Showing posts with label freshwater. Show all posts
Showing posts with label freshwater. Show all posts

Friday, August 8, 2025

Extreme Heat Risk

High temperatures on land


The above image, adapted from NOAA National Weather Service, shows extreme heat risk for multiple areas in the U.S. for August 9, 2025, with a location near Imperial, California highlighted with details.
Details for the forecast for this location are: 
- Wet bulb globe temperature: 93°F or 34°C
- Temperature: 102°F or 39°C
- Apparent Temperature: 117°F or 47°C
- Dew Point: 77°F or 25°C
- Relative Humidity: 46%
- Forecast for: August 9, 2025 21:00 UTC

On the above image, this extreme risk area is located at a latitude of 33.22° North. What is remarkable is that on the map there is also a high risk area that extends all the way from the southern border of the U.S. with Mexico to the northern border of the U.S. with Canada, with extreme risk areas showing up at latitudes North higher than for Toronto, Canada. 

The image below, again adapted from NOAA National Weather Service, shows a wet bulb globe temperature forecast for August 11, 2025, with an extreme heat warning highlighted (inset) for a location near Imperial, California.
Details for the forecast for this location are: 
- Wet bulb globe temperature: 95°F or 35°C
- Temperature: 109°F or 43°C
- Apparent Temperature: 121°F or 49°C
- Dew Point: 73°F or 23°C
- Relative Humidity: 32%
- Forecast for: August 11, 2025 21:00 UTC


[ from earlier post ]

The image below, adapted from the heat risk page at the NOAA National Weather Service, shows a forecast for August 9, 2025, updated 10.49 AM EST. The map shows high and extreme risk areas, including an extreme risk area centered around Grand Rapid, Michigan, which is located at a latitude of about 43° North.

The image below shows a heat stress forecast for August 11, 2025, with areas with extreme heat risk showing up in Michigan, while areas with major heat risk are showing up at latitudes as high as in Maine. 


The image below, adapted from Climate Reanalyzer, shows a three-day forecast of maximum temperatures run on August 8, 2025.


The above images illustrate that extreme weather events that come with very high, even fatal heat stress conditions can now increasingly occur almost anywhere in the U.S.

Friederike Otto, climatologist at Imperial College London concludes: “Even relatively cold Scandinavian countries are facing dangerous heatwaves today – no country is safe from climate change". 

High sea surface temperatures

In 2023, sea surface temperature anomalies first rose strongly (from 0.15°C on January 7, 2023, to 0.73°C on January 10, 2024). Then, sea surface temperature anomalies came down, in line with ENSO fluctuations (El Niño/La Niña). ENSO fluctuations and forecasts are also discussed in more detail further below. 

Yet, over the past few months, sea surface temperature anomalies have been rising again, reaching an anomaly of 0.44°C from 1991-2020 on August 14, 2025, as illustrated by the image on the right, adapted from Copernicus and based on ERA5 data.

The image below, adapted from ClimateReanalyzer and based on NOAA OISST v2.1 data, shows sea surface temperatures through August 14, 2025. Sea surface temperatures have risen recently to very high levels, reaching 20.96°C on August 14, 2024, an anomaly from 1982-2010 of 0.72°C.


The image below, adapted from Climate Reanalyzer, shows the one-day average sea surface temperature anomaly (from 1971-2000) on August 7, 2025.


[ click on images to enlarge ]
Speeding up Arctic sea ice demise

Arctic sea ice declines due to rising ocean heat. The above image shows very high sea surface temperature anomalies around and inside the Arctic Ocean. These anomalies go up and down with the change in seasons, but they are getting higher over time due to rising Earth Energy Imbalance.

The image on the right, from an earlier post, illustrates the huge amounts of heat that have accumulated in the ocean, showing equivalent ocean heat content on August 9, 2025.

The image on the right underneath shows North Atlantic sea surface temperatures as high as 32.8°C on August 5, 2025. The image shows heat moving up along the path of the Gulf Stream toward the Arctic, threatening to cause more loss of sea ice and permafrost.

    [ from earlier post, click to enlarge ]
Arctic sea ice also declines due to the sunlight heating up the sea ice. Where sea ice disappears, the water heats up rapidly. Arctic sea ice decline comes with feedbacks such as the albedo feedback, i.e. less sunlight getting reflected by sea ice means more heat is getting absorbed, further accelerating the temperature rise. More algae and soot settling on the sea ice can further contribute to albedo loss. 

Feedbacks of the temperature rise can manifest as changes in heat sinks and buffers, with rapid impact on the temperature rise. Oceans constitute a huge buffer that has taken up huge amounts of heat. The capacity of oceans to take up heat threatens to diminish, e,g, due to stratification and changes in ocean currents, as discussed in earlier post such as this one. 

