Editing IPCC:AR6/WGII/TS (section)

=== Ecosystems and biodiversity ===

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'''TS.C.1 Without urgent and ambitious emissions reductions, more terrestrial, marine and freshwater species and ecosystems will face conditions that approach or exceed the limits of their historical experience (''' '''''very high confidence''''' '''). Threats to species and ecosystems in oceans, coastal regions and on land, particularly in biodiversity hotspots, present a global risk that will increase with every additional tenth of a degree of warming (''' '''''high confidence''''' '''). The transformation of terrestrial and ocean/coastal ecosystems and loss of biodiversity, exacerbated by pollution, habitat fragmentation and land use changes, will threaten livelihoods and food security (''' '''''high confidence''''' ''').''' (Figure TS.5 ECOSYSTEMS) { 2.5.1, 2.5.2, 2.5.3, Figure 2.6, Figure 2.7, Figure 2.8, 2.5.4, Figure 2.11, Table 2.5, 3.2.4, 3.4.2, 3.4.3, 4.5.5, 9.6.2, 12.4, 13.10.2, 14.5.1, 14.5.2, 15.3.3, 16.4.2, 16.4.3, [https://www.ipcc.ch/chapter/ts#CCP1.2.4 CCP1.2.4] , [https://www.ipcc.ch/chapter/ts#CCP5.3.2 CCP5.3.2] , [https://www.ipcc.ch/chapter/ts#CCP5.2.7 CCP5.2.7] , CCP 7.3.5 }

'''TS.C.1.1 Near-term warming will continue to cause plants and animals to alter their timing of seasonal events (''' '''''high confidence''''' ''') and to move their geographic ranges (''' '''''high confidence''''' ''').''' Risks escalate with additional near-term warming in all regions and domains ( ''high confidence'' ). Without urgent and deep emissions reductions, some species and ecosystems, especially those in polar and already-warm areas, will face temperatures beyond their historical experience in coming decades (e.g., &gt;20% of species on some tropical landscapes and coastlines at 1.5°C global warming). Unique and threatened ecosystems are expected to be at high risk in the very near term at 1.2°C global warming levels ( ''very high confidence'' ) due to mass tree mortality, coral reef bleaching, large declines in sea-ice-dependent species and mass mortality events from heatwaves. Even for less vulnerable species and systems, projected climate change risks surpass hard limits to natural adaptation, increasing species at high risk of population declines ( ''medium confidence'' ) and loss of critical habitats ( ''medium to high confidence'' ) and compromising ecosystem structure, functioning and resilience ( ''medium confidence'' ). At a global warming of 2°C with associated changes in precipitation global land area burned by wildfire is projected to increase by 35% ( ''medium confidence'' ). (Figure TS.5 ECOSYSTEMS) { 2.5.1, 2.5.2, 2.5.3, 2.5.4, 2.6.1, Figure 2.6, Figure 2.7, Figure 2.8, Figure 2.9, Figure 2.11, Table 2.5, 3.4.2, 3.4.3, 3.5.5, 4.5.5, 9.6.2, 11.3.1, 11.3.2, 12.3, 13.10.2, 14.5.1, 14.5.2, 15.3.3, 16.4.2, 16.4.3, [https://www.ipcc.ch/chapter/ts#CCP1.2.1 CCP1.2.1] , [https://www.ipcc.ch/chapter/ts#CCP1.2.4 CCP1.2.4] , [https://www.ipcc.ch/chapter/ts#CCP5.3.2 CCP5.3.2] , [https://www.ipcc.ch/chapter/ts#CCP7.3 CCP7.3] , CCB DEEP, CCB SLR }

