Showing posts with label melting. Show all posts
Showing posts with label melting. Show all posts

Friday 10 July 2015

Arctic Sea Ice Collapse Threatens

The image below compares the Arctic sea ice thickness on July 14, 2012 (left panel) and on July 14, 2015 (right panel), using Naval Research Laboratory images.


The Naval Research Laboratory's 30-day animation below shows how this situation developed, ending with a forecast for July 17, 2015, run on July 9, 2015.


The dramatic decline of the sea ice, especially north of North America, is the result of a combination of factors, including:

  • very high levels of greenhouse gases over the Arctic Ocean
  • very high levels of ocean heat 
  • heatwaves over North America and Siberia extending high air temperatures over the Arctic Ocean
  • wildfires triggered by these heatwaves resulting in darkening compounds settling on snow and ice
  • very warm river water running into the Arctic Ocean, as illustrated by the image below.  


With still two months of melting to go before the sea ice can be expected to reach its minimum for 2015, the threat of sea ice collapse is ominous. The Arctic-News Blog has been warning for years about the growing chance of a collapse of the sea ice, in which case huge amounts of sunlight that previously were reflected back into space, as well as heat that previously went into melting the ice, will then instead have to be absorbed by the water, resulting in a dramatic rise of sea surface temperatures.

The image below shows the already very high sea surface temperature anomalies as at July 10, 2015.


More open water will then come with an increased chance of storms that can cause high sea surface temperatures to be mixed down all the way to seafloor of the Arctic Ocean, which in many cases is less than 50 m (164 ft) deep.

Meanwhile, ocean heat is accumulating off the coast of North America, as illustrated by the image below showing sea surface temperature as high as 31.8°C (89.24°F) on July 8-9, 2015.


Massive amounts of ocean heat will be carried by the Gulf Stream into the Arctic Ocean over the next few months. The combined result of high sea surface temperatures being mixed down to the seafloor and the ocean heat entering the Arctic Ocean from the Atlantic and Pacific Oceans can be expected to result in dramatic methane eruptions from the Arctic Ocean seafloor by October 2015.

Currently, methane levels are high, especially north of Greenland, as illustrated by the image below showing that on July 10, 2015 (am), levels as high as 2416 parts per billion were recorded at 6,041 m (19,820 ft) altitude, while mean methane levels also reached 1831 parts per billion at this altitude.


The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.





ARCTIC SEA ICE COLLAPSE THREATENSThis image compares the Arctic sea ice thickness on July 14, 2012 (left panel) and on...
Posted by Sam Carana on Friday, July 10, 2015

Wednesday 28 January 2015

Rain Storms Devastate Arctic Ice And Glaciers

by Veli Albert Kallio


The Norwegian Svalbard Islands are located just few hundred miles from the North Pole. It is a unique environment for glaciers: Here glaciers can survive almost at sea level. This means that ice is constantly brushed by thick low-altitude air, which also dumps increasinlgy rain instead of snow.

As a result of high ocean temperatures and of precipitation nowadays falling as rain for months, the melting of these glaciers now occurs 25 times faster than just some years ago.

This also spells bad news for Northern Greenland's low lying glaciers, which will face increasing summertime flash floods as the Arctic Ocean becomes ice free and warms up, and as precipitation falls in the form of rain, rather than snow.

Sea surface temperature of 17.5°C, west of Svalbard
click on image to enlarge
Last summer, for example, sea water west of the Svalbard reached +18C, which is perfect for swimming - but extremely bad for the cold glaciers on shore which mop up the warm moisture and rainfall from the warmed up ocean.

Flash floods falling on glacier soften the compacted snow very rapidly to honeycombed ice that is exceedingly watery and without any internal strength.

Such ice can collapse simply under its own weight and the pulverised watery ice in the basin forms a near frictionless layer of debris.

Darkening of the melting ice also hastens its warming and melting.

Aggressively honeycombed glacier ice floating on meltwater lake in nearby Iceland.   Image credit: Runólfur Hauksson


click on image to enlarge

Changes to the Jet Streams

As the Arctic continues to warm, the temperature difference between the equator and the Arctic declines. This slows down the speed at which the polar vortex and jet streams circumnavigate the globe and results in more wavier jet streams that can enter and even cross the Arctic Ocean and can also descend deep down over the continents, rather than staying between 50 and 60 degrees latitude, where the polar jet streams used to be (as discussed in a recent post).

