Arctic News: heat

Showing posts with label heat. Show all posts

Wednesday, July 24, 2024

High Wet Bulb Globe Temperature Danger

Wet Bulb Globe Temperature (WBGT) takes into account the effect of temperature, RH (relative humidity), wind speed, and solar radiation. WBGT is used by weather.gov to warn about extreme heat stress when in direct sunlight, as is forecast to occur in grey areas on July 26, 2024 at 21 UTC.

[ click on images to enlarge ]

The inset shows that a temperature of 113°F or 45°C and a Wet Bulb Globe Temperature of 95°F or 35°C is forecast for a location 8 miles south of Parker, Arizona, on July 26, 2024 at 21 UTC.

The above map illustrates that extreme heat stress can occur at higher latitudes, e.g. the grey areas in the north of the United States that extend into Canada. The danger occurs where high temperatures coincide with high relative humidity.

The image below further illustrates the danger. It shows that a 'feel like' temperature of 54°C (129.1°F) and a wet bulb temperature of 31°C (87.7°F) hit an area west of Wuhan, China, on July 23, 2024 at 10:00 UTC (green circle).

The temperature at that location in China wasn't the highest on the map, it was 36.4°C (97.4°F), which is high, but what further contributed to make conditions hard to bear was that relative humidity was 68%.

The image on the right, adapted from Climate Reanalyzer, shows a 3-day forecast of temperatures in the region, run on July 23, 2024.

Heat stress is the leading cause of weather-related deaths in the United States, as illustrated by the image below (credit: NOAA).

As the above image notes, the values for heat fatalities may be conservative. 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 study estimates that extreme heat accounted for 12,000 premature deaths in the contiguous U.S. from 2000 to 2010, and an analysis calculates that the summer 2022 heatwave killed 61,000 people in Europe alone.

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.

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.

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

• 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 facebook 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 facebook 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 facebook 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 facebook 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 facebook 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 facebook 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

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

Wednesday, July 3, 2024

Feedbacks

Water vapor feedback

There are numerous self-amplifying feedbacks that accelerate the temperature rise. One of them is the water vapor feedback. Just the temperature rise itself will cause more water vapor to be in the atmosphere.

[ from Moistening Atmosphere ]

The February 2024 temperature was 1.76°C above 1885-1915, which could be as much as 2.75°C above the pre-industrial temperature.

A 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere, as the extinction page points out.

The increase in water vapor in the atmosphere is a self-amplifying feedback, since water vapor is a powerful greenhouse gas, accelerating the temperature rise, as illustrated by the image on the right.

As illustrated by the image below, created with NOAA data, surface precipitable water reached 26.741 kg/m² in June 2024.

As the above image also illustrates, surface precipitable water reached a record high of 27.139 kg/m² in July 2023, and was much higher for each of the first six months in 2024 than for the same months in 2023.

More emissions of greenhouse gases (from earlier post)

As temperatures rise, due to stronger emissions of carbon dioxide, methane and nitrous oxide, there will be a corresponding extra amount of water vapor in the atmosphere.

Studies such as by Hubau (2020) warn that the uptake of carbon into Earth’s intact tropical forests peaked in the 1990s. Thawing permafrost can cause huge emissions of carbon dioxide, methane and nitrous oxide. Studies now warn that the Arctic has also changed from sink to source.

A study by Del Vecchi et al. (2024) suggests that a gradual thawing of Arctic permafrost could release between 22 billion and 432 billion tons of carbon dioxide by 2100 if current greenhouse gas emissions are reined in — and as much as 550 billion tons if they are not.

An analysis by Ramage et al. (2024) concludes that Arctic terrestrial permafrost now emits more greenhouse gases than it stores, and the trend is likely to accelerate as temperatures keep rising in the Arctic. The highest carbon dioxide emissions over the 2000-2020 period came from inland rivers and wildfires. The non-permafrost wetlands exhaled the most methane, and dry tundra released the most nitrous oxide.

The prospect of further releases looks dire. The analysis gives estimates that the upper three meters of permafrost region soils store 1,000 Gt of soil organic carbon, while deeper deposits could store an additional amount of as much as 1,000 Gt C. The analysis concludes that the permafrost region is the largest terrestrial carbon and nitrogen pool on Earth.

