Many geoengineering approaches to mitigating global climate change are being studied and evaluated.
Treehugger reports on one possibility:
“Scratch one geoengineering scheme off the list of last-ditch ways for humanity to save itself: New research from the UK’s National Oceanography Centre, Southampton shows that plans to pump nutrient-rich water up from the deep ocean in order the boost algae growth at the surface to absorb CO2 would likely only sequester a small amount of total anthropogenic carbon emissions, and if the system was stopped could lead to rapid release of greenhouse gases.”