What is the most cost-effective solution to climate change based on scientific evidence?
In researching my question to provide what is known so far I found the following information. I won't accept my own answer unless it gets the most upvotes.

I found this ranked list from 'Project Drawdown' (PD) that states Managing Refrigerants is the number one solution by GT CO2 reduction by total, but with an unknown cost. Offshore wind turbines (OFTs) seems to be the best solution by total reduction. Electric vehicles (EVs) has the highest savings, but with also the highest cost. 

Dividing the reduction amount by the savings leads to OVTs at 11.4 GT CO2 reduction per trillion USD a year (GCR/TUY), then Solar Farms (SFs) at 7.35 and EVs at 1.11 for the top three by savings. However, if all are calculated and ranked, the most reduction by savings is Tree Intercropping at 778 and methane digesters small at 137, the most reduction by cost is Nuclear Energy at 18254 and then Solar Water at 2033, but including the costs with negative numbers (not sure what that means) it's Landfill Methane at -1374 and Solar Farms at -458 GCR/TUY.

I'm not sure if they're including the cost of nuclear accidents or waste storage, since waste storage at least in the US has not been reconciled, and may not be fast enough, so using Solar Water at 2.033 GCR/BillionUY, it would cost 16.3 billion USD per year to reduce the CO2 we emit for energy. Based on a single strategy, that's 2.11 dollars per person in the world (7.7 billion) and $12.50 for every person in the developed world (1.3 billion). Is this correct?

In the PD FAQs they state, "Carbon pricing is a policy mechanism to implement solutions and not in itself a solution to global warming. It is the single most impactful policy proposal that would accelerate the adoption of every solution enlisted."

Adding a few other solutions I've found:


CO2 recapture in concrete can reduce it's emissions by 40% (it is 8% of global) and also the energy used. https://www.solidiatech.com/
Red mud as a carbon sink, using the hydroxides from aluminum smelting because of the high solubility of CO2 in them.
Relying on rock weathering from carbonic acid in rain and because "Coccolithophores account for half of the calcium carbonate creation in the ocean", some kind of phytoplankton farms harnessing their "potential for carbon sequestration but also for the production of high value products, such as fatty acids and pigments."