Marine Litter Thematic Assessment

Climate change affecting marine litter

There are links between climate change and marine plastic pollution (Ford et al., 2022), and measures could be beneficial in tackling both problems. Some marine species and ecosystems are vulnerable to both. Plastic contributes to greenhouse gas emissions throughout its life cycle. Engagement in solving plastic pollution (reducing plastic over-consumption) can increase action against climate change (reducing greenhouse emissions). Integrated approaches are needed, including conserving the blue economy and circular economy.

In the 2017 OSPAR Intermediate Assessment, two marine litter indicators were identified as potentially being affected by climate change: beach litter and the seafloor.

Litter may arrive on a given OSPAR beach via ocean currents, rivers, and wind drift from distant sources. Water currents, weather conditions and prevailing wind conditions have a significant influence on the deposition and retention of litter on beaches and therefore litter abundance.

The abundance of seafloor litter is also influenced by anthropogenic inputs, including litter transported by rivers, prevailing winds, and ocean currents, which can redistribute this material over long distances. Other studies have shown that, for example, the Bay of Biscay receives large amounts of litter from local rivers and transport that may result from large-scale circulation in the sub-region as a whole. Further knowledge would be useful on seasonal influences, weather patterns and changes in currents and their effect on litter distribution.

The exact effects that climate change will have on the marine litter issue in the North-East Atlantic are as yet unstudied and still difficult to predict. Therefore, the potential effects described below are hypothetical and highly uncertain, but form a starting point for further exploration of the issue. In general, climate change will not directly affect marine litter or its impact on biota per se, but its influence on atmospheric and ocean circulation may affect some of the pathways for and retention of litter.

Changing ocean currents (affecting the distribution of marine litter)

It was noted in the 2017 Indicator Assessment that changing weather patterns and currents caused by climate change may have an effect on marine litter distribution. A study by Welden and Lusher (2017) also discusses the potential impacts of global climate change on the abundance and distribution of marine plastic pollution. They state that a better understanding of changes in weather patterns and currents would allow a more targeted approach to marine litter:

‘’The ability to predict areas of plastic input and deposition would enable the identification of at-risk species, and it would allow for efforts to reduce and remove plastic debris at targeted locations. The current uncertainty as to the effects of global warming on our oceans is the greatest challenge in predicting the future patterns of plastic aggregation in relation to global circulation.’’

Changing weather patterns (higher and more frequent peak run-off events)

Changes in precipitation patterns due to climate change will probably increase the frequency and severity of peak rainfall events, which may result in increased flooding from rivers and rainfall. This may lead to increased discharge of debris and litter. The summer 2021 flooding events in North-western Europe unfortunately demonstrated the impact of such events, not only causing losses of life but also leading to large quantities of debris and litter moving downstream in the rivers.

Increase in beach tourism

It is possible that as average temperatures rise, the coastal areas around the North-East Atlantic will see an increase in leisure and tourism activities on their beaches, and a longer beach season, especially in northern Europe. This could lead to an increase in marine litter items associated with these activities, such as bottles, cans, food packages and other items.

Impact on fisheries

The future of fishing activity in the North-East Atlantic is uncertain and largely dependent on a number of differing factors including climate change. This could lead to changes in marine litter items associated with this activity.

Species migration and fragility

Changes in the temperature of the sea will cause the gradual migration of marine species from south to north. It is conceivable that marine litter could pose an extra threat to species that are already vulnerable, having been forced to adapt to new circumstances. For example, changing water temperatures could impact the availability of food, making the ingestion of marine litter more common.  

Conclusion

There are a number of ways in which climate change could affect the quantities of marine litter entering the marine environment, especially from rivers, and then the subsequent distribution and deposition of litter. While there may be a need to adapt to some of the changes, it is not currently a major factor influencing OSPAR’s marine litter objectives or selection of actions for the RAP on Marine Litter. More work is needed on risk assessment related to extreme weather events. Related to these events, the driving factor will be the need to protect vulnerable (upstream) communities from the devastating effects of flooding; these measures should in turn help to reduce inputs of marine litter. Because of the links between climate change and marine plastic pollution, integrated approaches could benefit both problems.

Ocean acidification is a perturbation of the physicochemical environment of the world’s oceans that changes the acidity of the water (pH). The way ocean acidification is influencing or could be influenced by marine litter was considered when drafting this assessment, however no clear links were described at this time.