Wednesday, April 1, 2026

Carbon dioxide highest in millions of years

Greenhouse gas concentrations

The highest daily average carbon dioxide (CO₂) concentration recorded by the Keeling Curve, maintained by Scripps Institution of Oceanography at Mauna Loa Observatory, was 432.81 parts per million (ppm), recorded on April 1, 2026. The image below shows CO₂ over thousands of years. 


The highest daily average CO₂ concentration recorded by NOAA at Mauna Loa, Hawaii, was 432.69 ppm, recorded on April 1, 2026 (yellow circle on the right). The image below shows hourly (red circles) and daily (yellow circles) averaged CO₂ values from Mauna Loa, Hawaii, over 31 days. In bold on the image are recent daily averages.


The image below shows daily (green circles), weekly (red lines) and monthly (blue lines) averages for the last year. The weekly average for the week beginning on March 22, 2026, was 430.93 ppm (red line top right). NOAA's CO₂ average daily concentrations were at a record high of 432.69 ppm, at Mauna Loa, Hawaii, on April 1, 2026.


To find CO₂ levels this high back in history, one needs to go back millions of years, as illustrated by the two images below, from an earlier post.


What makes current conditions even more dire is that not only are concentrations of CO₂ extremely high (without match going back millions of years) and rising, but the speed at which CO₂ is currently rising is also unprecedented, while additionally there has been an increase in total solar irradiance of ∼400 Wm⁻² since the formation of the Earth. The image below shows the combined climate forcing by changing CO₂ and solar output for the past 450 million years.


Between 14 and 15 million years ago, the temperature in central Europe was 20°C higher than today, as illustrated by the image below (adapted from a 2020 study by Methner et al.).

[ from earlier post, click on images to enlarge ]
Given today's extremely high CO₂ levels, why is the temperature in central Europe not 20°C higher today? The answer is that - for now - most of the extra heat trapped by the extremely high (and rising) greenhouse gas levels doesn't stay in the atmosphere, but is absorbed by oceans, by land, and in the process of melting ice. However, the capacity for oceans, land and ice to keep taking up more heat appears to be reducing fast, as described in more detail further below. 

Concentrations of carbon dioxide haven't been this high for millions of years, as confirmed by recent analysis led by Sarah Shackleton and Julia Marks-Peterson. Their analysis finds that, while the average temperature of the ocean has decreased by 2 to 2.5°C over the past 3 million years, average atmospheric carbon dioxide levels have likely remained below 300 parts per million over this time. Methane levels have also remained relatively stable. This makes the recent daily concentration of 432.81 ppm at Mauna Loa and the high recent methane levels (see earlier post) even more threatening and it means that, in addition to the key role of heat-trapping greenhouse gases, there were important contributions from other components of the climate system such as Earth’s reflectivity, variations in vegetation and/or ice cover and ocean circulation. There are many feedbacks and further contributors to acceleration of the temperature rise that could add up to a rise of more than 20°C by the end of 2026, as discussed in an earlier post. 

Earth energy imbalance

Outgoing longwave radiation is reducing due to rising greenhouse gases, resulting in an increasingly larger amount of extra energy. The image below depicts Earth energy imbalance.  
According to the IPCC AR6 WG1, 91% of the extra energy is taken up by oceans, 5% by land, 3% by ice melting and 1% remains in the atmosphere. Oceans, land and ice melting thus act as a buffer that did take up the vast majority (99%) of the extra energy, based on IPCC data.  

[ image by Leon Simons ]
Not only is the extra energy increasing, as depicted by the above image, but the proportions of where the extra energy is going is additionally changing. 

The ocean's capacity to act as an energy buffer is increasingly compromised by stratification, changes to ocean currents, changes in salinity, ocean oxygen depletion, acidification and more, as discussed in earlier posts such as this one. This is a big issue, since oceans take up 91% of the extra heat caused by greenhouse gases, so if there is even a 1% reduction in the heat taken up by oceans, the heat remaining in the atmosphere may double.  

Furthermore, the capacity for ice to act as a buffer by consuming energy in the process of melting is increasingly compromised by sea ice decline, by retreat of glaciers, and by darkening of ice due to dust, algae, black carbon and more. Arctic sea ice is facing a Blue Ocean Event with sea ice decline threatening to both dramatically lower albedo and reduce the ability for ocean heat to be consumed in the process of melting.  Mountain glaciers are also in decline and permafrost is approaching the point where thawing of permafrost will speed up rapidly, as discussed in earlier posts such as this one. 

