Controls on open-ocean North Atlantic ΔpCO 2 at seasonal and interannual time scales are different

• Published in: Geophysical Research Letters
• Main Authors: Henson, Stephanie A., Humphreys, Matthew P., Land, Peter E., Shutler, Jamie D., Goddijn-Murphy, Lonneke, Warren, Mark
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: North Atlantic
• Online Access: https://eprints.soton.ac.uk/423550/; https://eprints.soton.ac.uk/423550/1/Henson_et_al_2018_Geophysical_Research_Letters.pdf

The North Atlantic is a substantial sink for anthropogenic CO 2 . Understanding the mechanisms driving the sink's variability is key to assessing its current state and predicting its potential response to global climate change. Here we apply a time series decomposition technique to satellite and in situ data to examine separately the factors (both biological and nonbiological) that affect the sea-air CO 2 difference (ΔpCO 2 ) on seasonal and interannual time scales. We demonstrate that on seasonal time scales, the subpolar North Atlantic ΔpCO 2 signal is predominantly correlated with biological processes, whereas seawater temperature dominates in the subtropics. However, the same factors do not necessarily control ΔpCO 2 on interannual time scales. Our results imply that the mechanisms driving seasonal variability in ΔpCO 2 cannot necessarily be extrapolated to predict how ΔpCO 2 , and thus the North Atlantic CO 2 sink, may respond to increases in anthropogenic CO 2 over longer time scales.