Such deep descent over continents can cause very low temperatures on land, while at the same time oceans remain warm and are getting warmer, so the temperature difference between land and ocean increases, speeding up the winds between continents. On January 9, 2015, jet streams reached speeds between continents as high as 410 km/h (255 mps), as shown on above image. Also note the jet stream crossing the Arctic Ocean.

Faster winds means more water evaporation, and warmer air holds more water vapor, so this can result in huge rainstorms that can rapidly devastate the integrity of the ice.

[image and text in yellow panels by Sam Carana]

  

























I suspect that climatically-speaking we are currently entering a methane-driven Bøllinger warming state with the Northern Cryosphere now entering a phase of rapid warming and melting of anything frozen (snow, sea ice, permafrost and sea bed methane clathrates).

This will be rapidly followed by a Heindrich Iceberg Calving event when the warmed and wet ice sheet in Greenland gives away to its increased weight (due to excessive melt water accumulation within and beneath the ice sheet).

This dislodges the ice sheet’s top, due to accumulation of “rotten ice” (honeycombed, soft ice with zero internal strength) at the ice sheet’s base and perimeters.

A huge melt water pulse to the ocean ensues with Jōkullhaups and ice debris loading the ocean with vast amounts of cold fresh water.

Within weeks an immense climatological reversal then occurs as the ocean gets loaded up with ice debris and cold water leading to the Last Dryas cooling and to world-wide droughts.

This loading of the ocean with ice and water leads to severe climatic flop, as the ocean and atmosphere cool rapidly and as falling salinity and sea water temperature briefly reverse all of the current Bøllinger warming, until the climatic forcing of the greenhouse gases again takes over the process, in turn leading to a new melt water pulse as another ice sheet or shelf disintegrates by the next warming.

Today’s rapid melt water lake formation in Greenland and the ultra-fast melting of glaciers are suggestive of near imminent deglaciation process in the Arctic.

Germany’s and Japan’s recent decisions to remove all their nuclear reactors from the sea sides may prove their worth sooner than many think in the far more conservative US and UK where “glacial speed” still means “eons of time”. Good luck UK/US!

I think cold 'Dryases' are not real Ice Ages, but hiatuses in a progressive melting process which results from changes in sea water salinity and temperature due to increases of meltwater and ice debris runoff from continental snow and ice that melt. As ocean gets less saline and colder the sea ice and snow cover temporarily grows.

But in the long run the greenhouse gas forcing and ocean wins and the warmth and melting resumes until the next big collapse of ice shelf and/or ice sheet. Hence there are meltwater pulses (such as 1a, 1b, 1c) and Heindrich Ice Berg Calving surges (2, 1, 0 - the last one being also called "Younger Dryas" as the Arctic Dryas octopetala grew in South once again after Ice Ages).

The next cooling from collapse of Greenland ice dome would be Heindrich Minus One as the zero has already been allocated to Younger Dryas ice berg surge. Here is an article worth reading on this risk. In Antarctica we see currently (already) a sea ice growth hiatus driven by increased runoff of melt water and ice debris from the continent and its surrounding ice shelves that are rapidly disintegrating.



Abrupt climate change happened in just one year

A 2008 study by Achim Brauer et al. of lake sediments concluded that abrupt increase in storminess during the autumn to spring seasons, occurring from one year to the next at 12,679 yr BP. This caused abrupt change in the North Atlantic westerlies towards a stronger and more zonal jet, leading to deglaciation.

A 2009 study by Jostein Bakke et al. confirmed that increased flux of fresh meltwater to the ocean repeatedly resulted in the formation of more extensive sea ice that pushed the jet south once more, thus re-establishing the stadial state. Rapid oscillations took place until the system finally switched to the interglacial state at the onset of the Holocene.

References

- An abrupt wind shift in western Europe at the onset of the Younger Dryas cold period, Brauer et al.
http://www.nature.com/ngeo/journal/v1/n8/abs/ngeo263.html

- Rapid oceanic and atmospheric changes during the Younger Dryas cold period, Bakke et al.
http://www.nature.com/ngeo/journal/v2/n3/abs/ngeo439.html



Monday 16 June 2014

Warming of the Arctic Fueling Extreme Weather

Extreme weather

Heavy rains and floods hit Serbia and Bosnia in May 2014, as discussed in an earlier post.

Later in May, further flooding hit central Europe. From May 30 to June 1, 2014, parts of Austria received the amount of rain that normally falls in two-and-half months: 150 to 200 mm (5.9 to 7.9"), with some parts experiencing 250 mm (9.8").

What is fueling this extreme weather? Have a look at the image below.



