Rising CO2 levels puts all this at risk. Way to go, humans. (Darryl Leniuk/Digital Vision/Getty Images)

So thus far we’ve looked at a number of land- and air-based planet hacking schemes to counter global warming. But what about the ocean? As I promised Friday, we’re hitting the seven seas for the next couple of entries. First up: carbonate addition.

What we’re talking about here is dumping tons of ground limestone (calcium carbonate, CaCO3) into the ocean. The addition would increase the amount of CO2 that the ocean absorbs, as well as fight ocean acidification.

And just what is ocean acidification, you ask? Well, it’s another one of the planetary changes attributed to high levels of CO2 emissions. As Derek Markham points out over at Planetsave, the ocean absorbs a quarter of humanity’s annual CO2 emissions.

Granted, this puts a dent in the CO2 that would otherwise contribute to the greenhouse effect, but when saltwater absorbs CO2, it results in carbonic acid. Get too much of this and it becomes harder for coral to grow and assorted marine life to build their shells. The resulting blow to the rest of oceanic life could be catastrophic.

Carbonate addition is hardly a world-fixer, though. New Scientist estimates that the effort would prove much higher than the cost of cutting emissions and that it would take decades to put the plan in motion. There are also significant questions about how dumping all that limestone might adversely affect sea life as well.

Check back later for a look at another ocean-based planet hacking scheme. For now, consider what we’ve covered so far or head on back to the HowStuffWorks.com homepage.

10 Planet Hacking Schemes:
No. 10: Foresting
No. 9: Fake Plastic Trees
No. 8: Reflective Crops
No. 7: Space Mirrors
No. 6: Stratospheric Aerosols
No. 5: Giant Microwave