Greenhouse gas concentrations
Carbon dioxide (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 430.67 ppm (red line top right).
The image below shows hourly (red circles) and daily (yellow circles) averaged CO₂ values from Mauna Loa, Hawaii, over the last 31 days. The highest daily average CO₂ concentration on record, 431.95 ppm, was recorded at Mauna Loa, Hawaii, on March 28, 2026 (yellow circle on the right). The green inset shows daily averages since March 24, 2026.
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.
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| [ click on images to enlarge ] |
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.
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 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.
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).
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| [ Could a steep rise in land-only temperatures occur soon? - image from earlier post ] |
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, i.e. warnings that a strong El Niño may be on the way that could cause a strong rise in temperature in the course of 2026, a rise that 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.
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.
https://www.nature.com/articles/s41586-025-10032-y
discussed on Facebook at:
https://www.facebook.com/groups/arcticnews?multi_permalinks=10164017885199679
• 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
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























































