The capacity for land to take up heat also faces a tipping point: The Land Evaporation Tipping Point can get crossed locally when water is no longer available locally for further evapotranspiration, i.e. from all processes by which water moves from the land surface to the atmosphere via evaporation and transpiration, including transpiration from vegetation, evaporation from the soil surface, from the capillary fringe of the groundwater table, and from water bodies on land. Once this tipping point gets crossed, the land and atmosphere will heat up strongly, due to the extra heat, i.e. heat that was previously consumed by evaporation and thawing, as described at this page.

So, while the extra energy is increasing, as depicted by the above image, the capacity of oceans, land and ice to take up energy is decreasing and an increasingly large amount of extra heat therefore threatens to accumulate in the atmosphere, especially in the Northern Hemisphere over land and in the Arctic, where temperatures are rising faster than anywhere in the world.

Could the Northern Hemisphere land-only temperature rise exceed 3°C soon?

The upcoming El Niño could trigger a rapid and steep rise in temperature on land in the Northern Hemisphere, as illustrated by the combination image below that uses land-only data in the top panel and Northern Hemisphere data in the bottom panel. 

[ image from earlier post, discussed on facebook here ]
Arctic sea ice

The image below, adapted from dmi.dk, shows that Arctic sea ice volume was at a record low for the time of year on April 3, 2026.


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

• Keeling Curve - by Scripps Institution of Oceanography at UC San Diego 
https://keelingcurve.ucsd.edu

• NOAA - Global Monitoring Laboratory - Carbon Cycle Greenhouse Gases - Mauna Loa, Hawaii
https://gml.noaa.gov/ccgg/trends/mlo.html

• NOAA - Global Monitoring Laboratory - data viewer - Mauna Loa, Hawaii
https://gml.noaa.gov/dv/iadv/graph.php?code=MLO&program=ccgg&type=ts

• NOAA - Office of satellite and product operations - HEAP NUCAPS
https://www.ospo.noaa.gov/products/atmosphere/soundings/heap/nucaps/new/nucaps_products.html

• Broadly stable atmospheric CO2 and CH4 levels over the past 3 million years - by Julia Marks-Peterson et al.
https://www.nature.com/articles/s41586-025-10032-yand

• Global ocean heat content over the past 3 million years - by Sarah Shackleton et al.
https://www.nature.com/articles/s41586-026-10116-3
discussed on Facebook at:
https://www.facebook.com/groups/arcticnews/posts/10164017885199679

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

• Blue Ocean Event
https://arctic-news.blogspot.com/p/blue-ocean-event.html

• The threat of seafloor methane eruptions
https://arctic-news.blogspot.com/2025/11/the-threat-of-seafloor-methane-eruptions.html

• The 2026 El Nino - update March 2026
https://arctic-news.blogspot.com/2026/03/the-2026-el-nino-update-march-2026.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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Thursday, March 26, 2026

Signals flashing red indicating further acceleration toward climate collapse

Greenhouse gas concentrations

The image below shows hourly (red circles) and daily (yellow circles) averaged carbon dioxide (CO₂) values from Mauna Loa, Hawaii, over 31 days. The highest daily average CO₂ concentration on record, 431.95 ppm, was recorded at Mauna Loa, Hawaii, on March 28, 2026 (third yellow circle from the right). In bold on the image are recent daily averages, since March 24, 2026.


CO₂ average daily concentrations were at a record high of 431.95 parts per million (ppm), at Mauna Loa, Hawaii, on March 28, 2026. The image below shows daily (green circles), weekly (red lines) and monthly (blue lines) averages for the last year. The weekly average for the week beginning on March 22, 2026 was 430.93 ppm (red line top right).


The image below shows daily average CO₂ concentration at Mauna Loa, Hawaii since 2020. The highest daily average CO₂ concentration on record, 431.95 ppm, was recorded at Mauna Loa, Hawaii, on March 28, 2026.


Concentrations of carbon dioxide haven't been this high for millions of years, as confirmed by recent analysis led by Sarah Shackleton and Julia Marks-Peterson. Their analysis finds that, while the average temperature of the ocean has decreased by 2 to 2.5°C over the past 3 million years, average atmospheric carbon dioxide levels have likely remained below 300 parts per million over this time. Methane levels have also remained relatively stable. This makes the recent daily concentration of 431.95 ppm at Mauna Loa and the high recent methane levels (see image below) even more threatening and it means that, in addition to the key role of heat-trapping greenhouse gases, there were important contributions from other components of the climate system such as Earth’s reflectivity, variations in vegetation and/or ice cover and ocean circulation.

