Showing posts with label AMOC. Show all posts
Showing posts with label AMOC. Show all posts

Thursday, December 14, 2023

Double Blue Ocean Event 2024?

A double Blue Ocean Event could occur in 2024. Both Antarctic sea ice and Arctic sea ice could virtually disappear in 2024. A Blue Ocean Event (BOE) occurs when sea ice extent falls to 1 million km² or less, which could occur early 2024 for Antarctic sea ice and in Summer 2024 in the Northern Hemisphere for Arctic sea ice.

Antarctic sea ice loss

The situation regarding Antarctic sea ice extent is pictured in the image below, which shows that on December 12, 2023, Antarctic sea ice extent was 9.499 million km², a record low for the time of year.

[ image adapted from NSIDC ]

Antarctic sea ice extent was 1.788 million km² on February 21, 2023. Antarctic sea ice extent may well be much lower in February 2024, with sea ice loss fuelled by several self-reinforcing feedback loops, as discussed in an earlier post.

Arctic sea ice loss

The situation regarding Arctic sea ice extent is pictured in the image below.

[ image adapted from NSIDC ]

The above image shows that on December 12, 2023, Arctic sea ice extent was 9.499 million km², third lowest low for the time of year, behind 2016 and 2020.

Temperature November 2023



The above image shows the November 2023 temperature anomaly compared to a 1951-1980 base. The image below also shows the November 2023 temperature anomaly, but it is not compared to a 1951-1980 base (NASA's default), it is instead compared to a 1900-1923 base.

Of course, the temperature anomaly will be much higher when compared to pre-industrial. Further adjustments are required, because the NASA data are for sea surface temperatures (rather than temperatures of the air 2 meters above the sea surface). Also note the grey areas on the above map, signifying that no data are available for earlier years. This especially affects the Arctic, where the anomalies are highest, so disregarding these data is not appropriate. In the image below, data are adjusted by 0.99°C to reflect all this, as discussed at the pre-industrial page.

[ click on images to enlarge ]
The above image is created with NASA Land+Ocean monthly mean global temperature anomalies vs 1900-1923, adjusted by 0.99°C to reflect ocean air temperature, higher polar anomalies and a pre-industrial base. Blue: Polynomial trend based on Jan.1880-Nov. 2023 data. Magenta: Polynomial trend based on Jan. 2010-Nov. 2023 data.

The above images illustrate that temperatures are rising strongly in the Arctic, which gives a dire warning that a Blue Ocean Event could occur in Summer 2024 in the Northern Hemisphere that could further speed up global temperatures, as illustrated by the magenta-colored trend in the above image.

The situation is dire


Temperature anomalies in the Northern Hemisphere were more than 2°C above 1951-1980 recently (2.024°C in October 2023 and 2.058 in November 2023), as illustrated by the above image. Note that anomalies on the image are calculated from 1951-1980 and that anomalies from pre-industrial are higher.

Land-only temperature anomalies can be much higher than land+ocean anomalies, since oceans act as a buffer. It is therefore most important to look at the land-only temperature anomaly in the Northern Hemisphere, since that is where the highest anomalies occur, at the very places where most people live. Furthermore, as temperatures keep rising, more extreme weather events occur, with an increase in intensity, frequency, duration and area covered by such events. The urban heat island effect can further add to the rising high temperature peaks reached in cities.

The precautionary principle urges the world to closely watch peak hourly local wet-bulb globe temperatures, rather than to hide the full wrath of the temperature rise by focusing on global temperature anomalies that are compared to recent base periods and that are averaged over periods going back ten years or longer. 

Temperatures are rising most rapidly in the Arctic, which contributes to the occurrence of more extreme weather events. Low temperatures in Winter in the Arctic are essential to build up ice thickness to preserve sea ice as the melting season starts.

[ Climatology temperatures are 1979-2000 averages and anomalies are calculated
from 1979-2000 averages. Black line: 2023. Orange line: 2022. Grey line: 2016. ]

Arctic temperature hit a record high for the time of year on December 15, 2023, and an anomaly of 5°C, as the above image shows. Arctic anomalies are the highest in the world, as illustrated by the record 8.3°C anomaly that was reached on November 18, 2016. Since the chance that the current El Niño will slow down soon is minimal, Arctic anomalies could reach even higher records in the next few months.

On December 12, 2023, as said, Arctic sea ice extent was third lowest for the time of year, i.e. only 2016 and 2020 were lower. The years 2016 and 2020 had the highest annual temperature (a tie) on record and this annual temperature record is likely to be surpassed in 2023, while 2024 may be even worse, as the chance that the current El Niño will slow down soon is minimal.

[ Water Vapor tipping point ]

In the video below, Anton Petrov discusses the runaway greenhouse effect. 



This is important, as a very small increase in solar irradiation – leading to an increase of the global Earth temperature, of only a few tens of degrees – would be enough to trigger an irreversible runaway process on Earth and make our planet as inhospitable as Venus, a recent study concludes, as discussed at this post.

