Editing IPCC:AR6/SROCC/Chapter-1 (section)

=== 1.6.1 Mitigation and Adaptation Options in the Ocean and Cryosphere ===

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Mitigation and adaptation pathways to avoid dangerous anthropogenic interference with the climate system (United Nations, 1992) are considered in SR15 (IPCC, 2018). SROCC assesses several ocean and cryosphere-specific measures for mitigation and adaptation including options for to address the causes of climate change, support biological and ecological adaptation, and enhance societal adaptation (Figure 1.2). Other measures have been proposed, including solar radiation management and several other forms of carbon dioxide removal, but these are not addressed in SROCC as they are covered in other products of the IPCC Sixth Assessment Cycle (SR15 and AR6 Working Group III) and are outside the scope of SROCC. SROCC does assess indirect mitigation measures that involve the ocean and the cryosphere (Figure 1.2) by supporting biological and ecological adaptation, such as through reducing nutrient and organic carbon pollution (which moderates ocean acidification in eutrophied areas) and conservation (which preserves biodiversity and habitats) in coastal regions (Billé et al., 2013).

A literature-based expert assessment shows that ocean-related mitigation measures have trade-offs, with the greatest benefits derived by combining global and local measures ( ''high confidence'' ; Gattuso et al., 2018). Local measures, such as pollution reduction and conservation, provide significant co-benefits and few adverse side effects ( ''high confidence'' ; Sections 5.5.1, 5.5.2 ). They can be relatively rapidly implemented, but are generally less effective in addressing the global problem ( ''high confidence'' ; Sections 5.5.1, 5.5.2 ). Likewise, local efforts to decrease air pollution near mountain glaciers and other cryosphere components, for example reducing black carbon emissions, can bring regional-scale benefits for health and in reducing snow and ice-melt (Shindell et al., 2012; Box 2.2).

Well-chosen human interventions can enhance the adaptive capacity of natural systems to climate change. Such interventions through manipulating an ecosystem’s structural or functional properties (e.g., restoration of mangroves) may minimise climate change pressures, enhance natural resilience and/or re-direct ecosystem responses to reduce cascading risks on societies. In human systems, adaptation can involve both infrastructure (e.g., enhanced sea defences) and community-based action (e.g., changes in policies and practices). Adaptation options to ongoing climate change are most effective when considered together with mitigation strategies because there are limits to effective adaptation, mitigation actions can make adaptation more difficult, and some adaptation measures may increase greenhouse gas emissions.

Adaptation and mitigation decisions are connected with economic concerns. In SROCC, two main economic approaches are used. The first comprises the Total Economic Value method and the valuation of ecosystem services. SROCC considers the paradigm of sustainable development, and the linkages between climate impacts on ecosystem services (Section 5.4.1) and the consequences on SDGs including food security or poverty eradication (Section 5.4.2). The second economic approach used are formal decision analysis methods, which help to identify options (also called alternatives) that perform best or well with regards to given objectives. These methods include cost-benefit analysis, multi-criteria analysis and robust decision-making and are specifically relevant for appraising long-term investment decisions in the context of coastal adaptation (Section 4.4.4.6).

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'''Figure 1.2'''

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'''Figure 1.2 | Overview of the main ocean-cryosphere mitigation and adaptation measures to observed and expected changes in the context of this report. A longer description of these measures are given in SM1.3. Solar radiation management techniques are omitted because they are covered in other IPCC 6th Assessment Report (AR6) products. Governance and enabling conditions […]'''
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Figure 1.2 | Overview of the main ocean-cryosphere mitigation and adaptation measures to observed and expected changes in the context of this report. A longer description of these measures are given in SM1.3. Solar radiation management techniques are omitted because they are covered in other IPCC 6th Assessment Report (AR6) products. Governance and enabling conditions are implicitly embedded in all mitigation and adaptation measures. Some governance-based measures (e.g., institutional arrangements) are not included in this figure but are covered in Cross-Chapter Box 3 in Chapter 1 and in Chapters 2 to 6. GHG: greenhouse gases. Modified from Gattuso et al. (2018).

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