Showing posts with label climate. Show all posts
Showing posts with label climate. Show all posts

Thursday 11 February 2016

Methane's Role in Arctic Warming

Arctic Ocean hit most strongly by global warming



Over the past 12 months, global warming was felt most strongly over the Arctic Ocean, as above image illustrates. Over most parts of the Arctic Ocean, surface temperatures were above the top end of the scale, i.e. more than 2.5°C higher than in 1981-2010.

In January 2016, air temperatures close to sea level (at 925 hPa) were more than 6°C or 13°F above average across most of the Arctic Ocean, as NSIDC.org announced recenty. Moreover, daily average temperatures over many parts of the Arctic Ocean often exceed the top end of the scale, i.e. 20°C or 36°F higher than in 1979-2000, as illustrated by the Climate Reanalyzer forecast below.


So, how can temperature anomalies over the Arctic Ocean at this time of year be so much higher than elsewhere on Earth?

One factor is feedbacks such as changes to the jet stream and decline of snow and ice cover in the Arctic that makes that ever more sunlight is getting absorbed by the water of the Arctic Ocean, in turn causing further decline, as discussed in many earlier posts.

Right now, however, warming over the Arctic Ocean is very pronounced at a time of year when there is a wider temperature difference between the Arctic and the Equator, while there is little or no sunlight reaching the Arctic. So, albedo changes are less relevant, while changes to the jet stream would be expected to be less prominent now. Nonetheless, a strongly deformed jet stream can push a lot of warm air all the way up to the North Pole, while pushing a lot of cold air out of the Arctic over North America, as illustrated by the forecast on the right.

Let's look at some further factors that are at work.

High levels of greenhouse gases over the Arctic


The question was, why is warming hitting to Arctic Ocean so strongly at this time of year? Greenhouse gas levels are higher over the Arctic than elsewhere on Earth. Greenhouse gases trap heat that would otherwise be radiated out to space, and this greenhouse effect is occurring all year long.

[ click on images to enlarge them ]
Let's look more closely at carbon dioxide (CO2) levels. On February 4, 2016, CO2 level at Mauna Loa, Hawaii, was 405.83 ppm, as illustrated by the image on the right

The image below shows that global mean CO2 level on February 6, 2016, was 407 ppm at an altitude close to sea level (972 mb). The image also shows higher CO2 levels at higher latitudes north, with levels over 410 ppm showing up over most of the Northern Hemisphere. 




Carbon dioxide levels on Feb. 8, 2016, were as high as 416 ppm at a location over the Kara Sea (marked by the green circle at the top of the image on the right).

Nonetheless, the levels of carbon dioxide over the Arctic Ocean are not that much higher than elsewhere, i.e. not enough to explain such huge temperature anomalies.

Methane, another greenhouse gas, is also present over the Arctic Ocean at levels that are higher than the rest of the world, as illustrated by the image below, showing methane levels over 1900 ppb over most of the Arctic Ocean on February 4, 2016. 


In the case of methane, the situation is different than for carbon dioxide:
  • levels at the North Pole are more than 10% higher than at the South Poles, a much larger difference than for carbon dioxide. 
  • methane is reaching its highest levels over the Arctic Ocean from October onward to well into the next year. 
  • methane persists longer over the Arctic due to low hydroxyl levels there. 
  • methane levels over the Arctic Ocean are high, as increasingly large amounts of methane are rising up from the Arctic Ocean seafloor, making that this methane will inherently be highly concentrated over the Arctic, especially shortly after its release. 

In conclusion, it looks like methane is playing an increasingly large role in warming up the Arctic, especially given its large short-term potency as a greenhouse gas.

from: arctic-news.blogspot.com/p/methane.html

AMOC is carrying ever more heat into the Arctic Ocean

Besides methane, there is another big reason why temperature anomalies are so high over Arctic Ocean at this time of year. Huge amounts of heat are rising up from the water into the atmosphere over the Arctic Ocean, warming up the air over the water. The warmer the sea, the less ice will form. The weaker the ice, the more cracks and spots where heat gets transferred to the atmosphere.