Another buffer is the latent heat buffer that consumes heat in the process of melting snow and ice. Arctic sea ice is getting thinner over the years, and the amount of heat that can be absorbed in the process of melting is getting smaller over time. As the latent heat buffer diminishes, heat that was previously absorbed by the phase change from snow and ice to water, will therefore instead get absorbed by the water, further raising the temperature of the water. As sea ice thickness decreases over the years, less incoming ocean heat can be consumed by melting the remaining sea ice. 

More freshwater temporarily slows down melting of Arctic sea ice

   [ Bering Strait ]
Furthermore, Arctic sea ice decline is due to heat that is moving with the flow of rivers into the Arctic Ocean. The image on the right shows sea surface temperatures as high as 20.3°C in the Bering Strait on August 7, 2025.

Extreme weather events are getting more severe and are occurring more frequently, including heatwaves and thunderstorms on land that can extend over the Arctic Ocean. Rain falling on sea ice can speed up its demise. Heatwaves and storms over land can furthermore heat up the water of rivers and increase their flow, thus increasing the heat flowing into the Arctic Ocean. 

Also, more evaporation of sea water takes place over the North Atlantic, with more precipitation falling further down the track of the Gulf Stream and its extension north. This also adds more freshwater in the Arctic. 

Water from melting sea ice, from rivers and from precipitation is all freshwater, i.e. it contains no salt. The increase in freshwater at the surface of the Arctic Ocean has resulted in a temporary slowdown in the retreat of Arctic sea ice extent, due to a buffer that spans a maximum of 2°C (as depicted by image below on the right). 

Freshwater buffer looks set to be overwhelmed soon

    [ Saltier water, less sea ice, from earlier post ]
The higher the water's salt content, the lower its melting point. Seawater typically has a salinity of about 3.5% (35 grams of salt per liter of water). 

Sea ice starts melting when the temperature rises to about -2°C (28.4°F). By contrast, freshwater remains frozen as long as the temperature remains below 0°C (32°F).

As said, the increase in freshwater at the surface of the Arctic Ocean slows down the retreat of Arctic sea ice extent, but this is only a temporary slowdown. Given the speed at which the temperature of the water of the Arctic Ocean keeps rising, this temporary slowdown looks set to be overwhelmed soon and rapid melting of sea ice looks set to return with a vengeance. 


The above image shows Arctic sea ice concentration on August 14, 2025. 

Arctic and Antarctic - two different situations

The image below, by Eliot Jacobson, illustrates the rise of precipitable water (total column) over the years. 


Over the past two months (June-July 2025), the temperature over the Arctic Ocean has been slightly lower than 1951-1980, as illustrated by the image below. By contrast, areas with very high anomalies are visible between 60°S and 90°S. What's happening?


The image below shows that the precipitable water anomaly can be very high at both the North Pole and the South Pole. The image depicts the situation on August 9, 2025 18Z.  


In the Northern Hemisphere, water evaporates from the sea surface of the North Atlantic and the North Pacific. Prevailing winds carry much water vapor in the direction of the Arctic. Precipitation over the Arctic Ocean freshens the surface, forming a buffer that temporarily slows down the decline of the sea ice extent. Similarly, much of the precipitation over land is carried by rivers into the Arctic Ocean, also freshening the surface of the Arctic Ocean. And of course, heavy melting of Arctic sea ice in June and July 2025 has added further freshwater to the surface of the Arctic Ocean.

The slowdown of AMOC can also create a buffer by delaying the transport of ocean heat toward the Arctic Ocean, but given the increase of Earth's Energy Imbalance and the additional heat that is instead accumulating in the north Pacific and the North Atlantic, more heat looks set to eventually reach the Arctic Ocean, overwhelming such buffers. 

[ Precipitable water anomalies over Antarctica ]
In the Southern Hemisphere, water evaporates from the Southern Ocean and part of it falls on the Antarctic ice sheet, thickening the snow layer, as illustrated by the image on the right, showing a forecast of high precipitable water anomalies over Antarctica on August 20, 2025.

As a result, the Southern Ocean surface is getting more salty. As discussed in an earlier post, saltier surface waters sink more readily, allowing heat from the deep to rise, which can melt Antarctic sea ice from below, even during winter, making it harder for ice to reform. This vertical circulation also draws up more salt from deeper layers, reinforcing the cycle.

In conclusion, geographic differences result in different precipitation outcomes and this in turn causes salinity differences that are behind these temperature anomaly differences. 

