Arctic News: IPCC

Showing posts with label IPCC. Show all posts

Friday, March 6, 2026

Clouds Tipping Point

Clouds Tipping Point

The PBS Terra video below features the clouds tipping point, as also discussed in a recent post at the ArcticNews group.

The video mentions the 2019 analysis by Tapio Schneider that stratocumulus cloud decks become unstable and break up into scattered clouds when CO₂ levels rise above 1200 ppm, resulting in an abrupt additional temperature rise of 8°C (14°F), as discussed at the Clouds Tipping Point page.

The SSP5-8.5 pathway (Shared Socioeconomic Pathway, used by the IPCC), corresponding with a radiative forcing of 8.5 W/m⁻² in 2100, projects CO₂ concentration rises to levels as high 2206.4 ppm in the year 2250, i.e. well above 1200 ppm, as illustrated by the image below, from a 2020 study led by Malte Meinshausen. So, how much temperature rise could this cause?

SSP5-8.5 is often said to be a "worst-case" scenario, yet current developments may even exceed SSP5-8.5 projections, as discussed in an earlier post. The image below features in IPCC AR6 WG1 SPM. The total warming of the IPCC pathways (panel b) is dominated by CO₂ emissions that keep growing steadily in SSP5-8.5, while the maximum temperature rise stays well below 6°C.

Is this in conflict with the additional 8°C rise when the Clouds Tipping Point gets crossed? Let's analyze this. Importantly, the Clouds Tipping Points is at 1200 CO₂e, with contributions not only from CO₂, but also from methane, water vapor, etc.

[ from earlier post ]

Reductions in methane emissions can strongly reduce the total CO₂e, given methane's high Global Warming Potential (GWP). Could reductions in methane emissions keep the total CO₂e below 1200 ppm? In both the SSP1-1.9 and SSP1-2.6 pathways, methane emissions would fall after 2015, and methane emissions would also fall over time for SSP2-4.5, in which 2°C does get crossed, and for SSP5-8.5.

So, if the impact of methane is high and if methane emissions would strongly decline, could it be possible that 1200 CO₂e wouldn't get crossed? Conversely though, if growth in methane emissions continues, this can strongly push up the total CO₂e, as occurs in SSP3-7.0, but in that pathway there are less CO₂ emissions and less reductions in sulfur dioxide emissions.

Anyway, what happened after 2015, the year when politicians pledged at the Paris Agreement to take efforts to limit the temperature rise to 1.5°C? Lo and behold, methane emissions kept rising after 2015! There was record growth in methane concentrations in 2021, after which there was a bit of a slowdown in growth during the following years, but growth in methane concentration picked up pace again recently, as illustrated by the image below.

So, it appears again that SSP5-8.5 isn't the "worst-case scenario" in more than one way. An even worse case scenario would see strong emissions of both CO₂ and methane. Once more, it appears that politicians and collaborating scientists have been downplaying the temperature rise that is about to unfold. The IPCC produced a special report, called Global Warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways and the report's pathways don't seem to make sense in many ways, as also discussed in an earlier post.

The images above and below are from an earlier post, with the image below depicting an alternative pathway in which methane concentrations grow in line with the added magenta-colored trend that points at methane more than doubling by 2043. Such developments should have been included, at least in the margin of uncertainty.

The above text and images describe and depict horrendous dangers, yet the IPCC remains silent, refusing to warn people about the dangers and refusing to recommend effective policy pathways. Note that methane is only one of the contributors to a potentially horrific rise in temperature in the Arctic.

Historic growth in methane concentrations

Historic records could have given a stronger warning. Methane has historically risen faster than CO₂. As illustrated by the image on the right, based on IPCC and WMO data, and from an earlier post, methane in 2024 was 266% of what it was in 1750, whereas CO₂ in 2024 was 152% of what it was in 1750.

In fact, the rise in emission by people had already started well before 1750. Thousands of years ago emissions started to grow in agriculture, herding of animals and associated deforestation, as illustrated by the combination image below, adopted from Ruddiman et al. (2015).

