Based on current scientific assessments, including in this report (see Section 1), the likelihood of transgressing one or several ESTPs has been increasing and will likely grow substantially beyond 1.5°C warming, but no tipping process has been set in motion yet. Given that several tipping systems have been destabilised, and could be transgressed in the near term, it is imperative that decision makers start to develop appropriate governance frameworks to address the potential future impacts of ESTPs. If transgressed, ESTPs would severely undermine the pursuit of the SDGs, and reverse recent development progress around the world. The possibly short remaining window of time before the impacts of a tipping process could be felt should be used to increase preparedness, foster community resilience and invest in resources, processes and institutional capacity that would be needed to effectively respond to tipping-point impacts.
Section 2 of this report has assessed the highly diverse expected impacts of ESTPs which are summarised in Table 3.3.1. The assessment shows that ESTPs are very diverse, each with a distinct set of impact types and impact distribution over time and space. Given this diversity, different tipping points (or groups of tipping points) might require distinct kinds of policy responses and impact governance strategies, involving different sets of actors.
Table 3.3.1: Impacts of ESTPs
Overview of impacts and challenges of the various Earth system tipping elements. Please note the anticipated timescales of tipping points unfolding until new equilibrium is reached are best average estimates. GW = global warming; red highlights are temperature thresholds that we are currently approaching, the colouring of the ESTP column signifies the expected severity of the impacts, with darker red shades demonstrating greater severity. We also note the high uncertainty around secondary impacts (see Chapter 2.3 and 2.4)
Earth system tipping point | Sea level rise/coastal erosion | Extreme weather events | Feedback on global warming | Water shortages | Changes in precipitation | Regional temperature change | Ecosystem change | Release of pollutants | Infrastructure damage | Food security | Triggering other ESTPs | Secondary societal impacts | Thresholds, timescales & spatial extent |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Cryosphere | |||||||||||||
Greenland Ice Sheet collapse | Up to 7m sea level rise overall over 1000s years, together with WAIS potentially up to c. 2m by 2100 [IPCC AR6 WG1 Ch9], affecting 480 million people | Minor impact (local circulation changes) | Minor impact (~0.1°C over 1000s y.) | Water shortages due to coastal salinisation | Local impact possible effect on tropical monsoons via AMOC disruption [Defrance et al., 2017]) | Regional amplification of warming | Coastal areas, new exposed land in Greenland | Minor (some pollutants trapped in ice) | Threat to coastal power plants,Destruction of coastal built environment | Salinisation impacting agriculture & food security | Impact on AMOC/SPG as tipping may be reached sooner (but timescales unclear) | Displacement of coastal area popula- tions, conflicts over water etc, financial crises (stranded assets) | 0.8-3°C GW, long period (1000s y.), global impacts |
Arctic Sea Ice loss (not considered a tipping system in this report) | Increased coastal inundation and erosion from larger waves with more open ocean | Uncertain; possible contribution to increase in extreme weather events (e.g. Extreme European snowfall) | Uncertain, possibly ~+0.25°C for summer sea ice loss & ~+0.6 °C for winter sea ice loss, included in model projections | No impact | Local impact with more open water causing increased evaporation and increased precipitation, shift from snowfall to rainfall | Regional amplification of warming (particularly Arctic and Northern Hemisphere) | Details uncertain, but loss of sea ice is expected to substantially affect the marine Arctic ecosystems; impact on land ecosystems unclear | Changes in pollutant & microplastic transport in the ice-free Arctic; increased contaminant input from the Arctic coastal erosion | Possible damage through extreme weather events and through increased coastal erosion | Extreme weather events could destroy harvests, disruption of traditional Indigenous food systems | Amplifies regional warming over Greenland, AMOC/SPG, boreal forests & permafrost; coastal permafrost loss accelerated | Coastal erosion, loss of Indigenous ways of life, & possible extreme weather events contributing to conflicts, (temporary) displacement, anomie etc | NA for tipping; 4.5-8.7°C GW for gradual winter sea ice loss in models [McKay et al., 2022], fast (20 y.), global impacts |
