First evidence of human-caused climate change melting the West Antarctic Ice Sheet

A new study published this week reveals the first evidence of a direct link between human-induced global warming and melting of the West Antarctic Ice Sheet.  UK-US researchers say that curbing greenhouse gas emissions now could reduce the future sea-level contribution from this region.

Ice loss in West Antarctica has increased substantially in the last few decades and is ongoing.  Scientists have known for some time that ice loss in this region is caused by ocean-driven melt, and that varying winds in the region cause transitions between relatively warm and cool ocean conditions around key glaciers.  However, until now it was not clear how these naturally-occurring variations in the winds could cause ongoing ice loss. 

Publishing this week in the journal Nature Geoscience a UK-US science team report that, in addition to the natural variations, which last about a decade, there has been a longer-term change in the winds that can be linked with human activities.  This is an important result because continued ice loss could cause tens of centimetres of sea-level rise by the year 2100.

The research team combined satellite observations and climate model simulations to understand how winds over the ocean near West Antarctica have changed since the 1920s in response to rising greenhouse gas concentrations.  Their investigation reveals that human-induced climate change has caused a long-term change in the winds, and that warm ocean conditions have gradually become more prevalent as a result.

Lead author, Professor Paul Holland from the British Antarctic Survey (BAS), says:

“The impact of human-induced climate change on the West Antarctic Ice Sheet is not simple.  This is the first evidence for a direct link between human activities and the loss of ice from West Antarctica.

Our results imply that a combination of human activity and natural climate variations have caused ice loss in this region, accounting for around 4.5 cm of sea-level rise per century.”

The team also looked at model simulations of future winds. Prof Holland continues:

“An important finding is that if high greenhouse-gas emissions continue in future, the winds keep changing and there could be a further increase in ice melting.  However, if emissions of greenhouse gases are curtailed, there is little change in the winds from present-day conditions.  This shows that curbing greenhouse gas emissions now could reduce the future sea-level contribution from this region.”

Co-author, Professor Pierre Dutrieux from Lamont-Doherty Earth Observatory, Columbia University Earth Institute in New York, says:

“We knew this region was affected by natural climate cycles lasting about a decade, but these didn’t necessarily explain the ice loss.  Now we have evidence that a century-long change underlies these cycles, and that it is caused by human activities.”

Co-author, Professor Eric Steig from the University of Washington, says:

“These results solve a long-standing puzzle.  We have known for some time that varying winds near the West Antarctic Ice Sheet have contributed to the ice loss, but it has not been clear why the ice sheet is changing now.  Our work with ice cores drilled in the Antarctic Ice Sheet have shown, for example, that wind conditions have been similar in the past.  But the ice core data also suggest a subtle long-term trend in the winds.  This new work corroborates that evidence and, furthermore, explains why that trend has occurred.”

ENDS

West Antarctic ice loss influenced by anthropogenic forcing and internal climate variability is published by Paul R. Holland, Thomas J. Bracegirdle, Pierre Dutrieux, Adrian Jenkins and Eric J. Steig in the journal Nature Geoscience. Read it here (link will go live after embargo lifts): https://www.nature.com/articles/s41561-019-0420-9

Issued by the British Antarctic Survey Press Office:

Livia Oldland, Corporate and Internal Communications Manager | email: livand@bas.ac.uk | tel: +44 1223 221347; mobile: +44 7850 541910

Hannah Hickey, M.Sc., Sr. Public Information Officer / Science Writer University of Washington News | email: hickeyh@uw.edu | office: 001 206.543.2580 | direct: 001 206.616.7164 | @hickeyh

Kevin Krajick, Senior Editor, Science News | email: kkrajick@ei.columbia.edu | The Earth Institute/Lamont-Doherty Earth Observatory, Columbia University | 001 212-854-9729;  cell: 001 917-361-7766| http://blogs.ei.columbia.edu/author/kevin-krajick/

Notes to editors

Photographs of West Antarctica are available to download here:

ftp://ftp.nerc-bas.ac.uk/pub/photo/Antarctic_ice_loss

Note: right-click to save image first.

To download individual files: do not use an FTP Client, simply open the above link with any standard web browser (Firefox, IE, Safari etc), right click on the filename and select ‘save target/link/file as’ to begin the download

NB: if (when using a Mac) you are asked to login, simply click guest to proceed

Captions of images:

  • View of Dotson ice shelf calving front (western Amundsen Sea, West Antarctica) taken aboard the R/V Nathaniel B. Palmer after deploying the autonomous underwater vehicle Autosub3 under Pine Island ice shelf (credit: Pierre Dutrieux, Feb. 2009).
  • Aerial view of Getz ice shelf calving front (western Amundsen Sea, West Antarctica) taken from a helicopter after deploying Autonomous Phase Sensitive radar on the ice to measure ocean-driven ice shelf melt continuously (credit: Pierre Dutrieux, Jan. 2018).
  • View of Pine Island ice shelf calving front (eastern Amundsen Sea, West Antarctica) taken aboard the R/V Nathaniel B. Palmer after deploying the autonomous underwater vehicle Autosub3 under the ice (credit: Pierre Dutrieux, Feb. 2009).

The British Antarctic Survey (BAS), an institute of the Natural Environment Research Council (NERC), delivers and enables world-leading interdisciplinary research in the Polar Regions. Its skilled science and support staff based in Cambridge, Antarctica and the Arctic, work together to deliver research that uses the Polar Regions to advance our understanding of Earth as a sustainable planet. Through its extensive logistic capability and know-how BAS facilitates access for the British and international science community to the UK polar research operation. Numerous national and international collaborations, combined with an excellent infrastructure help sustain a world leading position for the UK in Antarctic affairs. For more information visit www.bas.ac.uk

Lamont-Doherty Earth Observatory is Columbia University’s home for Earth science research. Its scientists develop fundamental knowledge about the origin, evolution and future of the natural world, from the planet’s deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean, providing a rational basis for the difficult choices facing humanity. www.ldeo.columbia.edu | @LamontEarth

The University of Washington was founded in 1861 and is one of the pre-eminent public higher education and research institutions in the world. The UW has more than 100 members of the U.S. National Academies, elite programs in many fields, and annual standing since 1974 among the nation’s top five universities in receipt of federal research funding. Learn more at www.uw.edu

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