SSP5-8.5SSP5-8.5 is one of a number of Shared Socioeconomic Pathways (SSP). It is a scenario in which radiative forcing would be 8.5 W/m⁻² in 2100. The image on the right shows the IPCC projection of the temperature rise in 2081–2100 relative to 1850–1900 corresponding with a SPP5-8.5 scenario (from IPCC AR6 WG11 SPM).
The image below, created by Peter Carter, Climate Emergency Institute, the WMO's averaged 2025 global temperature increase of 1.44°C is indicated on a background of IPCC AR6 WG1 Figure 4.02 (a), illustrating that the WMO rise of 1.44°C for 2025 is spot on the SSP5-8.5 projection (in dark red).
A further image by Peter Carter is added below.
How much could temperatures rise?
The image below, adapted from ClimateReanalyzer, shows the CMIP6 SSP5-8.5 model pointing at a temperature rise of 1.661°C in February 2025, of 4.388°C in February 2083 and of 5.163°C in February 2100, when using a 1901-2000 base (temperatures will be higher when a genuinely pre-industrial base is used).
The map below shows the CMIP6 SSP5-8.5 rise versus 1881-1920 in February 2100. The map shows that the temperature rise in areas on land (where most people live) could be as much as 8°C higher in Feb 2100 in the SSP585 model.
The map warns that temperatures over large parts of the Arctic may be as much as 20°C higher than 1881-1920 in February 2100. This would suggest that by 2100 the snow and ice cover in the Arctic will have declined dramatically and that huge amounts of greenhouse gases will likely have been released from the seafloor of the Arctic Ocean and from thawing terrestrial permafrost, with huge albedo changes as well as loss of the latent heat buffer, further accelerating the temperature rise over the years. There are further contributors to a rapid and potentially huge temperature rise, so the SSP5-8.5 model may severely underestimate the temperature rise. Indeed, the SSP5-8.5 model may not be the worst-case scenario.
The CMIP6 SSP5-8.5 model can be used to project temperature rises beyond 2100, as illustrated by the image below, from an earlier post and from a 2016 paper by Brian O'Neill et al.
Next to the size of the temperature change, the rate of change is also important. Large changes did take place in prehistoric times, but they typically did take a long time to evolve. The current temperature rise looks set to be huge and also looks set to be rising at accelerating speed, dwarfing anything seen in previous extinction events. The image below, from an earlier post, shows extinction rates and temperature changes for the five major extinction events (grey vertical lines).
The image and quote below also featured in an earlier post by Andrew Glikson.
The image below, adapted from ClimateReanalyzer, shows the CMIP6 SSP5-8.5 model pointing at a temperature rise of 1.661°C in February 2025, of 4.388°C in February 2083 and of 5.163°C in February 2100, when using a 1901-2000 base (temperatures will be higher when a genuinely pre-industrial base is used).
The map below shows the CMIP6 SSP5-8.5 rise versus 1881-1920 in February 2100. The map shows that the temperature rise in areas on land (where most people live) could be as much as 8°C higher in Feb 2100 in the SSP585 model.
The map warns that temperatures over large parts of the Arctic may be as much as 20°C higher than 1881-1920 in February 2100. This would suggest that by 2100 the snow and ice cover in the Arctic will have declined dramatically and that huge amounts of greenhouse gases will likely have been released from the seafloor of the Arctic Ocean and from thawing terrestrial permafrost, with huge albedo changes as well as loss of the latent heat buffer, further accelerating the temperature rise over the years. There are further contributors to a rapid and potentially huge temperature rise, so the SSP5-8.5 model may severely underestimate the temperature rise. Indeed, the SSP5-8.5 model may not be the worst-case scenario.
The CMIP6 SSP5-8.5 model can be used to project temperature rises beyond 2100, as illustrated by the image below, from an earlier post and from a 2016 paper by Brian O'Neill et al.