A temperature rise of more than 10°C could unfold as early as by end 2026, due to contributions of gases (including water vapor), aerosols, albedo changes and further elements, in the process causing the clouds tipping point to get crossed, which could add a further 8°C to the rise.

This rise could in turn cause the water vapor tipping point to be crossed. The rise in water vapor alone could from then on suffice to push temperatures up further, in a runaway greenhouse process in which evaporation causes a global surface temperature rise of several hundred degrees Celsius. 

Arctic sea ice could have been even lower in extent, had the Atlantic meridional overturning circulation (AMOC) not been slowing down. As a result of AMOC's slowing down, less ocean heat is reaching the Arctic Ocean. Instead, a huge amount of ocean heat has been accumulating in the North Atlantic and much of this heat could soon be pushed abruptly into the Arctic Ocean as storms temporarily speed up currents that carry ocean heat into the Arctic Ocean.

Arctic sea ice volume is getting very low, as illustrated by the image on the right, adapted from Polar Portal

Meanwhile, Earth's radiation imbalance is very high, emissions are high and rising, and politicians refuse to act responsibly, all contributing to further deterioration of the situation, with the danger that ocean heat will reach and destabilize methane hydrates that are contained in sediments at the seafloor of oceans, resulting in massive methane eruptions, further pushing up global temperatures, as discussed in many earlier posts such as this one and this one

As more people become aware of the dire situation, widespread panic may set in, as this 2007 post warned about. People may stop showing up for work, resulting in a rapid loss of the aerosol masking effect, as industries that now co-emit cooling aerosols (such as sulfates) grind to a halt. Many people may start to collect and burn more wood, resulting in an increase in emissions that speed up the temperature rise. As temperatures rise, more fires could also break out in forests, peatlands and urban areas including landfills and waste dumps, further contributing to emissions that speed up the temperature rise.

Ominously, the highest methane levels on record (surface flasks) were recently reached at Barrow, Alaska, U.S., as illustrated by the image below.

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

• NSIDC - Interactive sea ice chart
https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph

• NOAA - December 2023 El Niño update
https://www.climate.gov/news-features/blogs/enso/december-2023-el-nino-update-adventure

• Climate Reanalyzer - November 2023 temperature anomaly
https://climatereanalyzer.org/research_tools/monthly_maps

• Climate Reanalyzer - Monthly reanalysis time series
https://climatereanalyzer.org/research_tools/monthly_tseries

• Climate Reanalyzer - Daily surface air temperature, Arctic
https://climatereanalyzer.org/clim/t2_daily/?dm_id=arctic

• NASA - maps
https://data.giss.nasa.gov/gistemp/maps

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

• First exploration of the runaway greenhouse transition with a 3D General Circulation Model - by Guillaume Chaverot et al.
https://www.aanda.org/articles/aa/full_html/2023/12/aa46936-23/aa46936-23.html
• Polar Portal

NOAA - Global Monitoring Laboratory - Barrow, Alaska


• Will temperatures keep rising fast?
https://arctic-news.blogspot.com/2023/12/will-temperatures-keep-rising-fast.html

• Will temperatures keep rising fast?
https://arctic-news.blogspot.com/2023/12/will-temperatures-keep-rising-fast.html

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


Thursday, July 27, 2023

Record high North Atlantic sea surface temperature

On July 25, 2023, the North Atlantic sea surface reached a record high temperature of 24.9°C. The previous record was in early September 2022, when the temperature peaked at 24.89°C, according to NOAA scientist Xungang Yin and as illustrated by the image below. 

In previous years, a La Niña was suppressing temperatures, whereas El Niño is now pushing up temperatures. Arctic sea ice typically reaches its minimum extent about half September. We are facing huge sea ice loss over the coming weeks.

Temperatures are very high (and rising) and the following eight points contribute to this rise:

1. Emissions are high and greenhouse gas levels keep rising, and this is increasing Earth's Energy Imbalance. Oceans take up 89% of the extra heat.

2. El Niño is pushing up temperatures, whereas in previous years La Niña was suppressing temperatures. 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.

In February 2016, when there was a strong El Niño, the temperature on land was 3.28°C (5.904°F) hotter than 1880-1896, and 3.68°C (6.624°F) hotter than February 1880 on land. Note that 1880-1896 is not pre-industrial, the difference will be even larger when using a genuinely pre-industrial base.

The above image, from an earlier post discussing extreme heat stress, adds a poignant punchline: Looking at global averages over long periods is a diversion, peak temperature rise is the killer!

[ click on images to enlarge ]
3. Sunspots in June 2023 were more than twice as high in number as predicted, as illustrated by the image on the right, from an earlier post and adapted from NOAA.

If this trend continues, the rise in sunspots forcing from May 2020 to July 2025 may well make a global temperature difference of more than 0.25°C, a recent analysis found.

4. A submarine volcano eruption near Tonga in January 2022 did add a huge amount of water vapor to the atmosphere, as discussed in an earlier post and also at facebook.

Since water vapor is a potent greenhouse gas, this further contributes to speeding up the temperature rise. A 2023 study calculates that the eruption will have a warming effect of 0.12 Watts/m² over the next few years.

