Climatic Effect of Antarctic Meltwater Overwhelmed by Concurrent Northern Hemispheric Melt

R. F. Ivanovic; L. J. Gregoire; A. D. Wickert; A. Burke

doi:10.1029/2018GL077623

Climatic Effect of Antarctic Meltwater Overwhelmed by Concurrent Northern Hemispheric Melt

R. F. Ivanovic, L. J. Gregoire, A. D. Wickert, A. Burke

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Abstract

Records indicate that 14,500 years ago, sea level rose by 12–22 m in under 340 years. However, the source of the sea level rise remains contentious, partly due to the competing climatic impact of different hemispheric contributions. Antarctic meltwater could indirectly strengthen the Atlantic Meridional Overturning Circulation (AMOC), causing northern warming, whereas Northern Hemisphere ice sheet meltwater has the opposite effect. This story has recently become more intriguing, due to increasing evidence for sea level contributions from both hemispheres. Using a coupled climate model with freshwater forcing, we demonstrate that the climatic influence of southern-sourced meltwater is overridden by northern sources even when the Antarctic flux is double the North American contribution. This is because the Southern Ocean is quickly resalinized by Antarctic Circumpolar water. These results imply that the pattern of surface climate changes caused by ice sheet melting cannot be used to fingerprint the hemispheric source of the meltwater.

Original language	English (US)
Pages (from-to)	5681-5689
Number of pages	9
Journal	Geophysical Research Letters
Volume	45
Issue number	11
DOIs	https://doi.org/10.1029/2018GL077623
State	Published - Jun 16 2018
Externally published	Yes

Bibliographical note

Funding Information:
R. F. I. is funded by Natural Environment Research Council (NERC) grant NE/K008536/1. Numerical climate model simulations made use of the N8 HPC Centre of Excellence (N8 consortium and EPSRC grant EP/K000225/1) and the University of Leeds Physical Climate Change Research Group high-performance computing resources. We are grateful to Piers Forster for helpful comments, to three anonymous reviewers for very constructive suggestions, and to Janet Sprintall for swift editorial handling. Presented model data are available from the University of Leeds Research Data repository, https://doi.org/ 10.5518/395.

Publisher Copyright:
©2018. The Authors.

Keywords

AMOC
MWP1a
hosing
ice sheets
meltwater
stability

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1029/2018GL077623

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title = "Climatic Effect of Antarctic Meltwater Overwhelmed by Concurrent Northern Hemispheric Melt",

abstract = "Records indicate that 14,500 years ago, sea level rose by 12–22 m in under 340 years. However, the source of the sea level rise remains contentious, partly due to the competing climatic impact of different hemispheric contributions. Antarctic meltwater could indirectly strengthen the Atlantic Meridional Overturning Circulation (AMOC), causing northern warming, whereas Northern Hemisphere ice sheet meltwater has the opposite effect. This story has recently become more intriguing, due to increasing evidence for sea level contributions from both hemispheres. Using a coupled climate model with freshwater forcing, we demonstrate that the climatic influence of southern-sourced meltwater is overridden by northern sources even when the Antarctic flux is double the North American contribution. This is because the Southern Ocean is quickly resalinized by Antarctic Circumpolar water. These results imply that the pattern of surface climate changes caused by ice sheet melting cannot be used to fingerprint the hemispheric source of the meltwater.",

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N2 - Records indicate that 14,500 years ago, sea level rose by 12–22 m in under 340 years. However, the source of the sea level rise remains contentious, partly due to the competing climatic impact of different hemispheric contributions. Antarctic meltwater could indirectly strengthen the Atlantic Meridional Overturning Circulation (AMOC), causing northern warming, whereas Northern Hemisphere ice sheet meltwater has the opposite effect. This story has recently become more intriguing, due to increasing evidence for sea level contributions from both hemispheres. Using a coupled climate model with freshwater forcing, we demonstrate that the climatic influence of southern-sourced meltwater is overridden by northern sources even when the Antarctic flux is double the North American contribution. This is because the Southern Ocean is quickly resalinized by Antarctic Circumpolar water. These results imply that the pattern of surface climate changes caused by ice sheet melting cannot be used to fingerprint the hemispheric source of the meltwater.

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Climatic Effect of Antarctic Meltwater Overwhelmed by Concurrent Northern Hemispheric Melt

Abstract

Bibliographical note

Keywords

UN SDGs

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