The water of the Arctic Ocean is getting warmer, compared to previous years, as the Gulf Stream heats up. When referring to the full length from the Gulf of Mexico to the Arctic Ocean, this current is often referred to as the North Atlantic Meridional Overturning Circulation (AMOC). The direction of AMOC's flow is determined by two forces, i.e. the flow of warm water from the Equator to the north, and the the flow east due to the Coriolis force. The result is warm, salty water is carried by AMOC in the upper layers of the Atlantic toward the north-east, to Arctic Ocean. Eventually, the water sinks and flows back as colder water through the deep Atlantic. As the NOAA image below shows, the amount of heat that has been carried by AMOC toward the Arctic Ocean has been increasing over the past few years.



Overall ocean temperatures are increasing, as discussed in posts such as Ocean Heat and Temperature Rise. As a result, more heat is getting carried toward the Arctic Ocean now. The Gulf Stream off the coast of North America is warming up strongly and is pushing more heat toward the Arctic ocean, compared to previous years. The result is illustrated by the image below, showing huge sea surface temperature anomalies in the Arctic Ocean near Svalbard, despite the cold lid on the north Atlantic, indicating that the heat is continuing to travel underneath the cold freshwater lid to the Arctic Ocean.


Such high sea surface temperature anomalies are not uncommon in the Arctic Ocean these days. The image below shows that on January 24, 2016, sea surface temperature was 12.3°C or 54.2°F at a location near Svalbard marked by the green circle, a 10.4°C or 18.7°F anomaly.

from: Arctic sea ice area at record low for time of year
Water now much warmer off the North American coast

The water off the east coast of North America is much warmer than it used to be due to emissions that extend from North America over the Atlantic Ocean due to the Coriolis force. The image below, from an earlier post, shows carbon dioxide levels as high as 511 ppm over New York on November 5, 2015, and as high as 500 ppm over the water off the coast of coast of New Jersey on November 2, 2015.

from the post: 2015 warmest year on record
The image below shows carbon monoxide levels. Carbon monoxide depletes hydroxyl, making it harder for methane to be oxidized. So again methane appears to be a major factor.

from: Arctic sea ice area at record low for time of year
Such emissions heat up the Gulf Stream and make that ever warmer water is carried underneath the sea surface all the way into the Arctic Ocean. 

Cold freshwater lid on the North Atlantic

Finally, the cold freshwater lid on the North Atlantic makes that less heat transfer occurs from ocean to atmosphere. This cold freshwater lid makes that more heat is flowing toward the Arctic Ocean just below the sea surface of the North Atlantic. 

sea ice speed and drift, forecast for February 18, 2016
This cold freshwater lid is spreading over the North Atlantic for a number of reasons: 
  • more melting of glaciers on Greenland, on Svalbard and in North Canada; 
  • more sea ice drifting into the Atlantic Ocean due to stronger winds. Storms move up the Atlantic in a circular way, speeding up sea ice drift along the edges of Greenland, as illustrated by this video and the images on the right;
  • stronger evaporation off the east coast of North America, with moisture being carried by stronger winds to the north-east, resulting in more precipitation settling on the water and thus freshwater getting added to the North Atlantic, as illustrated by the image below.


As above image also illustrates, this cold freshwater lid on the North Atlantic could also result in more heat being carried into the Arctic Ocean, due to reduced heat transfer to the atmosphere from water on its way to the Arctic Ocean.


Above image illustrates how higher temperatures over the Arctic (top panel) can go hand in hand with the cold freshwater lid over the North Atlantic (second panel), with high sea surface temperatures off the east coast of North America (third panel) and with higher precipitation over this cold freshwater lid (bottom panel).

The image below indicates that the cold freshwater lid on the North Atlantic also goes hand in hand with falling salinity levels.



Precipitation over the North Atlantic is increasing, due to stronger winds and storms there, as discussed in earlier posts such as this one and as illustrated by the images below. Stronger winds, storms with high levels of precipitation and higher waves can all make the cold freshwater lid spread further across the North Atlantic. 


Above image show that waves as high as 17.81 m or 58.4 ft were forecast for the North Atlantic on February 1, 2016, and as high as 17.31 m or 56.8 ft for February 8, 2016.


Conclusion

In conclusion, the danger is that ever more heat will arrive in the Arctic Ocean. This will result in greater melting of the sea ice, in a self-reinforcing feedback loop that makes that more sunlight gets absorbed by the Arctic Ocean (rather than being reflected back into space, as before).

On February 11, 2016, Arctic sea ice had - for this time of year - the lowest extent since satellite records started in 1979, as illustrated by the image below.

