Extreme Heat Risk

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

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

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

Speeding up Arctic sea ice demise

[ click on images to enlarge ]

The above image shows very high sea surface temperature anomalies around and inside the Arctic Ocean. These anomalies are getting higher by the day, due to Earth Energy Imbalance and the change of seasons.  

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.  

    [ from earlier post, click to enlarge ]

The image shows heat moving up along the path of the Gulf Stream toward the Arctic, threatening to accelerate loss of sea ice and permafrost. 

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. 

There are also buffers and once they are overwhelmed or disappear, the temperature rise will speed up rapidly. One example is the latent heat buffer. Arctic sea ice is getting thinner over the years, so the amount of heat that can be absorbed in the process of melting is getting smaller over time. 

As the latent heat buffer decreases, the heat that was previously absorbed by the phase change from ice to water, will therefore instead get absorbed by the water, further raising the temperature of the water. As the sea ice thickness decreases over the years, less incoming ocean heat can therefore 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 temperature 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 strongly, 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 has created a temporary slowdown in the decline of the sea ice, a buffer of 2°C (as depicted by the 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).

This slowdown in the melting of Arctic sea ice 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. 

The above image shows Arctic sea ice concentration on August 11, 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, giving the sea ice 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. 

The net result is illustrated by the image below. The global sea ice area anomaly was 2.72 million km² below the 1981-2010 mean on August 11, 2025, a standard deviation of -4.83σ from 1981-2010.

The image below shows Arctic sea ice volume through August 11, 2025. Volume was at a record daily low, as it has been for more than a year. 

What makes the dire state of the sea ice even more significant is that there currently are no El Niño conditions. The ENSO outlook favors borderline La Niña during the Northern Hemisphere fall and early winter 2025-2026, as discussed in a recent 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

• 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

• University of Miami - Rosenstiel School - North Atlantic OHC
https://isotherm.rsmas.miami.edu/heat/weba/atlantic.php

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

• 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

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

Wet Bulb Globe Temperature Tipping Point

High Wet Bulb Globe Temperatures (WBGT) are forecast to hit Louisiana, United States, over the next few days. The image below shows a forecast for August 2, 2023, 18 UTC, with WBGT as high as 35°C forecast for a location 10 miles South East of Abbeville, Louisiana, U.S.

WBGT is a measure used by weather.gov to warn about expected heat stress when in direct sunlight. It takes into account the effect of temperature, relative humidity, wind speed, and solar radiation on humans.

As temperatures and humidity levels keep rising, a tipping point can be reached where the wind factor no longer matters, in the sense that wind can no longer provide cooling. The human body can cool itself by sweating, which has a physiological limit that was long described as a 35°C wet-bulb temperature. Once the wet-bulb temperature reaches 35°C, one can no longer lose heat by perspiration, even in strong wind, but instead one will start gaining heat from the air beyond a wet-bulb temperature of 35°C.

Accordingly, a 35°C wet-bulb temperature (equal to 95°F at 100% humidity or 115°F at 50% humidity) was long seen as the theoretical limit, the maximum a human could endure.

A 2020 study (by Raymond et al.) warns that this limit could be regularly exceeded with a temperature rise of less than 2.5°C (compared to pre-industrial). A 2018 study (by Strona & Bradshaw) indicates that most life on Earth will disappear with a 5°C rise. Humans, who depend for their survival on many other species, will likely go extinct with a 3°C rise, as illustrated by the image below, from an earlier post.

A 2022 study (by Vecellio et al.) finds that the actual limit is lower — about 31°C wet-bulb or 87°F at 100% humidity — even for young, healthy subjects. The temperature for older populations, who are more vulnerable to heat, is likely even lower. In practice the limit will typically be lower and depending on circumstances could be as low as a wet-bulb temperature of 25°C.

The above image shows a Wet Bulb Globe Temperature of 35°C (95°F) forecast for August 11, 2023, 19 UTC, for a location near Baton Rouge, Louisiana, U.S. 

