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Mechanisms behind a steep rise in temperature

by
The image below shows the temperature rise from end 2022 through February 27, 2025, with trends added. 
The shading in the above image reflects the presence of El Niño conditions (pink shading) that push up temperatures, La Niña conditions (blue shading) that suppress temperatures, or neutral conditions (gray shading). Such short-term variables are smoothed out in the black linear trend that shows a steady rise of about 0.5°C over the three years from end 2022 to end 2025. 

This rise of 0.5°C over just 3 years (black linear trend in above image) is a much steeper rise than the black linear trend in the image below, which shows a rise of 1.1°C over the 81 years from 1941 to 2022.

As said, the recent rise in temperature depicted by the black linear trend in the image at the top is much steeper than the rise from 1941-2022 in the above image. The image at the top also features a red trend that warns that an even steeper rise could occur soon, as a result of the joint impact of at least ten mechanisms. 
1. ENSO changes – a transition away from the current La Niña conditions

2. Sunspots – higher than expected and reaching their peak in the current cycle in July 2025

3. Cooling aerosols – being reduced 

4. Earth’s Energy Imbalance – very high and rising, as illustrated by the image below. 
[ Image from Berkeley Earth: Earth’s Energy Imbalance is accelerating the temperature rise ]

5. Greater albedo loss – as a result of sea ice loss and loss of lower clouds

The above image is from Berkeley Earth and also features in an earlier post, illustrating the importance of Antarctic Sea ice loss in accelerating the temperature rise and thus also in reducing lower clouds. 
A Blue Ocean Event can be declared when sea ice area falls to a low of 1 million km² or less. As illustrated by the image below, Antarctic sea ice area reached 1.22 million km² on February 27, 2025, almost as low as the 1.05 million km² recorded on February 22, 2023, raising alarms that a Double Blue Ocean Event could occur in 2025, i.e. both for the Antarctic sea ice and for the Arctic sea ice. 
The image below illustrates that the global sea ice area is currently very low, resulting in less sunlight getting reflected back into space and more heat getting absorbed at the surface instead. 

The Arctic melt season looks set to start with the lowest Arctic sea ice area on record for the time of year, as illustrated by the image below. 

Albedo loss also occurs due to thawing of permafrost and retreat of glaciers, and – as said – due to loss of lower clouds as temperatures rise. 
6. More water vapor – as the temperature rise from pre-industrial turns out to be higher
[ from an earlier post ]
The above image illustrates that the February 2024 temperature was potentially 2.75°C above pre-industrial. A much higher rise from pre-industrial than the rise mentioned in the IPCC assessment reports would come with much more water vapor in the atmosphere. A 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere, since 7% more water vapor will be in the atmosphere for every 1°C warming. Extra water vapor will further amplify the temperature rise, since water vapor is a potent greenhouse gas. The image below shows high precipitable water anomalies over the Arctic Ocean on February 26, 2025. 

7. Ocean changes – it becomes increasingly hard for ocean heat to reach deeper parts of the ocean, due to stratification and due to changes in ocean currents, resulting in more heat accumulating at the surface instead. 
This mechanism is discussed in this 2024 post and also on facebook in posts such as this one, this one and in this one. 
[ from earlier post ]

Furthermore, slowdown of the Atlantic and Southern Meridional Overturning Circulation and increased stratification lead to depletion of nutrients (in particular phosphorus) in the ocean’s top layer, in turn decreasing phytoplankton growth and thus decreasing oxygen production and carbon sequestration, as a recent study confirms. 
Additionally, deoxygenation occurs as temperature rise, since warm water holds less oxygen than cold water. Oxygen is used by methanotroph bacteria to oxidize methane that is rising up from the seafloor, so less oxygen also increases methane entering the atmosphere.