Thousands of years ago, methane concentrations were as low as 550 ppb, while CO₂ concentrations were as low as 260 ppm. So, methane in 2024 was 335% of what it was thousands of years ago, whereas CO₂ in 2024 was 163% of what it was thousands of years ago. In other words, methane concentrations have risen twice as fast as CO₂ concentrations.

[ from earlier post ]

As discussed in earlier posts such as this one and this one, the IPCC keeps downplaying the dangers that we're facing, and one way the IPCC does so is by manipulating the outlook of CO₂, methane and sulfur dioxide emissions. Another way is to downplay the historic temperature rise, which is important, since a larger historic rise would also come with more water vapor in the air, a powerful greenhouse gas that causes a self-amplifying feedback further increasing the temperature rise.

Existential threat

So, are we facing an existential threat? The speed at which temperatures are rising is unprecedented in the historic record. Historically, people have been pushing up the temperature for thousands of years, due to deforestation and further activities by people.

[ image from Tierney et al (2025), also discussed at ArcticNews group ]

Activities by people have already pushed temperatures up from a genuinely pre-industrial base for thousands of years, maybe by more than 2°C.

The above image, from an earlier post, illustrates that, in the Northern Hemisphere, 2025 was the third year in a row with temperature anomalies more than 1.5°C above 1951-1980 and much more when compared to pre-industrial, as discussed in the inset. Note also that El Niño wasn't elevating temperatures in 2025.

[ from the post When will humans go extinct? ]

A 3°C rise constitutes an important threshold, since humans will likely go extinct with such a rise. The top panel in the above image shows a potential 10°C rise, while we may already be more than 2°C above pre-industrial.

A further 1°C can quickly be added due to the move from a La Niña into the next El Niño, albedo loss and further feedbacks such as extra water vapor as temperatures rise, seafloor methane eruptions, fires, collapse of society causing abrupt termination of the sulfur aerosol masking effect. If society collapses, greenhouse gases with a high GWP and long lifetime could be emitted as substances leak from warehouses, waste dump fires, etc. Furthermore, aerosols from sulfur dioxide could fall out of the air in a matter of weeks, all contributing to a rapid temperature rise.

The IPCC appears to have painted scenarios that are shrouded in dubious politics, rather than relating to best-available science and a realistic outlook on future developments. As an example, differences in projected decline in aerosols from sulfur dioxide between the various Shared Socioeconomic Pathways can make a huge difference.

How much could temperatures rise? James Hansen points out that equilibrium global warming for today’s GHG amount is 10°C, which is reduced to 8°C by today’s human-made aerosols. This 10°C rise is held back by oceans and ice acting as a buffer and by aerosols. How long would it take for a 10°C rise to unfold? Heat sinks could abruptly turn into sources, e.g. due to sea ice loss and changes in wind, soil and oceans such as ocean stratification.

Keep in mind that concentrations of greenhouse gases are still rising. Also keep in mind that the land-only temperature rise is higher than the global rise and most people live on land. Many people also live in areas where the rise is stronger than average during heatwaves and due to the Urban Heat Island effect. The conclusion is that humans are functionally extinct if temperatures keep rising. Importantly, changes in biodiversity can have terrible consequences, and much of this is ignored by the IPCC.

Biodiversity collapse

[ from: When Will We Die? ]

A 2025 analysis by David Fastivich et al. finds that, historically, vegetation responded at timescales from hundreds to tens of thousands of years, but not at timescales shorter than about 150 years. It takes centuries for tree populations to adapt - far too slow to keep pace with today’s rapidly warming world. Vegetation depends on the presence of a lot of things including healthy soil, microbes, moisture, nutrients and habitat.

A 2025 analysis led by Thiago Gonçalves-Souza concludes that species turnover does not rescue biodiversity in fragmented landscapes.

A 2018 study by Strona & Bradshaw indicates that most life on Earth will disappear with a 5°C rise (see box on the right). Humans, who depend on a lot of other species, will likely go extinct with a 3°C, as discussed in the earlier post When Will We Die?