Barents Sea Ice loss (not a tipping system, low confidence) | No impact | Unclear; potential contribution to increase in extreme weather events (Europe) | Negligible impact | No impact | Possible regional impacts in Europe | Local warming | Local ecosystems (marine & bordering land) | Unclear, but changes in circulation can affect pollution redistribution (e.g. of mercury) | Possible damage through extreme weather events | Possible extreme weather events could destroy harvests | Small impact on AMOC & regional boreal forests | Possible extreme weather events contributing to conflicts, (temporary) displacement, anomie etc | NA for tipping, (but 1.5-1.7°C GW in some models) [McKay et al., 2022], fast (25 y.), regional & global impacts |
Permafrost thaw | Abrupt thaw can amplify coastal erosion | Minor impact (can lead to increased lightning strikes and wildfire ignition) | Release of greenhouse gases, driving further global warming | Complex changes to the local water table via abrupt drainage, thermokarst lake formation | Minor impact | No impact | Boreal/tundra ecosystems | Release of contaminants such as mercury into the environment | Disrupts travel in Arctic and isolates settlementsBuilt infrastructure damage and destruction | Impact on permafrost-agroecosystems and community-level food storage in frozen underground cellars | Important but uncertain impact on Boreal forest dieback/expansion tipping points | Anomie among regional population inhabiting the areas, due to livelihood and cultural loss | NA for tipping, abrupt thaw more common from 1.5°C GW [McKay et al., 2022], medium-term (~200 y.) regional & global impacts |
West Antarctic Ice Sheet collapse | 3-5m sea level rise overall over 100s-1000s y, together with GrIS potentially up to c. 2m by 2100 [IPCC AR6 WG1 Ch9], affecting 480 million people | Minor impact; possible massive iceberg release events in Southern Ocean | Minor impact (potentially ~0.05°C over 100s-1000s y.) | Water shortages due to sea level-induced coastal salinisation | Local impact | Regional warming amplification | Coastal area, new exposed islands and seas in West Antarctica | No impact | Threat to coastal power plants,Destruction of coastal built environment | Salinisation impacting agriculture & food security | May affect East Antarctic ice sheets & possibly Southern Ocean overturning circulation | Displacement of coastal area popula- tions, conflicts over water etc., financial crises (stranded assets) | 1-3°C GW, long period (2000 y.), global impacts |
East Antarctic IceSheet (marine & non-marine) collapse | Up to 53m total sea level rise potential; sea level rise of several metres possible over 100s-1000s of years | Minor impact; possible massive iceberg release events in Southern Ocean | Additional warming of potentially ~0.6°C over 10,000s y. | Water shortages due to coastal salinisation | Local impact | Regional warming amplification | Coastal areas, new exposed land and seas in East Antarctica | No impact | Threat to coastal power plants,Destruction of coastal built environment | Salinisation impacting agriculture & food security | Collapse of ice sheet in marine basins could accelerate land-based ice sheet tipping & Southern Ocean overturning circulation | Displacement of coastal area populations, conflicts over water etc, financial crises (stranded assets) | 2-6°C GW marine & 6-10°C GW non-marine, very long period (10,000 y.), global impacts |
Extrapolar glacier retreat | Up to 0.2m sea level rise | No impact | Minor impact (potentially ~0.08°C) | Impact of freshwater supply from meltwater in many regions of the world (e.g. Central Asia, Europe) leading to water shortages | No impact | Localised warming amplification | Changes in surrounding montane & downstream ecosystem, new land exposed | Minor (some pollutants trapped in ice) | Destabilisa- tion of valley sides could lead to landslides, glacier collapse events can cause floods/mud- slides | Water shortages impacting agriculture & food security | No impact | Conflicts over water etc, anomie due to livelihood and cultural loss | Regionally variable (but potentially widespread from ~2°C GW, e.g. in Europe) [McKay et al., 2022], medium-term (200 y.), regional impacts |
Ocean/Atmosphere Circulation | |||||||||||||
AMOC collapse | Regional sea level changes (fall in convection region & North European Shelf seas, rise further south) | Shift in jet stream and storm tracks affecting weather patterns in Europe, potential increase in extreme weather events, e.g. cold winters in Europe, south-ward hurricanes shift | Partial & temporary counteraction of global warming | Southward shift in ITCZ leading to drying in the Sahel and Southern Asia; Some models project drying in parts of the Amazon | Summer monsoon weakening and shifts in Africa and Asia | Up to 10°C cooling in North Atlantic and 3°C cooling in Northern Europe / Eastern Canada, warming amplification in Southern Hemisphere | Drastic shifts in many ecosystems on land and in the sea around the world, e.g. Amazon drying | Affects dust aerosols via monsoon disruption in those regions; ocean circulation changes can affect pollutant pathways | Shifted