Chu on this too

Point:

Overwhelming scientific evidence shows that CO₂ emissions from fossil fuels have caused the climate to change, and a dramatic reduction of these emissions is essential to reduce the risk of future devastating effects. ~ Steven Chu

Counterpoint:

Much remains to be learned about the cycling of carbon in the deep ocean. For example, a recent discovery is that larvacean mucus houses (commonly known as "sinkers") are created in such large numbers that they can deliver as much carbon to the deep ocean as has been previously detected by sediment traps.[6] Because of their size and composition, these houses are rarely collected in such traps, so most biogeochemical analyses have erroneously ignored them. (Link)