'''TS.C.1.2 Risks to ecosystem integrity, functioning and resilience are projected to escalate with every tenth of a degree increase in global warming (''' '''''very high confidence''''' ''').''' Beginning at 1.5°C warming, natural adaptation faces hard limits, driving high risks of biodiversity decline, mortality, species extinction and loss of related livelihoods ( ''high confidence'' ). At 1.6°C (median estimate), &gt;10% of species are projected to become endangered, increasing to &gt;20% at 2.1°C, representing severe biodiversity risk ( ''medium confidence'' ) ''.'' These risks escalate with warming, most rapidly and severely in areas at both extremes of temperature and precipitation ( ''high confidence'' ). With warming of 3°C, &gt;80% of marine species across large parts of the tropical Indian and Pacific Ocean will experience potentially dangerous climate conditions ( ''medium confidence'' ). Beyond 4°C warming, projected impacts expand, including extirpation of approx. 50% of tropical marine species ( ''medium confidence'' ) and biome shifts (changes in the major vegetation form of an ecosystem) across 35% of global land area ( ''medium confidence'' ). These will lead to a shift of much of the Amazon rainforest to drier and lower-biomass vegetation ( ''medium confidence'' ), poleward shifts of boreal forest into treeless tundra across the Arctic and upslope shifts of montane forests into alpine grassland ( ''high confidence'' ). (Figure TS.5 ECOSYSTEMS) { 2.3.2, 2.5, 2.5.1, 2.5.2, 2.5.3, 2.5.4, 3.4.2, 3.4.3, 9.6.2, 11.3.1, 11.3.2, 12.3, 13.3.1, 13.4.1, 13.10.2, 16.4.3, 16.5.2, Figure 2.6, Figure 2.7, Figure 2.8, Figure 2.11, Figure 3.18, Table 2.6.7, Box 3.2, 9.6.2, Box 11.2, [https://www.ipcc.ch/chapter/ts#CCP1.2.1 CCP1.2.1] , [https://www.ipcc.ch/chapter/ts#CCP1.2.2 CCP1.2.2] , [https://www.ipcc.ch/chapter/ts#CCP5.3.1 CCP5.3.1] , [https://www.ipcc.ch/chapter/ts#CCP5.3.2.3 CCP5.3.2.3] , CC6P4, [https://www.ipcc.ch/chapter/ts#CCP7.3 CCP7.3] , CCB EXTREMES }

'''TS.C.1.3 Damage and degradation of ecosystems exacerbate the projected impacts of climate change on biodiversity (''' '''''high confidence''''' '''). Space for nature is shrinking as large areas of forest are lost to deforestation (''' '''''high confidence''''' '''), peat draining and agricultural expansion, land reclamation and protection structures in urban and coastal settlements (''' '''''high confidence''''' ''').''' Currently less than 15% of the land and 8% of the ocean are under some form of protection, and enforcement of protection is often weak ( ''high confidence'' ). Future ecosystem vulnerability will strongly depend on developments in society, including demographic and economic change ( ''high confidence'' ). Deforestation is projected to increase the threat to terrestrial ecosystems, as is increasing the use of hard coastal protection of cities and settlements by the sea for coastal ecosystems. Coordinated and well-monitored habitat restoration, protection and management, combined with consumer pressure and incentives, can reduce non-climatic impacts and increase resilience ( ''high confidence'' ). Adaptation and mitigation options, such as afforestation, dam construction and coastal infrastructure placements, can increase vulnerability, compete for land and water and generate risks for the integrity and functioning of ecosystems ( ''high confidence'' ). { 2.2, 2.3, 2.3.1, 2.3.2, 2.4.3, 2.5.4, 2.6.2, 2.6.3, 2.6.4, 2.6.5, 2.6.6, 2.6.7, Figure 2.1, 3.4.2, 3.5, 3.6.3, 4.5.5, 9.6.2, 9.6.3, 9.6.4, 9.7.2, 11.3.1, 12.3.3, 12.3.4, 13.3.2, 13.4.2, 13.10.2, 13.11.3, 14.5.2, 14.5.4, [https://www.ipcc.ch/chapter/ts#CCP5.2.1 CCP5.2.1] , [https://www.ipcc.ch/chapter/ts#CCP5.2.5 CCP5.2.5] , [https://www.ipcc.ch/chapter/ts#CCP5.3.2 CCP5.3.2] , [https://www.ipcc.ch/chapter/ts#CCP5.4.1 CCP5.4.1] , CCB NATURAL, CCB SLR }

