From the linked study:
between 1998 and 2022 across 41 countries from six continents [...] total emission reductions between 0.6 billion and 1.8 billion metric tonnes CO2.
Oof, it very much reads like that's total over 24 years, rather than per year. Global emissions being over 37 billion tonnes last year and rising, if my quick googling is to be believed.
a small fraction had a big impact
I wonder what glowing words would be left to describe a hypothetical situation where we were actually making things better, rather than just making them worse fractionally more slowly.