Editing IPCC:AR6/SROCC/SPM (section)

==== Observed Impacts on Ecosystems ====

'''A.4. Cryospheric and associated hydrological changes have impacted terrestrial and freshwater species and ecosystems in high mountain and polar regions through the appearance of land previously covered by ice, changes in snow cover, and thawing permafrost. These changes have contributed to changing the seasonal activities, abundance and distribution of ecologically, culturally, and economically important plant and animal species, ecological disturbances, and ecosystem functioning. ( ''high confidence'' ) {2.3.2, 2.3.3, 3.4.1, 3.4.3, Box 3.4, Figure SPM.2}'''

'''A.4.1''' [[File:7dd9d5f1c0e829eec2bf341c5154813e SPM-Icon-xxoo.png]] Over the last century some species of plants and animals have increased in abundance, shifted their range, and established in new areas as glaciers receded and the snow-free season lengthened ( ''high confidence'' ). Together with warming, these changes have increased locally the number of species in high mountains, as lower-elevation species migrate upslope ( ''very high confidence'' ). Some cold-adapted or snow-dependent species have declined in abundance, increasing their risk of extinction, notably on mountain summits ( ''high confidence'' ). In polar and mountain regions, many species have altered seasonal activities especially in late winter and spring ( ''high confidence'' ). {2.3.3, Box 3.4}

'''A.4.2''' [[File:7dd9d5f1c0e829eec2bf341c5154813e SPM-Icon-xxoo.png]] Increased wildfire and abrupt permafrost thaw, as well as changes in Arctic and mountain hydrology have altered frequency and intensity of ecosystem disturbances ( ''high confidence'' ). This has included positive and negative impacts on vegetation and wildlife such as reindeer and salmon ( ''high confidence'' ). {2.3.3, 3.4.1, 3.4.3}

'''A.4.3''' [[File:7dd9d5f1c0e829eec2bf341c5154813e SPM-Icon-xxoo.png]] Across tundra, satellite observations show an overall greening, often indicative of increased plant productivity ( ''high confidence'' ). Some browning areas in tundra and boreal forest are indicative that productivity has decreased ( ''high confidence'' ). These changes have negatively affected provisioning, regulating and cultural ecosystem services, with also some transient positive impacts for provisioning services, in both high mountains ( ''medium confidence'' ) and polar regions ( ''high confidence'' ). {2.3.1, 2.3.3, 3.4.1, 3.4.3, Annex I: Glossary}

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'''A.5. Since about 1950 many marine species across various groups have undergone shifts in geographical range and seasonal activities in response to ocean warming, sea ice change and biogeochemical changes, such as oxygen loss, to their habitats ( ''high confidence'' ). This has resulted in shifts in species composition, abundance and biomass production of ecosystems, from the equator to the poles. Altered interactions between species have caused cascading impacts on ecosystem structure and functioning ( ''medium confidence'' ). In some marine ecosystems species are impacted by both the effects of fishing and climate changes ( ''medium confidence'' ). {3.2.3, 3.2.4, Box 3.4, 5.2.3, 5.3, 5.4.1, Figure SPM.2} '''

'''A.5.1''' [[File:37d9ca019c63e0a7a080aaca0b2016e4 SPM-Icon-oxox.png]] Rates of poleward shifts in distributions across different marine species since the 1950s are 52 ± 33 km per decade and 29 ± 16 km per decade ( ''very likely'' ranges) for organisms in the epipelagic (upper 200 m from sea surface) and seafloor ecosystems, respectively. The rate and direction of observed shifts in distributions are shaped by local temperature, oxygen, and ocean currents across depth, latitudinal and longitudinal gradients ( ''high confidence'' ). Warming-induced species range expansions have led to altered ecosystem structure and functioning such as in the North Atlantic, Northeast Pacific and Arctic ( ''medium confidence'' ). {5.2.3, 5.3.2, 5.3.6, Box 3.4, Figure SPM.2}