5. Aerosol changes are also contributing to the temperature rise, such as less Sahara dust than usual and less sulfur aerosols that are co-emitted with fossil fuel combustion, which previously masked the full impact of greenhouse gases.

6. The Jet Stream is getting increasingly deformed as the temperature difference between the Arctic and the Tropics narrows, and this can strongly increase the intensity, duration and frequency of extreme weather events in the Northern Hemisphere. 

The image on the right shows North Atlantic sea surface temperatures as much as 8.2°C or 14.7°F higher than 1981-2011 (green circle) on July 24, 2023. The image also shows that the Jet Stream is very deformed and features many circular patterns that contribute to stronger heating up of the North Atlantic, especially along the path of the Gulf Stream where the Jet Stream has a strong presence.

Deformation of the Jet Stream can also lead to stronger heatwaves on land that extend over the Arctic Ocean, which in turn can also strongly heat up the water of rivers that end in the Arctic Ocean. The image on the right shows huge amounts of heat surrounding Arctic sea ice and also shows that on July 28, 2023, the sea surface was as much as 19.7°C or 35.4°F hotter than 1981-2011 at an area where the Ob River meets the Kara Sea (green circle).

7. 
AMOC (the Atlantic meridional overturning circulation) is slowing down, further contributing to more hot water accumulating in the North Atlantic. Instead of reaching the Arctic Ocean gradually, a huge part of this heat that is now accumulating in the
North Atlantic may abruptly be pushed into the Arctic Ocean by strong storms that gain strength as the Jet Stream gets increasingly deformed. This danger grows as more ocean heat is accumulating in the North Atlantic and this situation threatens to cause huge eruptions of methane from the seafloor. 

8. Increased stratification, as temperatures rise, combines with increased meltwater and with stronger evaporation over the North Atlantic and stronger precipitation further down the path of the Gulf Stream. This threatens to result in the formation of a freshwater lid on top of the North Atlantic, enabling more hot water to flow underneath this lid into the Arctic Ocean, further increasing the methane threat.


Arctic reaches record high air temperature

The Arctic reached a record high 2-meter air temperature of 5.81°C on July 27, 2023, almost 2°C higher than the daily mean for the period 1979-2000, as illustrated by the image below. Arctic sea ice typically reaches its minimum extent half September, when the temperature in the Arctic falls below 0°C and water at the surface starts refreezing. 


One danger is that, as more heat is reaching sediments at the seafloor of the Arctic Ocean, hydrates will be destabilized, resulting in eruption of huge amounts of methane from the seafloor.

As sea ice melts away, less sunlight gets reflected back into space, so more heat will reach the Arctic ocean and heat up the water, as discussed at the albedo page.

Furthermore, Arctic sea ice is already very thin, as illustrated by the image on the right. The thinner the sea ice, the less heat can be consumed in the process of melting the ice, as discussed at the latent heat page.

These are just three out of numerous developments that could unfold in the Arctic soon, such as tipping points getting crossed and feedbacks starting to kick in with greater ferocity, as discussed in an earlier post.

Latent heat loss, feedback #14 on the Feedbacks page

Feedbacks

Syee Weldeab et al., in a 2022 study, looked at the early part (128,000 to 125,000 years ago) of the penultimate interglacial, the Eemian, when meltwater from Greenland caused a weakening of the Atlantic meridional overturning circulation (AMOC). “What happens when you put a large amount of fresh water into the North Atlantic is basically it disturbs ocean circulation and reduces the advection of cold water into the intermediate depth of the tropical Atlantic, and as a result warms the waters at this depth,” he said. “We show a hitherto undocumented and remarkably large warming of water at intermediate depths, exhibiting a temperature increase of 6.7°C from the average background value,” Weldeab said.

Weldeab and colleagues used carbon isotopes (13C/12C) in the shells of microorganisms to uncover the fingerprint of methane release and methane oxidation across the water column. “This is one of several amplifying climatic feedback processes where a warming climate caused accelerated ice sheet melting,” he said. “The meltwater weakened the ocean circulation and, as a consequence, the waters at intermediate depth warmed significantly, leading to destabilization of shallow subsurface methane hydrates and release of methane, a potent greenhouse gas.”

Furthermore, more methane over the Arctic would push up temperatures locally over the Arctic Ocean as well as over permafrost on land. A 2020 study by Turetsky et al. found that Arctic permafrost thaw plays a greater role in climate change than previously estimated.

Ominously, some very high methane levels were recorded recently at Barrow, Alaska, as illustrated by the NOAA image below.
Further feedbacks can make the situation even more threatening. As an example, dissolved oxygen in oceans decreases as the temperature rises, further pushing up the temperature rise, as discussed, e.g., in a 2022 study by Jitao Chen et al. As the temperature rises, soil moisture content decreases, further pushing up temperatures, as discussed in an earlier post.