The image shows a number of feedbacks that are accelerating warming in the Arctic. Feedback #14 refers to (latent) heat that previously went into melting. With the demise of the snow and ice cover, an increasing proportion of this heat gets absorbed and contributes to accelerated warming in the Arctic.

As the sea ice heats up, 2.06 J/g of heat goes into every degree Celsius that the temperature of the ice rises. While the ice is melting, all energy (at 334J/g) goes into changing ice into water and the temperature remains at 0°C (273.15K, 32°F). 

Once all ice has turned into water, all subsequent heat goes into heating up the water, at 4.18 J/g for every degree Celsius that the temperature of water rises.

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

Currently, the energy equivalent of 1.5 million Hiroshima bombs goes into melting of the Arctic sea ice each year, according to calculations by Sam Carana.

As the ice disappears, this energy will instead be absorbed elsewhere and cause temperatures in the Arctic to rise further, indicated as feedback #14.

This comes on top of the albedo feedback #1 that can on its own more than double the net radiative forcing resulting from the emissions caused by all people of the world, according to calculations by Prof. Peter Wadhams.

Further feedbacks include changes to the polar vortex and jet stream that are in turn causing more extreme weather, as also described in the earlier post Feedbacks in the Arctic.


Global Warming

Higher levels of greenhouse gases are trapping more heat in the atmosphere, resulting in more intense heatwaves in some places, while stronger winds and greater evaporation of water from the sea lead to stronger rainfall in other places. Global warming thus contributes to more extreme weather around the globe.

The Arctic is hit not only by the warming resulting from greenhouse gas emissions, but also by emissions of soot, dust and other compounds that settle on the snow and ice cover and speed up its demise.

As illustrated by the image below, by Nuccitelli et al., most heat goes into the oceans. A substantial amount of heat also goes into the melting of ice.

A lot of ocean heat is transported by the Gulf Stream into the Arctic Ocean. The North Atlantic is hit particularly strongly by pollution from North America, as illustrated by the image below.

[ screenshot from Perdue University's Vulcan animation ]
Heat carried by the Gulf Stream into the Arctic Ocean contributes to high sea surface anomalies in the Arctic, as illustrated by the image below. Arctic sea ice is under threat from heat from the North Atlantic, while heat from the Pacific Ocean that was in part caused by pollution from east-Asia is now threatening to enter the Arctic Ocean through the Bering Strait, as illustrated by the image below that shows areas with sea surface temperature anomalies well over 8 degrees Celsius. 

[ click on image to enlarge ]
Warmer water in the Arctic Ocean in turn causes methane to be released from the seafloor of the Arctic Ocean, as discussed further below. 


Accelerated Warming in the Arctic

As said, warming hits the Arctic particularly strongly due to feedbacks such as albedo changes caused by the demise of the snow and ice cover in the Arctic. Another feedback is a changing jet stream. The jet stream used to circumnavigate the globe at high speed, separating climate systems that used to be vastly different above and below the jet stream. Accelerated warming in the Arctic is decreasing the temperature difference between the Arctic and the Equator, in turn causing the jet stream to slow down and become wavier. As a result, air can more easily move north to south and visa versa, especially when the jet stream's waves expand vertically and take a long time to move from west to east (i.e. a blocking pattern).

These changes to the jet stream are fueling extreme weather events. In the May/June event, a large loop had developed in the jet stream over Europe and got stuck in place, making a strong southerly wind carry moisture-laden air from the Mediterranean Sea over Central Europe, clashing with colder air flowing down from the north as the jet stream was stuck in such a blocking pattern.

Record May heat hit northern Finland and surrounding regions of Russia and Sweden. Earlier in May (on May 19) an all-time national heat record was set of 91.4°F (33.0°C) in St. Petersburg, Russia, slashing the previous record by a wide margin. This temperature was unprecedented in records in St. Petersburg that started in 1881 and show a previous May record set in 1958 of 87.6°F (30.9°C).

The compilation below shows the jet stream on three days (May 24, 25 and 27), on top of surface temperature anomalies for those days.

[ click on image to enlarge ]

Further illustrating the event is the animation below, showing the jet stream from May 26 to June 11, 2014. Note that this is a 14.5 MB file that may take some time to fully load.

[ click on image to enlarge ]
Methane

Huge methane emissions took place from the seafloor of the Arctic Ocean from September 2013 to March 2014. These emissions have meanwhile risen up higher in the atmosphere and have moved closer to the equator.