The biggest danger is that, as the Arctic Ocean continues to warm, huge amounts of methane will erupt abruptly from the seafloor of the Arctic Ocean, driving up temperatures over the Arctic dramatically and triggering ever more methane eruptions, resulting in a rapid escalation into runaway warming.

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



Over the past 12 months, global warming was felt most strongly over the Arctic Ocean. Over most parts of the Arctic...
Posted by Sam Carana on Thursday, February 11, 2016

Friday 23 October 2015

September 2015 Sea Surface Warmest On Record

Arctic Sea Ice Extent Growth Seals Off Arctic Ocean



Arctic sea ice increased rapidly in October 2015, after reaching its annual minimum in September. As the image below shows, the growing sea ice extent has effectively sealed off the Arctic Ocean from the atmosphere, resulting in less evaporation and heat transfer from the ocean to the atmosphere.

The Naval Research Laboratory 30-days animation (up to October 22, with forecast added up to October 30) on the right shows that sea ice has grown in extent, adding plenty of very thin sea ice, while the existing ice has hardly increased its thickness.

The Buffer Has Gone

Thick sea ice used to extend meters below the sea surface in the Arctic, where it could consume massive amounts of ocean heat through melting this ice into water. As such, thick sea ice acted as a buffer. Over the years, Arctic sea ice thickness has declined most dramatically. This means that the buffer that used to consume massive amounts of ocean heat carried by sea currents into the Arctic Ocean, has now largely gone.

Latent heat loss, feedback #14 on the Feedbacks page
Cold Freshwater Lid on North Atlantic

Meanwhile, especially from 2012, huge amounts of freshwater have run off Greenland, with the accumulated freshwater now covering a huge part of the North Atlantic, acting as a lid that prevents ocean heat to evaporate from the North Atlantic.


Since it's freshwater that is now covering a large part of the surface of the North Atlantic, it will not easily sink in the very salty water that was already there. The water in the North Atlantic was very salty due to the high evaporation, which was in turn due to high temperatures and strong winds and currents. Freshwater tends to stay on top of more salty water, even though the temperature of the freshwater is low, which makes this water more dense. The result of this stratification is less evaporation in the North Atlantic, and less transfer of ocean heat to the atmosphere, and thus lower air temperatures than would have been the case without this colder surface water.

Cold freshwater lid on North Atlantic, feedback #28 on the Feedbacks page
The cold lid over the North Atlantic has meanwhile expanded. Greenland has been experiencing wild weather swings this month, with temperatures shifting from one extreme end of the scale to the other end. The image below shows temperature anomalies on October 17 (left panel), October 23 (center panel) and a forecast for October 30 (right panel). Temperatures are forecast to swing back to the extreme high end of the scale, pushing up temperature anomalies for the Arctic as a whole to as high as 2.37°C on October 30, 2015.

Wild weather swings causing methane releases, feedback #21 on the Feedbacks page
These wild weather swings over Greenland threaten to cause cracks in the ice, with methane hydrates in the ice becoming destabilized, resulting in releases of huge amounts of methane from hydrates and free gas into the atmosphere, as earlier discussed as feedback #21 on the Feedbacks page.

Strong winds have further contributed to extend the cold lid over the North Atlantic, while also making cold air flow from Greenland over the North Atlantic. This is illustrated by the image below, depicting the situation on October 23, 2015, with the left panel showing surface wind speed, while the right panel shows the resulting sea surface temperature anomalies. 


The video below shows surface wind speed forecasts in the Arctic from October 25 to November 1, 2015.



Ocean Temperature Rise

NOAA analysis shows that the global sea surface in September 2015 was the warmest on record, at 0.81°C (1.46°F) above the 20th century average of 16.2°C (61.1°F). On the Northern Hemisphere, the anomaly was 1.07°C (1.93°F).

[ click on image to enlarge ]
Of all the excess heat resulting from people's emissions, 93.4% goes into oceans. Accordingly, the temperature of oceans has risen substantially over the years and - without action - the situation only looks set to get worse.

