Editing IPCC:AR6/WGI/Chapter-12 (section)

==== 12.3.4.3 Lake, River and Sea Ice ====

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Reductions in the duration of thick sea, lake and river ice influence ecosystems as well as ice fishing, hunting, dog sledding and snowmobiling, which are recreation activities for some but vital aspects of many traditional indigenous communities ( [[#Durkalec--2015|Durkalec et al., 2015]] ; [[#AMAP--2017|AMAP, 2017]] ; [[#Baztan--2017|Baztan et al., 2017]] ; [[#Arp--2018|Arp et al., 2018]] ; [[#Rokaya--2018|Rokaya et al., 2018]] ; [[#Knoll--2019|Knoll et al., 2019]] ; [[#Meredith--2019|Meredith et al., 2019]] ; [[#Sharma--2019|Sharma et al., 2019]] ). The seasonal extent of thin ice and iceberg density also determines the viability of shipping lanes and seasonal roads ( [[#Valsson--2011|Valsson and Ulfarsson, 2011]] ; [[#Pizzolato--2016|Pizzolato et al., 2016]] ; [[#AMAP--2017|AMAP, 2017]] ; [[#Mullan--2017|Mullan et al., 2017]] ; [[#Sturm--2017|Sturm et al., 2017]] ), oil and gas exploration timing ( [[#Schaeffer--2012|Schaeffer et al., 2012]] ) and the seasonality of phytoplankton blooms ( [[#Oziel--2017|Oziel et al., 2017]] ). Sea ice is a critical aspect of some ecosystems and fisheries ( [[#Massom--2010|Massom and Stammerjohn, 2010]] ; [[#Jenouvrier--2014|Jenouvrier et al., 2014]] ; [[#Bindoff--2019|Bindoff et al., 2019]] ; [[#Meredith--2019|Meredith et al., 2019]] ). Various definitions of ‘ice free’ Arctic Ocean conditions can be tailored to represent transportation needs, including thresholds of ice coverage (&lt;5% or &lt;30% or &lt;1 million km <sup>2</sup> ) in September or over a four-month period ( [[#Laliberté--2016|Laliberté et al., 2016]] ; [[#Jahn--2018|Jahn, 2018]] ).

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