'''TS.C.1.4 Changes induced by climate change in the physiology, biomass, structure and extent of ecosystems will determine their future carbon storage capacity (''' '''''high confidence''''' ''').''' In terrestrial ecosystems, the fertilisation effects of high atmospheric CO 2 concentrations on carbon uptake will be increasingly saturated and limited by warming and drought ( ''medium confidence'' ). Increases in wildfires, tree mortality, insect pest outbreaks, peatland drying and permafrost thaw ( ''high confidence'' ) all exacerbate self-reinforcing feedbacks between emissions from high-carbon ecosystems and warming with the potential to turn many ecosystems that are currently net carbon sinks into sources ( ''medium confidence'' ) ''.'' In coastal areas beyond 1.5°C warming, blue carbon storage by mangroves, marshes and seagrass habitats are increasingly threatened by rising sea levels and the intensity, duration and extent of marine heatwaves, as well as adaptation options (including coastal development) ( ''high confidence'' ). Changes in ocean stratification are projected to reduce nutrient supply and alter the magnitude and efficiency of the biological carbon pump ( ''medium confidence'' ). { 2.5.2, 2.5.3, 2.5.4, Figure 2.9, Figure 2.11, 3.2.2, 3.4.2, 3.4.3, Box 3.4, 9.5.10, 9.6.2, 10.4.2, 10.4.3, 11.3.1, 11.3.4, Box 11.5, 12.3.3, 12.3.4, 12.3.5, 12.3.6, Table 12.6, 13.3.1, 14.5.1, 15.3.3, CCB SLR, [https://www.ipcc.ch/chapter/ts#CCP1.2.4 CCP1.2.4] , [https://www.ipcc.ch/chapter/ts#CCP1.3 CCP1.3] , [https://www.ipcc.ch/chapter/ts#CCP7.3 CCP7.3] , WGI AR6 5.4 }

'''TS.C.1.5 Extinction risk increases disproportionately from global warming of 1.5°C to 3°C and is especially high for endemic species and species rendered less resilient by human-induced non-climate stressors (''' '''''very high confidence''''' ''').''' The median values for percentage of species at very high risk of extinction are 9% at 1.5°C, 10% at 2°C, 12% at 3°C, 13% at 4°C and 15% at 5°C ( ''high confidence'' ), with the likely range of estimates having a maximum of 14% at 1.5°C and rising to a maximum of 48% at 5°C. Extinction risks are higher for species in biodiversity hotspots ( ''medium confidence'' ), reaching 24% of species at very high extinction risk above 1.5°C, with yet higher proportions for endemic species of 84% in mountains ( ''medium confidence'' ) and 100% on islands ( ''medium confidence'' ). Thousands of individual populations are projected to be locally lost, which will reduce species diversity in some areas where there are no species moving in to replace them, for example, in tropical systems ( ''high confidence'' ). Novel species interactions at the cold edge of species’ distribution may also lead to extirpations and extinctions of newly encountered species ( ''low confidence'' ). Palaeo records indicate that at extreme warming levels (&gt;5°C), mass extinctions of species occur ( ''medium confidence'' ). Among the thousands of species at risk, many are species of ecological, cultural and economic importance. { 2.3.1, 2.3.3, 2.5.1, 2.5.2, 2.5.3, 2.5.4, Figure 2.1, Figure 2.6, Figure 2.7, Figure 2.8, Figure 2.11, 3.4.2, 3.4.3, 4.5.5, 9.6.2, 13.3.1, 13.4.1, 13.10.1, 13.10.2, [https://www.ipcc.ch/chapter/ts#CCP1.2.1 CCP1.2.1] ¸ [https://www.ipcc.ch/chapter/ts#CCP1.2.4 CCP1.2.4] , [https://www.ipcc.ch/chapter/ts#CCP5.3.1 CCP5.3.1] , CCB PALEO }