Heat is the leading cause of weather-related deaths in the United States, as illustrated by the above image (credit: NOAA). Heat fatalities may be conservative figures. Recent research finds that where heat is being listed as an official cause of death, this likely underestimates the full toll of these events. Extreme heat can trigger heart attacks and strokes. In addition, some heart disease risk factors, such as diabetes—as well as heart medications, such as diuretics and beta blockers—can affect a person’s ability to regulate their body temperature and make it difficult to handle extreme heat. The study finds that extreme heat accounted for about 600-700 additional deaths from cardiovascular disease annually. A recent study estimates that extreme heat accounted for 12,000 premature deaths in the contiguous U.S. from 2000 to 2010, and a recent analysis calculates that the summer 2022 heatwave killed 61,000 people in Europe alone. 

The image below shows a temperature (°F) forecast for August 1, 2023, from Climate Reanalyzer. 

The video below discusses this.

Misery Index

The image below show a high reading on the 'Misery Index', the perceived ('feels like') temperature that is used by nullschool.net, combining wind chill and the heat index (which in turn combines air temperature and relative humidity, in shaded areas). A Misery Index temperature of 56.1°C or 133.1°F was recorded at a location off the coast of the United Arab Emirates (green circle) on August 5, 2023.

The temperature at that location at the time was 35.2°C or 95.4°F, lower than the temperature on the land surrounding the Gulf, but the relative humidity at that spot over the water was 78%, and that combination led to this very high 'feels like' temperature. 

This constitutes a warning. The sea, rivers and lakes are traditionally seen as places to go to, to cool off. However, high temperatures combined with high humidity over water bodies can result in conditions that go beyond what humans can bear. 

Climate change danger assessment

The image below, earlier discussed here, expands risk assessment beyond its typical definition as the product of the severity of impact and probability of occurrence, by adding a third dimension: timescale, in particular imminence.

Imminence alone could make that the danger constituted by rising temperatures needs to be acted upon immediately, comprehensively and effectively. While questions may remain regarding probability, severity and timescale of the dangers associated with climate change, the precautionary principle should prevail and this should prompt for action, i.e. comprehensive and effective action to reduce damage and improve the situation is imperative and must be taken as soon as possible.

Rapidly rising temperatures constitute tipping points in several ways 

Firstly, there is a biological threshold beyond which rising temperatures become lethal for humans, as discussed above. 

Secondly, as Gerardo Ceballos describes in the video below and in a 2017 analysis, there is a biological tipping point that threatens annihilation of species via the ongoing sixth mass extinction. Researchers such as Gerardo Ceballos (2020), Kevin Burke (2018) and Ignation Quintero (2013) have for years warned that mammals and vertebrates cannot keep up with the rapid rise in temperature. Humans are classified as vertebrate mammals, indicating that we will not avoid the fate of extinction, Guy McPherson (2020) adds. 

Thirdly, there are further tipping points, e.g. social-political ones. On the one hand, it would be good if people became more aware, as this could prompt more people into supporting the necessary action. On the other hand, as temperatures keep rising, there is also a danger that panic will break out, dictators will grab power and civilization as we know it will collapse abruptly, as warned about earlier, e.g. in 2007.  

Conclusion

In conclusion, to combat rising temperatures, transforming society is needed urgently, along the lines of this 2022 post in combination with declaration of a climate emergency.

Links

• Wet Bulb Globe Temperature
https://digital.mdl.nws.noaa.gov

• National Weather Service - Wet Bulb Globe Temperature: How and when to use it
https://www.weather.gov/news/211009-WBGT

• The emergence of heat and humidity too severe for human tolerance - by Colin Raymons et al. (2020)
https://www.science.org/doi/10.1126/sciadv.aaw1838

• Brief periods of dangerous humid heat arrive decades early
https://www.climate.gov/news-features/featured-images/brief-periods-dangerous-humid-heat-arrive-decades-early

