The above image, adapted from NASA and the image below, adapted from Climate Reanalyzer and using the same baseline, illustrate the September 2023 temperature anomaly.
September 2023 was the month with the highest temperature anomaly on record. What contributed to this?
El Niño
The temperature rose about 0.5°C from November 2022 to March 2023, and this occurred at a time when we were not even in an El Niño yet, as illustrated by the above image, from an earlier post. Below is an updated image, from January 1950 to September 2023, adapted from NOAA
There are further reasons why the temperature can be expected to keep rising beyond September 2023.
Aerosols that have a cooling effect, such as dust and sulfates (SO₄), are also important. As fossil fuel is burned, sulfates are co-emitted. Since they pollute the air, measures have been taken and are being taken to reduce them, e.g. in shipping, and this has pushed up the temperature rise. Meanwhile, cooling aerosols such as sulfates are still high. As illustrated by the image below, adapted from nullschool.net, SO₄ was as high as 8.621 τ at the green circle on October 6, 2023, at 07:00 UTC. In future, SO₄ could fall dramatically, e.g. in case of a sudden economic collapse, reducing the aerosol masking effect rapidly and abruptly causing a substantial rise in temperature.
The above image was created by Zach Labe with NSIDC data (Arctic + Antarctic) for each year from 1979 to 2023 (satellite-era; NSIDC, DMSP SSM/I-SSMIS). The image illustrates that global sea ice extent recently reached the largest anomaly in the satellite record. Anomalies are calculated using a 5-day running mean from a climatological baseline of 1981-2010. 2016 is shown with a yellow line. 2023 is shown using a red line (updated 10/16/2023).
As said, there are many factors behind the temperature increase around latitude -60° (South). As Paul mentions, this latitude receives a lot of sunlight around the year. Therefore, it is not surprising that, as oceans continue to heat up, there is huge loss of sea ice at this latitude, as well as loss of lower clouds, while open oceans are additionally less efficient than sea ice when it comes to emitting in the far-infrared region of the spectrum. The image below, adapted from NASA, shows a white band around -60° (South), indicating that the Southern Ocean has long been colder there than elsewhere, but has recently started to catch up with the global temperature rise.
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| [ click on images to enlarge ] |
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The current El Niño is still strengthening, as illustrated by the image on the right, adapted from IRI.
Further contributors
Further contributors
There are further reasons why the temperature can be expected to keep rising beyond September 2023.
The number of sunspots has been higher than predicted and looks set to keep rising above predicted levels until July 2025, as discussed here.
The eruption of the submarine volcano near Tonga in January 2022 caused a lot of water vapor to reach high up into the atmosphere and this may still contribute to the temperature rise, as discussed here.
Aerosols that have a cooling effect, such as dust and sulfates (SO₄), are also important. As fossil fuel is burned, sulfates are co-emitted. Since they pollute the air, measures have been taken and are being taken to reduce them, e.g. in shipping, and this has pushed up the temperature rise. Meanwhile, cooling aerosols such as sulfates are still high. As illustrated by the image below, adapted from nullschool.net, SO₄ was as high as 8.621 τ at the green circle on October 6, 2023, at 07:00 UTC. In future, SO₄ could fall dramatically, e.g. in case of a sudden economic collapse, reducing the aerosol masking effect rapidly and abruptly causing a substantial rise in temperature.
After little change in the Antarctic sea ice extent graph for decades, extent loss was dramatic in 2022 and even more dramatic in 2023, as less and less sunlight was getting reflected back into space and instead was getting absorbed by the water of the Southern Ocean, as illustrated by the image below, adapted from NSIDC.
Sea ice retreat comes with loss of albedo, i.e. loss of the amount of sunlight reflected back into space, resulting in more heat getting absorbed in the Southern Ocean, making it a self-reinforcing feedback loop. Clouds constitute another self-reinforcing feedback loop; a warmer Southern Ocean 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 a recent 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).
