed on the last day, when the big powers were distracted by the question of comparability of efforts! 8/16

Long-term strategies frame short-term strategies: Nationally Determined Contributions (NDCs) that each country sets for itself to design its own development pathway. This ratchet mechanism requires every country to increase climate plans -starting in 2020 9/16

We bet on a learning process – on the power of the diffusion of ideas and technologies. The ratchet mechanism works because as technologies and economies change, countries can feel confident in setting more ambitious targets they might not have dreamed of before. 10/16

In just one example, since the first plans in 2015, electric vehicles have developed faster and further than we could have imagined at the time. Now countries can set much stronger transport decarbonization targets in new plans than they could back then 11/16

So of course the 2015 plans submitted are not enough to get us to climate safety. But this doesn't mean the Paris Agreement has failed – it was built knowing these early plans wouldn't be enough, and was designed to flexibly enable continually increased ambition 12/16

Since 2015, the world has changed. You felt this happening below the surface: as insurers panicked about the costs of climate impacts, as coal continued to fail - as people realized the transition is inevitable and a major opportunity for a healthier & more equitable world 13/16

Today, we see expectations and policies are converging. Net Zero by 2050 is the reference point – committed to by governments including the EU, UK, Japan, and with China by 2060 14/16

But not just by governments – companies and investors are using it as the reference point of where the money is moving, and making decisions accordingly 15/16

5 years later, I can confidently say – while there's still major work to be done, the #ParisAgreement itself not just surviving, but is now the overarching global framework for the better societies and economies of the future! 16/16