Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

​The Arctic Ocean is warming at two to three times the global rate¹ and is perceived to be a bellwether for ocean acidification^{2, 3}. Increased CO₂ concentrations are expected to have a fertilization effect on marine autotrophs⁴, and higher temperatures should lead to increased rates of planktonic primary production⁵. Yet, simultaneous assessment of warming and increased CO₂ on primary production in the Arctic has not been conducted. Here we test the expectation that CO₂-enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO₂ enhances GPP (by a factor of up to ten) over a range of 145–2,099 μatm; however, the greatest effects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO₂-enhanced primary production has significant implications for metabolic balance in a warmer, CO₂-enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.