[ click on images to enlarge ]

The above combination image shows methane levels as high as 2240 parts per billion (ppb) close to sea level (left panel, 1000 mb) and as high as 2541 ppb at a slightly higher altitude (right panel, 840 mb) recorded by the NOAA 21 satellite on March 11, 2026 AM. The combination image below shows methane levels as high as 231 ppb at 1000 mb (left panel) and as high as 2576 ppb at 399.1 mb (right panel) recorded by the NOAA 20 satellite on March 11, 2026 PM.


Together, these combination images support the suggestion that a burst of methane did enter the atmosphere at a location over the ocean, resulting in very high methane levels in the morning slightly above sea level and even higher methane levels higher up in the atmosphere later that day. 

Sea surface temperature

The image below shows world (60°S–60°N, 0–360°E) sea surface temperatures from NOAA OISST V2.1. The sea surface temperature was 21.15°C on March 27, 2026, a record high temperature for the time of year and a +0.75°C anomaly compared to 1982-2010. The sea surface temperature has risen by 0.46°C since the start of 2026.


Furthermore, changes in salinity and ocean currents, together with ocean stratification, ocean oxygen depletion and sea ice loss can result in oceans changing from heat sinks into heat sources, resulting in more heat remaining in the air and getting transferred to the air, as discussed in earlier post such as this one and as discussed in this analysis, also discussed here.

Earth Albedo

The image below, adapted from an image by Eliot Jacobson, shows now much the Earth Albedo (reflectivity) has fallen from February 23 through January 2026.


Arctic sea ice

One of the contributors to albedo loss is Arctic sea ice loss. The image below, adapted from NSIDC, shows that on March 25, 2026, the Arctic sea ice extent was 14.011 million km², the lowest extent on record for the time of year.

The image below, adapted from ads.nipr.ac.jp, shows that Arctic sea ice extent was 13.37 million km² on March 27, 2026, the lowest sea ice extent on record for the time of year. 

The situation is very dangerous, since we're moving out of a La Niña (which is suppressing the temperature) into an El Niño (which will be elevating the temperature). 

The danger is that a Blue Ocean Event will occur in 2026 if Arctic sea ice continues to be low and if melting from April 2026 onward will be strong. A Blue Ocean Event can be said to occur when virtually no sea ice remains to keep consuming ocean heat that is entering the Arctic Ocean mainly from the Atlantic Ocean. Virtually no sea ice could be 1 million km² or less in sea ice extent, but it could also be measured in area, as illustrated by the image below.

The image below shows that the Arctic sea ice area was the lowest on record on March 25, 2026. Arctic sea ice area was 13.43 million km² on March 25, 2012, and area was 12.31 million km² on March 25, 2026, i.e. a difference of 1.12 million km² and the same difference as there was on March 20, 2026. Arctic sea ice area was 2.24 million km² on September 12, 2012, so with this difference persisting, Arctic sea ice area would be 1.12 million km² in September 2026, or very close to a Blue Ocean Event.


The danger that a Blue Ocean Event will occur in September 2026 is further illustrated by the image below. The image, from an earlier post, which shows Arctic sea ice volume in the past 25 years. Markers show April (blue) and September (red) volume, corresponding with the year's maximum and minimum. In 2025, Arctic sea ice reached a record low maximum volume, as well as a record low minimum volume.


As illustrated by the above image, adapted from dmi.dk, Arctic sea ice volume was very low in April 2025, so while relatively little melting took place from April 2025 to September 2025, a record low Arctic sea ice volume was still reached in September 2025. The above image shows Arctic sea ice volume through mid February 2026, with an analysis of the strength of the melting between April (annual maximum) and September (annual minimum) by means of the bars colored magenta (strong melting) and green (little melting).

If the downward trend in annual maxima (blue circles) continues, Arctic sea ice looks set to reach an even lower maximum volume in April 2026. The difference between strong melting (magenta) and little melting (green) is 3000 km³, so if strong melting will take place from April 2026, this may well cause a Blue Ocean Event to occur later in 2026. A Blue Ocean Event could also be said to occur when only 1000 km³ or less Arctic sea ice volume remains. The image below, adapted from dmi.dk, shows that Arctic sea ice volume was at a record low for the time of year on March 31, 2026. 


Could the N.H land-only temperature rise by more than 3°C in 2027?

The image below, adapted from Copernicus, shows that the global surface air temperature was 14.31°C on March 26, 2026, the highest temperature on record for the time of year. 