Terrestrial vertebrates are more in danger than many other species, as they depend on numerous other species for food. Humans are terrestrial vertebrates and humans are large warm-blooded mammals with high metabolic rates, thus requiring more food and habitat. It also takes humans many years to reach maturity. 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 go extinct, as discussed in earlier posts such as this one and this one.

A 2025 analysis led by Joseph Williamson concludes that many species that live together appear to share remarkably similar thermal limits. That is to say, individuals of different species can tolerate temperatures up to similar points. This is deeply concerning as it suggests that, as ecosystems warm due to climate change, species will disappear from an ecosystem at the same time rather than gradually, resulting in sudden biodiversity loss. It also means that ecosystems may exhibit few symptoms of heat stress before a threshold of warming is passed and catastrophic losses occur. A 224 analysis by Michael Van Nuland et al. finds that tree symbioses with ectomycorrhizal fungi mean that they need to move together for successful migration.

In the video below, Guy McPherson explains that forests cannot keep up with the speed at which temperatures are rising.

Guy McPherson mentions the study by William Farfan-Rios et al. that finds that Amazonian and Andean tree communities are not tracking current climate warming. Further science snippets: The Amazon is also getting drier as deforestation shuts down atmospheric rivers. Thunderstorms are a major driver of tree death in tropical forests. Hot droughts cause catastrophic tree die-offs. Aboveground biomass in Australian tropical forests now a net carbon source.

Huge temperature rise

[ from the Extinction page ]

The image on the right illustrates how such dangers could be further amplified by the threat of war and collapse of centralized society.

As people seek to occupy the last few habitable areas left, many people may stop showing up for work, resulting in a rapid loss of the aerosol masking effect, as industries that now co-emit cooling aerosols (such as sulfates) come to a grinding halt. As it becomes harder to obtain food and fuel for cooking and heating, and as the grid shuts down due to conflicts, many people may start collecting and burning more wood, decimating the forests that are left and resulting in more emissions that further speed up the temperature rise.

As temperatures rise, huge fires could also break out not only in forests, peatlands and grassland, but also in urban areas (including backyards, landfills and buildings, in particular warehouses containing flammable materials, chemicals and fluorinated gases), further contributing to more emissions that speed up the temperature rise.

As the likeliness of further accelerating warming, the severity of its impact, and the ubiquity and the imminence with which it will strike all become more clear and manifest—the more sobering it is that, while a mere 3°C rise may suffice to cause human extinction, a much larger temperature rise may unfold abruptly, as illustrated by the bar-chart on the right.

The image below, from an earlier post, shows monthly data from May 2022 through May 2025, with a trend added that warns about 1200 parts per million (ppm) getting crossed in 2028.

As said, crossing the clouds tipping point at 1200 ppm CO₂ could - on its own - push temperatures up by 8°C globally, on top of the temperature rise caused by the forcing that resulted in the crossing of this tipping point. Moreover, the clouds tipping point is actually at 1200 ppm CO₂e (carbon dioxide equivalent), so when taking into account the impact of growth of other gases, strengthening feedbacks and further mechanisms, this tipping point could be crossed much earlier than in 2028, potentially as early as in 2026.

Methane in the atmosphere could be doubled within years if a trend unfolds as depicted in the image below, from an earlier post. A rapid rise is highlighted in the inset and reflected in the trend, which is based on January 2023-October 2024 methane data, as issued in February 2025.

[ Double the methane in March 2026? Image from earlier post, click on images to enlarge ]

A rise like the one depicted in the trend could eventuate as rising ocean heat destabilizes methane hydrates contained in sediments at the seafloor of the Arctic Ocean. The temperature rise in the Arctic would accelerate since the methane would initially have a huge temperature impact over the Arctic and cause depletion of hydroxyl, of which there is very little in the atmosphere over the Arctic in the first place. Such a rise in methane would also dramatically increase concentrations of ozone in the troposphere and concentrations of water vapor in the stratosphere.