The Threat

As ocean temperatures continue to rise, especially in the North Atlantic, the Gulf Stream will keep carrying ever warmer water from the North Atlantic into the Arctic Ocean. Without the buffer of thick sea ice to consume the increasing amount of ocean heat, the threat is that ocean heat will increasingly reach the seafloor and unleash huge methane eruptions from destabilizing clathrates. Such large methane eruptions will then warm the atmosphere at first in hotspots over the Arctic and eventually around the globe, while also causing huge temperature swings and extreme weather events, contributing to increasing depletion of fresh water and food supply, as further illustrated by the image below, from an earlier post.
[ click on image at original post to enlarge ]

October 2015 Sea Surface Temperature Update

The North Atlantic continues to be very warm. Sea surface temperature anomalies were as high as 7.9°C or 14.2°F at a location off the east coast of North America on October 22, 2015. Anomalies were 8.1°C or 14.5°F at that same spot on October 16, 2015.


Sea surface temperature anomalies were as high as 7.5°C or 13.6°F at a location near Svalbard on October 25, 2015. On October 9, 2015, sea surface temperatures were as high as 13.1°C or 55.6°F at that same location near Svalbard (marked by green circle on image below), an anomaly of 9.5°C or 17.2°F. These temperatures indicate that the water can be much warmer below the surface than at the surface, and that this warm water is transported by the Gulf Stream below the surface of the North Atlantic into the Arctic Ocean. The animation below switches between the above two dates and also shows that the cold freshwater lid on the North Atlantic has meanwhile extended further south.


In the Bering Strait, warm water also keeps flowing into the Arctic Ocean. At the location marked by the green circle on the image below, sea surface temperatures were as high as 7.3°C or 45.1°F on October 22, 2015, an anomaly of 5.7°C or 10.2°F.


Methane

The images below show high methane concentrations over the Arctic.


Above image shows methane levels at low altitude on October 22, 2015. Because of its height, there are no data at this altitude for Greenland. The image below shows methane concentrations at a higher altitude, with high methane levels showing up over Greenland on October 16, 2015.


Climate Plan

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

Malcolm Light comments

GLOBAL EXTINCTION IS NOW SIX YEARS CLOSER

The following comments refer to Figure 224 below. All historical floating ice appears to have been lost in the Arctic by September 2015 so we can assume that the 5+ year old ice pack has largely gone by this time. The 5+ year old ice pack was only predicted to melt back by 2021.7 consequently this year's volume of ice melting has occurred 6 years earlier than the previous prediction. The previous estimate of the final loss of 1 year Arctic floating ice from polynomial data was 2037.7 which now corrects to 2031.7, 16 years in the future.

Previous estimates of when the average atmospheric global temperature anomaly increase would reach 6°C was 2034.7, by which time massive global extinction would be proceeding. The new corrected time for this event is 2034.7 - 6 = 2028.7 which is 13 years in the future. During the major Permian Extinction event, which was caused by a massive methane build-up in the atmosphere, the mean surface atmospheric temperature increased by 5°C over 13 years. As the present mean global surface atmospheric temperature is already greater than 1°C hotter than the mean, we will be looking at at least a 6°C temperature increase by 2028 with its associated global extinction event. This is a frightening correlation between the new predicted 6°C average global surface atmospheric temperature rise and what is known to have occurred during the major Permian extinction event, both of which were caused by a massive buildup of methane in the atmosphere. We are clearly in for a very rough-hot ride in the next decade as the terminal global extinction event approaches.

Malcolm P.R. Light (Dr)
Earth Scientist
Figure 224. Arctic sea ice melt back times estimated from area, volume and thickness anomalies compared to various extinction zones defined by the global atmosphere temperature field. Credit: Malcolm Light. Click on image to enlarge.

Related

- Ocean Temperature Rise
http://arctic-news.blogspot.com/2014/10/ocean-temperature-rise.html

- Ocean Temperature Rise Continues

- Gulf Stream brings ever warmer water into Arctic Ocean
http://arctic-news.blogspot.com/2015/06/gulf-stream-brings-ever-warmer-water-into-arctic-ocean.html

- The Mechanism leading to Collapse of Civilization and Runaway Global Warming
http://arctic-news.blogspot.com/p/the-mechanism.html

- The Threat of Global Warming causing Near-Term Human Extinction
http://arctic-news.blogspot.com/p/threat.html

- Warming Arctic Ocean Seafloor Threatens To Cause Huge Methane Eruptions
http://arctic-news.blogspot.com/2015/09/warming-arctic-ocean-seafloor-threatens-to-cause-huge-methane-eruptions.html

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



NOAA analysis shows that the global sea surface in September 2015 was the warmest on record, at 0.81°C (1.46°F) above...
Posted by Sam Carana on Friday, October 23, 2015

Saturday 10 October 2015

Arctic Sea Ice 2015 - update 11

Arctic sea ice extent has been growing rapidly recently. The image below shows extent up to October 9, 2015 (marked by red dot).


