Climate variability and change in the subpolar Southern Ocean (and its impact on biogeochemistry and marine ecosystems)
Climate variability and change in the subpolar Southern Ocean (and its impact on biogeochemistry and marine ecosystems)Dr. Graeme MacGilchrist - https://gmacgilchrist.github.io
The ocean around Antarctica, south of the polar front, has both local importance (as a haven for unique and diverse ecosystems) and global climatic significance (as a region of anthropogenic heat and carbon uptake and glacial melt). The climate of the region is characterized by substantial interannual-to-decadal variability on top of the forced climate change signal, both of which imprint themselves on the region’s local and global impact. In this talk, I will present research from two studies: one considering the region’s interannual variability and another its forced change.
Interannual variability of primary production in the sea-ice zone
Using perfect model experiments in an Earth System Model, we show that primary production in the sea-ice zone is predictable up to several years in advance, with regional differences in the predictability time horizon. We describe a causal mechanism that links the predictability of primary production to that of sea-ice extent, itself arising from sea-ice persistence and memory of upper ocean heat content.
Forced change in response to Antarctic Ice Sheet melt
Perturbation experiments were used to investigate the impact of Antarctic Ice Sheet melt in two climate models differing primarily in their horizontal ocean grid resolution. A watermass transformation framework reveals a distinct response of the abyssal waters in the two models. The abyssal water volume declines 4 times faster in the higher resolution model, owing to an interplay between dense shelf water formation and interior ocean mixing, with implications for the oceanic uptake of heat and carbon in a changing climate.