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

• Clouds feedback and tipping point

https://arctic-news.blogspot.com/p/clouds-feedback.html

• Advances in Paleoclimate Data Assimilation - by Jessice Tierney et al. (2025)

https://www.annualreviews.org/content/journals/10.1146/annurev-earth-032320-064209

discussed on Facebook at:
https://www.facebook.com/groups/arcticnews/posts/10163934412354679

• Coupled, decoupled, and abrupt responses of vegetation to climate across timescales - by David Fastivich et al. (2025)

https://www.science.org/doi/10.1126/science.adr6700

discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10163832954534679

• Amazonian and Andean tree communities are not tracking current climate warming - by William Farfan-Rios et al. (2025)
https://www.pnas.org/doi/10.1073/pnas.2425619122

• Clustered warming tolerances and the nonlinear risks of biodiversity loss on a warming planet - by Joseph Williamson et al. (2025)
https://royalsocietypublishing.org/rstb/article/380/1917/20230321/109625/Clustered-warming-tolerances-and-the-nonlinear

• Climate mismatches with ectomycorrhizal fungi contribute to migration lag in North American tree range shifts - by Michael van Nuland et al. (2024)
https://www.pnas.org/doi/10.1073/pnas.2308811121

discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10163832955574679

• Species turnover does not rescue biodiversity in fragmented landscapes - by Thiago Gonçalves-Souza et al. (2025)
https://www.nature.com/articles/s41586-025-08688-7
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10162452301209679

• 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

Thursday, May 22, 2025

Paris Agreement thresholds crossed (update May 2025)

High temperatures persist

In the image below, created with NASA data, the decade from 1904 through 1913 is used as a custom base, illustrating that the temperature anomaly has been more than 1.5°C above this base for each of the past consecutive 22 months (July 2023 through April 2025), and even longer when compared to a pre-industrial base. The red line shows a trend (two-year Lowess Smoothing) that is pointing at 2°C above this base (1904-1913) getting crossed in the course of 2026.

[ trend points at 2°C above 1904-1913 getting crossed in 2026 ]

The temperature rise on land looks even more threatening, as illustrated by the image below.

The above image shows land only monthly temperature anomalies from 1880-1920, with the red line (2-year Lowess Smoothing trend) showing an acceleration in April 2022. If extended, the red line points at crossing 3°C in the course of 2026. Humans are likely to go extinct with a 3°C rise, as discussed in earlier posts such as this one.

An earlier analysis mentions that, when using 1750 as a base, this could add 0.3°C to the historic rise. The analysis adds that when using an even earlier base, even more could be added to the historic temperature rise.

Those who seek to delay or sabotage climate action typically call for use of a late base, in efforts to minimize the historic temperature rise. Using an earlier base can mean that temperatures are already higher than the thresholds that politicians at the adoption of the Paris Agreement pledged wouldn't be crossed, and it can also imply that the temperature rise is accelerating faster and further, due to stronger feedbacks such as more water vapor in the atmosphere and disappearance of lower clouds, all of which would constitute a stronger call for climate action.

The image below illustrates that air temperatures in the Northern Hemisphere have been very high over the past few months, at times reaching record high temperatures for the time of year, e.g. the temperature in the Northern Hemisphere was 10.08°C on May 14, 2025, the highest temperature on record for that day.

[ from earlier post, click on images to enlarge ]

These record high temperatures are the more significant as they were reached under ENSO-neutral conditions. On May 24, 2025, the sea surface temperature was 27.51°C, 0.35°C below 1991-2020, in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño, as illustrated by the image below. The Niño 3.4 anomaly is now lower than it has been for each day in March 2025, when La Niña conditions dominated.

The ENSO outlook below is dated May 8, 2025. It shows that ENSO-neutral conditions are likely to persist for the remainder of 2025, edging on La Niña conditions.

The ENSO outlook is dated May 18, 2025.

As said, to see such high temperatures under ENSO-neutral conditions is significant, it indicates that feedbacks are stronger than many models have anticipated, which implies that feedbacks will continue to grow stronger, given the rapid temperature rise over the past few years (black trend). A new El Niño may develop soon, potentially in April 2026, as the red trend in the image below warns about. The result could be a huge rise in temperature over the course of 2026 (red trend).

