About the author:

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Jennifer Ross is a PhD student at the University of Sheffield, supervised by Prof Grant Bigg, University of Sheffield, Prof Bob Marsh, University of Southampton and Dr Yifan Zhao, Cranfield University. Her PhD, funded by the global insurance and reinsurance provider AXA XL, focuses on how a melting Greenland Ice Sheet is likely to affect the ocean, in terms of iceberg numbers and meltwater input.

There are two main ways the Greenland Ice Sheet loses mass: through iceberg formation and ice sheet melt and runoff. Mass loss has been accelerating in recent years, so it is becoming increasingly important that we try to understand how this is likely to affect the ocean locally and on a global scale, in terms of ocean risk associated with phenomena ranging from iceberg numbers along shipping lanes to climate and sea-level rise.

The Labrador Sea is an important region of North Atlantic Deep Water formation, which plays a key role in the Atlantic Meridional Overturning Circulation, which in turn distributes heat around the globe. Changes in the Labrador Sea ocean currents can result in different storm tracks, temperatures and precipitation patterns, and therefore has a widespread effect on climate.

A melting Greenland Ice Sheet also has direct implications for human life on this planet, by causing sea-level rise. The Intergovernmental Panel on Climate Change suggest that it is ‘very likely’ that the contribution of the Greenland Ice Sheet to global sea level has increased from 0.09 mm between 1992–2001 to 0.59 mm for the period 2002–2011 (Church et al., 2013). It has also been estimated that a reducing Greenland Ice Sheet is responsible for 25% of current sea-level rise.

Figure 1. The white triangles show where icebergs are commonly found in the ice season, and the yellow box shows the area patrolled by the International Ice Patrol during this time. The red arrows are popular shipping routes (Navcen.uscg.gov, 2020).

Large-Scale Flood Risk

To mitigate this large-scale flood risk, vast amounts of money will have to be invested at a localised level, especially as coastal living has become increasingly popular in recent years, and a premium is often applied to live within a few miles of the coast (Haigh et al., 2020). In the UK, tourism often contributes a large amount of money to local coastal economies, and there are societal implications for introducing bulky flood defences to quaint fishing villages. However, it seems likely that the majority of any government funding would be applied to coastal cities, leaving much of the countryside and smaller towns and villages at the mercy of the rising tide.

Icebergs have been of public interest since the sinking of the RMS Titanic in 1912, off the coast of Newfoundland, Canada. While few ships sink from collisions with icebergs in this region nowadays, due mainly to daily forecasts of iceberg activity provided by the International Ice Patrol (see here), icebergs still pose a direct risk to shipping and stationary platforms in the North-West Atlantic. Re-routing to avoid icebergs can have serious financial implications for shipping, as it may take them days off course (the location of international shipping lanes can be seen in Figure 1). Fixed oil platforms (i.e. those secured to the seabed) are usually placed in relatively shallow water, so large icebergs will ground before reaching the platform. However, as rigs cannot avoid the icebergs, to reduce the risk of significant damage from collision, the rigs manage approaching icebergs with water cannons and towing, and initiate a shutdown of the rig if the iceberg cannot be re-routed and, as a last resort, the rig is strengthened (Fuglem et al., 2015). The return on oil is currently high enough to warrant its costly extraction. However, as the Arctic warms and sea ice retreats, companies may look further north for this restricted resource. The retreating sea ice also allows for shipping and tourist vessels to venture further north than they could previously, with all its associated increased risk. This risk is heightened by the limited rescue facilities in the Arctic; any mistake or mechanical failure here could easily prove fatal.

Photo from Dr Darrel Swift, University of Sheffield

Methods to Predict Iceberg Flux and Meltwater Intensity

To try to address these issues, we have developed statistical methods to predict iceberg flux past 48°N Lat. In addition, we are using ocean models to detect the effect of meltwater on the ocean. The statistical models use Labrador Sea surface temperatures, the North Atlantic Oscillation, the surface mass balance of the Greenland Ice Sheet, and previous year’s iceberg total to make a prediction. This is used to judge whether the following ice season will be of high, low or medium iceberg intensity. We predict a low to medium intensity year in 2020. This may be a result of sea surface temperatures in the Labrador Sea being higher than usual, melting many of the icebergs before they pass 48°N Lat., or melting sea ice that may be trapping them. A lower-intensity year may also be caused by wind patterns that ground icebergs along the Canadian coast before they can reach 48°N Lat.

Photo from Dr Darrel Swift, University of Sheffield

Meltwater Input to Further Rise

To conclude, the melting Greenland Ice Sheet has a range of direct and indirect risks associated with it. Iceberg numbers vary heavily from year to year in the region patrolled by the International Ice Patrol, but the general trend shows increased numbers. Meltwater input into the ocean is also increasing. Forward-looking, this is likely to rise further. It is therefore important that we try to understand and predict these risks now, rather than wait until we feel the effects on a global scale. An improved understanding of the system and the ability to reliably forecast hazardous conditions will be beneficial especially for the shipping industry in the region, with major rewards to scientists and forecasters able to help support safe operations in the northern regions – safe for both, human and environment.

To close, Dr John Wardman, Senior Science Specialist, Science and Natural Perils, AXA XL, comments that ‘increasing sea level rise is expected to have significant ramifications for coastal exposures (Kulp and Strauss, 2019), and 2018 saw the first commercial ship to traverse the Northern Sea Route in the winter without the assistance of an icebreaker. Impending risks associated with sea-level rise and a potential increase in Arctic shipping activity will require a greater number and diversity of risk transfer solutions through the use of re/insurance products and other ‘soft’ mitigation strategies. The insurance industry is keeping a keen eye on the Arctic, but it is still too early to know exactly how or when the melting Greenland Ice Sheet will directly impact the market.’

References

Church, J.A., P.U. Clark, A. Cazenave, J.M. Gregory, S. Jevrejeva, A. Levermann, M.A. Merrifield, G.A. Milne, R.S. Nerem, P.D. Nunn, A.J. Payne, W.T. Pfeffer, D. Stammer and A.S. Unnikrishnan, 2013: Sea Level Change. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Fuglem, M., Stuckey, P., King, T. and Brown, M., 2015, May. Iceberg Drift Forecast Requirements for Offshore Platforms Utilizing Facility Side-Tracking to Avoid Impacts. In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering (pp. V008T07A039-V008T07A039). American Society of Mechanical Engineers.

Haigh, I.D., Nicholls, R.J., Penning-Roswell, E. and Sayers, P., 2020. Impacts of climate change on coastal flooding, relevant to the coastal and marine environment around the UK. MCCIP Science Review 2020, pp.546-565.

Kulp, Scott A., and Benjamin H. Strauss. “New elevation data triple estimates of global vulnerability to sea-level rise and coastal flooding.” Nature communications 10.1 (2019): 1-12.

Navcen.uscg.gov. (2020). Iceberg Locations. [online] Available at: https://www.navcen.uscg.gov/?pageName=IcebergLocations [Accessed 12 Feb. 2020].