Conclusion

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

• N. Atlantic ocean temperature sets record high: US agency

• Nullschool
https://earth.nullschool.net

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

• Copernicus
https://climate.copernicus.eu

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

• A Prehistoric Climate Feedback Loop - Paleoclimatologist uncovers an ancient climate feedback loop that accelerated the effects of Earth's last warming episode (news release)
Evidence for massive methane hydrate destabilization during the penultimate interglacial warming - by Syee Weldeab et al. (study, 2022)

• Marine anoxia linked to abrupt global warming during Earth’s penultimate icehouse - by Jitao Chen et al. (2022)

• Carbon release through abrupt permafrost thaw - by Merritt Turetsky et al. (2020)
• NOAA - Global Monitoring Laboratory - Barrow, Alaska
https://gml.noaa.gov/dv/iadv/graph.php?code=BRW&program=ccgg&type=ts


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

• Will there be Arctic sea ice left in September 2023?
• Dire situation gets more dire every day
https://arctic-news.blogspot.com/2023/07/dire-situation-gets-more-dire-every-day.html

• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html

• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html





Monday, August 22, 2022

Dangerously large Arctic sea ice extent

Arctic sea ice extent was 5.88 million km² on August 21, 2022, larger in extent than in any of the years from 2010 through 2021 at this time of year, as illustrated by the NSIDC image below. 


At first glance, one might think that this relatively large extent was a sign of healthy sea ice. After all, the larger the sea ice, the more sunlight gets reflected back into space. At the same time, however, the situation is very dangerous, as there is a growing risk that large eruptions of methane will occur from the seafloor of the Arctic Ocean.

Why is the situation so dangerous? There are many contributors to the danger, three of them are:

1. Ice acts as a seal

Ice acts as a seal, insulating the soil from warmer air and holding the soil together, like a glue. A 2022 study by Elizabeth Webb et al. concludes that rainwater carries heat into the soil and accelerates permafrost thaw, and the glue that holds the soil together disappears. This can open up underground channels that drain the surface. 

Rainwater can also travel along cracks deeper into sediments, where the heat can destabilize methane hydrates, resulting in the release of large amounts of methane into the atmosphere from hydrates and from gas underneath hydrates. As temperatures rise in the Arctic, more rain will fall over the Arctic, increasing this danger.


Where rain falls onto the sea ice, the rainwater also adds heat to the sea ice, speeding up its demise, and stronger winds can further accelerate this. The compound impact is that such feedbacks accelerate the pace at which the Arctic is warming, but as long as air temperatures are low enough, there will continue to be sea ice that acts as a seal, impeding transfer of ocean heat from the Arctic Ocean to the atmosphere. 

Temperatures in the Arctic are rising faster than in the rest of the world. As temperatures rise in the Arctic, increased precipitation, meltwater and runoff from land, and flow of freshwater from rivers all decrease salinity of the water in the Arctic Ocean. Lower salinity makes it harder for sea ice to melt. 

As temperatures in the Arctic are rising faster than in the rest of the world, the Jet stream is getting deformed. Deformation of the Jet Stream causes more wind to go over the Arctic Ocean, which can cool down the sea surface, resulting in more extensive sea ice. 

Furthermore, we're currently in the depth of a persistent La Niña (NOAA image on the right), and the associated lower air temperatures further contribute to a relatively larger extent of the sea ice. 

More extensive sea ice in turn makes it harder for ocean heat to be transferred to the atmosphere, thus instead raising the temperature of the water of the Arctic Ocean.


The larger the sea ice is in extent, the less ocean heat can be transferred from the Arctic Ocean to the atmosphere, which means that more heat will remain in the Arctic Ocean.

2. Lid on North Atlantic

Ocean stratification is increasing globally, as ocean warming is stronger for upper layers versus the deep ocean. Stratification increased from 1960 to 2018 by 5.3% for the upper 2000m and by as much as 18% for the upper 150m, while salinity changes also play an important role locally, a 2020 study finds.

[ SSTA (left) and SST (right), August 23, 2022 - click on image to enlarge ]

Deformation of the Jet Stream can at times strongly increase evaporation over the North Atlantic with more precipitation further down the path of the Atlantic meridional overturning circulation (AMOC).

Deformation of the Jet Stream can also increase runoff from land (including from melting glaciers).

In both these cases, this can contribute to the formation and growth of a relatively cold, freshwater lid at the surface of the North Atlantic.


This lid on the North Atlantic reduces transfer of ocean heat to the atmosphere and enables large amounts of salty, warm water to enter the Arctic Ocean, diving under the sea ice. 

This lid also increases the risk of a sudden, large influx of hot, salty water. Slowdown of AMOC causes ocean heat to accumulate, while more warm water travels underneath this lid (instead of at the sea surface) toward the Arctic Ocean. As the Jet Stream gets more deformed, strong winds along the path of AMOC can at times speed up the flow of water that travels underneath this cold freshwater lid over the North Atlantic, suddenly pushing large amounts of salty, warm water into the Arctic Ocean. 

3. Latent heat buffer loss

The navy.mil combination image below has three panels. The left panel shows the sea ice on August 30, 2012, the center panel shows the sea ice on August 30, 2015, and the right panel shows a forecast for the sea ice for August 30, 2022, run on August 22, 2022.