Note that the joint CO₂e of emissions in this analysis only covers part of global emissions, e.g. the analysis excludes emissions from Arctic subsea permafrost and from oceans in general, from many mountain areas and from the Southern Hemisphere. The study also appears to have excluded emissions caused by anthropogenic disturbances such as clear-cutting, logging and fracking activities in the region, while calculations typically use a low global warming potential (GWP) for methane (100-year horizon).

Miesner et al. (2023) warn that an additional 2822 Gt of organic carbon is stored in subsea Arctic shelf permafrost and Huang et al. (2024) warn that the top two meters of soil globally holds about 2300 Gt of inorganic carbon, which has been left out of environmental models, and 23 Gt of this carbon may be released over the next 30 years.

The transition from sink to source of the region is an important feedback of the temperature rise that is not fully reflected in many climate models. According to the IPCC, 14–175 Gt CO₂e (in carbon dioxide and methane) gets released per 1°C of global warming, which is likely to underestimate the situation by downplaying many feedbacks. Despite the dire situation, the IPCC keeps promoting less effective policies such as support for biofuel and tighter fuel efficiency standards, as discussed in earlier posts such as this 2022 one.

Further feedbacks

The image below illustrates the mechanism of how multiple feedbacks accelerate the heating up of the atmosphere.

Feedback #1: albedo loss (loss of reflectivity) as sea ice melts due to rising temperatures and due to the ice getting covered by soot, dust, algae, meltpools and rainwater pools;

Feedback #14: loss of the latent heat buffer - as sea ice disappears, heat can no longer be consumed by the process of melting, and the heat will instead go into increasing the temperature;

Feedback #16: eruptions of seafloor methane - as more heat reaches the seafloor of the Arctic Ocean, sediments and hydrates contained in them destabilize, resulting in methane releases;

Feedback #25: extra water vapor feedback - rising temperatures will result in more water vapor in the atmosphere (7% more water vapor for every 1°C warming), further amplifying the temperature rise, since water vapor is a potent greenhouse gas;

Feedback #19: distortion of the Jet Stream as the temperature difference narrows between the Arctic and the Tropics, in turn causing further feedbacks to kick in stronger, such as hot air moving into the Arctic and cold air moving out, and more extreme weather events bringing heavier rain and more intense heatwaves, droughts and forest fires that cause black carbon to settle on the sea ice;

Feedback #28: freshwater lid on the North Atlantic - melting of sea ice and glaciers and thawing of the permafrost results in meltwater accumulating in the North Atlantic, where it forms a cold freshwater lid on top of the water; this lid grows further due to more rain falling on top of this lid. This results in less evaporation and transfer of heat from the North Atlantic to the atmosphere, and more ocean heat getting carried by the Gulf Stream underneath the sea surface into the Arctic Ocean.

There is interaction between feedbacks; the image's focus is on illustrating the mechanism, rather than the proportional contribution or the order of feedbacks over time. Sea ice decline comes with both loss of albedo and loss of the latent heat buffer, each of which will accelerate the temperature rise of the water of the Arctic Ocean, thus contributing to the threat that hydrates contained in sediments at the seafloor of the Arctic Ocean will be destabilized, which in turn threatens to cause eruption of huge amounts of methane.

A further danger lies in changes occurring to wind and ocean current patterns; the temperature rise will cause stronger wind, waves and storms, as well as deformation of the Jet Stream. In addition, the temperature rise causes loss of reflectivity of clouds and more ocean stratification, exacerbated by more freshwater accumulating at the surface of oceans, due to stronger ice melting, due to heavier runoff from land and rivers and due to changes in wind patterns and ocean currents and circulation. In the North Atlantic, there is the additional danger that formation of a freshwater lid will cause huge amounts of ocean heat to be pushed into the Arctic Ocean and enter the atmosphere as sea ice disappears.

Further developments

Furthermore, developments such as rising emissions from industry, transport, land use, forest fires and waste fires, ocean acidification and reductions in sulfur emissions can all contribute to further acceleration of the temperature rise.