The above image was created by Zach Labe with NSIDC data (Arctic + Antarctic) for each year from 1979 to 2023 (satellite-era; NSIDC, DMSP SSM/I-SSMIS). The image illustrates that global sea ice extent recently reached the largest anomaly in the satellite record. Anomalies are calculated using a 5-day running mean from a climatological baseline of 1981-2010. 2016 is shown with a yellow line. 2023 is shown using a red line (updated 10/16/2023).
In the video below, Paul Beckwith discusses the importance of loss of sea ice at around -60° (South).
The above image also illustrates that anomalies are highest in the Arctic, narrowing the temperature difference between the Arctic and the Tropics, with the air flow slowing down accordingly.
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| [ image adapted from Copernicus ] |
Forest fires in Canada have been releasing massive amounts of emissions that push up the temperature, including greenhouse gases such as carbon dioxide, warming aerosols such as black carbon & brown carbon and NMVOC (non-methane volatile organic carbon) and carbon monoxide that reduce the availability of hydroxyl, resulting in more methane and ozone in the atmosphere.
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| [ NH sea surface temperature anomaly ] |
At the same time, slowing down of the Atlantic Meridional Ocean Current (AMOC) can result in more ocean heat accumulating at the surface of the North Atlantic, as illustrated by the image on the right, from an earlier post.
As temperatures rise, increased meltwater runoff from Greenland and more icebergs moving south, in combination with stronger ocean stratification and stronger storms over the North Atlantic, can also cause a freshwater lid to form at the surface of North Atlantic that can at times enable a lot of hot water to get pushed abruptly underneath this lid toward the Arctic Ocean. The danger is that more heat will reach the seafloor and destabilize methane hydrates contained in sediments at the seafloor of the Arctic ocean.
As temperatures rise, increased meltwater runoff from Greenland and more icebergs moving south, in combination with stronger ocean stratification and stronger storms over the North Atlantic, can also cause a freshwater lid to form at the surface of North Atlantic that can at times enable a lot of hot water to get pushed abruptly underneath this lid toward the Arctic Ocean. The danger is that more heat will reach the seafloor and destabilize methane hydrates contained in sediments at the seafloor of the Arctic ocean.
Ominously, very high methane levels continue to be recorded at Barrow, Alaska, as illustrated by the image below, adapted from NOAA.
The next few months will be critical as Arctic sea ice is sealing off the Arctic Ocean from the atmosphere, trapping heat underneath the ice and making it harder for ocean heat to get transferred from the Arctic Ocean to the atmosphere above the Arctic. Furthermore, sea ice is very thin, reducing the latent heat buffer that could otherwise have consumed ocean heat.
The next danger is that the thin Arctic sea ice will rapidly retreat early next year as a warming Arctic Ocean will transfer more heat to the atmosphere over the Arctic, resulting in more rain and more clouds in the atmosphere over the Arctic, speeding up sea ice loss and further pushing up the temperature rise over the Arctic, as discussed at the feedbacks page, which also discusses how less Arctic sea ice can push up temperatures through the emissivity feedback. As temperatures rise over the Arctic, permafrost on land also threatens to thaw faster, threatening to cause huge releases of greenhouse gases, including carbon dioxide, methane and nitrous oxide.
The next danger is that the thin Arctic sea ice will rapidly retreat early next year as a warming Arctic Ocean will transfer more heat to the atmosphere over the Arctic, resulting in more rain and more clouds in the atmosphere over the Arctic, speeding up sea ice loss and further pushing up the temperature rise over the Arctic, as discussed at the feedbacks page, which also discusses how less Arctic sea ice can push up temperatures through the emissivity feedback. As temperatures rise over the Arctic, permafrost on land also threatens to thaw faster, threatening to cause huge releases of greenhouse gases, including carbon dioxide, methane and nitrous oxide.
Meanwhile, emissions of greenhouse gases keep rising, further pushing up the temperature, as illustrated by the image below, from an earlier post.
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| [ Global energy-related greenhouse gas emissions 2000-2022, adapted from EIA ] |
There are numerous further feedbacks that can accelerate the temperature rise and tipping points that can get crossed and cause even more abrupt rise of the temperature. One of these is the clouds tipping point that in itself can cause a temperature rise of 8°C, as discussed here. Further feedbacks are also discussed at the Extinction page.
