The Arctic Monitoring and Assessment Programme AMAP releases scientific assessment reports (AARs) that provide the fully-referenced scientific basis for an assessment of pollution in the Arctic. Contributing to the new AMAP Radioactivity Assessment for 2008 put together by Mark Dowdall (NRPA), we have compiled information on anticipated changes of marine transport routes to the Arctic for the 21st century.

Despite an agreement in several basic aspects of climate change, there remains a considerable spread of IPCC class model results in a lot of regional features. Since a number of processes relevant for the marine transport of radionuclides, such as convection, depend on subtle balances, uncertainty for the consequences remains high. Therefore conclusions have to remain tentative. We have discussed a number of anticipated changes which, however, exhibit some robustness, when comparing different model experiments.
Most importantly, the reduction of ice cover, especially in summer, will lead to less importance of sea ice a transport medium for radionuclides from atmospheric fallout and from incorporated sediment. This will likely lead to a reduced export and a larger fraction of the radionuclides staying in the Arctic Ocean.

For radionuclides imported with water from the Nordic Seas, the anticipated increase of vertical mixing and convection in the Arctic Ocean could lead to an increased fraction of radionuclides in the mid-depth water. This would consequently increase the residence time in the Arctic, as compared to a surface transport. As a consequence of increased anti-clockwise motion in the Arctic, favoring the Atlantic Water pathway to reach further into the Canadian Basin, a larger fraction of radionuclides transported with the surface water from the European side might enter this part of the Arctic.

We have based our overview on known sources of radionuclides. New sources may, however, arise, in part due to the changes of physical conditions in the Arctic. An example is the possible increase of ship transport due to aprolonged navigatable season or open Northen Sea Routes. Such activities may involve transport of reprocessing waste, or the use of ships with nuclear propulsion systems.