Could the temperature rise by more than 3°C soon? The upcoming El Niño could trigger a rapid and steep rise in temperature on land in the Northern Hemisphere, as illustrated by the combination image below that uses land-only data in the top panel and Northern Hemisphere data in the bottom panel. While the image shows NASA data from 2011 until 2028 (top panel, land-only) and data from 2011 until 2029 (bottom panel, N.H), the trends are calculated using annual data from 2010 through 2025. The quartic trends point at the temperature crossing 3°C in the Northern Hemisphere in early 2028 (bottom), and on land-only in early 2027.  


There are compound impacts such as that the temperature will rise faster on land in the Northern Hemisphere, and even faster during heatwaves in large cities where they are affected by the Urban Heat Island effect. Moreover, the 1880-1920 base is not pre-industrial, the outlook may be even more dire when using a genuinely pre-industrial base. 

Note also that the above are annual average temperature anomalies, i.e. the average for higher and lower anomalies during the year. A recent study shows that extreme global climate outcomes may occur even under moderate 2°C warming for several sectors. For droughts in global key breadbasket regions, precipitation extremes over highly populated areas and fire weather extremes across forests, global climatic impact-drivers at 2°C of global warming may turn out to be much more extreme than model-averaged projections at 3°C or 4°C warming. Indeed, the peaks are more critical than the averages. 

Recent research finds that, while fully frozen permafrost can be considered both to function as a seal preventing subsurface gases being released, and to prevent the creation of new CO₂ and CH₄, gas permeability increases by about 25–100 times during thawing, with most permeability change occurring in the −5°C to −1°C range, indicating that the protective gas seal previously provided by permafrost will be lost as permafrost thaws.

The danger is that the temperature will not merely "overshoot" the 3°C threshold, but that the temperature will continue to rise, especially on land in the Northern Hemisphere, and accelerate over the Arctic. Given the severity, ubiquity and imminence of the danger, one would think that highlighting the danger will prompt people into taking effective climate action, but the outlook is that the temperature will continue to rise for at least a few years, hence the choice of the trend and the canvas, which in the above image is limited to 3°C and until 2028, respectively 2029 (as also discussed on facebook here).

Polynomial trends such as the one in the above image can highlight warnings about dangers that are discussed in this post and in earlier posts, in particular warnings that a strong El Niño is on the way which could cause a strong rise in temperature in the course of 2026 and trigger further acceleration of the temperature rise. 

Indeed, the rise resulting from a strong El Niño would come on top of a temperature rise that is already accelerating due to high concentrations of greenhouse gases, while deforestation and numerous feedbacks are kicking in with greater ferocity, and while the temperature rise is amplified in the Arctic (see image below, from earlier post), which could lead to a Blue Ocean Event soon, further speeding up the temperature rise and resulting in loss of permafrost, eruption of methane from the seafloor of the Arctic Ocean, further loss of lower clouds, etc.


The above image, from an earlier post, shows that the 2025 Arctic temperature was 3.431°C higher than in 1951-1980. The only year on record that had an anomaly higher than 2025 was 2016, when there was a super El Niño.

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

• NOAA - Global Monitoring Laboratory - Carbon Cycle Greenhouse Gases - Mauna Loa, Hawaii
https://gml.noaa.gov/ccgg/trends/mlo.html

• NOAA - Global Monitoring Laboratory - data viewer - Mauna Loa, Hawaii

• NOAA - Office of satellite and product operations - HEAP NUCAPS

• Broadly stable atmospheric CO2 and CH4 levels over the past 3 million years - by Julia Marks-Peterson et al.
https://www.nature.com/articles/s41586-025-10032-y
and
• Global ocean heat content over the past 3 million years - by Sarah Shackleton et al.

• Earth Albedo - by Eliot Jacobson

• NASA - GISS Surface Temperature Analysis - custom plots
https://data.giss.nasa.gov/gistemp/graphs_v4/customize.html
quartic trend analysis was discussed earlier on facebook at: 

• NSIDC - Sea Ice Extent
https://nsidc.org/sea-ice-today/sea-ice-tools/charctic-interactive-sea-ice-graph

• Kevin Pluck - sea ice visuals
https://seaice.visuals.earth

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

• Copernicus

• Blue Ocean Event
https://arctic-news.blogspot.com/p/blue-ocean-event.html

• Moderate global warming does not rule out extreme global climate outcomes - by Emanuele Bevacqua et al.
https://www.nature.com/articles/s41586-026-10237-9
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10164067383004679

• Measurement of Gas Fraction and Gas Permeability of Thawing Permafrost Caused by Climate Change - by Paul Glover et al. 
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025EF007232
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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, from an earlier post.


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 image below is also from that earlier post. The image depicts 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, i.e. as a potential development. 

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.