temperatures/precipitation & weather patterns/extremes no longer matching infrastructure tolerance ranges | Threat to food security because of impacts on marine life (reduction of plankton),changes in precipitation severely impacting agriculture (particularly wheat and maize) & food security (particularly in Europe) | Warming amplification in Southern Hemisphere accelerating Antarctic Ice Sheet melt and coral bleaching, Amazon drying; monsoon (African and Asian) shifts accelerated | Conflicts over food and water, displacement from uninhabitable areas, anomie, financial crises, etc | NA in this report, 1.4-8°C GW elsewhere (but low confidence) McKay et al., 2022], Possibly relatively fast (~50 y. To centuries) Complex global impacts with strong regional differences |
Labrador- Irminger Seas Convection (Subpolar Gyre) collapse | 20-30cm sea level rise along North-East seaboard of North America | Similar to AMOC but possibly smaller impact, e.g. amplified cold winter blocking events in Europe & increase in summer heat wave frequency | Similar to AMOC but magnitude of impact is unclear | Similar to AMOC but possibly smaller impact | Similar to AMOC but impact is not completely clear | Up to 2-3°C cooling in North Atlantic, global warming counteracted in Northern Europe / Eastern Canada | Large changes in ecosystems in affected regions (e.g. reduced North Atlantic productivity, regional ocean acidification, deoxygenation) | Impact unclear, but could be similar to AMOC | Similar to AMOC but smaller impact | Major disruptions of agriculture in Northern Europe and Sahel, impacting food security | Similar to AMOC but impact is not completely clear, potentially a large change in N. Atlantic ecosystems | Conflicts over food and water, displacement from uninhabitable areas, anomie, financial crises, etc | 1.1-3.8°C GW, very fast (10 years), regional impacts |
Monsoon shifts (intensification or collapse, e.g. South Asian, West African, South American) | No impact | Monsoon intensity & extremes projected to increase with warming, or strong drop due to aerosol-induced collapse | No Impact | Shifted precipitation may lead to water shortages | Drastic precipitation changes | Change in tropical and subtropical climates | Change in vegetation and ecosystems in general relying on the monsoon | Changes to where monsoons redistribute air pollution | More intense monsoons overwhelming current infrastructure; monsoon collapse leaving infrastructure mal-adapted | Changed vegetation, agriculture dependent on monsoon rainfall will impact livelihoods and food security | WAM could drive Sahel greening, SAM could affect Amazon | Conflicts over food and water, displacement from uninhabitable areas, anomie, etc | Interhemispheric AOD asymmetry >0.15, AMOC collapse, Amazon dieback; 2-3.5°C for WAM in some models McKay et al., 2022], relatively fast (50 y.), regional impacts |
Biosphere | |||||||||||||
Amazon rainforest dieback | No impact | Increasing extreme weather events (e.g. wet bulb spikes, wildfires) in region | Additional global warming (0.1-0.2°C, depending on extent) | Decreased precipitation may lead to water shortages | Declining regional precipitation in Amazon and Southern Cone region | Over 1°C extra regional warming | Parts of rainforest (particularly in South & East) shift to degraded forest or savannah | Smoke from increased wildfires | Minor impact | Decreased precipitation would impact agricultural belt of Brazil and into Southern Cone | Amplified global warming, bringing other warming thresholds closer | Conflicts over food and water, displacement from uninhabitable areas, anomie, | 2-6°C GW (without deforestation) ~20-40% deforestation, relatively fast (100 y.), regional and global impacts |
Boreal Forest Southern dieback / Northern expansion | No impact | Increasing extreme weather events (e.g. wildfires) | Complex effects – dieback releases carbon but reduces albedo, expansion vice versa | May change with evapotranspiration-induced weather pattern shifts | Changes to evapotranspiration likely to shift regional weather patterns | Regional changes due to changes in land albedo | Shift to open, steppe/prairie-like ecosystems in south, tundra afforestation in north | Smoke from wildfires | Minor impact | Disruption of traditional Indigenous food systems | Complex interplay with permafrost thaw, northern expansion adds to Arctic warming; drives lake browning | Anomie among regional population inhabiting the areas, due to livelihood and cultural loss | 1.4-5°C GW southern dieback, 1.5-7.2°C GW northern expansion, relatively fast (100 y.), regional impacts |