The image illustrates that Arctic sea ice is currently larger in extent than it was in 2012 and 2015 at this time of year, while there has been a dramatic reduction in thickness of the sea ice over time.

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.


This ice has meanwhile all but disappeared, so without this latent heat buffer further incoming heat must go elsewhere, i.e. the heat will further raise the temperature of the water of the Arctic Ocean.

Compound impact

The danger is that, as more salty, warm water keeps arriving in the Arctic Ocean while the latent heat buffer has largely disappeared and while sea ice extent is relatively large, this will raise the temperatures and salinity levels at the bottom of the Arctic Ocean enough to destabilize hydrates in sediment at the seafloor of the Arctic Ocean, resulting in methane eruptions both from these hydrates and from free gas underneath these hydrates.

[ The Buffer has gone, feedback #14 on the Feedbacks page ]
Very high methane levels

The Copernicus image below shows a forecast of high levels of methane over the Arctic on August 28, 2022 18:00 UTC at 500 hPa. 


Methane levels are already at record high and growth is accelerating, even without an extra burst of seafloor methane. The NOAA record shows that methane grew by 18.31 ppb in 2021, the highest annual growth on record. 

The most recent monthly NOAA data are for the globally averaged marine surface mean for April 2022, which was 1909.9 ppb. This is 18.7 ppb higher than April 2021, as illustrated by the image on the right, from an earlier post.

NOAA's data are for marine surface measurements. More methane tends to accumulate at higher altitudes, as illustrated by the two data images on the right.

The top data image on the right shows methane recorded by the MetOp satellite on August 22, 2022 am. The image shows means of 1972 ppb at five pressure levels (of 280 mb and less), with a peak level of 2543 ppb, the highest that day, occurring at 218 mb.

The second data image on the right shows methane means recorded by the MetOp satellite on August 25, 2022 pm of 1975 ppb at four pressure levels (at 254 mb, 266 mb, 280 mb and 283 mb).

The image underneath on the right shows a methane peak of 2622 ppb (marked by the red oval), recorded by the N20 satellite on August 20, 2022 am at 399.1 mb. High methane levels are visible north of Siberia, indicating that much of the methane may originate in the Arctic.

Another N20 satellite image is added underneath showing high methane concentrations over the Arctic, also on August 20, 2022 am, but at 695.1 mb, which is much closer to sea level. This confirms that much of the methane may have originated in the Arctic.

An image is added underneath from another satellite, the MetOp satellite, also showing high methane concentrations over the Arctic, also on August 20, 2022 am, this time at 586 mb, further confirming that much of the methane may have originated in the Arctic.

A large abrupt methane release could double the methane in the atmosphere. Methane releases from the seafloor of the Arctic Ocean are very dangerous because there is very little hydroxyl in the atmosphere over the Arctic to break down the methane.
A level twice as high as that 1975 ppb mean is a mean of 3950 ppb, and when using a 1-year GWP of 200, this translates into 790 ppm CO₂e, i.e. only 410 ppm away from the 1200 ppm clouds tipping point.

The average monthly CO₂ at Mauna Loa, Hawaii, was 420.99 ppm both in May and in June 2022. As illustrated by the image on the right, average daily CO₂ hasn't been below 416 ppm in July and August 2022, while some hourly measurements were around 425 ppm CO₂.
On August 25, 2022 16:30 UTC, CO₂ at the North Pole was 422 ppm, as illustrated by the nullschool.net image on the right. 

In other words, a large eruption of methane from the seafloor of the Arctic Ocean could abruptly cause the joint CO₂e of just two greenhouse gases, i.e. methane and CO₂, to cross the 1200 ppm clouds tipping point globally and trigger a further 8°C global temperature rise, due to the clouds feedback alone. When adding further forcers, a huge temperature rise could be triggered even with far less methane erupting from the seafloor.

Conclusion

In conclusion, there is a growing danger that methane will erupt from the seafloor of the Arctic Ocean and cause a dramatic rise in temperature.

Even without such eruption of methane from the seafloor of the Arctic Ocean, temperatures look set to rise strongly soon, as we move into an El Niño and face a peak in sunspots. 

Either way, the resulting temperature rise could drive humans extinct as early as in 2025 with temperatures continuing to skyrocket in 2026

This makes it in many respects rather futile to speculate about what will happen beyond 2026. At the same time, the right thing to do now is to help avoid the worst things from happening, through comprehensive and effective action as described in the Climate Plan.


Arctic sea ice (earlier posts in 2022)

• Arctic sea ice June 2022 - why the situation is so dangerous
https://arctic-news.blogspot.com/2022/06/arctic-sea-ice-june-2022-why-situation-is-so-dangerous.html

• Arctic sea ice July 2022
https://arctic-news.blogspot.com/2022/07/arctic-sea-ice-july-2022.html

• Arctic sea ice August 2022


Further links

• Permafrost thaw drives surface water decline across lake-rich regions of the Arctic - by Elizabeth Webb et al. 
also discussed at: 

• Increasing ocean stratification over the past half-century - by Guancheng Li et al. 
https://www.nature.com/articles/s41558-020-00918-2

• The ocean has become more stratified with global warming - news release

• IPCC AR6 WG1 SPM


• NOAA - Globally averaged marine surface annual mean methane growth rates.

