Slower nutrient stream suppresses Subarctic Atlantic Ocean biological productivity in global warming

• Published in: Proceedings of the National Academy of Sciences
• Other Authors: Whitt, Daniel B. (author), Jansen, Malte F. (author)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Subarctic
• Online Access: https://doi.org/10.1073/pnas.2000851117

NA18OAR4310408 Earth system models (ESMs) project that global warming suppresses biological productivity in the Subarctic Atlantic Ocean as increasing ocean surface buoyancy suppresses two physical drivers of nutrient supply: vertical mixing and meridional circulation. However, the quantitative sensitivity of productivity to surface buoyancy is uncertain and the relative importance of the physical drivers is unknown. Here, we present a simple predictive theory of how mixing, circulation, and productivity respond to increasing surface buoyancy in 21st-century global warming scenarios. With parameters constrained by observations, the theory suggests that the reduced northward nutrient transport, owing to a slower ocean circulation, explains the majority of the reduced productivity in a warmer climate. The theory also informs present-day biases in a set of ESM simulations as well as the physical underpinnings of their 21st-century projections. Hence, this theoretical understanding can facilitate the development of improved 21st-century projections of marine biogeochemistry and ecosystems. 1658541 1852977