Good @WSJ article by @greg_ip featuring my speculation that theres a real chance global CO2 emissions peaked in 2019. But there are some huge caveats to this projection that we should keep in mind; I'd personally only give it close to even odds! wsj.com/articles/coron… 1/8 
First, my analysis assumes that in a world without COVID-19 global emissions would have peaked around 2024, and that the economic shock from COVID-19 will result in a large enough reduction in GDP (relative to a COVID-free world) that emissions will remain below 2019 levels. 2/8
This is based on assuming that both the average GDP growth of the past decade (2010-2019) and rate of decarbonization (CO2 per GDP) continue over the next five years. This is a big IF! The rate of decarbonization over the last decade has been pretty linear. BUT... 3/8
If we look back to the prior decade (2000-2009) the rate of decarbonization was stagnant, as countries invested heavily in new coal and other fossil fuel plants: 4/8
I'm cautiously optimistic that recent growth in clean energy (renewables, EVs, etc.) driving global decarbonization will continue or even accelerate. But its hardly guaranteed, and policy (and COVID-19 recovery efforts) will play a big role in determining our path forward. 5/8
Its also possible that recovery from COVID-19 would lead to faster GDP growth rates from 2022 onward than in a non-COVID world. My model uses IMF projections for 2020 and 2021 for COVID impacts of but assumes a return to average GDP growth over the past decade 2023+ 6/8Ths
So while I'm of the opinion that we were heading toward peak emissions pre-COVID and this shock might hasten that peak, I'm also cognizant that there remains huge uncertainties in future emissions pathways that are hard to reduce! 7/8
Finally, its important to emphasize that peak emissions is only a small first step. To limit warming below 2C emissions need to fall rapidly. Currently we are on course for a long plateau in emissions without additional strong policy interventions or tech innovations. 8/8
The upside of making bold short-term projections is that I won't have to wait too long to be proven wrong :-p. FIN
