Impacts of a Disappearing Arctic Sea Ice Cover Peter Wadhams Professor of Ocean Physics Department of Applied Mathematics and Theoretical Physics University of Cambridge Cambridge Society for the Application of Research, 15 October 2012

The Earth is warming rapidly…

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Arctic ice is disappearing in summer….

Record minimum ice extent in Sept

Ice drift summer 2007 Aug/Sept 2007

EM3002 multibeam sonar in forward sonar dome Fitting multibeam to a submarine – Kongsberg EM3002 on HMS “Tireless” March 2007, Arctic Ocean transect

Submarine track

UK submarine cruises in Greenland Sea prior to

Example of multiyear ridge intersected by refrozen lead – note poorer resolution than AUV due to greater depth (120 m) and speed of vehicle. But longer range (2000 km of data).

First use of a through-ice AUV – Gavia plus Geoswath sonar from APLIS 2007 ice camp in Beaufort Sea. Vehicle operated under first-year ridge (foreground) from black and red hut (background)

Working hut (right) and 3-man sleeping hut (left) in field of multi-year ridging

Figure 2. Sonar swath west of the deployment. A nearby multiyear ridge (left back) showing very solid smoothed ice blocks intersected by leads. Isolated pinnacles in first year ice in foreground.

High-resolution multibeam of the first-year ridge. Detail in red is genuine resolution of small broken ice blocks (see diver photo)

Contour maps of mean ice drafts from Eurasian Basin, October 1976 and May 1987 (Wadhams, Nature, 1990) Mean drafts from April 2004 (Initial Processing)

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Changing MY fraction (Kwok et al, 2009 )

retreat of sea ice from around Greenland speeds summer melt, accelerating sea level rise

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BUT… exposure of the shelves leads to permafrost melt and methane release, both offshore and on land SSG Copenhagen Russia Canada Greenland Lomonosov Ridge Alpha-Mendeleev Ridge

Oil exploration will be easier

…and will extend into areas previously considered too hostile, like the NE Greenland shelf

Conclusions So long as carbon emissions continue to increase, global warming will continue to develop.So long as carbon emissions continue to increase, global warming will continue to develop. Even if carbon emissions were to stop entirely, there would still be some continued warming for several decades.Even if carbon emissions were to stop entirely, there would still be some continued warming for several decades. If present trends continue, average warming at low latitudes will be about 4°C by end of 21 st Century.If present trends continue, average warming at low latitudes will be about 4°C by end of 21 st Century. Multiply this by 2-4 for high latitudes.Multiply this by 2-4 for high latitudes. This will be accompanied by GLOBAL SEA LEVEL RISE (about 1 m in century); LOWER PRECIPITATION in key tropical regions leading to desertification, reduced food production, and loss of rain forestThis will be accompanied by GLOBAL SEA LEVEL RISE (about 1 m in century); LOWER PRECIPITATION in key tropical regions leading to desertification, reduced food production, and loss of rain forest Possible surprises: methane boost from permafrost melt causing short term acceleration of warming, other effects not yet spotted (cf. ocean acidification).Possible surprises: methane boost from permafrost melt causing short term acceleration of warming, other effects not yet spotted (cf. ocean acidification).

Antarctic sea ice extent Winter (September) Summer (March)