We can fix the climate in one of two ways:
Remove carbon dioxide
If burning fossil fuels puts carbon dioxide (CO2) into the atmosphere, can we get it out?
Air capture— extracting CO2 directly from the air using metal boxes or “sodium trees.” The captured CO2 then has to be concentrated and piped to burial sites underground.
Biochar— when heated without oxygen, plant material turns into charcoal. This biochar, with its trapped carbon, can be spread on the soil and lasts for many decades.
Liming the oceans— oceans absorb some of the CO2 from the air, but the extra CO2 also makes them more acidic. Adding lime would offset the acidification, allowing more CO2 to be soaked up.
Stop solar radiation
Can we reduce the amount of sunlight reaching the Earth’s surface, and so cool the planet?
Painting roofs white— there are not enough roofs to make a difference.
Space mirrors— millions of small ones could be oriented to reflect sunlight away from Earth, but it’s still science fiction.
Marine cloud brightening— a serious proposal with special ships spraying micro-droplets of salt water into the air to help form low-lying marine clouds that reflect sunlight back into space.