Ocean Acidification Post-Paris: Gauging Law and Policy Responses in Light of Evolving Scientific Knowledge

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Paris Agreement, International Ocean Governance, Climate Change and Policy


On 12 December 2015, 195 States agreed on the text of the Paris Agreement, opening a new phase in the global response to the threat of climate change. The Agreement has been lauded as an “historic breakthrough in that it seems to have broken a decade long impasse” in climate change negotiations. The impressive number of ratifications to date and its quick entry into force are indicators of this diplomatic success. The Agreement achieved this remarkable feat by fundamentally changing the approach to climate change cooperation. The Kyoto Protocol, generally considered unsuccessful to influence States’ action, was drafted on the premise of jointly negotiated (i.e., top-down) and binding emission targets with strong consequences in case of non-compliance and rigid differentiation between developed and developing countries. The Paris Agreement, in contrast, is a universal agreement that adopts a managerial approach to climate change cooperation under the premise that “self imposed, voluntary commitments [nationally determined contributions or NDCS] are more likely to be met than those imposed by the global community.” The achievement has not been without its skeptics. Key reasons for concern are the absence of binding obligations to reduce greenhouse gases (GHGS) and the inadequacy of current pledges to limit global warming. Political instability was also introduced by the decision of the United States of America’s President on 1 June 2017 to withdraw from the Agreement. This decision has (so far) not affected the level of participation in the Agreement but may temper other countries’ long-term efforts to reduce GHGS emissions as well as the overall prospects of limiting the impacts of climate change. A further uncertainty is whether the Paris Agreement is an adequate response to “the other CO2 problem” – ocean acidification (OA). The oceans have played an important role in mitigating atmospheric warming by absorbing a significant amount of anthropogenic carbon dioxide (CO2). An estimated 48 percent of the total CO2 emitted by human activities between 1800 and 1994 has been absorbed by the ocean. This service comes at a cost. The addition of anthropogenic CO2 to the oceans changes its chemistry, increasing the concentrations of CO2, bicarbonate ions, and hydrogen ions, thus moving oceans toward more acidic conditions. On average, the ocean pH has fallen by 0.1 pH units since preindustrial times, which represents a 30 percent increase in the concentration of hydrogen ions. In turn, the concentration of carbonate ions has decreased, making waters more corrosive to calcium carbonate minerals (aragonite and calcite) by lowering its saturation state (Ω) and shoaling the saturation horizon. By 2007, solubility of calcium carbonate had already increased by 20 percent. Although the extent of the impact of these changes to marine life is still not well understood, evidence shows that they may be significant and irreversible at time scales relevant for society. This article analyzes to what extent, and with which limitations, the international climate regime, and particularly the newly adopted Paris Agreement, addresses or can address OA. It does so in a six-part format. The first part sets the stage for the analysis by summarizing the scientific understandings of OA and its impacts. The second part maps the pre-Paris policy and legal framework to address OA, highlighting the central role of the United Nations Framework Convention on Climate Change (UNFCCC), and briefly discussing the history of OA in the climate change negotiations up to the Paris Agreement. The third part addresses the promises of the Paris Agreement for dealing with OA, while the fourth part reviews its challenges and shortcomings. Part five discusses other international initiatives relevant to OA, including United Nations General Assembly resolutions and climate change responses under multilateral environmental agreements (MEAS). Part six concludes with an overall assessment of international law and policy responses to date and suggests possible further actions under and outside the climate change regime.