; (5) the ocean is losing oxygen at an unprecedented rate, and oxygen loss will very likely emerge over 59 to 80 percent of the ocean surface by 2031–2050; (6) harmful algal blooms have expanded and increased in frequency in coastal environments since the 1980s as a result of ocean warming, acidification, and oxygen loss; (7) in some regions, fish and shellfish stocks are already on the brink of collapsing; (8) environmental stressors like ocean acidification, oxygen loss, and warming ocean temperatures are expected to further compromise the abundance, productivity, and food-web interactions of species; (9) the decrease in biodiversity, and decline and shifts in distribution of fisheries will affect the livelihoods and food-security of coastal communities; (10) warmer ocean temperatures are fueling extreme weather events; (11) currently rare extreme sea level events are expected to occur frequently by 2050; (12) in the absence of significant adaptation efforts, extreme events associated with sea level rise, like erosion, flooding, and salinization, are expected to significantly increase; (13) nearly 50 percent of coastal wetlands have been lost over the 20th century, and 20 to 90 percent of coastal wetlands are projected to be lost by 2100 as a result of sea level rise and habitat degradation; (14) coastal blue carbon ecosystems can contribute to climate mitigation by storing carbon; (15) river runoff in snow-dominated and glacier-fed basins are projected to change in response to projected snow cover and glacier decline; (16) glacial and snow meltwater reductions have resulted in reduced water supply, declined agriculture productivity, and increased wildfires in mountain regions and the Arctic; (17) tourism and outdoor recreation activities have been negatively affected by the cryosphere decline; (18) Arctic sea ice is declining in all months of the year and sea-ice free summers are increasingly likely under 2°C of global warming