• Evaluating the 35°C wet-bulb temperature adaptability threshold for young, healthy subjects (PSU HEAT Project) - by Daniel Vecellio et al. (2022)
https://journals.physiology.org/doi/full/10.1152/japplphysiol.00738.2021
Discussed at: https://www.facebook.com/groups/arcticnews/posts/10159973158374679

• NOAA - Weather Fatalities 2022
https://www.weather.gov/hazstat

• The Effects of Heat Exposure on Human Mortality Throughout the United States - by Drew Shindell (2021)

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GH000234

• Heat-related mortality in Europe during the summer of 2022 - by Joan Ballester et al.
https://www.nature.com/articles/s41591-023-02419-z

Discussed at: https://www.facebook.com/groups/arcticnews/posts/10160875637104679

• As Temperatures Spike, So Do Deaths from Heart Disease (2022 News release)
https://www.acc.org/About-ACC/Press-Releases/2022/03/22/20/06/As-Temperatures-Spike-So-Do-Deaths-from-Heart-Disease

• Association of Extreme Heat and Cardiovascular Mortality in the United States: A County-Level Longitudinal Analysis From 2008 to 2017 - by Sameed Khatana et al. (2022)
https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.122.060746

• Co-extinctions annihilate planetary life during extreme environmental change, by Giovanni Strona and Corey Bradshaw (2018)
https://www.nature.com/articles/s41598-018-35068-1
Discussed at: https://www.facebook.com/groups/arcticnews/posts/10156903792219679

• When will we die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Climate Reanalyzer - Hourly Forecast Maps
https://climatereanalyzer.org/wx/fcst/?mdl_id=nam&dm_id=conus-lc&wm_id=t2

• PBS video - Too HOT and HUMID to Live: Extreme Wet Bulb Events are on the Rise 
https://www.pbs.org/video/too-hot-and-humid-to-live-extreme-wet-bulb-events-are-on-th-fazocs

• Nullschool
https://earth.nullschool.net

• How agriculture hastens species extinction | 60 Minutes (CBS News) | Gerardo Ceballos
https://www.youtube.com/watch?app=desktop&v=f21WWocqR-c

• Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines - by Gerardo Ceballos, Paul R. Ehrlich and Rodolfo Dirzo (2017)
https://www.pnas.org/content/114/30/E6089

• Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction - by Gerardo Ceballos, Paul Ehrlich, and Peter Raven (2020)
https://www.pnas.org/content/early/2020/05/27/1922686117

Discussed at: https://www.facebook.com/groups/arcticnews/posts/10158460232764679

• Rates of projected climate change dramatically exceed past rates of climatic niche evolution among vertebrate species - by Ignatio Quintero et al. (2013) 

https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.12144

• Pliocene and Eocene provide best analogs for near-future climates - by Kevin Burke et al. (2018)
https://www.pnas.org/doi/10.1073/pnas.1809600115

Discussed at: https://www.facebook.com/groups/arcticnews/posts/10156972951354679

• Earth is in the Midst of Abrupt, Irreversible Climate Change - by Guy McPherson (2020)
https://www.onlinescientificresearch.com/articles/earth-is-in-the-midst-of-abrupt-irreversible-climate-change.pdf

Discussed at: https://www.facebook.com/groups/arcticnews/posts/10160004947844679

• Ten Dangers of Global Warming
https://arctic-news.blogspot.com/p/ten-dangers-of-global-warming.html

• Extreme heat stress

https://arctic-news.blogspot.com/2023/06/extreme-heat-stress.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

Extreme heat stress

Heatwaves

High Wet Bulb Globe Temperature (WBGT) is forecast to hit the Southeastern United States over the next few days. The image below shows a forecast for June 29, 2023, 18 UTC with WBGT as high as 34°C (93°F) forecast for a location near Jackson, Mississippi, U.S. 

[ click on images to enlarge ]

WBGT is a measure used by weather.gov to warn about expected heat stress when in direct sunlight. It estimates the effect of temperature, relative humidity, wind speed, and solar radiation on humans using a combination of temperatures from three thermometers:

• A Wet bulb measures the temperature read by a thermometer covered in a wet cloth. As water evaporates from the cloth, evaporation cools the thermometer. This mirrors how the human body cools itself with sweat.
• A black globe is used to measure solar radiation. Solar radiation heats the globe and wind blowing across it cools the globe.
• A Dry bulb calculates the air temperature measured in the shade. It is the temperature you would see on your thermometer outside.