The image below, adapted from NASA, shows that the September 2023 NASA Land+Ocean temperature was 1.78°C higher than it was in September 1923. The anomaly is 1.74°C when compared to a base centered around the year 1900 (1885-1915). The 1.74°C anomaly can be adjusted by 0.99°C to reflect a pre-industrial base, air temperature and higher polar anomalies (as shown in the box on the bottom right of the image), adding up to a potential anomaly of 2.73°C.
A warmer atmosphere holds more water vapor, at a rate of 7% for each Degree Celsius the temperature rises. As temperatures keep rising, ever more water vapor will be sucked up by the atmosphere. This will also cause more droughts, reducing the ability of land to sustain vegetation and provide soil cooling through shading and through evaporation and formation of lower clouds, as discussed here. More water vapor in the atmosphere will also speed up the temperature rise because water vapor is a potent greenhouse gas. This makes it critical to assess by how much the temperature has already risen.
NASA data up through September 2023
The image below, adapted from NASA, shows that the September 2023 NASA Land+Ocean temperature was 1.78°C higher than it was in September 1923. The anomaly is 1.74°C when compared to a base centered around the year 1900 (1885-1915). The 1.74°C anomaly can be adjusted by 0.99°C to reflect a pre-industrial base, air temperature and higher polar anomalies (as shown in the box on the bottom right of the image), adding up to a potential anomaly of 2.73°C.
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Blue: Polynomial trend based on Jan.1880-Sep.2023 data. Magenta: Polynomial trend based on Jan.2010-Sep.2023 data. |
The above image is created with NASA Land+Ocean monthly mean global temperature anomalies vs 1885-1915, adjusted by 0.99°C to reflect ocean air temperature, higher polar anomalies and a pre-industrial base, and has trends added.
Conclusion
Alarms bells have been sounding loud and clear for a long time, as discussed in posts such as this one, warning that the temperature could rise by more than 3°C by 2026. The above magenta graph shows how this could occur as early as next year (end 2024).
The precautionary principle should prevail and the looming dangers should prompt people into demanding comprehensive and effective action to reduce the damage and to improve the situation. To combat rising temperatures, a transformation of society should be undertaken, along the lines of this 2022 post in combination with a declaration of a climate emergency.
Links
• NASA - global maps
• NOAA - ENSO and Temperature bars
https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-sst_table
• Nullschool.net
• NSIDC - sea ice graph
• Zach Labe - Global sea ice - extent, concentration, etc.
https://data.giss.nasa.gov/gistemp/zonal_means
• Copernicus - Northern Hemisphere wildfires: A summer of extremes
https://atmosphere.copernicus.eu/northern-hemisphere-wildfires-summer-extremes
• NOAA - Barrow Atmospheric Baseline Observatory, United States
https://gml.noaa.gov/dv/iadv/graph.php?code=BRW&program=ccgg&type=ts
• Paul Beckwith - Accelerated Global Warming from Antarctic Sea Ice Collapse: Albedo, Latitude, Snow Cover on Ice…
https://www.youtube.com/watch?v=-5P1W4TrczQ
• Copernicus - Northern Hemisphere wildfires: A summer of extremes
https://atmosphere.copernicus.eu/northern-hemisphere-wildfires-summer-extremes
• NOAA - Barrow Atmospheric Baseline Observatory, United States
https://gml.noaa.gov/dv/iadv/graph.php?code=BRW&program=ccgg&type=ts
• Paul Beckwith - Accelerated Global Warming from Antarctic Sea Ice Collapse: Albedo, Latitude, Snow Cover on Ice…
https://www.youtube.com/watch?v=-5P1W4TrczQ
• NASA custom plots
https://data.giss.nasa.gov/gistemp/graphs_v4/customize.html
• Transforming Society
https://data.giss.nasa.gov/gistemp/graphs_v4/customize.html
• Transforming Society