Warm-water coral reef die-off | Decreased coastal protection (coastal erosion) | Increased vulnerability to extreme weather events | Limited impact on GW until very long term | No impact | Minor impacts | Minor impact | Tropical and subtropical coral reefs mostly die-off, resulting in great biodiversity loss | No impact | Loss of coastal protection services may require engineered replacements | Impact on marine food web, Impact on 500 million livelihoods and food security | Possible interaction with nearby mangroves and seagrass die-off and marine regime shifts | Conflicts over decreasing fish stock, anomie because of livelihood and culture loss, etc. | 1-1.5°C GW, plus non-climate thresholds, very fast (10 years), regional and global impacts |
Coastal ecosystem regime shifts (mangroves/seagrass) | Decreased coastal protection (coastal erosion) | Increased vulnerability to extreme weather events | Loss of C sink and release of GHGs, but small impact at global scale | Reduced coastal protection can allow greater seawater ingress, with storms and, aquifer salinisation | Minor impact | No impact | Many mangroves & seagrass ecosystems die-off, resulting in great biodiversity & ecosystem services loss | No impact | Loss of coastal protection services may require engineered replacements | Impact on marine food web, fishery and food security | Possible interaction with nearby coral reef die-off and marine regime shifts | Conflicts over decreasing fish stock, anomie because of livelihood and culture loss, etc | ~1.5oC GW, but highly uncertain and spatially variable; Regional impacts |
Savannahs & grasslands (ecosystem regime shift) | No impact | Greater vulnerability to drought or extremely high rainfall | Shifts in carbon storage – some GHG release possible (but globally small) | Greater groundwater depletion (with shrub encroach- ment) | Regional precipitation changes | Complex regional temperature change from changes to albedo and eco- hydrology | Change in vegetation, leading to biodiversity loss, reduced fires with shrub encroachment | No impact | Minor impact | Loss of grazing lands will impact livelihoods and food security | Possible interaction with nearby dryland and tropical forest tipping points | Conflicts over food and water, displacement from uninhabitable areas, anomie, etc | Regionally variable rainfall & fire thresholds, regional impacts |
Temperate forestsdieback | No impact | Increased wildfires | Carbon emissions (amplifying global warming) | Less atmospheric water supply and groundwater recharge | Changes to evapotranspiration likely to shift regional weather patterns | Regional warming in summer due to less evaporative cooling and cloud cover | Change in forest ecosystems leading to biodiversity loss | Smoke from wildfires | Minor impact | Loss of indirect ecosystem services (e.g. pollinators, groundwater recharge) | Possible impacts on nearby boreal forest | Anomie because of loss of livelihoods and cultural loss | Thresholds unknown regional impacts |
Drylands (ecosystem regime shift) | No impact | Greater vulnerability to drought or extremely high rainfall | Shifts in carbon storage – some GHG release possible (but globally small) | Aridification may lead to water shortage, groundwater depletion with shrub encroach- ment | Regional precipitation changes, leading to aridification in some areas | Complex regional temperature change from changes to albedo and eco- hydrology | Aridification/desertification or shrub encroachment, leading to biodiversity loss | No impact | Minor impact | Aridification/desertification or shrub encroachment will impact agriculture and food security | Possible interaction with nearby savannah and tropical forest tipping points | Conflict over water and land, displacement from uninhabitable areas, anomie, etc | Aridity indices (0.2, 0.3, 0.45) for aridification, regional impacts |
Freshwater lakes (eutrophication-driven anoxia) | No impact | No impact | Increased GHG emissions (reduced for salinisation) could impact GW | Water quality decline could lead to water shortages | Minor impact | Minor impact | Lake ecosystem regime shift, biodiversity loss | Some algae blooms are toxic | Minor impacts | Freshwater fish stock decline could impact food security; water shortages could impact agriculture and food security | No impact | Conflict over water, anomie due to livelihood and cultural loss, etc | Variable for each lake, but higher risk beyond 50-100 mgP/m3 and 2.5 (1–4) mg N/l Impacts in lake regions, with great regional differences in impact severity |
Marine environment regime shift | Minor impact (loss of kelp forests could reduce coastal protection in some places) | No impact | Major changes in ocean productivity, carbon sinks & ocean biogeochemistry could have moderate impact on GW | No impact | Minor impact | Minor impact | Biodiversity loss from trophic cascades and regime shifts | Coastal eutrophication can lead to e.g. toxic ‘red tides’ | Minor impact | Fish stock collapse could impact food security | Minor impact via reduced carbon sink amplifying GW | Conflicts over decreasing fish stock, anomie because of livelihood and culture loss, etc | Multiple drivers with highly localised thresholds; global and regional impacts; multi-decadal to centennial timescales |