As said, the slowdown in the decline of Arctic sea ice extent that results from the increase in freshwater is temporary. Given the speed at which the temperature of the water of the Arctic Ocean keeps rising, this temporary slowdown looks set to be overwhelmed soon and rapid melting of sea ice looks set to return with a vengeance.

By contrast, the dramatic decrease in sea ice around Antarctica looks set to continue long-term, as a feedback that is amplified by albedo loss, lower emissivity, loss of the sea ice's latent heat buffer, ocean current changes and salinity changes. 

Dire state of sea ice

The net result is illustrated by the image below. The global sea ice area anomaly was 2.62 million km² below the 1981-2010 mean on August 13, 2025, a standard deviation of -4.13σ from 1981-2010. The image shows that the global sea ice area anomaly was well below 1981-2010 in the years 2023, 2024 and 2025, which is remarkable, since there was a La Niña early in 2025. The year 2016 is also marked, since 2016 was a strong El Niño year.
The image below shows Arctic sea ice volume through August 11, 2025, when volume was at a record daily low, as it has been for more than a year. 

High temperatures and dire state of sea ice despite borderline La Niña

What makes these high temperatures on land and the dire state of the sea ice even more significant is that there currently are no El Niño conditions. As illustrated by the image on the right, adapted from NOAA, the ENSO outlook (CFSv2 ensemble mean, black dashed line) favors borderline La Niña conditions during the Northern Hemisphere fall and early winter 2025-2026, which suppresses temperatures.

Over the past few months, there's been a zigzag pattern of rises and falls in sea surface temperatures in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño, as illustrated by the image below.


On August 11, 2025, the temperature in Niño 3.4 reached 26.51°C, an anomaly of 0.36°C vs 1991-2020. An El Niño event is defined by NOAA as an episode of at least five consecutive 3-month running mean sea surface temperature anomalies vs 1971-2000 surpassing the threshold of 0.5°C in the Niño 3.4 area, as illustrated by the image below.


The image on the right, adapted from ECMWF, shows the El Niño forecast through August 2026. The next El Niño may emerge soon, and it may continue to grow in strength in the course of 2026. 

The temperature rise is accelerating and the rise could accelerate even more due to decreases in buffers (as described above), due to strengthening feedbacks, especially during an El Niño, and due to further reduction of the aerosol masking effect, which are all developments that could rapidly speed up existing feedbacks and trigger new feedbacks. 

Seafloor methane

One of the most dangerous feedbacks is methane erupting from the seafloor of the Arctic Ocean. The image below shows hourly methane average recorded at the Barrow Atmospheric Baseline Observatory (BRW), a NOAA facility located near Utqiaġvik (formerly Barrow), Alaska, at 71.32 degrees North. 


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 (National Oceanic and Atmospheric Administration), National Weather Service
https://digital.weather.gov

• NOAA - heat risk graphics
https://www.wpc.ncep.noaa.gov/heatrisk/graphics

• Climate Reanalyzer
https://climatereanalyzer.org

• Heat Stress in the US
https://arctic-news.blogspot.com/2025/07/heat-stress-in-the-us.html

• High feels like temperature forecast (2024)
https://arctic-news.blogspot.com/2024/08/high-feels-like-temperature-forecast.html

• Wet Bulb Globe Temperature Tipping Point (2023)
https://arctic-news.blogspot.com/2023/07/wet-bulb-globe-temperature-tipping-point.html

• ‘No country is safe’: deadly Nordic heatwave supercharged by climate crisis, scientists say 

• Eliot Jacobson - Total Column Precipitable Water 1943 through July 2025
https://www.facebook.com/photo/?fbid=122244827390164489

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

• Danish Meteorological Institute - Arctic sea ice thickness and volume

• NOAA - Oceanic Niño Index (ONI)

• ECMWF - El Niño forecast

• NOAA - Global Monitoring Laboratory
https://gml.noaa.gov/dv/iadv



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Friday, March 22, 2024

Atlantic ocean heat threatens to unleash methane eruptions

The image below shows that the monthly Atlantic surface temperature anomaly in February 2024 was 1.176°C when compared to a 1951-1980 base.

[ click on images to enlarge ]

The image below shows that the monthly Atlantic surface temperature anomaly in February 2024 was 1.435°C when compared to a 1901-2000 base. 


The difference illustrates the importance of selecting a base to calculate anomalies from. The anomaly indicates how much heat has accumulated in the Atlantic, and it is even larger for February 2024 when using a genuinely pre-industrial base, as discussed earlier.

