ACINN Graduate Seminar - SS 2026

2026-05-13 at 12:00 (on-line and on-site) in the seminar room

Atmospheric Rivers in Antarctica

Michelle Maclennan

British Antarctic Survey, Cambridge, UK

 

Despite the accelerating, dynamic loss of ice from Antarctica, the ice sheet has had a net negative contribution to sea level rise for the past five years. The hiatus is thanks, in part, to extreme storms, which have produced enough precipitation to offset (and more) sea level rise from ice discharge. Among these, atmospheric rivers and explosive cyclones drive the most impactful marine air intrusions into the continent, transporting vast amounts of water vapor poleward from the extratropics. At present, Antarctic atmospheric rivers offset 1 mm of sea level rise annually by augmenting the surface mass balance, and mid-high range warming scenarios suggest a threefold increase in their precipitation at the end of this century. At the same time, these powerful storms can cause large waves, sea ice advection, melting, and breakup, surface melting on ice shelves, and rainfall, meaning they have nonlinear impacts on the Southern Ocean and Antarctic climate system. Furthermore, the magnitude of their present-day impacts, and projected future changes, are highly sensitive to the choice of atmospheric river detection tool. Here, we explore these complex events at every scale – from high resolution regional climate modelling of the cloud structure and impacts of a particularly destructive atmospheric river at the sea ice margin, to diagnosing the synoptic drivers of these events, to assessing their trends and uncertainties in future projections – all through the lens of their compounding impacts on ice sheets, the ocean, and sea level rise.

 

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