Table 1.

Biotic responses to sea surface warming and ocean carbonation/acidification and their feedback potential to the climate system

Feedback process	Sign of feedback	Sensitivity	Capacity	Longevity
Responses to ocean warming
Nutrient supply to oligotrophic ocean		+++	±0	++
Nutrient supply to HNLC areas	negative	++	++	+++
Nutrient utilization efficiency	negative	++	++	+++
Nutrient inventory	positive		++	+++
Organic matter remineralisation	positive
Responses to ocean acidification
Calcification	negative	+†	+	+‡
Ballast effect	positive		+++	+++
Stoichiometry	negative	++†	++	++
Extracellular organic matter production	negative	++†	+++	‡
Nitrogen fixation	negative	++†	+	‡

Responses are characterized with regard to feedback sign, sensitivity, capacity, and longevity by using best guesses; we use ±0 for negligible, + for low, ++ for moderate, and +++ for high. Empty boxes indicate missing information/ understanding.

^†Available information mainly based on short-term perturbation experiments.

^‡Potential for adaptation presently unknown. HNLC, high nutrient, low chlorophyll.