• NOAA - Trends in Atmospheric Carbon Dioxide

• NOAA - MetOp satellite 

• NOAA - N20 satellite

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

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

• NOAA - Monthly Temperature Anomalies Versus El Niño
https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202207/supplemental/page-4

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

• NSIDC - Arctic sea ice concentration
https://nsidc.org/arcticseaicenews

• NSIDC - Chartic, interactive sea ice graph
https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph

• NOAA - Trends in Atmospheric Methane
https://gml.noaa.gov/ccgg/trends_ch4

• nullschool
https://earth.nullschool.net

• Naval Research Laboratory
https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/arctic.html

• Understanding the Permafrost–Hydrate System and Associated Methane Releases in the East Siberian Arctic Shelf - by Natalia Shakhova et al. (2019)
https://www.mdpi.com/2076-3263/9/6/251


• Warning of mass extinction of species, including humans, within one decade
https://arctic-news.blogspot.com/2017/02/warning-of-mass-extinction-of-species-including-humans-within-one-decade.html

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

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

• Latent Heat Buffer
https://arctic-news.blogspot.com/p/latent-heat.html

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

• Clouds feedback
https://arctic-news.blogspot.com/p/clouds-feedback.html

• How much time is there left to act?
https://arctic-news.blogspot.com/p/how-much-time-is-there-left-to-act.html

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

• Cataclysmic Alignment
https://arctic-news.blogspot.com/2022/06/cataclysmic-alignment.html

• Human Extinction by 2025?
https://arctic-news.blogspot.com/2022/07/human-extinction-by-2025.html

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

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



Wednesday, January 30, 2019

A Revision of Future Climate Change Trends

By Andrew Glikson

Abstract


As the Earth continues to heat, paleoclimate evidence suggests transient reversals will result in accentuating the temperature polarities, leading to increase in the intensity and frequency of extreme weather events.

Pleistocene paleoclimate records indicate interglacial temperature peaks are consistently succeeded by transient stadial freeze events, such as the Younger Dryas and the 8.5 kyr-old Laurentide ice melt, attributed to cold ice melt water flow from the polar ice sheets into the North Atlantic Ocean. The paleoclimate evidence raises questions regarding the mostly linear to curved future climate model trajectories proposed for the 21ᵗʰ century and beyond, not marked by tipping points. However, early stages of a stadial event are manifest by a weakening of the North Atlantic overturning circulation and the build-up of a large pool of cold water south and east of Greenland and along the fringes of Western Antarctica. Comparisons with climates of the early Holocene Warm Period and the Eemian interglacial when global temperatures were about +1°C higher than late Holocene levels. The probability of a future stadial event bears major implications for modern and future climate change trends, including transient cooling of continental regions fringing the Atlantic Ocean, an increase in temperature polarities between polar and tropical zones across the globe, and thereby an increase in storminess, which need to be taken into account in planning global warming adaptation efforts.

Introduction

Reports of the International Panel of Climate Change (IPCC)⁽¹⁾, based on thousands of peer reviewed science papers and reports, offer a confident documentation of past and present processes in the atmosphere⁽²⁾, including future model projections (Figure 1). When it comes to estimates of future ice melt and sea level change rates, however, these models contain a number of significant departures from observations based on the paleoclimate evidence, from current observations and from likely future projections. This includes departures in terms of climate change feedbacks from land and water, ice melt rates, temperature trajectories, sea level rise rates, methane release rates, the role of fires, and observed onset of transient stadial (freeze) events⁽³⁾. Early stages of stadial event/s are manifest by the build-up of a large pool of cold water in the North Atlantic Ocean south of Greenland and along the fringes of the Antarctic continent (Figure 2).
Figure 1. IPCC AR5: Time series of global annual mean surface air temperature anomalies relative to 1986–2005
from CMIP5 (Coupled Model Inter-comparison Project) concentration-driven experiments.
Projections are shown for each RCP for the multi model mean (solid lines) and the 5–95%
range (±1.64 standard deviation) across the distribution of individual models (shading).⁽⁴⁾
Hansen et al. (2016) (Figure 2) used paleoclimate data and modern observations to estimate the effects of ice melt water from Greenland and Antarctica, showing cold low-density meltwater tend to cap increasingly warm subsurface ocean water, affecting an increase ice shelf melting, accelerating ice sheet mass loss (Figure 3) and slowing of deep water formation (Figure 4). Ice mass loss would raise sea level by several meters in an exponential rather than linear response, with doubling time of ice loss of 10, 20 or 40 years yielding multi-meter sea level rise in about 50, 100 or 200 years.