8. Latent heat buffer loss – as sea ice, permafrost and glaciers disappear.
Latent heat is energy associated with a phase change, such as the energy consumed when ice turns into water. During a phase change, the temperature remains constant. As long as there is ice, additional heat will be absorbed by the process of ice turning into water, so the temperature doesn’t rise at the surface.

The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C. The energy required to melt a volume of ice can raise the temperature of the same volume of rock by as much as 150ºC.

Warmer water flowing into the Arctic Ocean causes Arctic sea ice to lose thickness and thus volume, diminishing its capacity to act as a buffer that consumes ocean heat entering the Arctic Ocean from the North Atlantic. This means that – as sea ice thickness decreases – a lot of incoming ocean heat can no longer be consumed by melting the sea ice from below, and the heat will therefore contribute to higher temperatures of the water of the Arctic Ocean. Similarly, there is a point beyond which thawing of permafrost on land and melting of glaciers can no longer consume heat, and all further heat will instead warm up the surface. 
[ from earlier post ]
[ Arctic sea ice volume, click to enlarge ]

The image on the right shows Arctic sea ice volume up to February 27, 2025. Arctic sea ice volume in 2024 and 2025 has been much lower than in previous years.

More incoming heat therefore threatens to reach the seafloor of the Arctic Ocean and destabilize methane hydrates contained in sediments at the seafloor, resulting in eruptions of huge amounts of methane, in turn threatening increased loss of permafrost, resulting in additional emissions.

The danger is especially large in the Arctic, which contains huge amounts of methane and which is hit most strongly by the temperature rise, as illustrated by the image below.

9. More emissions from the environment – as sinks turn into sources, and as there are more emissions from methane hydrate eruptions, from thawing permafrost, from flooded areas, and from fires (including fires in forests, peatland, grassland, urban waste in backyards and landfills, and fires in buildings, especially in warehouses containing flammable materials and chemicals), as temperatures keep rising. 
10. More emissions from human action and inaction – as more people start to realize how dire the situation is and as they seek to occupy the most habitable areas left. 
A recent analysis estimates that just the emissions from the war in Ukraine since Russia’s full-scale invasion rival the annual emissions of four European nations combined (i.e. Austria, Hungary, Czech Republic and Slovakia). More emissions may also result from more biofuel and wood getting burned in vehicles, heaters and power plants, as it becomes harder to obtain fossil fuel and as the grid shuts down, due to conflicts and people no longer showing up for work. 

Ominously, very high temperature anomalies are forecast over the Arctic Ocean for November 2025.
[ Very high temperature anomalies forecast over Arctic Ocean, from earlier post ]
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

• Copernicus
https://climate.copernicus.eu

• Berkeley Earth – Global Temperature Report for 2024

• Did a Terminal Temperature Acceleration Event start in December 2024?

• Did the climate experience a Regime Change in 2023?

• Sea ice loss
https://arctic-news.blogspot.com/2025/02/sea-ice-loss.html

• Kevin Pluck – seaice.visuals.earth
https://seaice.visuals.earth

• Sunspots
https://arctic-news.blogspot.com/p/sunspots.html

• Albedo, latent heat, insolation and more
https://arctic-news.blogspot.com/p/albedo.html

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

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Cold freshwater lid on North Atlantic

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

• Observed declines in upper ocean phosphate-to-nitrate availability – by Skylar Gerace et al. (2025) 
https://www.pnas.org/doi/10.1073/pnas.2411835122
• Oxygenating the Arctic

• Danish Meteorological Institute – Arctic sea ice volume and thickness

https://ocean.dmi.dk/arctic/icethickness/thk.uk.php

• Arctic and Antarctic Data Archive System (ADS) of the National Institute of Polar Research of Japan

https://ads.nipr.ac.jp

• Climate Reanalyzer
https://climatereanalyzer.org

• Forest fires push up greenhouse gas emissions from war in Ukraine

• Climate damage caused by Russia’s war in Ukraine in three years – the key numbers

• Tropical Tidbits

https://www.tropicaltidbits.com

• 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