'''TS.C.2 Cumulative stressors and extreme events are projected''' '''to increase in magnitude and frequency (''' '''''very high confidence''''' ''') and will accelerate projected climate-driven shifts in ecosystems and loss of the services they provide to people (''' '''''high co''''' '''''nfidence''''' '''). These processes will exacerbate both stress o''' '''n systems already at risk from climate impacts and non-climate impacts like habitat fragmentation and pollution (''' '''''high confidence''''' '''). The increasing frequency and severity of extreme events will decrease the recovery time available for ecosystems (''' '''''high confidence''''' '''). Irreversible changes will occur from the interaction of stressors and the occurrence of extreme events (''' '''''very high confidence''''' '''), such as the expansion of arid systems or total loss of stony coral and sea ice communities.''' { 2.3, 2.3.1, 3.2.2, 3.4.2, 3.4.3, 13.3.1, 13.4.1, 13.10.2, 14.5.2, 14.5.5, 14.5.9, Box 14.2, Box 14.4 }

'''TS.C.2.1. Ecosystem integrity is threatened by the positive feedback between direct human impacts (land use change, pollution, overexploitation, fragmentation and destruction) and climate change (''' '''''high confidence''''' ''').''' In the case of the Amazon forest, this could lead to large-scale ecological transformations and shifts from a closed, wet forest into a drier and lower-biomass vegetation ( ''medium confidence'' ). If these pressures are not successfully addressed, the combined and interactive effects between climate change, deforestation and forest degradation, and forest fires are projected to lead to a reduction of over 60% of the area covered by forest in response to 2.5°C global warming level ( ''medium confidence'' ). Some habitat-forming coastal ecosystems, including many coral reefs, kelp forests and seagrass meadows, will undergo irreversible phase shifts due to marine heatwaves with global warming levels &gt;1.5°C and are at high risk this century even in &lt;1.5°C scenarios that include periods of temperature overshoot beyond 1.5°C ( ''high confidence'' ). Under SSP1–2.6, coral reefs are at risk of widespread decline, loss of structural integrity and transitioning to net erosion by mid-century due to the increasing intensity and frequency of marine heatwaves ( ''very high confidence'' ). Due to these impacts, the rate of sea level rise is ''very likely'' to exceed that of reef growth by 2050, absent adaptation. In response to heatwaves, bleaching of the Great Barrier Reef is projected to occur annually if warming increases above 2.0°C, resulting in widespread decline and loss of structural integrity ( ''very high confidence'' ). Global warming of 3.0°C–3.5°C increases the likelihood of extreme and lethal heat events in western and northern Africa ( ''medium confidence'' ) and across Asia. Drought risks are projected to increase in many regions over the 21st century ( ''very high confidence'' ). { 2.5.2, 2.5.4, 3.4.2, 3.4.3, 9.5.3, 9.10, 10.2.1, 10.3.7, 11.3.1, 11.3.2, Box 11.2, Table 11.14, 13.3.1, 13.4.1, 14.5.3, Box 14.3, [https://www.ipcc.ch/chapter/ts#CCP7.3.6 CCP7.3.6] }