Below is a comparison of sea ice thickness as on October 6, for the years (from left to right) 2012, 2013, 2014 and 2015. The comparison shows that decline has been strongest where sea ice used to be the thickest, i.e. over 3 meters thick.


One of the reasons why the thickest Arctic sea ice has declined so dramatically over the years is the rising ocean heat that is melting the sea ice from underneath. The image below illustrates the situation on October 5, 2015, when sea surface temperature anomalies were as high as 6.4°C, 7.4°C and 7.3°C (11.5°F 13.2°F and 13.1°F) off the North American coast, and as high as 9.4°C (16.8°F) near Svalbard.


Water temperatures are very high in the Arctic, as further illustrated by the image below showing Arctic sea surface temperature anomalies as at October 9, 2015.



Rising ocean heat is further illustrated by the graph below, showing August sea surface temperature anomalies on the Northern Hemisphere over the years.
The situation is very dangerous, due to feedbacks and their interaction. The thicker sea ice used to act as a buffer, consuming ocean heat in the melting process. Without thicker sea ice, ocean heat threatens to melt the sea ice from below right up to the surface, causing the entire sea ice to collapse. As the sea ice declines, more open water will give rise to stronger winds and waves.

Furthermore, sunlight that was previously reflected back into space will instead be absorbed by the water, causing rapid rise of the temperature of the water. In places such as the East Siberian Arctic Shelf, the water is on a average only 50 m deep, so warmer water is able to reach the seafloor more easily there. As ocean heat keeps rising, there's a growing risk that heat will reach the Arctic Ocean seafloor and destabilize methane hydrates in sediments at the Arctic Ocean seafloor.

The image below shows a non-linear trend that is contained in the temperature data that NASA has gathered over the years, as described in an earlier post. A polynomial trendline points at global temperature anomalies of over 4°C by 2060. Even worse, a polynomial trend for the Arctic shows temperature anomalies of over 4°C by 2020, 6°C by 2030 and 15°C by 2050, threatening to cause major feedbacks to kick in, including albedo changes and methane releases that will trigger runaway global warming that looks set to eventually catch up with accelerated warming in the Arctic and result in global temperature anomalies of 16°C by 2052.

[ click on image to enlarge ]
The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.

Comparison of sea ice thickness on October 6, for the years (from left to right) 2012, 2013, 2014 and 2015, shows that...

Posted by Sam Carana on Saturday, October 10, 2015

Friday 25 September 2015

Warming Arctic Ocean Seafloor Threatens To Cause Huge Methane Eruptions

Rapidly growing 'Seal' over Arctic Ocean



Arctic sea ice extent and especially concentration are now growing rapidly, as illustrated by the Naval Research Lab animation on the right.

This means that the sea ice is effectively sealing off the water of the Arctic Ocean from the atmosphere, reducing the chances of transfer of ocean heat from the water to the atmosphere. Conversely, the risk grows that ocean heat will reach the seafloor.

Furthermore, this seal makes that less moisture evaporates from the water, which together with the change of seasons results in lower hydroxyl levels at the higher latitudes of the Northern Hemisphere, in turn resulting in less methane being broken down in the atmosphere over the Arctic.

Rising Ocean Heat



Water temperatures are very high in the Arctic. Above image shows Arctic sea surface temperature anomalies as at September 24, 2015. The risk of ocean heat reaching the Arctic Ocean seafloor has increased significantly over the years, due to rising ocean heat, as illustrated by the graph below, showing August sea surface temperature anomalies on the Northern Hemisphere over the years. 

[ from the earlier post: August 2015 Had Highest Sea Surface Temperature on Record ]
Ocean heat is increasing because people's emissions are making the planet warmer and more than 93% of the extra heat goes into the oceans.