Linear to curved temperature trends portrayed by the IPCC to the year 2300 (Figure 1) are rare in the Pleistocene paleo-climate record, which abrupt include warming and cooling variations during both glacial (Dansgaard-Oeschger cycles; Ganopolski and Rahmstorf 2001⁽⁵⁾; Camille and Born, 2019⁽⁶⁾) and interglacial (Cortese et al. 2007⁽⁷⁾) periods. Hansen et al.’s (2016) model includes sharp drops in temperature, reflecting stadial freezing events in the Atlantic Ocean and the sub-Antarctic Ocean and their surrounds, reaching -2°C over several decades (Figure 5).
Figure 2. 2055-2060 surface-air temperature to +1.19°C above 1880-1920
(AIB model modified forcing, ice melt to 1 meter) From: Hansen et al. (2016)⁽⁸⁾
Figure 3. Greenland and Antarctic ice mass change. GRACE data are extension of Velicogna et al. (2014)⁽⁹⁾
gravity data. MBM (mass budget method) data are from Rignot et al. (2011)⁽¹⁰⁾. Red curves are gravity
data for Greenland and Antarctica only; small Arctic ice caps and ice shelf melt add to freshwater input.⁽¹¹⁾
Figure 4. (a) AMOC (Sverdrup⁽¹²⁾) at 28°N in simulations (i.e., including freshwater injection of 720 Gt year−1 in 2011
                around Antarctica, increasing with a 10-year doubling time, and half that amount around Greenland).
(b) SST (°C) in the North Atlantic region (44–60°N, 10–50°W).
Temperature and sea level rise relations during the Eemian interglacial⁽¹³⁾ about 115-130 kyr ago, when temperatures were about +1°C or higher than during the late stage of the Holocene, and sea levels were +6 to +9 m higher than at present, offer an analogy for present developments. During the Eemian overall cooling of the North Atlantic Ocean and parts of the West Antarctic fringe ocean due to ice melt led to increased temperature polarities and to storminess⁽¹⁴⁾, underpinning the danger of global temperature rise to +1.5°C. Accelerating ice melt and nonlinear sea level rise would reach several meters over a timescale of 50–150 years (Hansen et al. 2016)

Figure 5. Global surface-air temperature to the year 2300 in the North Atlantic and Southern Oceans,
including stadial freeze events as a function of Greenland and Antarctic ice melt doubling time

Portents of collapse of the Atlantic Meridional Ocean Circulation (AMOC)


The development of large cold water pools south and east of Greenland (Rahmstorf et al. 2015⁽¹⁵⁾) and at the fringe of West Antarctica (Figures 1 and 5) signify early stages in the development of a stadial, consistent with the decline in the Atlantic Meridional Ocean Circulation (AMOC) (Figure 4). These projections differ markedly from linear model trends (Figure 1). IPCC models mainly assume long term ice melt⁽¹⁶⁾, stating “For the 21st century, we expect that surface mass balance changes will dominate the volume response of both ice sheets (Greenland and Antarctica). A key question is whether ice-dynamical mechanisms could operate which would enhance ice discharge sufficiently to have an appreciable additional effect on sea level rise”⁽¹⁷⁾. The IPCC conclusion is difficult to reconcile with studies by Rignot et al. (2011) reporting that in 2006 the Greenland and Antarctic ice sheets experienced a “combined mass loss of 475 ± 158 Gt/yr, equivalent to 1.3 ± 0.4 mm/yr sea level rise”⁽¹⁸⁾. For the Antarctic ice sheet the IEMB team (2017) states the sheet lost 2,720 ± 1,390 billion tonnes of ice between 1992 and 2017, which corresponds to an increase in mean sea level of 7.6 ± 3.9 millimeter⁽¹⁹⁾.

A non-linear climate warming trend, including stadial freeze events, bears significant implications for planning future adaptation efforts, including preparations for transient deep freeze events in parts of Western Europe and eastern North America, for periods lasting several decades (Figure 5) and coastal defenses against enhanced storminess arising from increased temperature contrasts between the cooled regions and warm tropical latitudes.

Imminent climate risks

Climate model projections for the 21ᵗʰ to 23ʳᵈ centuries need to take paleoclimate evidence more fully into account, including the transient stadial effects of ice melt water flow into the oceans and amplifying feedbacks of global warming from land and oceans. Radiative forcing⁽²⁰], increasing with concentration of atmospheric greenhouse gases and rising by about 0.04 Watt/m²/year over the last 50 years⁽²¹⁾, totaled by more than 2 Watt/m², equivalent to ~3.0°C (~1.5°C per W/m²)⁽²²⁾. The rise of mean global temperatures to date by 0.9°C since 1880⁽²³⁾ therefore represents lag effect, pointing to potential temperature rise by approximately two degrees Celsius. A further rise in global temperatures would be enhanced by amplifying feedbacks from land and oceans, including exposure of water surfaces following sea ice melting, reduction of CO₂ concentration in water, release of methane and fires. Climate change trajectories would be highly irregular as a result of stadial events affected by flow of ice melt water into the oceans. Whereas similar temperature fluctuations and stadial events occurred during past interglacial periods (Cortese et al. 2007⁽²⁴⁾; Figure 6), when temperature fluctuations were close to ~1°C, further rises in temperature in future would enhance the intensity and frequency of extreme weather events, entering uncharted territory unlike any recorded during the Pleistocene, rendering large parts of the continents uninhabitable.