The images on the right earlier featured in a 2016 post. 

The top image, an animation from the EPA, illustrates that a relatively small rise in average temperature can have a huge impact and result in a lot more hot weather as well as in even more extreme hot weather.

[ from earlier post ]

The three images underneath, from the IPCC, show the effect on extreme temperatures when (a) the mean temperature increases, (b) the variance increases, and (c) when both the mean and variance increase for a normal distribution of temperature.

The thermodynamic wet-bulb temperature is determined by temperature, humidity and pressure (hPa), and it is the lowest temperature that can be achieved by evaporative cooling of a water-wetted ventilated surface.

As temperatures and humidity levels keep rising, there comes a point where the wind factor no longer matters, in the sense that wind can no longer provide cooling.

The human body can cool itself by sweating, which has a physiological limit that was long described as a 35°C wet-bulb temperature. Once the wet-bulb temperature reaches 35°C, one can no longer lose heat by perspiration, even in strong wind, but instead one will start gaining heat from the air beyond a wet-bulb temperature of 35°C. 

Accordingly, a 35°C wet-bulb temperature (equal to 95°F at 100% humidity or 115°F at 50% humidity) was long seen as the theoretical limit, the maximum a human could endure. 

A 2020 study (by Raymond et al.) warns that this limit could be regularly exceeded with a temperature rise of less than 2.5°C (compared to pre-industrial). A 2018 study (by Strona & Bradshaw) indicates that most life on Earth will disappear with a 5°C rise. Humans, who depend for their survival on many other species, will likely go extinct with a 3°C rise, as illustrated by the image below, from an earlier post.

A 2022 study (by Vecellio et al.) finds that the actual limit is lower — about 31°C wet-bulb or 87°F at 100% humidity — even for young, healthy subjects. The temperature for older populations, who are more vulnerable to heat, is likely even lower. In practice the limit will typically be lower and depending on circumstances could be as low as a wet-bulb temperature of 25°C.

The images below show high readings on the 'Misery Index', the perceived temperature that is used by nullschool.net, combining wind chill and the heat index (which in turn combines air temperature and relative humidity, in shaded areas).

The image below shows a forecast for June 29, 2023 20 UTC, with weather conditions prolonged by circular wind patterns at 250 hPa (Jet Stream), while the Jet Stream is crossing the Equator (bottom left). Temperatures as high as 39.9°C (103.7°F) combined with a relative humidity of 35% result in perceived temperatures as high as 45°C (112.9°F) at the green circle.

As it turned out, the perceived temperature was as high as 44.9°C or 112.7°F on June 29, 2023 19 UTC, due to a 39.1°C or 102.5°F temperature and a 38% relative humidity at the surface, and with conditions prolonged by a distorted Jet Stream (at 250 hPa), with circular wind patterns and winds crossing the Equator.

The image below shows high readings on the 'Misery Index' for parts of Pakistan. On June 22, 2023, an air temperature of 45.4°C (113.7°F) and a relative humidity of 25% resulted in a perceived temperature of 51°C (123.7°F) at the area marked by the green circle. 

The above image also shows the Jet Stream (wind at 250 hPa). Distortion of the Jet Stream can lead to circular wind patterns that amplify heatwaves. As temperature rise, the temperature difference between the Equator and the Arctic narrows, distorting the Jet Stream resulting in more extreme  weather.

Perceived (feels like) air temperatures as high as 53.1°C or 127.7°F were recorded in Pakistan on July 4, 2023, 09 UTC (at green circle), with a 46.7°C or 116.1°F temperature and a 24% relative humidity recorded at the surface. Also, Jet Stream deformation shows up (at 250 hPa), with circular wind patterns and wind crossing the Equator (at the image bottom).