In the above analysis, CO₂ emissions keep rising in the CMIP6 SSP5-8.5 model until 2100, to then fall gradually to current levels (a), while CO₂ concentrations in the atmosphere keeps rising and concentrations remain at levels beyond 2000 ppm (b), corresponding with radiative forcing (RF) rising to and remaining at 12.5 W/m⁻² (c) and average global temperature change rising to and remaining at 8°C by 2300 in the CMIP6 SSP5-8.5 model (d).
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| [ from earlier post, click on images to enlarge ] |
Equilibrium climate sensitivity (ECS) can be used to convert RF into °C temperature rise. CMIP6 ECS estimates are higher than the IPCC AR6 ECS. A recent study led by James Hansen uses 1.2°C per W/m⁻², which in the scenario pictured above would result in a temperature rise of 9.6°C in 2100 and of 15°C in 2250 and many years beyond 2250. Hansen et al. add that equilibrium global warming for today’s GHG amount is 10°C, which is reduced to 8°C by today’s human-made aerosols.
A 2020 analysis by Jorgen Randers et al. (image on the right) points out that, even if all greenhouse gas emissions by people could stop immediately and even if the temperature anomaly could fall to 0.5°C above pre-industrial, greenhouse gas levels would start rising again after 2150 and keep rising for centuries to come.
The danger is even more menacing when including the full wrath of rising temperatures in the Arctic causing sediments at the seafloor of the Arctic Ocean to get destabilized, resulting in eruptions of huge amounts of methane, on top of continued emissions.
The danger is even more menacing when including the full wrath of rising temperatures in the Arctic causing sediments at the seafloor of the Arctic Ocean to get destabilized, resulting in eruptions of huge amounts of methane, on top of continued emissions.
How fast could temperatures rise?
The image and quote below also featured in an earlier post by Andrew Glikson.
“The paleoclimate record shouts to us that, far from being self-stabilizing, the Earth's climate
system is an ornery beast which overreacts even to small nudges” (Wally Broecker)
system is an ornery beast which overreacts even to small nudges” (Wally Broecker)
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| [ from an earlier post ] |
The image below further illustrates that temperatures may currently be rising much faster than they ever did in history.
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| [ from earlier post ] |
Contributors to a potentially huge temperature rise
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| [ see the Extinction page ] |
The bar-chart on the right conceptually dates back to 2016, when analysis of contributions concluded they could add up to a potentially huge rise in temperature in the near future. The bar-chart includes an 8°C rise when CO₂e crosses 1200 ppm (note that CO₂ gets well above 2000 ppm in the above O'Neil analysis).
The image below uses NASA Land-only temperature anomalies versus 1880-1920, illustrating that temperature could rise much more rapidly than SSP5-8.5 suggests.
The image below illustrates that the 1.5°C threshold was crossed for temperatures on land since 2015, when politicians pledged (at the Paris Agreement) to take efforts to prevent a rise of more than 1.5°C from pre-industrial from occurring.
The image below illustrates that the 1.5°C threshold was crossed for temperatures on land since 2015, when politicians pledged (at the Paris Agreement) to take efforts to prevent a rise of more than 1.5°C from pre-industrial from occurring.
Note that this 1880-1920 base is not pre-industrial; temperature anomalies can be higher when using a genuinely pre-industrial base.
The image below has a polynomial trend added that points at 3°C getting crossed on land in early 2027.
As discussed, crossing 3°C on land is important, since most people live on land and there are indications that such a rise will cause many species (including humans) to go extinct.
Below are 14 contributors to a potentially huge temperature rise:
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| [ Image from earlier post, also discussed on facebook ] |
1. High and rising greenhouse gas concentrations
2. Earth Energy Imbalance rapid and accelerating rise
3. Rapid and accelerating decline in Earth Albedo
- Sea ice decline
- Snow and ice cover on land decline
- The aerosol masking effect getting reduced
- Lower clouds reflectivity decline
4. Further feedback kicking in with accelerating ferocity
- Water vapor feedback
- Ocean stratification, acidification and hypoxia (dead zones)
- Polar amplification of the temperature rise
Climate Emergency Declaration
The situation is dire and unacceptably dangerous, and the precautionary principle necessitates rapid, comprehensive and effective action to reduce the damage and to improve the outlook, where needed in combination with a Climate Emergency Declaration, as described in posts such as in this 2022 post and this 2025 post, and as discussed in the Climate Plan group.
