Carbon dioxide (CO₂) concentrations grew by 3.75 parts per million (ppm) during 2024, the highest growth rate on record.
The annual global average surface concentration of CO₂ for 2024 was 422.79 ppm, according to NOAA data.
The image below shows the monthly global average surface concentration of CO₂ through January 2025.
On April 16, 2025, concentrations of CO₂ at Mauna Loa, Hawaii, had exceeded 430 ppm for six days in a row, as illustrated by the image below.
On April 20, 2025, concentrations of CO₂ at Mauna Loa, Hawaii, reached 430.64 ppm, the highest daily average on record. To find higher levels, one needs to go back millions of years.
Methane
IPCC AR6 gives N₂O a global warming potential (GWP) of 273 over both 500 years and 100 years, and of 118 over 20 years, while its lifetime is 120 years. Furthermore, N₂O is currently the most significant ozone depleting substance (ODS) being emitted. The impact of N₂O as ODS has grown strongly over the years, relative to other ODS. Nitrogen fertilizers are typically produced with natural gas, thus further driving up concentrations of methane in the atmosphere.
The impact of nitrogen fertilizers may also have been underestimated; a 2022 study concludes that when ammonia, nitric acid and sulfuric acid are present together, they contribute strongly to the formation of cirrus clouds. Cirrus clouds exert a net positive radiative forcing of about 5 W m⁻², according to IPCC AR6, as discussed in this 2022 post.
Temperature anomalies for February-March 2025 over the Arctic were as much as 20°C higher than 1951-1980, as illustrated by the image on the right.
The fact that these anomalies occurred at a time of year when little or no sunlight was yet reaching the Arctic indicates that the cause of these very high anomalies is extremely high ocean heat.
New El Niño?
Conditions are dire. Temperatures and concentrations of greenhouse gases are high and rising fast, sea ice is disappearing, sunspots are at a high point in this cycle and a new El Niño may emerge soon. The image below shows NOAA's outlook.
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| [ from earlier post, also note the recent discussion on monthly methane ] |
Nitrous oxide
The image below shows globally averaged marine surface monthly mean nitrous oxide (N₂O) data through December 2024 (red circles), with a trend added that points at 1000 ppb getting crossed in 2031, tripling current levels.
While using different periods and types of trends can result in trends that don't show such a steep rise, the point is that such a steep rise in N₂O could eventuate, based on recent data. The rise could become even steeper, given that N₂O emissions caused by people come mainly from applying nitrogen fertilizers and animal waste to farmland and pastures, and that policy control over emissions from nitrogen fertilizers is largely absent or ineffective, while farmers are increasingly using nitrogen fertilizers in efforts to increase crop yield, especially where yields are falling due to rising temperatures and more extreme weather events.
IPCC AR6 gives N₂O a global warming potential (GWP) of 273 over both 500 years and 100 years, and of 118 over 20 years, while its lifetime is 120 years. Furthermore, N₂O is currently the most significant ozone depleting substance (ODS) being emitted. The impact of N₂O as ODS has grown strongly over the years, relative to other ODS. Nitrogen fertilizers are typically produced with natural gas, thus further driving up concentrations of methane in the atmosphere.
The impact of nitrogen fertilizers may also have been underestimated; a 2022 study concludes that when ammonia, nitric acid and sulfuric acid are present together, they contribute strongly to the formation of cirrus clouds. Cirrus clouds exert a net positive radiative forcing of about 5 W m⁻², according to IPCC AR6, as discussed in this 2022 post.
A huge increase in nitrous oxide emissions could result from thawing permafrost, as discussed below.
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| [ from earlier post ] |
Arctic hit most strongly
The Arctic is hit most strongly by the temperature rise, as illustrated by the image below showing the ERA5 global temperature anomaly for February-March 2025 versus 1951-1980.
The image below shows the NCEP global temperature anomaly for February-March 2025 versus 1951-1980.
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| [ Arctic hit hard, click to enlarge ] |
The fact that these anomalies occurred at a time of year when little or no sunlight was yet reaching the Arctic indicates that the cause of these very high anomalies is extremely high ocean heat.
New El Niño?
The image below shows temperatures in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño.
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| [ Arctic sea ice volume, click to enlarge ] |
Feedbacks and further mechanisms
These conditions threaten to further drive up temperatures, while further acceleration of the temperature rise threatens to occur due to strengthening feedbacks and further mechanisms including eruptions of seafloor methane, sea ice loss and changes in ocean currents and wind patterns.
High ocean temperatures are already causing Arctic sea ice volume to be very low compared to earlier years, as illustrated by the image on the right and as discussed in this earlier post.
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 manifest—the more sobering it is to realize that a mere 3°C rise may suffice to cause human extinction.
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
• NOAA - Global averaged marine surface annual mean carbon dioxide data
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_gl.txt
• NOAA - Annual Mean Global Carbon Dioxide Growth Rates
• NOAA - ENSO: Recent Evolution, Current Status and Predictions - 14 April 2025
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
• Danish Meteorological Institute - Arctic sea ice volume and thickness
https://ocean.dmi.dk/arctic/icethickness/thk.uk.php
• 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
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 manifest—the more sobering it is to realize that a mere 3°C rise may suffice to cause human extinction.
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
• NOAA - Global averaged marine surface annual mean carbon dioxide data
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_gl.txt
• NOAA - Annual Mean Global Carbon Dioxide Growth Rates
https://gml.noaa.gov/ccgg/trends/gl_gr.html
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10162561012229679
• NOAA - Nitrous oxide emissions grew 40 percent from 1980 to 2020, accelerating climate change
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10162561012229679
• NOAA - Nitrous oxide emissions grew 40 percent from 1980 to 2020, accelerating climate change
https://research.noaa.gov/nitrous-oxide-emissions-grew-40-percent-from-1980-to-2020-accelerating-climate-change
• N₂O is currently the most significant ozone-depleting substance being emitted
• N₂O is currently the most significant ozone-depleting substance being emitted
• NOAA - ENSO: Recent Evolution, Current Status and Predictions - 14 April 2025
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
• Danish Meteorological Institute - Arctic sea ice volume and thickness
https://ocean.dmi.dk/arctic/icethickness/thk.uk.php
• 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