Meanwhile, heatwave conditions have also been affecting China, Texas and Mexico recently, with all-time high temperature records broken in each of these places. 

The press release of a 2022 Unicef report has the title 559 million children currently exposed to high heatwave frequency, rising to all 2.02 billion children globally by 2050. 

Fire and smoke from fires

An additional hazard is fire and the smoke from fires. The image below shows biomass-burning aerosols from fires in Canada extending over the North Atlantic on June 25, 2023, 03 UTC.

The forecast for June 29, 2023 21 UTC below shows remnants of the Canadian forest fires reaching Western Europe.

Feedbacks

As temperatures rise, fire and smoke hazards increase due to self-reinforcing feedback loops, including: 

• 

  [ Two out of numerous feedbacks ]

  Albedo loss and Jet Stream distortion:
  - as sea ice melts away and gets covered by meltpools and rainwater pools, soot, dust, and algae, the resulting albedo loss further pushes up temperatures
  - the narrowing temperature difference between the Arctic and the Tropics causes Jet Stream distortion, resulting in more extreme weather, incl. stronger storms that come with more lightning and can carry more oxygen to fires and spread fires faster and wider, and more intense heatwaves that can dramatically push up local temperatures, further intensifying droughts and forest fires
• a further self-reinforcing feedback loop is that water that was previously present in the soil, is increasingly moving up into the atmosphere, as the atmosphere sucks up more water vapor (7% more water vapor for every 1°C in temperature rise ), resulting in:
  - less evapotranspiration from vegetation, in turn resulting in less clouds and rain, thus pushing up temperatures and drying out soil and vegetation even more
  - erosion and less healthy vegetation that is more vulnerable to pests and diseases such as bark beetles, resulting in an increase in dead trees providing more fuel for fires

[ from earlier post ]

The image on the right, from a news release associated with a 2022 study, shows changes in atmospheric thirst, measured in terms of reference evapotranspiration from 1980-202 (in mm).

As temperatures rise due to people's emissions, more evaporation will take place over both land and oceans, but not all water will return as precipitation, so more water vapor will stay in the air and droughts affecting the soil and vegetation will intensify.

[ from earlier post ]

Water in the soil acts as a buffer, slowing down the temperature rise, so drier soil will heat up faster and further, causing land surface temperatures to rise even more and amplifying the impact of Urban heat island and Heat dome phenomena.

The image on the right, adapted from ESA, shows land surface temperatures as high as 65°C (149°F) in India on April 26, 2022. Note that land surface temperatures can be substantially higher than air temperatures.

The Copernicus image below shows Spain on 11 July 2023, where the Land Surface Temperature (LST), i.e. the temperature of the soil, in some areas of Extremadura (Spain) exceeded 60°C or 140°F, as measured by the Sea and Land Surface Temperature Radiometer (SLSTR) instrument, a feature of the Copernicus Sentinel-3 satellites. 

How high could temperatures rise?

The image below, from NASA, shows that February 2016 was 3.24°C or 5.83°F hotter on land than 1850-1890. Note that 1850-1890 is not pre-industrial, while the 2016 peak was reached during an El Niño, which raises the question how much hotter than pre-industrial it will be at the peak of the current El Niño. 

The image below says it even more poignantly: Looking at global averages over long periods is a diversion, peak temperature rise is the killer!

The above image shows that February 2016 was 3.28°C (5.904°F) hotter than 1880-1896 on land, and 3.68°C (6.624°F) hotter compared to February 1880 on land.

World temperature was at a new record high of 17.18°C or 62.92°F on July 4, 2023 (black). Both in 2022 (orange) and in 2016 (grey), the temperature reached 16.92°C or 62.46°F (on July 24, 2022 and August 13+14, 2016). The year 2016 is important, since it was a strong El Niño year and we're now again in an El Niño.

A 2023 study led by Tao Lian predicts the current El Niño to be strong. Moving from the bottom of a La Niña to the peak of a strong El Niño could make a difference of more than half a degree Celsius, as discussed in an earlier post.