Compared to June 2013, mean methane levels at higher altitudes are now well over 10 ppb higher at higher altitudes while there has been only little change closer to the ground. Since these mean levels are global means, the difference is even more pronounced at specific locations on the Northern hemisphere, where clouds of methane originating from the Arctic are contributing to the occurence of heat waves.

The contribution of methane to such heatwaves depends on the density of the methane at the time in the atmosphere over the location during such events.

Highest global mean methane levels varied from 1907 ppb to 1812 ppb for the period June 6 to 15, 2014, as illustrated by the image on the right, and peak methane concentration varied a lot from day to day. On June 6, 2014, peak readings as high as 2516 ppb were recorded.

Indicative for what can be the result is the temperature anomaly on May 19, when temperatures went up as high as 91.4°F (33.0°C) in St. Petersburg, Russia, slashing the previous record by a wide margin, of more than 2°C, as described above


Conclusion

The situation is the Arctic is threatening to escalate into runaway warming and urgently requires comprehensive and effective action as discussed at the Climate Plan blog.


References

- May 2014 Global Weather Extremes Summary

- Extreme Jet Stream Pattern Triggers Historic European Floods
http://www.wunderground.com/blog/JeffMasters/extreme-jet-stream-pattern-triggers-historic-european-floods


Related posts

- The Biggest Story of 2013
http://arctic-news.blogspot.com/2013/12/the-biggest-story-of-2013.html

- Climate Plan
http://climateplan.blogspot.com
- More extreme weather can be expected
http://arctic-news.blogspot.com/2014/05/more-extreme-weather-can-be-expected.html

- Extreme weather strikes around the globe - update
http://arctic-news.blogspot.com/2014/02/extreme-weather-strikes-around-the-globe-update.html

- Escalating extreme weather events to hammer humanity (by Paul Beckwith)
http://arctic-news.blogspot.com/2014/04/escalating-extreme-weather-events-to-hammer-humanity.html

- Our New Climate and Weather (by Paul Beckwith)
http://arctic-news.blogspot.com/2014/01/our-new-climate-and-weather.html

- Our New Climate and Weather - part 2 (by Paul Beckwith)
http://arctic-news.blogspot.com/2014/01/our-new-climate-and-weather-part-2.html

- Changes to Polar Vortex affect mile-deep ocean circulation patterns
http://arctic-news.blogspot.com/2012/09/changes-to-polar-vortex-affect-mile-deep-ocean-circulation-patterns.html

- Polar jet stream appears hugely deformed
http://arctic-news.blogspot.com/2012/12/polar-jet-stream-appears-hugely-deformed.html




Monday 7 April 2014

Permafrost thawing could accelerate global warming


"If the permafrost melts entirely, there would be 5x the amount of carbon in the atmosphere than there is now" - Jeff Chanton

Jeff Chanton, the John Widmer
Winchester Professor of
Oceanography at Florida State.
A team of researchers lead by Florida State University have found new evidence that permafrost thawing is releasing large quantities of greenhouse gases into the atmosphere via plants, which could accelerate warming trends.

The research is featured in the newest edition of the Proceedings of the National Academy of Sciences.

“We’ve known for a while now that permafrost is thawing,” said Suzanne Hodgkins, the lead author on the paper and a doctoral student in chemical oceanography at Florida State. “But what we’ve found is that the associated changes in plant community composition in the polar regions could lead to way more carbon being released into the atmosphere as methane.”

Permafrost is soil that is frozen year round and is typically located in polar regions. As the world has gotten slightly warmer, that permafrost is thawing and decomposing, which is producing increased amounts of methane.

Relative to carbon dioxide, methane has a disproportionately large global warming potential. Methane is 33 times more effective at warming the Earth on a mass basis and a century time scale relative to carbon dioxide.

Changes in plant community composition in the polar regions could lead to way more carbon being released into the atmosphere as methane

As the plants break down, they are releasing carbon into the atmosphere. And if the permafrost melts entirely, there would be five times the amount of carbon in the atmosphere than there is now, said Jeff Chanton, the John Widmer Winchester Professor of Oceanography at Florida State.

“The world is getting warmer, and the additional release of gas would only add to our problems,” he said.

Chanton and Hodgkins’ work, “Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production,” was funded by a three-year, $400,000 Department of Energy grant. They traveled to Sweden multiple times to collect soil samples for the study.

The research is a multicontinent effort with researchers from North America, Europe and Australia all contributing to the work.



References

- Permafrost thawing could accelerate global warming - Florida State University news release
http://news.fsu.edu/More-FSU-News/Permafrost-thawing-could-accelerate-global-warming

- Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production