As said, different bases can be used, e.g. in the above images anomalies are calculated versus bases such as 1904-1913, 1880-1920, 1991-2020 and 1901-2000. None of them is pre-industrial. So, what would the temperature anomaly look like when a genuinely pre-industrial base was used?

The image below, from an earlier post, uses NASA monthly data through March 2023. Data are first adjusted from NASA's default 1951-1980 base to an earlier 30-year base, i.e. a 1886-1915 base, and then further adjusted by 0.99°C to reflect ocean air temperatures, higher polar anomalies and a pre-industral base.

The image below is an update, the same adjustments are made to data through April 2025.

How the 0.99°C adjustment in the above images is calculated is shown in the bright yellow inset of the image below.

[ from April 2024 post, click on images to enlarge ]

The images show that, when adjusting the data and using a genuinely pre-industrial base, the temperature rise may have already crossed both the 1.5°C and the 2°C thresholds that politicians at the 2015 Paris Agreement pledged shouldn't and wouldn't be crossed.

IPCC keeps downplaying the danger

The IPCC keeps downplaying the danger in many ways. One way the IPCC does this is by selecting a base that minimizes the temperature rise and then to keep making the claim that we're still well below the 1.5°C threshold. The above image, from an April 2024 post, shows that the February 2024 temperature was 1.76°C above 1885-1915, and potentially 2.75°C above pre-industrial (bright yellow inset right). The red line (a six-months Lowess smoothing trend) highlights the steep rise that had already taken place by then. Minimizing the temperature rise will also minimize feedbacks that come with the temperature rise, such as a rise in water vapor and loss of lower clouds, which are self-amplifying feedbacks that further accelerate the temperature rise. In other words, by minimizing the historic temperature rise, the IPCC also seeks to minimize the rise to come.

[ from a 2014 post, click on images to enlarge ]

An additional way used by the IPCC to downplay the danger is to suggest there was a "carbon budget", as if there was an amount of carbon to be divided among polluters that could continue to be consumed for decades to come.

The image on the right, from a 2014 post, points at the fallacy and deceit that comes with a carbon budget, carbon credits, offsets and net-zero emission targets that would, according to the IPCC, accomplish and maintain a "balance" between sources and sinks.

Instead, comprehensive and effective action is needed on multiple lines of action, simultaneously yet separately.

Indeed, action is needed to reduce concentrations of carbon both in oceans and in the atmosphere, while on land, the soil carbon content needs to increase, which can best be achieved by methods such as pyrolysis of biowaste and adding the resulting biochar to the soil, to reduce emissions, reduce fire hazards, sequester carbon, support the presence of moisture & nutrients in the soil and thus support the health & growth of vegetation, as discussed at the Climate Plan group and the biochar group.

The IPCC has failed on at least three points:
1. failed to warn about the historic temperature rise and associated larger feedbacks

2. failed to warn about mechanisms that could cause further acceleration of temperature rise soon

3. failed to point at the best ways to combat climate change.

Higher temperatures come with feedbacks, as illustrated by the image below, from an earlier post.

[ the temperature in the atmosphere can keep rising, even in the absence of further emissions ]

The above image illustrates how feedbacks and crossing of tipping points can cause the temperature of the atmosphere to keep rising, even in the absence of further emissions, due to shrinking heat sinks (e.g. sea ice thickness loss and oceans taking up less heat).

The IPCC failed to warn about Antarctic sea ice decline, and - importantly - the amplifying impact of Antarctic sea ice decline on the global temperature rise. This was addressed in an earlier post as follows:
Sea ice loss results in less sunlight getting reflected back into space and instead getting absorbed by the ocean and the impact of Antarctic sea ice loss is even stronger than Arctic sea ice loss, as Antarctic sea ice is located closer to the Equator, as pointed out by Paul Beckwith in a video in an earlier post. A warmer Southern Ocean also comes with fewer bright clouds, further reducing albedo, as discussed here and here. For decades, there still were many lower clouds over the Southern Ocean, reflecting much sunlight back into space, but these lower clouds have been decreasing over time, further speeding up the amount of sunlight getting absorbed by the water of the Southern Ocean, and this 'pattern effect' could make a huge difference globally, as this study points out. Emissivity is a further factor; open oceans are less efficient than sea ice when it comes to emitting in the far-infrared region of the spectrum (feedback #23 on the feedbacks page).