Additionally, the June 2023 number of sunspots is more than twice as high as predicted, as illustrated by the image on the right, adapted from NOAA.

Furthermore, the 2022 Tonga submarine volcano eruption did add a huge amount of water vapor to the atmosphere, as discussed in an earlier post.

Alarm bells have been ringing for many years. As an example, the image below featured in a 2015 post, showing non-linear trends including a polynomial trendline (1: blue) pointing at global temperature anomalies of over 4°C by 2060. 

Moreover, a polynomial trend for the Arctic (2: red) threatens to cause major feedbacks to kick in, triggering runaway global warming (3: white) that looks set to catch up with accelerated warming in the Arctic and result in global temperature anomalies of 16°C by 2052.

[ from a 2015 post, click on image to enlarge ]

In the 2019 video below, Roger Hallam talks with Stephen Sackur from the BBC's HardTalk series. 

Climate change danger assessment

The image below, earlier discussed here, expands risk assessment beyond its typical definition as the product of the severity of impact and probability of occurrence, by adding a third dimension: timescale, in particular imminence.

Conclusion

Imminence alone could make that the danger constituted by rising temperatures needs to be acted upon immediately, comprehensively and effectively. While questions may remain regarding probability, severity and timescale of the dangers associated with climate change, the precautionary principle should prevail and this should prompt for action, i.e. comprehensive and effective action to reduce damage and improve the situation is imperative and must be taken as soon as possible. To combat rising temperatures, transforming society is needed, along the lines of this 2022 post in combination with declaration of a climate emergency.

[ image from Climate Emergency Declaration ]

Accordingly, everyone is encouraged to support and share this Climate Emergency Declaration.

Links

• Wet Bulb Globe Temperature
https://digital.mdl.nws.noaa.gov

• National Weather Service - Wet Bulb Globe Temperature: How and when to use it
https://www.weather.gov/news/211009-WBGT

• Nullschool.net
https://earth.nullschool.net

• Weather tracker: China issues heatstroke alert amid historic heatwave
https://www.theguardian.com/environment/2023/jun/23/weather-tracker-china-issues-heatstroke-alert-amid-historic-heatwave

• Peaks matter
https://arctic-news.blogspot.com/2018/08/peaks-matter.html

• It could be unbearably hot in many places within a few years time
https://arctic-news.blogspot.com/2016/07/it-could-be-unbearably-hot-in-many-places-within-a-few-years-time.html

• The emergence of heat and humidity too severe for human tolerance - by Colin Raymons et al. (2020)
https://www.science.org/doi/10.1126/sciadv.aaw1838

• Brief periods of dangerous humid heat arrive decades early

https://www.climate.gov/news-features/featured-images/brief-periods-dangerous-humid-heat-arrive-decades-early

• Evaluating the 35°C wet-bulb temperature adaptability threshold for young, healthy subjects (PSU HEAT Project) - by Daniel Vecellio et al. (2022) 

https://journals.physiology.org/doi/full/10.1152/japplphysiol.00738.2021
Discussed at: https://www.facebook.com/groups/arcticnews/posts/10159973158374679

• Co-extinctions annihilate planetary life during extreme environmental change, by Giovanni Strona and Corey Bradshaw (2018)
https://www.nature.com/articles/s41598-018-35068-1

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

• When Will We Die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Copernicus - Biomass-burning aerosols
https://atmosphere.copernicus.eu/charts/packages/cams/products/aerosol-forecasts

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

• Will there be Arctic sea ice left in September 2023?
https://arctic-news.blogspot.com/2023/05/will-there-be-arctic-sea-ice-left-in-september-2023.html

• Clausius–Clapeyron relation
https://en.wikipedia.org/wiki/Clausius–Clapeyron_relation

• Urban heat island
https://en.wikipedia.org/wiki/Urban_heat_island

• Heat dome
https://en.wikipedia.org/wiki/Heat_dome

• ESA - Heatwave across India
https://www.esa.int/ESA_Multimedia/Images/2022/04/Heatwave_across_India