Links
• Climate Emergency Institute
https://www.climateemergencyinstitute.com
image discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10163795386309679
• The climate change runaway chain reaction-like process - by Andrew Glikson
Amplifying feedbacks leading to accelerated planetary temperatures
https://www.facebook.com/SamCarana/posts/10165533175460161
• Pre-industrial
https://arctic-news.blogspot.com/p/pre-industrial.html
• When Will We Die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html
• Extinction
https://arctic-news.blogspot.com/p/extinction.html
• The threat of seafloor methane eruptions
https://arctic-news.blogspot.com/2025/11/the-threat-of-seafloor-methane-eruptions.html
• Feedbacks in the Arctic
https://arctic-news.blogspot.com/p/feedbacks.html
• Water Vapor Feedback
https://arctic-news.blogspot.com/2024/09/water-vapor-feedback.html
• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html
• Endangerment Finding in danger?
https://arctic-news.blogspot.com/2025/04/endangerment-finding-in-danger.html
• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html
• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html
• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html
3. Rapid and accelerating decline in Earth Albedo
- Sea ice decline
- Snow and ice cover on land decline
- The aerosol masking effect getting reduced
- Lower clouds reflectivity decline
4. Further feedback kicking in with accelerating ferocity
- Water vapor feedback
- Ocean stratification, acidification and hypoxia (dead zones)
- Polar amplification of the temperature rise
- Jet Stream distortion and more extreme weather events
- Sea currents such as AMOC and SMOC slowing down
- Decline in the capacity of oceans and land to take up CO₂ and heat
5. Thinning of sea ice resulting in loss of the ability to consume incoming ocean heat
6. More fuel getting burned worldwide
7. Worldwide rise in agricultural emissions
8. Depletion of soil moisture and water from lakes, rivers and aquifers
9. Deforestation, loss of soil carbon and associated emissions
- Sea currents such as AMOC and SMOC slowing down
- Decline in the capacity of oceans and land to take up CO₂ and heat
5. Thinning of sea ice resulting in loss of the ability to consume incoming ocean heat
6. More fuel getting burned worldwide
7. Worldwide rise in agricultural emissions
8. Depletion of soil moisture and water from lakes, rivers and aquifers
9. Deforestation, loss of soil carbon and associated emissions
- Forest fires increase
- Trees becoming more vulnerable to droughts, fires, pests and diseases
- More trees cut and burned to create pasture, for construction and energy use
- Increase in ozone due to storms and lightning
10. Loss of wildlife and biodiversity
11. Pollution of water and soil
10. Loss of wildlife and biodiversity
11. Pollution of water and soil
- Oil spills on sea, infrastructure collapse on land
- Pesticides, agricultural chemicals, etc.
- Plastic and PFAS contamination
- Flooding and fires in urban areas (waste, toxic substances from warehouses, etc.)
- Pollution from military activities
12. Politicians hardly take environmental and climate action
13. Many media focus on selling consumables instead of on climate action
14. Meanwhile, a new El Niño may emerge in the course of 2026
While each of these points is alarming in itself, they can also amplify each other and together they can cause a dramatic and rapid temperature rise, as discussed in a recent post and as illustrated and supported by the rapidly rising polynomial trend in the image, which is based on many years of historic data and which adds further weight to important warnings.
12. Politicians hardly take environmental and climate action
13. Many media focus on selling consumables instead of on climate action
14. Meanwhile, a new El Niño may emerge in the course of 2026
While each of these points is alarming in itself, they can also amplify each other and together they can cause a dramatic and rapid temperature rise, as discussed in a recent post and as illustrated and supported by the rapidly rising polynomial trend in the image, which is based on many years of historic data and which adds further weight to important warnings.
When could humans go extinct?