Ocean temperatures have been measured for a long time. Reliable records go back to at least 1880. Ever since records began, the oceans were colder than they are now. Back in history, there may have been higher temperature peaks - the last time when it was warmer than today, during the Eemian Period, peak temperature was a few tenths of a degree higher than today. In many ways, however, the situation now already looks worse than it was in the Eemian. "The warm Atlantic surface current was weaker in the high latitude during the Eemian than today", says Henning Bauch. Furthermore, carbon dioxide levels during the Eemian were well under 300 ppm. So, there could well have been more pronounced seasonal differences then, i.e. colder winters that made that the average ocean temperature didn't rise very much, despite high air temperature in summer. By contrast, today's high greenhouse levels make Earth look set for a strong ocean temperature rise.

And indeed, this is illustrated by above image, showing a polynomial trendline that points at a rise of almost 2°C by 2030. This trendline is contained in ocean temperature data from 1880 for the August Northern Hemisphere sea surface temperature anomalies.

Cold Freshwater 'Lid' on North Atlantic



Note that the above ocean temperature graph and the above video only show sea surface temperatures. Underneath the surface, water can be even warmer. The Gulf Stream reaches its maximum temperatures off the North American coast in July. It can take some four months for this heat to travel along the Gulf Coast and reach destinations farther in the Arctic Ocean. Water warmed up off Florida in July may only reach waters beyond Svalbard by October or November.

The image below shows that on August 22, 2015, at a location near Florida marked by the green circle, sea surface temperatures were as high as 33.4°C (92.1°F), an anomaly of 3.8°C (6.8°F).


The image below shows sea surface temperatures on August 22, 2015, as an indication of the huge amount of ocean heat has accumulated in the Atlantic Ocean off the coast of North America.


The huge amounts of energy entering the oceans translate into higher temperatures of the water and of the air over the water, as well as higher waves and stronger winds.

Ocean heat carried by the Gulf Stream from Florida via the North Atlantic into the Arctic Ocean.
The image on the left shows that on August 25, 2015, sea surface temperatures near Svalbard were recorded as high as 17.3°C (63.1°F), as marked by the green circle, a 12.1°C (21.8°F) anomaly.

This indicates that ocean heat did reach that location from underneath the sea surface. In other words, subsurface temperatures of the water carried along by the Gulf Stream can be substantially higher than temperatures of the water at the surface, and this can be the case for the water all the way from the coast of North America to the Arctic Ocean.

The Gulf Stream keeps pushing much of this very warm water north, into the Arctic Ocean, where it threatens to unleash huge methane eruptions from the Arctic Ocean seafloor.

The combination image below shows the Gulf stream carrying warm water from the coast of North America into the Arctic Ocean on September 12, 2015, and sea surface reaching temperatures as high as 14.6°C (58.3°F) that day at a location near Svalbard (marked by green circle), an 9.8°C (17.6°F) anomaly

[ click on image to enlarge ]
The combination image below shows that sea surface temperature anomalies still are very high. The left panel shows that anomalies on September 25, 2015 were as high as +6°C (+10.8°F) in the North Atlantic (location marked by green circle), compared to 1901-2011. The right panel shows anomalies on September 26, 2015, in the North Atlantic of +0.81°C (+1.46°F) and in the North Pacific of +1.02°C (+1.84°F), compared to 1971-2000.


Below is an update on the situation. On October 5, 2015, sea surface temperature anomalies were as high as 6.4°C, 7.4°C and 7.3°C (11.5°F 13.2°F and 13.1°F) off the North American coast, and as high as 9.4°C (16.8°F) near Svalbard.


Speed of surface water was as high as 1.6 m/s (3.6 mph) on October 5, 2015. This wasn't as high as some of the speeds reached earlier in the year (a speed of 2.16 m/s or 4.7 mph was recorded on August 15, 2015), but it does indicate how strong the Gulf Stream still is at this time of year. Water speed slows down as the Gulf Stream progresses toward the Arctic Ocean. While speeds as high as 0.22 m/s and 0.24 m/s (0.5 mph) were recorded near Svalbard and Norway, overall speed was a lot lower in this part of the Atlantic.

What is making the situation worse is depicted in the images below. From 2012, huge amounts of freshwater have run off Greenland, with the accumulated freshwater now covering a huge part of the North Atlantic, as illustrated by the image below. 