Links

• Moistening Atmosphere
https://arctic-news.blogspot.com/p/moistening-atmosphere.html

• Did the climate experience a Regime Change in 2023?

https://arctic-news.blogspot.com/2024/04/did-the-climate-experience-a-regime-change-in-2023.html

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

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

• NOAA - Physical Sciences Laboratory
https://psl.noaa.gov

• Arctic Sea Ice Alert

https://arctic-news.blogspot.com/2024/06/arctic-sea-ice-alert.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

Sunday, June 2, 2024

Have feedbacks taken over?

For about one year now, global temperature anomalies have been extremely high, as illustrated by the image below, created with a screenshot from Copernicus, showing an anomaly from 1991-2020 of 0.86°C on June 1, 2024.

What could be behind these persistently high temperatures? Many causes such as El Niño and sunspots have been discussed in earlier posts. How much do emissions contribute to these high temperatures?

Despite pledges by politicians to ensure that temperatures would not cross 1.5°C above pre-industrial, the growth rate of the concentration of carbon dioxide in the atmosphere appears to be accelerating, as illustrated by the image below, adapted from NOAA and showing concentration of carbon dioxide at Mauna Loa, Hawaii.

Have feedbacks taken over as the dominant driver of the temperature rise? The image below shows NOAA March 2009 through May 2024 monthly CO₂ concentration at Mauna Loa (black) with a trend (magenta) added for a joint 30-year coverage. The trend shows how CO₂ could cross the clouds tipping point at 1200 ppm (parts per million) in 2038, which in itself would push up temperatures by a further 8°C.

What could cause such a steep rise? Many studies point at organic carbon and inorganic carbon releases from soils that could further raise both CO₂ concentrations and temperatures. A recent study by Weiskopf (2024) finds that biodiversity declines from climate and land use change could lead to a global loss of up to 103.14 GtC for a global sustainability scenario and up to 145.95 GtC for a fossil-fueled development scenario, indicating a self-reinforcing feedback loop where higher levels of climate change lead to greater biodiversity loss, in turn leading to greater carbon emissions.

The clouds tipping point is actually at 1200 ppm CO₂e (carbon dioxide equivalent), so it could be crossed even earlier when also taking into account more methane, nitrous oxide, etc. As discussed in an earlier post, the daily mean CO₂ on April 26, 2024, was 428.59 ppm, while peak daily average methane is approaching 2000 parts per billion (ppb) at Mauna Loa, Hawaii. A methane concentration of 2000 ppb corresponds, at a Global Warming Potential (GWP) of 200, with 400 ppm CO₂e. Together with the daily average CO₂ concentration of 428.63 ppm this adds up to a joint CO₂e of 828.63 ppm, i.e. only 371.37 ppm away from the clouds tipping point.

This 371.37 ppm CO₂e could be added almost immediately by a burst of seafloor methane less than the size of the methane that is currently in the atmosphere (about 5 Gt). There is plenty of potential for such an abrupt release, given the rising ocean heat and the vast amounts of methane present in vulnerable sediments at the seafloor of the Arctic Ocean, as discussed in earlier posts such as this one and at the threat page.

There are many further developments and feedbacks that should be taken into account. Furthermore, note that anomalies in the image at the top are calculated from a 1991-2000 base. The temperature rise and the resulting feedbacks are even larger when anomalies are calculated from a pre-industrial base.

[ from earlier post ]

[ from Moistening Atmosphere ]

The above image, created with NASA content, shows that the February 2024 temperature was 1.76°C above 1885-1915, which could be as much as 2.75°C above pre-industrial (bright yellow inset right).

A 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere, as the extinction page points out. The increase in water vapor in the atmosphere is a self-amplifying feedback, since water vapor is a powerful greenhouse gas, further accelerating the temperature rise.

Surface precipitable water reached a record high of 27.139 kg/m² in July 2023, as illustrated by the image below, adapted from NOAA.

[ from earlier post ]

Worryingly, data for the first four months of 2024 are way higher than they were in 2023 at the same time of year, which raises fears that surface precipitable water will reach an even higher peak in 2024 than was reached in 2023. The situation is depicted even more clearly on the image below, created with the same data.

As said, more water in the atmosphere further accelerates the temperature rise. Furthermore, high relative humidity also makes high temperatures more unbearable. The human body can cool itself by sweating, which has a physiological limit that was long described as a 35°C wet-bulb temperature, i.e. 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.