'''TS.C.2.2 Pests, weeds and disease occurrence and distribution are projected to increase with global warming, amplified by climate change induced extreme events (e.g., droughts, floods, heatwaves and wildfires), with negative consequences for ecosystem health, food security, human health and livelihoods (''' '''''medium confidence''''' ''').''' Invasive plant species are predicted to expand both in latitude and altitude ( ''high confidence'' ). Climatically disrupted ecosystems will make organisms more susceptible to disease via reduced immunity and biodiversity losses, which can increase disease transmission. Risks of climate-driven emerging zoonoses will increase. Depending on location and human–wildlife interactions, climate-driven shifts in distributions of wild animals increase the risk of emergence of novel human infectious diseases, as has occurred with SARS, MERS and SARS-CoV-2 ( ''medium confidence'' ). Changes in the rates of reproduction and distribution of weeds, insect pests, pathogens and disease vectors will increase biotic stress on crops, forests and livestock ( ''medium evidence, high agreement'' ). Pest and disease outbreaks will require greater use of control measures, increasing the cost of production, food safety impacts and the risk of biodiversity loss and ecosystem impacts. These control measures will become costlier under climate change ( ''medium confidence'' ). { 2.4.2, 2.5.1, 2.5.2, 3.5.5, 4.2.4, 4.2.5, 4.3.1, 5.4.1, 5.4.3, 5.5.2, 5.9.4, 5.12, 11.3.1, 13.5.1, 14.5.4, 14.5.6, CCB ILLNESS, CCB MOVING PLATE, CCB COVID }

'''TS.C.2.3 The ability of natural ecosystems to provide carbon storage and sequestration is increasingly impacted by heat, wildfire, droughts, loss and degradation of vegetation from land use and other impacts (''' '''''high confidence''''' ''')''' '''''.''''' Limiting the global temperature increase to 1.5°C, compared to 2°C, could reduce projected permafrost CO 2 losses by 2100 by 24.2 GtC ( ''low confidence'' ). A temperature rise of 4°C by 2100 is projected to increase global burned area 50–70% and fire frequency by approx. 30%, potentially releasing 11–200 GtC from the Arctic alone ( ''medium confidence'' ). Changes in plankton community structure and productivity are projected to reduce carbon sequestration at depth ( ''low'' to ''medium confidence'' ). { 2.5.2, 2.5.3, 2.5.4, Figure 2.11, Table 2.5, 3.4.2, 3.4.3, 3.4.2, 4.2.4, 13.3.1, 13.4.1, Box 14.7, Box 3.4 }

'''TS.C.2.4 Climate change impacts on marine ecosystems are projected to lead to profound changes and irreversible losses in many regions, with negative consequences for human ways of life, economy and cultural identity (''' '''''medium confidence''''' ''').''' For example, by 2100, 18.8% ± 19.0% to 38.9% ± 9.4% of the ocean will ''very likely'' undergo a change of more than 20 days (advances and delays) in the start of the phytoplankton growth period under SSP1-2.6 and SSP5-8.5 respectively ( ''low confidence'' ). This altered timing increases the risk of temporal mismatches between plankton blooms and fish spawning seasons ( ''medium'' to ''high confidence'' ) and increases the risk of fish recruitment failure for species with restricted spawning locations, especially in mid- to high latitudes of the northern hemisphere ( ''low confidence'' ) but provide short-term opportunities to countries benefiting from shifting fish stocks ( ''medium confidence'' ). { 3.4.2, 3.4.3, 3.5.6, 5.8.3, 5.9.3, 11.3.1, 13.4.1, 13.5.1, 14.5.2, [https://www.ipcc.ch/chapter/ts#CCP6.3 CCP6.3] , CCB MOVING SPECIES }

'''TS.C.2.5 Warming pathways that temporarily increase global mean temperature over 1.5°C above pre-industrial for multi-decadal time spans imply severe risks and irreversible impacts in many ecosystems (''' '''''high confidence''''' ''').''' Major risks include loss of coastal ecosystems such as wetlands and marshlands from committed sea level rise associated with overshoot warming ( ''medium confidence'' ), coral reefs and kelps from heat-related mortality and associated ecosystem transitions ( ''high confidence'' ), disruption of water flows in high-elevation ecosystems from glacier loss and shrinking snow cover, and local extinctions of terrestrial species. { 2.5, 3.4.2, 3.4.4, 4.7.4, 9.6.2, 12.3, 13.10.2, [https://www.ipcc.ch/chapter/ts#CCP5.3.1 CCP5.3.1] }

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