As the likeliness of a huge and accelerating temperature rise, the severity of its impact, and the ubiquity and the imminence with which it will strike all become more apparent and manifest—the more sobering it is to realize that a mere 3°C rise will likely suffice to cause human extinction.
As the likeliness of a huge and accelerating temperature rise, the severity of its impact, and the ubiquity and the imminence with which it will strike all become more apparent and manifest—the more sobering it is to realize that a mere 3°C rise will likely suffice to cause human extinction.
A 2018 study (by Strona & Bradshaw) indicates that most life on Earth will disappear with a 5°C rise. What does this mean for humans?
Terrestrial vertebrates are more in danger than many other species, since they depend on numerous other species for food. Humans are terrestrial vertebrates and humans are also large warm-blooded mammals with high metabolic rates, thus requiring more habitat. It also takes a long time for humans to reach maturity. Additionally, humans have become addicted to processed food, fossil fuels, plastic, etc. Furthermore, humans require large amounts of fresh water, including for sweating when temperatures rise. A 3°C rise may therefore suffice to cause humans to disappear, as illustrated by the image below.
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| [ from earlier post ] |
Climate Emergency Declaration
The situation is dire and unacceptably dangerous, and the precautionary principle necessitates rapid, comprehensive and effective action to reduce the damage and to improve the outlook, where needed in combination with a Climate Emergency Declaration, as described in posts such as in this 2022 post and this 2025 post, and as discussed in the Climate Plan group.
Links
• Climate Emergency Institute
https://www.climateemergencyinstitute.com
image discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10163795386309679
https://www.facebook.com/groups/arcticnews/posts/10163807449809679
• WMO confirms 2025 was one of warmest years on record
https://wmo.int/news/media-centre/wmo-confirms-2025-was-one-of-warmest-years-record
• WMO confirms 2024 as warmest year on record at about 1.55°C above pre-industrial level
https://wmo.int/news/media-centre/wmo-confirms-2024-warmest-year-record-about-155degc-above-pre-industrial-level
• IPCC AR6 WG1 Figure 4.2 (a)
https://www.ipcc.ch/report/ar6/wg1/figures/chapter-4/figure-4-2
• Climate Reanalyzer
https://climatereanalyzer.org
• The Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6 - by Brian O'Neill et al. (2016)
https://gmd.copernicus.org/articles/9/3461/2016
• Is CMIP6 SSP585 the worst-case scenario? (2024 post)
• WMO confirms 2025 was one of warmest years on record
https://wmo.int/news/media-centre/wmo-confirms-2025-was-one-of-warmest-years-record
• WMO confirms 2024 as warmest year on record at about 1.55°C above pre-industrial level
https://wmo.int/news/media-centre/wmo-confirms-2024-warmest-year-record-about-155degc-above-pre-industrial-level
• IPCC AR6 WG1 Figure 4.2 (a)
https://www.ipcc.ch/report/ar6/wg1/figures/chapter-4/figure-4-2
• Climate Reanalyzer
https://climatereanalyzer.org
• The Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6 - by Brian O'Neill et al. (2016)
https://gmd.copernicus.org/articles/9/3461/2016
• Greenhouse gas rising
Amplifying feedbacks leading to accelerated planetary temperatures
https://arctic-news.blogspot.com/2021/06/the-climate-change-runaway-chain-reaction-like-process.html
also discussed on facebook at: https://www.facebook.com/SamCarana/posts/10165533175460161
• Pre-industrial
https://arctic-news.blogspot.com/p/pre-industrial.html
• When Will We Die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html
• Extinction
https://arctic-news.blogspot.com/p/extinction.html
• The threat of seafloor methane eruptions
https://arctic-news.blogspot.com/2025/11/the-threat-of-seafloor-methane-eruptions.html
• Feedbacks in the Arctic
https://arctic-news.blogspot.com/p/feedbacks.html
• Water Vapor Feedback
https://arctic-news.blogspot.com/2024/09/water-vapor-feedback.html
• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html
• Endangerment Finding in danger?
https://arctic-news.blogspot.com/2025/04/endangerment-finding-in-danger.html
• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html
• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html
• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html



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