'''A.5.2''' [[File:37d9ca019c63e0a7a080aaca0b2016e4 SPM-Icon-oxox.png]] In recent decades, Arctic net primary production has increased in ice-free waters ( ''high confidence'' ) and spring phytoplankton blooms are occurring earlier in the year in response to sea ice change and nutrient availability with spatially variable positive and negative consequences for marine ecosystems ( ''medium confidence'' ). In the Antarctic, such changes are spatially heterogeneous and have been associated with rapid local environmental change, including retreating glaciers and sea ice change ( ''medium confidence'' ). Changes in the seasonal activities, production and distribution of some Arctic zooplankton and a southward shift in the distribution of the Antarctic krill population in the South Atlantic are associated with climate-linked environmental changes ( ''medium confidence'' ). In polar regions, ice associated marine mammals and seabirds have experienced habitat contraction linked to sea ice changes ( ''high confidence'' ) and impacts on foraging success due to climate impacts on prey distributions ( ''medium confidence'' ). Cascading effects of multiple climate-related drivers on polar zooplankton have affected food web structure and function, biodiversity as well as fisheries ( ''high confidence'' ). {3.2.3, 3.2.4, Box 3.4, 5.2.3, Figure SPM.2}

'''A.5.3''' [[File:aa4c791c8b6f965d8de1653e5ac59fbc SPM-Icon-ooox.png]] Eastern Boundary Upwelling Systems (EBUS) are amongst the most productive ocean ecosystems. Increasing ocean acidification and oxygen loss are negatively impacting two of the four major upwelling systems: the California Current and Humboldt Current ( ''high confidence'' ). Ocean acidification and decrease in oxygen level in the California Current upwelling system have altered ecosystem structure, with direct negative impacts on biomass production and species composition ( ''medium confidence'' ). {Box 5.3, Figure SPM.2}

'''A.5.4''' [[File:aa4c791c8b6f965d8de1653e5ac59fbc SPM-Icon-ooox.png]] Ocean warming in the 20th century and beyond has contributed to an overall decrease in maximum catch potential ( ''medium confidence'' ), compounding the impacts from overfishing for some fish stocks ( ''high confidence'' ). In many regions, declines in the abundance of fish and shellfish stocks due to direct and indirect effects of global warming and biogeochemical changes have already contributed to reduced fisheries catches ( ''high confidence'' ). In some areas, changing ocean conditions have contributed to the expansion of suitable habitat and/or increases in the abundance of some species ( ''high confidence'' ). These changes have been accompanied by changes in species composition of fisheries catches since the 1970s in many ecosystems ( ''medium confidence'' ). {3.2.3, 5.4.1, Figure SPM.2}

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'''A.6. Coastal ecosystems are affected by ocean warming, including intensified marine heatwaves, acidification, loss of oxygen, salinity intrusion and sea level rise, in combination with adverse effects from human activities on ocean and land ( ''high confidence'' ). Impacts are already observed on habitat area and biodiversity, as well as ecosystem functioning and services ( ''high confidence'' ). {4.3.2, 4.3.3, 5.3, 5.4.1, 6.4.2, Figure SPM.2}'''

'''A.6.1''' [[File:c2dab058529f43e723961cf4dccd97c2 SPM-Icon-ooxx.png]] Vegetated coastal ecosystems protect the coastline from storms and erosion and help buffer the impacts of sea level rise. Nearly 50% of coastal wetlands have been lost over the last 100 years, as a result of the combined effects of localised human pressures, sea level rise, warming and extreme climate events ( ''high confidence'' ). Vegetated coastal ecosystems are important carbon stores; their loss is responsible for the current release of 0.04–1.46 GtC yr –1 ( ''medium'' ''confidence'' ). In response to warming, distribution ranges of seagrass meadows and kelp forests are expanding at high latitudes and contracting at low latitudes since the late 1970s ( ''high confidence'' ), and in some areas episodic losses occur following heatwaves ( ''medium confidence'' ). Large-scale mangrove mortality that is related to warming since the 1960s has been partially offset by their encroachment into subtropical saltmarshes as a result of increase in temperature, causing the loss of open areas with herbaceous plants that provide food and habitat for dependent fauna ( ''high confidence'' ). {4.3.3, 5.3.2, 5.3.6, 5.4.1, 5.5.1, Figure SPM.2}

'''A.6.2''' [[File:c2dab058529f43e723961cf4dccd97c2 SPM-Icon-ooxx.png]] Increased sea water intrusion in estuaries due to sea level rise has driven upstream redistribution of marine species ( ''medium confidence'' ) and caused a reduction of suitable habitats for estuarine communities ( ''medium confidence'' ). Increased nutrient and organic matter loads in estuaries since the 1970s from intensive human development and riverine loads have exacerbated the stimulating effects of ocean warming on bacterial respiration, leading to expansion of low oxygen areas ( ''high confidence'' ). {5.3.1}

