Updated Calcs for staying "well below 2.0 C" with GHG reduction alone

[Ron Baiman]

Updated data calcs.  The 2019 estimate has been reduced, so going forward requires 4.7% yearly reduction rather than 6.1%,  but as most of the decline in global GHG from 2019 to 2021 was due to the pandemic, the big question is whether global GHG emissions will plateau in 2023?  In other words any sustained decline in GHG is still not clearly visible in the data.  Latest calcs and links to data summarized below:

Global GHG emissions would have needed to decline by 4.65%/year from an estimated 54.82 GT CO2e in 2019 (https://ourworldindata.org/greenhouse-gas-emissions#annual-greenhouse-gas-emissions-how-much-do-we-emit-each-year) to achieve a 35 GT CO2e level in 2030 and a 66% chance of limiting average global temperature increase to below 1.8 C (file:///C:/Users/rbaiman/Downloads/EGR2022-3.pdf , Table ES.2). However, global GHG emissions declined by an average of only 0.3% a year from 2019 to an estimated 54.49 GT CO2e in 2021 (https://ourworldindata.org/greenhouse-gas-emissions#annual-greenhouse-gas-emissions-how-much-do-we-emit-each-year ). As  a consequence , we must now reduce global GHG emission by 4.7% per year to reach 35 GT by 2030.

There is no  real-world scenario under a system  of voluntary NDCs that will produce a 4.7%/year reduction in CO2e.  Indeed, the 0.3% yearly GHG reduction from 2019 to 2021 is less than 1/15th of the 4.7%  yearly reduction needed, and that reduction was largely attributed to the Covid-10 Pandemic.  In 2022, global GHG emissions increased and, depending on the state of the economy, could potentially plateau in 2023 or increase, not decline (https://www.scientificamerican.com/article/will-global-emissions-plateau-in-2023-four-trends-to-watch/)

Best,

Ron