Companies worldwide are involved in gearing up methods that together must be environmentally sound, permanently removing CO2 for at least 100 years, financially viable and together capable of removing 25 gigatons of CO2 per year.

Source: https://www.bangordailynews.com/2023/04/17/opinion/letters/letter-climate-change-moonshot/

The notable IEA and IRENA studies both estimated about 7-8 gigatons of carbon capture, utilization, and storage would be needed annually by 2050, in addition to major changes in how the globe consumes energy.

Source: https://energycentral.com/o/ourenergylibrary/scaling-carbon-capture-requires-competitive-policy-mechanisms

Then they ran a set of 20,000-year-long simulations with carbon emissions ranging from 0 to 4,000 gigatons of carbon.

Source: https://phys.org/news/2023-03-greenland-ice-sheet.html