'''A.6.3''' [[File:c2dab058529f43e723961cf4dccd97c2 SPM-Icon-ooxx.png]] The impacts of sea level rise on coastal ecosystems include habitat contraction, geographical shift of associated species, and loss of biodiversity and ecosystem functionality. Impacts are exacerbated by direct human disturbances, and where anthropogenic barriers prevent landward shift of marshes and mangroves (termed coastal squeeze) ( ''high confidence'' ). Depending on local geomorphology and sediment supply, marshes and mangroves can grow vertically at rates equal to or greater than current mean sea level rise ( ''high confidence'' ). {4.3.2, 4.3.3, 5.3.2, 5.3.7, 5.4.1}

'''A.6.4''' [[File:c2dab058529f43e723961cf4dccd97c2 SPM-Icon-ooxx.png]] Warm-water coral reefs and rocky shores dominated by immobile, calcifying (e.g., shell and skeleton producing) organisms such as corals, barnacles and mussels, are currently impacted by extreme temperatures and ocean acidification ( ''high confidence'' ). Marine heatwaves have already resulted in large-scale coral bleaching events at increasing frequency ( ''very high confidence'' ) causing worldwide reef degradation since 1997, and recovery is slow (more than 15 years) if it occurs ( ''high confidence'' ). Prolonged periods of high environmental temperature and dehydration of the organisms pose high risk to rocky shore e cosystems ( ''high confidence'' ). {SR1.5, 5.3.4, 5.3.5, 6.4.2, Figure SPM.2}

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'''Figure SPM.2'''

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'''Figure SPM.2 | Synthesis of observed regional hazards and impacts in ocean (top) and high mountain and polar land regions (bottom) assessed in SROCC. For each region, physical changes, impacts on key ecosystems, and impacts on human systems and ecosystem function and services are shown. For physical changes, yellow/green refers to an increase/decrease, respectively, in […]'''
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[[File:2df5b5912775f9eb3a0c94a3eaf6169e SROCC_SPM2_Final_RGB.jpg]]

Figure SPM.2 | Synthesis of observed regional hazards and impacts in ocean <sup>[[#fn:24|24]]</sup> (top) and high mountain and polar land regions (bottom) assessed in SROCC. For each region, physical changes, impacts on key ecosystems, and impacts on human systems and ecosystem function and services are shown. For physical changes, yellow/green refers to an increase/decrease, respectively, in amount or frequency of the measured variable. For impacts on ecosystems, human systems and ecosystems services blue or red depicts whether an observed impact is positive (beneficial) or negative (adverse), respectively, to the given system or service. Cells assigned ‘increase and decrease’ indicate that within that region, both increase and decrease of physical changes are found, but are not necessarily equal; the same holds for cells showing ‘positive and negative’ attributable impacts. For ocean regions, the confidence level refers to the confidence in attributing observed changes to changes in greenhouse gas forcing for physical changes and to climate change for ecosystem, human systems, and ecosystem services. For high mountain and polar land regions, the level of confidence in attributing physical changes and impacts at least partly to a change in the cryosphere is shown. No assessment means: not applicable, not assessed at regional scale, or the evidence is insufficient for assessment. The physical changes in the ocean are defined as: Temperature change in 0–700 m layer of the ocean except for Southern Ocean (0–2000 m) and Arctic Ocean (upper mixed layer and major inflowing branches); Oxygen in the 0–1200 m layer or oxygen minimum layer; Ocean pH as surface pH (decreasing pH corresponds to increasing ocean acidification). Ecosystems in the ocean: Coral refers to warm-water coral reefs and cold-water corals. The ‘upper water column’ category refers to epipelagic zone for all ocean regions except Polar Regions, where the impacts on some pelagic organisms in open water deeper than the upper 200 m were included. Coastal wetland includes salt marshes, mangroves and seagrasses. Kelp forests are habitats of a specific group of macroalgae. Rocky shores are coastal habitats dominated by immobile calcified organisms such as mussels and barnacles. Deep sea is seafloor ecosystems that are 3000–6000 m deep. Sea-ice associated includes ecosystems in, on and below sea ice. Habitat services refer to supporting structures and services (e.g., habitat, biodiversity, primary production). Coastal Carbon Sequestration refers to the uptake and storage of carbon by coastal blue carbon ecosystems. Ecosystems on Land: Tundra refers to tundra and alpine meadows, and includes terrestrial Antarctic ecosystems.

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