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Ambitious and rapid action is needed to reduce climate change and its impacts – and the first large-scale assessment of ocean-based solutions shows that the focus should be on the oceans. The study examines the feasibility of 13 ocean-based measures to reduce atmospheric carbon dioxide (CO2), combat ocean warming and / or reduce impacts such as ocean acidification and pollution. 39. It identifies oceanic renewable energies as the most promising and several local marine conservation and restoration options as "no regrets measures", which should be expanded and implemented immediately, but concludes that all other measures are still too uncertain to be recommended without further investigation. Posted in Frontiers in Marine Science as part of the collection of articles titled "Success Stories at the Ocean, Climate and Human Interface", the study highlights the trade-offs and challenges the governance issues associated with all solutions and stresses that the greatest benefit will be to combine global and local solutions through political cooperation.
Current projects to reduce CO2 emissions under the 2015 Paris Agreement are not enough to keep global temperatures below an increase of 20 ° C from pre-industrial levels. Despite the major role of oceans in climate regulation, ocean-based solutions to climate change have received relatively little attention from land-based solutions.
"The ocean already removes about 25% of anthropogenic CO2 emissions – and could absorb and store much more," said lead author Dr. Jean-Pierre Gattuso of CNRS, in a statement. La France. "However, there are currently few indications on at-sea interventions that will reduce the magnitude and effects of climate change."
To fill this gap, Gattuso and an international team of experts collaborating in The Ocean Solutions Initiative evaluated 13 global and local measures. These fall into four categories: reduction of CO2 concentrations in the atmosphere; increase the proportion of solar radiation returned to space; protect marine ecosystems; and manipulate biological and ecological adaptation to the impacts of climate change.
The team analyzed the potential of each measure to reduce three climatic factors: ocean warming, ocean acidification and sea level rise, as well as its state of technological readiness, its advantages, disadvantages, cost-effectiveness and governability. They also examined the potential of each measure to reduce impacts on key marine ecosystems, namely coral reefs, mangroves and salt marshes, seagrass beds and arctic habitats, as well as ecosystem services. fisheries, aquaculture and coastal protection.
A shift to ocean-based renewable energies has proven to be the highest potential for immediately addressing the causes of climate change.
"Not only offshore wind farms, wave energy and other oceanic renewable energies have a huge potential for reducing carbon emissions, but they are also cost-effective and ready to be implemented on a large scale," he said. said the co-author of the study, Dr. Alexandre Magnan from the French Institute of Sustainable Development and International Relations.
The study also identifies local efforts of moderate efficiency aimed at reducing ocean acidification and sea level rise.
"Reducing marine pollution, stopping the over-exploitation of marine resources, re-establishing hydrological flows and protecting marine habitats are all technically ready and offer considerable benefits," said Gattuso. "The restoration and conservation of coastal vegetation, such as mangroves, salt marshes and seagrass beds, in order to increase the absorption of CO2 and reduce additional emissions, are also possible with some disadvantages. "
Other measures were found to have high potential to combat climate change factors, but were not feasible. A potentially important and permanent intervention to consume CO2 and / or neutralize the acidity of the oceans is to add alkaline materials to the ocean. However, "the feasibility and benefits need to be weighed against the financial costs and environmental impacts of mining or the production of large quantities of alkaline materials distributed worldwide, as well as potential impacts on marine life, "said Gattuso.
One could also eliminate large amounts of CO2 by fertilizing the ocean with iron to increase the amount of phytoplankton – but this is difficult to implement and manage. Another approach is to apply foam to the surface of the ocean to improve the reflection of solar radiation. However, the effect would only last as long as the moss remains in place, a few days to just a few months, and would have dramatic consequences on plants and animals.
"Our study shows that all measures involve trade-offs and that decisions must consider their relevance in terms of costs, benefits and ease of governance," said Magnan. "The potential of ocean-based options to deal with climate change and its impacts is very high and depends on the ability of societies, locally and internationally, to decide on the right mix of measures."
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More information:
Frontiers in Marine Science, DOI: 10.3389 / fmars.2018.00337
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