The images also highlight the potential for the slowing down of the Atlantic meridional overturning circulation (AMOC) to contribute to more heat accumulating at the surface of the Atlantic Ocean.

As temperatures rise, many feedbacks are kicking in with greater ferocity, including increased stratification of oceans, loss of sea ice, loss of reflectivity of clouds and increased freshwater due to stronger melting of sea ice and glacial ice, due to heavier runoff from land and rivers and due to changes in ocean circulation.

While this may look to cause less ocean heat to reach the Arctic Ocean at the moment, the result is that a huge amount of ocean heat is accumulating in the North Atlantic that threatens to abruptly move into the Arctic Ocean. The danger is that an influx of ocean heat can cause large amounts of methane to erupt from the seafloor of the Arctic Ocean. 

The inset on the top image illustrates that, as people's emissions raise the temperature, this rise can strengthen wind, evaporation, ocean currents and rainfall locally, resulting in greater potential for a lid to form and spread at the surface of the North Atlantic. As temperatures rise and winds strengthen, more evaporation can occur in one place and more rain can then fall further down the path of the Gulf Stream, i.e. an ocean current that extends into the Arctic Ocean, as part of AMOC. This rain further contributes to the freshwater accumulation at the surface of the North Atlantic.

In the video below, Guy McPherson discusses a recent study by Marilena Oltmanns et al. on some of these issues.


This page further discusses formation of a cool freshwater lid at the surface of the North Atlantic and the contribution to this of Jet Stream changes. The image below shows that the Jet Stream reached speeds as high as 455 km/h or 283 mph north of Washington on February 18, 2024 03:00 UTC, with Instantaneous Wind Power Density as high as 387.5 kW/m².

From earlier post Blue Ocean Event 2024?

A huge amount of ocean heat is accumulating in the North Atlantic and threatens to abruptly move into the Arctic Ocean. The danger is that, due to strong wind along the path of the Gulf Stream, huge amounts of ocean heat will abruptly get pushed into the Arctic Ocean, with the influx of ocean heat causing destabilization of hydrates contained in sediments at the seafloor of the Arctic Ocean, resulting in eruptions of huge amounts of methane. 

Strong hurricanes can significantly add to the danger. More hurricanes are forecast for the 2024 Atlantic hurricane season than during 1950-2020, as illustrated by the image below. 


Many of the dangers have been discussed before, e.g. the danger that sea currents in the Arctic Ocean will change direction, in this 2017 post. 

Arctic sea ice thickness warning

The compilation image below shows Arctic sea ice on March 28, 2024. The satellite image (left) may indicate extensive sea ice, but clouds can obscure things. The other image (right) indicates that sea ice in a large area from the Laptev Sea down to the North Pole may be very thin.


The image below illustrates the decline of Arctic sea ice volume over the years.


The images above and below show that Arctic sea ice volume has recently been the lowest on record for the time of year.


Given that Arctic sea ice currently is still relatively extensive, this low volume indicates that sea ice is indeed very thin, which must be caused by ocean heat melting sea ice from below, since little or no sunshine is yet reaching the Arctic at the moment and air temperatures are still far below freezing point, so where ocean heat may be melting sea ice away from below, a thin layer of ice will quickly be reestablished at the surface. 

This situation looks set to dramatically change over the next few months, as air temperatures will rise and as more ocean heat will reach the Arctic Ocean. Moreover, as illustrated by the map below, much of the thicker sea ice is located off the east coast of Greenland. This sea ice and the purple-colored sea ice can be expected to melt away quickly with the upcoming rise in temperatures over the next few months.


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

• Climate Reanalyzer

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

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

• European summer weather linked to North Atlantic freshwater anomalies in preceding years - by Marilena Oltmanns et al.
https://wcd.copernicus.org/articles/5/109/2024/wcd-5-109-2024-discussion.html
discussed at facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10161330866254679

• Science Snippets: Arctic Sea Ice Affects European Summers, Marine Life, and All Life on Earth - by Guy McPherson
https://www.youtube.com/watch?v=X09vtWNDuDw

• nullschool 
https://earth.nullschool.net

• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html

• Extended range forecast of Atlantic seasonal hurricane activity and landfall strike probability for 2024 - by Philip Klotzbach et al.
https://tropical.colostate.edu/forecasting.html
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10161346323759679

• Arctic Ocean Feedbacks
https://arctic-news.blogspot.com/2017/01/arctic-ocean-feedbacks.html

• NASA Worldview satellite images
https://worldview.earthdata.nasa.gov

• University of Bremen - Arctic sea ice
https://seaice.uni-bremen.de/start

• Danish Meteorological Institute - Arctic sea ice volume and thickness


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Friday, January 27, 2017

Arctic Ocean Feedbacks


The world is warming rapidly, and the Arctic is warming much more rapidly than the rest of the world. In December 2016, the temperature anomaly from latitude 83°N to the North Pole was 8 times as high as the global anomaly. Above forecast for February 6, 2017, shows that temperatures over parts of the Arctic Ocean will be as much as 30°C or 54°F higher than they were in 1979-2000. How can it be so much warmer in a place where, at this time of year, little or no sunlight is shining? The Arctic Ocean is warming particularly rapidly due to a multitude of feedbacks, some of which are illustrated on the image below.