Figure 6. (A) Evolution of sea surface temperatures in 5 glacial-interglacial transitions recorded in ODP 1089
at the sub-Antarctic Atlantic Ocean. Lower grey lines – δ¹⁸O measured on Cibicidoides plankton;
Black lines – sea surface temperature. Marine isotope stage numbers are indicated on top of diagrams.
Note the stadial temperature drop events following interglacial peak temperatures, analogous
to the Younger Dryas preceding the onset of the Holocene (Cortese et al. 2007⁽²⁵⁾).
(B) Mean temperatures for the late Pleistocene and early Holocene.

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Andrew Glikson
by Andrew Glikson
Earth and Paleo-climate science, Australia National University (ANU) School of Anthropology and Archaeology,
ANU Planetary Science Institute,
ANU Climate Change Institute,
Honorary Associate Professor, Geothermal Energy Centre of Excellence, University of Queensland.

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Notes

(1) IPCC, Special Report, Global Warming of 1.5 ºC
https://www.ipcc.ch
https://www.ipcc.ch/sr15/

(2) Climate Council, Report, The good, the bad and the ugly: limiting temperature rise to 1.5°C
https://www.climatecouncil.org.au/resources/limiting-temperature-rise/

(3) Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous, by James Hansen et al.
https://www.atmos-chem-phys.net/16/3761/2016/

(4) IPCC Climate Change 2013: Technical Summary, p.89
http://www.climatechange2013.org/images/figures/WGI_AR5_Fig12-5.jpg
http://www.climatechange2013.org/images/report/WG1AR5_TS_FINAL.pdf

(5) Rapid changes of glacial climate simulated in a coupled climate model, by Andrey Ganopolski and Stefan Rahmstorf
https://www.nature.com/articles/35051500
https://www.ncbi.nlm.nih.gov/pubmed/11196631

(6) Coupled atmosphere-ice-ocean dynamics in Dansgaard-Oeschger events, by Camille Li and Andreas Born
https://www.sciencedirect.com/science/article/pii/S0277379118305705

(7) The last five glacial‐interglacial transitions: A high‐resolution 450,000‐year record from the subantarctic Atlantic, by G. Cortese, A. Abelmann and R. Gersonde
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007PA001457

(8) Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous, by James Hansen et al. (2016)
https://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016-avatar-web.png
https://www.atmos-chem-phys.net/16/3761/2016/

(9) Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time‐variable gravity data, by I. Velicogna et al.
https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014GL061052

(10) Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, by E. Rignot et al. (2011)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2011GL046583

(11) Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous, by James Hansen et al.
https://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016.pdf

(12) Sverdrup: Unit of flow – 1 Sv is equal to 1,000,000 m³ per second
https://en.wikipedia.org/wiki/Sverdrup

(13) Eemian Interglacial Stage
https://www.britannica.com/science/Eemian-Interglacial-Stage

(14) Giant boulders and Last Interglacial storm intensity in the North Atlantic, by Alessio Rovere et al. (2017)
http://moraymo.us/wp-content/uploads/2018/03/Rovereetal_PNAS_2017.pdf
Northern hemisphere winter storm tracks of the Eemian interglacial and the last glacial inception, by F. Kaspar (2006)
https://www.clim-past.net/3/181/2007/cp-3-181-2007.pdf

(15) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation, by Stefan Rahmstorf et al. (2015)
https://www.nature.com/articles/nclimate2554

(16) The UN's Devastating Climate Change Report Was Too Optimistic, by Nafeez Ahmed (Oct 16, 2018)
https://motherboard.vice.com/en_us/article/43e8yp/the-uns-devastating-climate-change-report-was-too-optimistic

(17) IPCC Third Assessment Report, Working Group I: The Scientific Basis
https://archive.ipcc.ch/ipccreports/tar/wg1/416.htm

(18) Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, by E. Rignot et al. (2011)
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL046583

(19) Mass balance of the Antarctic Ice Sheet from 1992 to 2017
https://www.nature.com/articles/s41586-018-0179-y.epdf

(20) Radiative forcing – the difference between incoming radiation and radiation reflected back to space
https://en.wikipedia.org/wiki/Radiative_forcing

(21) Climate Change in a Nutshell: The Gathering Storm, by James Hansen (18 December 2018)
http://www.columbia.edu/~jeh1/mailings/2018/20181206_Nutshell.pdf

(22) Target atmospheric CO2: Where should humanity aim?, by James Hansen (2008)
https://arxiv.org/abs/0804.1126

(23) NASA: Global temperature
https://climate.nasa.gov/vital-signs/global-temperature/

(24) The last five glacial‐interglacial transitions: A high‐resolution 450,000‐year record from the subantarctic Atlantic, by G. Cortese, A. Abelmann and R. Gersonde
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007PA001457

(25) The last five glacial‐interglacial transitions: A high‐resolution 450,000‐year record from the subantarctic Atlantic, by G. Cortese, A. Abelmann and R. Gersonde
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007PA001457

This is an edited version of an article at Global Research
Copyright © Dr. Andrew Glikson, 2019