Project Drawdown released their 2020 Update last week. It's now completely freely available and, in my opinion, the most accessible quantitative reference on climate solutions.
Updated table of climate solutions: https://drawdown.org/solutions/table-of-solutions
Drawdown 2020 review (requires email registration to download): https://drawdown.org/drawdown-framework/drawdown-review-2020
Notably, Reducing food waste has moved up to take the top rank, followed by Health and Education and then Plant-based diets. Refrigerant management, the previous top priority, is now ranked fourth, followed by Tropical forest restoration.
Three out of those five are already front and center in EAs' awareness anyway; but Reducing food waste and Refrigerant management perhaps less so. I'm curious to hear whether this may compel folks to update their mental models (or why not).
I think drawdown has lots of flaws as a prioritisation source.
(1) How they arrive at the ranking is unclear - the details on the models at the time I looked were very unclear.
(2) Technologies should be assessed as part of a whole system rather than individually. e.g. Having lots of energy storage makes sense when you have intermittent power sources like solar, but not much when you have controllable ones like gas with carbon capture. So, it doesn't really make sense to assess the possible climate contribution of storage independently of everything else because its contribution depends on the whole system. Figuring out what energy system each country should have depends significantly on local context. e.g solar makes a lot of sense in Australia, but very little in England.
(3) I didn't think that the potential contribution of various different energy technologies was well justified, and provided a false sense of certainty. E.g. nuclear could in principle supply the vast majority of global low carbon energy supply, but you have to think about all the potential unclear political barriers. Solar and wind could provide maybe up to 40% electricity, but you need to think about the massive land use implications of this and the consequent local opposition
(4) They don't talk about neglectedness, which is a crucial determinant of what difference donors can make on the margin. Wind and solar will probably be important going forward, but philanthropists are already ploughing hundreds of millions of dollars into advocating for them in Europe and the US. In contrast, things like CCS and nuclear get almost no money. Even less attention is paid to things like low carbon heavy duty transport.
(5) Some of the research seemed to be lacking in places. e.g. they put refrigerant management very high, but there are strong arguments suggesting that we should deprioritise short-lived climate pollutants. Similar thoughts apply to plant-based diets.
(6)The ranking is from the point of view of governments to a large extent. This isn't a flaw but does make it less relevant for people donating.