Such developments were discussed in a 2021 post that featured the image below, with the caption that a 5 Gt burst of seafloor methane would double the methane in the atmosphere and could instantly raise CO₂e level to above 1200 ppm, thus triggering the cloud feedback (panel top right). Even with far less methane, levels of further pollutants could rise and feedbacks could strengthen, while sulfate cooling could end, and a 18.44°C rise (from pre-industrial) could occur by 2026 (left panel).


How appropriate is the use of a multiplier of 200 to convert the impact of methane in parts per million (ppm) methane to ppm CO₂e? After all, carbon dioxide equivalence (CO₂e) was introduced by politicians in the Kyoto Protocol, which was adopted in 1997 and uses a Global Warming Potential (GWP) of greenhouse gases over a 100-year horizon to calculate their carbon dioxide equivalence. Is GWP a tool behind specific politics? How much sense does it make to calculate methane's GWP over 100 years, given that methane's atmospheric perturbation lifetime is less than 12 years and methane has its highest impact immediately after it enters the atmosphere? What multiplier should be used to calculate the impact of an extra 5 Gt of methane? 

The image on the right, from an earlier post, shows trends based on IPCC AR6 GWP values pointing at a GWP for methane of 150 for a 9-year horizon and pointing at an even higher GWP for a shorter horizon. 

A short horizon makes sense when calculating the immediate impact of, say, a 5 Gt burst of methane from the seafloor of the Arctic Ocean.

There are other ways to calculate the impact, e.g. one can also look at radiative forcing. It makes sense to also take into account the indirect impact of methane, as done in the image below. The image conceptually dates back to 2019 when the analysis by Tapio Schneider et al. was published, hence the use of radiative forcing from the IPCC AR5 WG1 SPM report that was published in 2013.

The image below shows three blocks each of about 400 ppm CO₂e, adding up to 1200 ppm CO₂e. The bottom block (purple) represents the CO₂ present in the atmosphere, i.e. on May 9, 2013, CO₂ surpassed 400 ppm at Mauna Loa. It is noted that extra CO₂ has less impact as its abundance grows, whereas extra CH₄ has a stronger impact.

The block in the middle (dark red) shows the methane already in the atmosphere, with the note that IPCC AR5 gives CH₄ an impact of 0.97 W/m⁻² (see top of image), or 57.74% of the impact of about 400 ppm CO₂. Yet, the impact of methane could rise to 400 ppm CO₂e, for reasons described in the following paragraph. 

The spectral band where most heat is trapped by CO₂ is more saturated than the band where most heat is trapped by CH₄. The impact of additional CH₄ will increase as its abundance grows, whereas the impact of additional CO₂ will decrease as abundance grows. Abrupt eruptions of 5 Gt of seafloor CH₄ will cause hydroxyl depletion. Since there is already very little hydroxyl present over the Arctic, large eruptions of CH₄ from the seafloor of the Arctic Ocean would strongly increase the lifetime of CH₄ there, trigger feedbacks and increase its global warming impact. The warming impact of an extra 5 Gt of CH₄ could therefore approach the impact of the CO₂ that was in the atmosphere on May 9, 2013, and this would not only apply to the methane that is added by such eruptions, but it would also increase the impact of CH₄ already present in the atmosphere. 

The block of 400 ppm CO₂e at the top of the bar (red) represents an extra 5 Gt of CH₄ resulting from a burst of methane erupting from the seafloor of the Arctic Ocean. Some of the methane arising from the seafloor will be broken down in the water by microbes, but many of the seas in the Arctic Ocean are very shallow and when large amounts of methane erupt in the form of plumes and move at high speed through the water column, only a small part of the methane can be broken down on its way up through the water column. Anyway, the point is that 5 Gt of methane abruptly entering the atmosphere could have an immediate impact of 400 ppm CO₂e which would also raise the impact of the block of existing CH₄ to 400 ppm CO₂e. 


Jointly, the three blocks each of 400 ppm CO₂e add up to 1200 ppm CO₂e, i.e. the tipping point where stratocumulus decks start to disappear abruptly, resulting in an additional temperature rise of 8°C. Even when CO₂ levels are lowered again after the stratocumulus breakup, the stratocumulus decks only reform once the CO₂ levels drop below 300 ppm, as discussed at the Clouds Tipping Point page.

Historic growth in methane concentrations

Historic records could have given a stronger warning than the IPCC pathways. 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 been pushing up the temperature from a genuinely pre-industrial base for thousands of years, maybe by more than 2°C, as illustrated by the bottom panels on the image below.

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, the speed in the projected decline in aerosols from sulfur dioxide in 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  

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

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

• 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


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