• Evaporative Demand Increase Across Lower 48 Means Less Water Supplies, Drier Vegetation, and Higher Fire Risk
https://www.drought.gov/news/evaporative-demand-increase-across-lower-48-means-less-water-supplies

• A Multidataset Assessment of Climatic Drivers and Uncertainties of Recent Trends in Evaporative Demand across the Continental United States - by Christine Albano et al. (2022)

https://journals.ametsoc.org/view/journals/hydr/23/4/JHM-D-21-0163.1.xml

• Carbon dioxide crosses 422 ppm

https://arctic-news.blogspot.com/2022/04/carbon-dioxide-crosses-422-ppm.html

• 559 million children currently exposed to high heatwave frequency, rising to all 2.02 billion children globally by 2050

https://www.unicef.org/press-releases/heatwaves-report

• Copernicus - Scorching heatwave hits Spain 
https://www.copernicus.eu/en/media/image-day-gallery/scorching-heatwave-hits-spain

• NASA - custom plots 
https://data.giss.nasa.gov/gistemp/graphs_v4/customize.html

• Climate Reanalyzer - World Daily 2-meter Air Temperature (90-90°N, 0-360°E)
https://climatereanalyzer.org/clim/t2_daily

• NOAA - Solar cycle sunspot number progression
https://www.swpc.noaa.gov/products/solar-cycle-progression

• A Strong 2023/24 El Niño is Staged by Tropical Pacific Ocean Heat Content Buildup - by Tao Lian et al. (2023)

https://spj.science.org/doi/10.34133/olar.0011

• 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

How many deaths could result from failure to act on climate change?

A recent OECD analysis concludes that outdoor air pollution is killing more than 3.5 million people a year globally. The OECD estimates that people in its 34 Member countries would be willing to pay USD 1.7 trillion to avoid deaths caused by air pollution. Road transport is likely responsible for about half.

[ from an earlier post ]

A 2012 report by DARA calculated that 5 million people were dying each year from climate change and carbon economies, mostly from indoor smoke and (outdoor) air pollution.

Back in 2012, a Reuters report calculated that this could add up to a total number of 100 million deaths over the coming two decades. This suggests, however, that failure to act on climate change will not cause even more deaths due to other causes.

Indeed, failure to act on climate change could result in many more deaths due to other causes, in particular food shortages. As temperatures rise, ever more extreme weather events can be expected, such as flooding, heatwaves, wildfires, droughts, and subsequent crop loss, famine, disease, heat-stroke, etc.

So, while currently most deaths are caused by indoor smoke and outdoor air pollution, in case of a failure to act on climate change the number of deaths can be expected to rise most rapidly among people hit by heat stress, famine, fresh water shortages, as well as wars over who controls access to land, food, fresh water, etc.

How high could figures rise? Below is an update of an image from the earlier post Arctic Methane Impact with a scale in both Celsius and Fahrenheit added on the right, illustrating the danger that temperature will rise to intolerable levels if little or no action is taken on climate change. The inset shows projected global number of annual climate-related deaths for these two scenarios, i.e. little or no action, and also shows a third scenario of comprehensive and effective action that instead seeks to bring temperature rise under control.

[ click on image to enlarge ]

For further details on comprehensive and effective climate action, see the ClimatePlan.


Links

• The Cost of Air Pollution | OECD analysis, published May 2014
http://www.oecd.org/environment/cost-of-air-pollution.htm

• DARA Climate Vulnerability Monitor
http://daraint.org/climate-vulnerability-monitor/climate-vulnerability-monitor-2012/

• 100 mln will die by 2030 if world fails to act on climate - report | REUTERS
http://www.reuters.com/article/2012/09/25/climate-inaction-idINDEE88O0HH20120925

• Arctic Methane Impact
https://arctic-news.blogspot.com/2013/11/arctic-methane-impact.html

• Is death by lead worse than death by climate? No. | by Paul Beckwith
https://arctic-news.blogspot.com/2012/10/is-death-by-lead-worse-than-death-by-climate-no.html

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