A 2022 study (by Vecellio et al., 2022) finds that the actual limit is lower — about 31°C wet-bulb or 87°F at 100% relative 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, as discussed in an earlier post.

Temperature in either °C or °F and the relative humidity for spots on Earth can be viewed at nullschool, and then the associated wet-bulb temperature can be calculated here.

North Atlantic

There are numerous tipping points and non-linear, self-amplifying feedbacks that can all contribute, interact and start to kick in with greater ferocity, amplifying and further accelerating the rise, as discussed at the feedbacks page.

What could push up temperatures dramatically is loss of Arctic sea ice, as discussed in earlier posts such as this one. Ominously, the North Atlantic sea surface temperature anomaly has risen strongly recently, as illustrated by the images below.

The maps below, adapted from Climate Reanalyzer, show sea surface temperatures (left) and sea surface temperature anomalies (right) on June 2, 2024.

North Atlantic sea surface temperatures keep rising, as illustrated by the image below that highlights temperature anomalies from 1951-1980 for May 2022, May 2023 and May 2024.

[ click on images to enlarge ]

Links

• United Nations - Adoption of the Paris Agreement (2015)

https://unfccc.int/sites/default/files/english_paris_agreement.pdf

• NOAA - Global Monitoring Laboratory - Carbon Cycle Gases, Mauna Loa, Hawaii, U.S.
https://gml.noaa.gov/dv/iadv/graph.php?code=MLO&program=ccgg&type=ts

• NASA - datasets and images
https://data.giss.nasa.gov

• Climate Reanalyzer
https://climatereanalyzer.org

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

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

• Copernicus - Climate Pulse

https://pulse.climate.copernicus.eu

• NOAA - Physical Sciences Laboratory
https://psl.noaa.gov

• Amplifying feedback loop between drought, soil desiccation cracking, and greenhouse gas emissions - by Farshid Vahedifard et al.
https://iopscience.iop.org/article/10.1088/1748-9326/ad2c23
discussed on facebook at
https://www.facebook.com/groups/arcticnews/posts/10161298567849679

• Size, distribution, and vulnerability of the global soil inorganic carbon - by Yuanyuan Huang et al. https://www.science.org/doi/10.1126/science.adi7918
discussed at facebook at
https://www.facebook.com/groups/arcticnews/posts/10161354439024679

• Biodiversity loss reduces global terrestrial carbon storage - by Sarah Weiskopf et al. (2024) https://www.nature.com/articles/s41467-024-47872-7

Discussed at Facebook at:
https://www.facebook.com/groups/arcticnews/posts/10161454674974679

• Very high temperatures in Tropics
https://arctic-news.blogshttps://arctic-news.blogspot.com/2023/07/wet-bulb-globe-temperature-tipping-point.htmlpot.com/2024/05/very-high-temperatures-in-tropics.html

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

• Wet Bulb Globe Temperature Tipping Point

https://arctic-news.blogspot.com/2023/07/wet-bulb-globe-temperature-tipping-point.html

• 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 facebook at:

https://www.facebook.com/groups/arcticnews/posts/10159973158374679

• Temperature rise may soon accelerate even more
https://arctic-news.blogspot.com/2024/05/temperature-rise-may-soon-accelerate-even-more.html

• nullschool

https://earth.nullschool.net

• wet bulb temperature calculator

https://www.mit.edu/~eltahirgroup/calTW.html

• Convert the temperature between Celsius and Fahrenheit

Tuesday, April 30, 2024

Arctic sea ice under threat

The image below indicates that Arctic sea ice volume has meanwhile passed its annual maximum. Over the coming months, volume can be expected to decrease rapidly. The image also highlights that, over the past few months, Arctic sea ice volume has been the lowest on record for the time of year.

The image below illustrates the decline of Arctic sea ice volume over the years. The image also confirms that the annual maximum volume was recently reached and that it was the lowest maximum for the 24 years on record.

Given that Arctic sea ice currently is still relatively extensive, this record 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, keeping sea ice extent relatively large for now.

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.