A 2024 study led by Norman Loeb finds that large decreases in stratocumulus and middle clouds over the sub-tropics and decreases in low and middle clouds at mid-latitudes are the primary reasons for increasing absorbed solar radiation trends in the northern hemisphere.

Slowing down of the Atlantic meridional overturning circulation (AMOC) can cause more heat to accumulate at the ocean surface. Higher sea surface temperatures also come with greater stratification (image below, from earlier post).

Stratification and further changes in oceans and in wind patterns can cause a freshwater lid to form on top of the ocean surface, enabling more hot & salty water to flow underneath this lid (feedback #28), contributing to calving of glaciers and destabilization of sediments at the seafloor.

Increases in water vapor in the atmosphere, loss of sea ice and loss of lower clouds are three self-amplifying feedbacks, i.e. as temperatures rise, such feedbacks will push temperature up even further and due to their self-amplification, the temperature rise will accelerate.

Sea ice loss

One feedback of high temperatures and high concentrations of greenhouse gases is loss of sea ice. Polar amplification of the temperature rise is hitting the Arctic hard, and is also causing dramatic loss of Antarctic sea ice. Global sea ice area has been very low for the past few years, as illustrated by the image below. This has caused a lot of sunlight that was previously reflected back into space, to instead get absorbed by the sea surface. On May 24, 2025, global sea ice area was 17.75 million km², lowest on record for the day.

The image below, adapted from the Danish Metereological Institute, shows that Arctic sea ice volume on May 29, 2025, was at a record low for the time of year, as it has been for more than a year.

Sea ice is disappearing over large parts of the Arctic Ocean. The image below, adapted from the University of Bremen, shows sea ice concentration on May 29, 2025.

The screenshot below, from an earlier post, further illustrates the dangers that come with sea ice loss. Eruptions of methane from the seafloor of the Arctic Ocean is one of the most terrifying dangers.

As the image below illustrates, some of the thickest sea ice disappears from the Arctic Ocean as it gets broken up by sea currents and the pieces get moved out along the edges of Greenland. The image shows how, on May 27, 2025, the sea ice gets broken up just north of Greenland, due to ocean currents that will also move the pieces to the south, alongside the edges of Greenland, toward the North Atlantic.

[ click on images to enlarge ]

Climate Emergency Declaration

The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as discussed at this group.

Links

• NASA - datasets and images
https://data.giss.nasa.gov

• When Will We Die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Copernicus - Climate Pulse
https://pulse.climate.copernicus.eu

• Climate Reanalyzer
https://climatereanalyzer.org

• NOAA - Climate Prediction Center - ENSO: Recent Evolution, Current Status and Predictions
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

• NOAA - Climate Prediction Center - El Niño/Southern Oscillation (ENSO) Diagnostic Discussion

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml

• Pre-industrial
https://arctic-news.blogspot.com/p/pre-industrial.html

• Feedbacks
https://arctic-news.blogspot.com/p/feedbacks.html

• NOAA - Office of Satellite And Product Operations - Sea Surface Temperatures
https://www.ospo.noaa.gov/products/ocean/sst/contour/index.html

• Nullschool.net
https://earth.nullschool.net

• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html

• Cold freshwater lid on North Atlantic
https://arctic-news.blogspot.com/p/cold-freshwater-lid-on-north-atlantic.html

• Danish Meteorological Institute - Arctic sea ice volume and thickness
https://ocean.dmi.dk/arctic/icethickness/thk.uk.php

• University of Bremen
https://seaice.uni-bremen.de/start

• NASA - Worldview satellite images
https://worldview.earthdata.nasa.gov

• 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

Friday, May 3, 2024

Is CMIP6 SSP585 the worst-case scenario?

