Editing IPCC:AR6/SROCC/Chapter-3 (section)

==== 3.3.3.4 Ecosystems ====

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For Greenland and Svalbard, there is ''limited evidence'' with ''high agreement'' that the retreat of marine-terminating glaciers will alter food supply to higher trophic levels of marine food webs (Meire et al., 2017 <sup>[[#fn:r1292|1292]]</sup> ; Milner et al., 2017 <sup>[[#fn:r1293|1293]]</sup> ). The consequences of changes in glacial systems on marine ecosystems are often mediated via the fjordic environments that fringe the edge of the ice sheets, for example changing physical-chemical conditions have affected the benthic ecosystems of Arctic fjords (Bourgeois et al., 2016 <sup>[[#fn:r1294|1294]]</sup> ). The amplification of nutrient fluxes caused by enhanced upwelling at calving fronts (Meire et al., 2017 <sup>[[#fn:r1295|1295]]</sup> ), combined with high carbon/nutrient burial and recycling rates (Wehrmann et al., 2013 <sup>[[#fn:r1296|1296]]</sup> ; Smith et al., 2015 <sup>[[#fn:r1297|1297]]</sup> ), plays an important role in sustaining high productivity of the Arctic fjord ecosystems of Greenland and Svalbard (Lydersen et al., 2014 <sup>[[#fn:r1298|1298]]</sup> ). Glacier retreat, causing glaciers to shift from being marine-terminating to land-terminating, can reduce the productivity in coastal areas off Greenland with potentially large ecological implications, also negatively affecting production of commercially harvested fish (Meire et al., 2017 <sup>[[#fn:r1299|1299]]</sup> ). There is also evidence that marine-terminating glaciers are important feeding areas for marine mammals and seabirds at Greenland (Laidre et al., 2016 <sup>[[#fn:r1300|1300]]</sup> ) and Svalbard (Lydersen et al., 2014 <sup>[[#fn:r1301|1301]]</sup> ).

For Antarctica ''',''' there is ''high agreement'' based on ''medium evidence'' that ice shelf retreat or collapse is leading to new marine habitats and to biological colonisation (Gutt et al., 2011 <sup>[[#fn:r1302|1302]]</sup> ; Fillinger et al., 2013 <sup>[[#fn:r1303|1303]]</sup> ; Trathan et al., 2013 <sup>[[#fn:r1304|1304]]</sup> ; Hauquier et al., 2016 <sup>[[#fn:r1305|1305]]</sup> ; Ingels et al., 2018 <sup>[[#fn:r1306|1306]]</sup> ). The loss of ice shelves and retreat of coastal glaciers around the AP in the last 50 years has exposed at least 2.4 × 10 4 km 2 of new open water. These newly-revealed habitats have allowed new phytoplankton blooms to be produced resulting in new marine zooplankton and seabed communities (Gutt et al., 2011 <sup>[[#fn:r1307|1307]]</sup> ; Fillinger et al., 2013 <sup>[[#fn:r1308|1308]]</sup> ; Trathan et al., 2013 <sup>[[#fn:r1309|1309]]</sup> ; Hauquier et al., 2016 <sup>[[#fn:r1310|1310]]</sup> ) (Section 3.2.3.2.1), and have resulted in enhanced carbon uptake by coastal marine ecosystems ( ''medium confidence'' ), although quantitative estimates of biological carbon uptake are highly variable (Trathan et al., 2013 <sup>[[#fn:r1311|1311]]</sup> ; Barnes et al., 2018 <sup>[[#fn:r1312|1312]]</sup> ). Newly available habitat on coastlines may also provide breeding or haul out sites for land-based predators such as penguins and seals (Trathan et al., 2013 <sup>[[#fn:r1313|1313]]</sup> ) ( ''low confidence'' ). Fjords that have been studied in the subpolar western AP are hotspots of abundance and biodiversity of benthic macro-organisms (Grange and Smith, 2013 <sup>[[#fn:r1314|1314]]</sup> ) and there is evidence that glacier retreat in these environments can impact the structure and function of benthic communities (Moon et al., 2015 <sup>[[#fn:r1315|1315]]</sup> ; Sahade et al., 2015 <sup>[[#fn:r1316|1316]]</sup> ) ( ''low confidence'' ).

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