Sea surface temperatures at record high

The image below, created with Climate Reanalyzer screenshots, shows that the sea surface temperature (SST 60°S - 60°N mean) was 21.2°C on April 24, 2024, reaching yet another record high.

[ image from earlier post ]

These record high sea surface temperatures are reached as long-term sea surface temperatures are falling and as El Niño is predicted to weaken, which is fueling fears that feedbacks are kicking in with accelerating ferocity.

The image below, adapted from NOAA, shows global ocean temperature anomalies from 1901-2000, with the green line (LOcally Estimated Scatterplot Smoothing) giving a warning that higher temperature anomalies could be coming up.

[ image from earlier post ]

The image below shows that the monthly Atlantic surface temperature anomaly in March 2024 was 1.422°C when compared to a 1901-2000 base.

The high anomalies over the past two months indicate how much heat has accumulated in the Atlantic, and these anomalies are even higher when using a 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.

Arctic sea ice under threat

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 for now, 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.

An enormous amount of ocean heat has accumulated and is still further accumulating in the North Atlantic and much of this heat threatens to abruptly move into the Arctic Ocean. The danger is that, due to strong wind along the path of the Gulf Stream and extensions of this current into the Arctic Ocean, 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.

The danger is growing, due to a number of factors. Firstly, the amount of ocean heat in the North Atlantic is increasing. Secondly, Arctic sea ice volume is at record low, implying that there is little or no buffer left to consume ocean heat flowing from the Atlantic Ocean into the Arctic Ocean.

Latent heat is energy associated with a phase change, such as the energy consumed when solid ice turns into water (i.e. melts). During a phase change, the temperature remains constant. Sea ice acts as a buffer that absorbs heat, while keeping the temperature at zero degrees Celsius. As long as there is sea ice in the water, this sea ice will keep absorbing heat, so the temperature doesn't rise at the sea 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 danger is that, as the buffer disappears that until now has consumed huge amounts of ocean heat, further heat will reach methane hydrates at the seafloor of the Arctic Ocean, causing them to get destabilized resulting in release of methane from these hydrates and from free gas underneath that was previously sealed by the hydrates.

[ The Buffer has gone, feedback #14 on the Feedbacks page ]

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, from an earlier post.

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

• Climate Reanalyzer
https://climatereanalyzer.org

• NOAA - Ocean temperature anomalies
https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/global/time-series/globe/ocean/1/0/2015-2024?filter=true&filterType=loess

• Atlantic ocean heat threatens to unleash methane eruptions
https://arctic-news.blogspot.com/2024/03/atlantic-ocean-heat-threatens-to-unleash-methane-eruptions.html

• Feedbacks in the Arctic
https://arctic-news.blogspot.com/p/feedbacks.html

• North Atlantic heating up
https://arctic-news.blogspot.com/2024/04/north-atlantic-heating-up.html

• 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

Friday, September 15, 2023

Seafloor methane tipping point reached

The bold black line at the top of the image below, adapted from Climate Reanalyzer, shows extremely high sea surface temperatures up to September 13, 2023, much higher than in any previous year on record.

The image below, created with NASA data, shows why these extremely high sea surface temperatures are so worrying. The image shows monthly mean global surface temperature anomalies (open ocean) vs 1901-1930. The ochre trend, based on January 1900-August 2023 data, indicates the latent heat tipping point was crossed in 2021 and the seafloor methane tipping point could be crossed in 2033. The red trend, based on August 2008-August 2023 data and better reflecting variables such as El Niño, indicates that the seafloor methane tipping point could be crossed late 2023. Data show the seafloor methane tipping point was reached in August 2023.

The latent heat tipping point is estimated to correspond with a sea surface temperature anomaly of 1°C above the long term average, 1901-1930 on the above image, as discussed in earlier posts such as this one.

Sea ice constitutes a latent heat buffer, consuming incoming heat as it melts. While the ice is melting, all energy (at 334 J/g) goes into changing ice into water and the temperature remains at 0°C (273.15K or 32 °F). Once all ice has turned into water, all subsequent energy goes into heating up the water, and will do so at 4.18 J/g for every 1°C the temperature of the water rises.