The image below, adapted from Climate Reanalyzer, shows the temperature in the year 2100, in a CMIP6 SSP585 scenario. The image shows how much the temperature will have risen in 2100, at 2 meters above the surface and compared to the period 1979-2000.

The image below shows a progressive temperature rise reaching 4.589°C in 2100 compared to the same period, i.e. 1979-2000 and in a CMIP6 SSP585 scenario.

The 1979-2000 period is relatively recent. The temperature has been rising for longer than that. The image below shows a progressive temperature rise reaching 4.91°C by 2100 in a CMIP6 SSP585 scenario when instead using a 1901-2000 period as a base.

The 1901-2000 period is also relatively recent, much later than pre-industrial. When using a pre-industrial base, the temperature rise will be well over 5°C.

As illustrated by the top image, the temperature rise over land will be much higher than over oceans, which makes the situation even more dire, given that most people live on land and could face a rise of 8°C by 2100 in a CMIP6 SSP585 scenario.

In a CMIP6 SSP585 scenario, temperatures are projected to keep rising strongly beyond 2100, as illustrated by the image below, from a 2016 paper by Brian O'Neill et al.

In the study by Brian O'Neill et al., CO₂ emissions keep rising until 2100, to then fall gradually to current levels, while the CO₂ concentration in the atmosphere keep rising, to remain at levels beyond 2000 ppm and result in a temperature rise of 8°C by 2300 in a CMIP6 SSP585 scenario.

Is CMIP6 SSP585 the worst-case scenario?

To check whether CMIP6 SSP585 is indeed the worst-case scenario, one can look at how fast CO₂ is rising. According to the IEA, global energy-related CO₂ emissions grew in 2023, reaching a new record high of 37.4 Gt (or 10.098 GtC). The image below, from a recent post, confirms the recent acceleration in CO₂ concentrations, while showing the potential for CO₂ concentration to cross 1200 ppm before the year 2060.

In other words, CO₂ may well be rising even faster than anticipated in a CMIP6 SSP585 scenario, while this scenario doesn't take into account the potential for CO₂e concentrations to cross 1200 ppm much earlier than 2100 (inset), e.g. before 2060 as illustrated by the red trend in the main image. Furthermore, CMIP6 SSP585 doesn't take into account that, in addition to the temperature rise resulting from high greenhouse gas concentrations, crossing the clouds tipping point at 1200 ppm in itself would push up temperatures by a further 8°C.

Indeed, the clouds tipping point could be crossed even earlier when also taking into account methane, nitrous oxide and further greenhouse gases, while there are additional developments such as organic carbon and inorganic carbon release from soils that could further raise both CO₂ concentrations and temperatures. The Extinction page and posts such as this one and this one warn about the potential for a temperature rise of well over 18°C unfolding as early as 2026.

In conclusion, the temperature looks set to be rising higher and faster at accelerating rate, dwarfing anything seen in previous extinction events, as illustrated by the image below, from an earlier post.

"Now I am become Death, the destroyer of worlds."

The above image is a screenshot from the video (further above) in which physicist J. Robert Oppenheimer reflects on the first test of the atomic bomb. His haunting words mark the moment when science met conscience.

Similarly, climate change is a destroyer of worlds with unfathomable consequences, yet politicians refuse to heed the warnings, in an unprecedented breach of moral values, neglect of the precautionary principle, betrayal of trust and violation of the duty of care.

As a result, the IPCC persists with downplaying the potential for dangerous developments in efforts to hide the need for the most effective climate action. The IPCC keeps pointing at less effective policies such as support for BECCS and biofuel, while continuing to make it look as if there was a carbon budget to divide among polluters, as if polluters could continue to pollute for decades to come, as discussed in earlier posts such as this one.

Meanwhile, a 2018 study (by Strona & Bradshaw) indicates that most life on Earth will disappear with a 5°C rise. Humans, who depend for their survival on many other species, will likely go extinct with a 3°C rise, as illustrated by the image below, from an earlier post.

Links

• 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

• International Energy Agency (IEA) - CO2 Emissions in 2023 report
https://www.iea.org/reports/co2-emissions-in-2023

• September 2023, highest anomaly on record?