As the Arctic is warming more rapidly than the rest of the world, the temperature difference between the Arctic and the northern latitudes decreases, which makes the jet stream wavier. Jennifer Francis has written extensively about jet stream changes as a result of rapid warming in the Arctic. In the video below, Peter Sinclair interviews Jennifer Francis on these changes.


The changes to the jet stream make it easier for warm air from the south to enter the Arctic and for cold air to move out of the Arctic deep down into North America and Eurasia. At the same time, this also increases the temperature difference between the continents and the oceans, which is quite significant given the rapid warming of oceans across the globe. The result of the greater temperature difference between oceans and continents is that stronger winds are now flowing over the oceans along the jet stream tracks.

Stronger winds come with more evaporation and rain, which accumulates as freshwater at the surface of the North Atlantic and the North Pacific. The freshwater acts as a seal, as a lid on the ocean, making that less heat gets transferred from underneath the freshwater lid to the atmosphere. This makes that more heat can travel underneath the sea surface through the North Atlantic and reach the Arctic Ocean.


On January 28, 2017, sea surface temperature anomalies as high as 18.4°C (or 33.1°F) were showing up off the coast of Japan.


The situation is illustrated by above images, showing areas over the North Atlantic and the North Pacific (blue) where the sea surface was colder than it was in 1981-2011. Over these colder areas, winds are stronger due to the changes to the jet stream. On January 28, 2017, temperature anomalies were as high as 18.4°C (or 33.1°F) off the coast of Japan, while temperature anomalies were as high as 10.9°C (or 19.5°F) near Svalbard in the Arctic on January 27, 2017.

The image on the right shows sea surface temperature anomalies from 1971-2000.

The video below shows precipitation over the Arctic, run on January 27, 2017, and valid up to February 4, 2017.


Beaufort Gyre and Transpolar Drift
Changes to wind patterns can also affect sea currents in the Arctic Ocean such as the Beaufort Gyre and the Transpolar Drift. In the video below, at around 7:00, Paul Beckwith warns that further loss of sea ice will make these sea currents change direction, which in turn will draw more warm seawater from the North Atlantic into the Arctic Ocean.

As more ocean heat enters the Arctic Ocean and as sea ice retreats, more heat and water vapor will rise from the Arctic Ocean into the atmosphere over the Arctic. Increased water vapor will make it harder for heat to escape into space, i.e. more heat will remain trapped in the atmosphere and this will add to global warming.


The changes to the jet stream and the associated changes discussed above all lead to further warming of the Arctic Ocean, next to the warming caused by other feedbacks such as loss of albedo and loss of ice as a heat buffer. Together, sea ice loss and these associated feedbacks could cause global temperatures to rise by 1.6°C by 2026.

There are further feedbacks affecting the Arctic, as described at this page. One of the most dangerous feedbacks is methane escaping from the seafloor of the Arctic Ocean. As the temperature of the Arctic Ocean keeps rising, it seems inevitable that more and more methane will rise from its seafloor and enter the atmosphere, at first strongly warming up the atmosphere over the Arctic Ocean itself - thus causing further methane eruptions - and eventually warming up the atmosphere across the globe.

Above image paints a dire warning. The image shows that methane levels were as high as 2562 ppb on January 28, 2017. The image further shows high methane levels off the coast of Siberia and also where water from Nares Strait enters Baffin Bay.

Feedbacks and further elements of a potential temperature rise by 2026 of more than 10°C above prehistoric levels are further described at the extinction page.

The situation is dire and calls for comprehensive and effective action as described in the Climate Plan.


Links

• Climate Plan
http://arctic-news.blogspot.com/p/climateplan.html

• Feedbacks
http://arctic-news.blogspot.com/p/feedbacks.html

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

• 2016 well above 1.5°C
http://arctic-news.blogspot.com/2017/01/2016-well-above-1.5c.html

• Accelerating Warming of the Arctic Ocean
http://arctic-news.blogspot.com/2016/12/accelerating-warming-of-the-arctic-ocean.html


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