[ The Latent Heat Buffer ]

Once Arctic sea ice has become very thin, ocean heat that was previously consumed by melting the sea ice, no longer gets consumed by melting of the sea ice, and further incoming heat instead gets absorbed by the Arctic Ocean, rapidly pushing up the temperature of the water of the Arctic Ocean.

The latent heat tipping point has meanwhile been crossed. Loss of this buffer is linked to the seafloor methane tipping point, i.e. the point where additional heat reaches the seafloor and destabilizes hydrates contained in sediments at the seafloor. This tipping point comes with multiple self-reinforcing feedback loops, such as explosive growth in methane volume setting off further destabilization, rapid rise of Arctic temperatures, loss of permafrost and loss of albedo, and release of further greenhouse gases.

Crossing of the seafloor methane tipping point will occur later than crossing of the latent heat tipping point, i.e. the seafloor methane tipping point corresponds with a higher ocean temperature anomaly, estimated to correspond with a sea surface temperature anomaly of 1.35°C above the long term average.

The current situation is particularly precarious in the Arctic, as the North Atlantic Ocean is very hot and the Gulf Stream keeps pushing hot water toward the Arctic Ocean, while Arctic sea ice has become very thin and the latent heat tipping point has been crossed.

As the temperature of the Arctic Ocean keeps rising, more heat can reach sediments located at the seafloor, since much of the Arctic Ocean is very shallow and sediments at the seafloor of the Arctic Ocean can contain vast amounts of methane.

The danger is that additional heat will destabilize hydrates in these sediments, leading to explosive eruptions of methane, as its volume increases 160 to 180-fold when leaving the hydrates, and resulting in huge eruptions of methane both from the destabilizing hydrates and from methane that is present in the form of free gas underneath the hydrates.

[ from earlier post, click on images to enlarge ]

The above image, from an earlier post, illustrates that warnings have been given before about the danger of these two tipping points getting crossed in the Arctic. In the above image, the trends are based on annual sea surface temperature data for the Northern Hemisphere. The seafloor methane tipping point is estimated to correspond with ocean temperature anomalies reaching 1.35°C above the long term average.

The image below further illustrates the high sea surface temperatures in and around the Arctic Ocean, with the red to yellow colors indicating temperature anomalies above the 1981-2011 average, and the green circle marking a sea surface temperature anomaly near the North Pole of 0.4°C on September 13, 2023.

The image below illustrates how incoming ocean heat that previously was consumed in the process of melting of the sea ice, is now causing the water of the Arctic Ocean to heat up, with more heat reaching the seafloor of the Arctic Ocean, which has seas that in many places are very shallow.

[ Latent heat loss, feedback #14 on the Feedbacks page ]

Further adding to the danger is that destabilization of methane hydrates can cause huge amounts of methane to erupt with great force from the seafloor in the form of plumes. Consequently, little of the methane can be broken down in the water by microbes, while there is very little hydroxyl in the atmosphere over the Arctic Ocean to break down the methane that enters the atmosphere.

[ click on images to enlarge ]

Ominously, very high methane levels continue to be recorded at Barrow, Alaska, as illustrated by the above NOAA image.

The MetOp satellite image on the right shows methane levels, with the magenta color indicating the highest methane levels recorded at surface level (1000 mb), on September 15, 2023 am.

The N20 satellite image underneath shows methane levels at an altitude corresponding with 487 mb on September 10, 2023 am. The magenta color again indicates the highest methane levels recorded at the time.

Note the high levels over the Beaufort Sea and elsewhere over the Arctic Ocean, as well as high levels recorded over oceans in the Southern Hemisphere.

Climate Emergency Declaration

A catastrophe of unimaginable proportions is unfolding. Life is disappearing from Earth and runaway heating could destroy all life on Earth. At 5°C heating, most life on Earth will have disappeared. When looking only at near-term human extinction, 3°C will likely suffice.

The situation is dire and is getting more dire every day, which calls for a Climate Emergency Declaration and implementation of comprehensive and effective action, as described in the Climate Plan with an update at Transforming Society.

Links

• Climate Reanalyzer - daily sea surface temperature
https://climatereanalyzer.org/clim/sst_daily

• NASA - GISS Surface Temperature Analysis

https://data.giss.nasa.gov/gistemp/graphs_v4/customize.html

• nullschool.net