Since it's freshwater that is now covering a large part of the surface of the North Atlantic, it will not easily sink in the very salty water that was already there. The water in the North Atlantic was very salty due to the high evaporation, which was in turn due to high temperatures and strong winds and currents. As said, freshwater tends to stay on top of more salty water, even though the temperature of the freshwater is low, which makes this water more dense. The result of this stratification is less evaporation in the North Atlantic, and less transfer of ocean heat to the atmosphere, and thus lower air temperatures than would have been the case without this colder surface water.


As meltwater accumulates at the surface of the North Atlantic, will it slow down the Gulf Stream?

More elongated curves and eddies forming where the meltwater meets the Gulf Stream appears to make that it will indeed take longer for surface water to travel from the coast of North America to the Arctic Ocean. However, the speed reached within such eddies may actually be higher. After all, the amount of extra heat that enters the oceans keeps growing and this extra energy will likely translate into warmer water carried in greater volumes and at higher speed by the Gulf Stream underneath the surface of the North Atlantic into the Arctic Ocean, be it that the more curved patterns of the currents will increase the overall time it takes for water to travel the distance, especially at the surface.

Importantly, as global warming continues to heat up the oceans, the accumulated freshwater at the surface of the North Atlantic makes that less ocean heat can be transferred from the water to the atmosphere there, i.e. the freshwater is acting like a lid. Similarly, the Arctic sea ice is acting as a seal over the Arctic Ocean, as seasons change. In conclusion, the highest temperatures of the water of the Arctic Ocean, especially at greater depth, are yet to be reached this year.


Above image illustrates that, while Arctic sea water at the surface reaches its highest temperatures in the months from July to September, water at greater depth reaches its highest temperatures only in October through to the subsequent months.

Methane Eruptions from Arctic Ocean Seafloor

In the Arctic Ocean, this more salty newly-arriving warm water will tend to dive under the freshwater that has formed from the melting of sea ice over the past few months. The danger is thus that warmer water will be pushed into the Arctic Ocean at lower depth, and that it will reach the seafloor of the Arctic Ocean.

Huge amounts of methane are contained in sediments on the Arctic Ocean seafloor. Ice acts like a glue, holding these sediments together and preventing destabilization of methane hydrates. 

Pingos and conduits. Hovland et al. (2006)
Warmer water reaching these sediments can penetrate them by traveling down cracks and fractures in the sediments, and reach the hydrates. The image on the right, from a study by Hovland et al., shows that hydrates can exist at the end of conduits in the sediment, formed when methane did escape from such hydrates in the past. Heat can travel down such conduits relatively fast, warming up the hydrates and destabilizing them in the process, which can result in huge abrupt releases of methane.

Heat can penetrate cracks and conduits in the seafloor, destabilizing methane held in hydrates and in the form of free gas in the sediments.

Elsewhere, methane hydrates will typically be located at great depth, making it more difficult for ocean heat to reach them. In the Arctic, much of the water is very shallow. The East Siberian Arctic Shelf (ESAS) is on average only 50 m deep, making it easier for heat to reach the seafloor and also making that methane that escapes will have to travel through less water, reducing the chances that methane will be broken down by microbes on the way up through the water. Furthermore, hydroxyl levels are very low over the Arctic, making that the methane will not quickly be broken down in the atmosphere over the Arctic either.

The big melt in Greenland and the Arctic in general is causing further problems. Isostatic adjustment following melting can contribute to seismic events such as earthquakes, shockwaves and landslides that can destabilize methane hydrates contained in sediments on the Arctic Ocean seafloor.


Above image shows methane levels as high as 2554 parts per billion, on the morning of September 23, 2015, in the bottom panel, and strong methane releases over the ESAS, as indicated by the solid magenta-colored areas in the top panel, on the afternoon of the previous day at lower altitude. These are indications of methane releases from the seafloor of the Arctic Ocean. Strong winds over the ESAS, as the image below shows, may have contributed, by mixing warm water down to the seafloor.


On the morning of September 25, 2015, methane reached levels as high as 2629 ppb, while mean global level reached a record high 1846 ppb. The video below, created with Climate Reanalyzer images,  shows strong winds over the Arctic for the period September 26 to October 3, 2015.


The video below, created by Cameron Forge with Climate Reanalyzer images, shows Arctic air temperature anomalies end September - early October, 2015.



Air Temperature Rise

NOAA data show that the year-to-date land surface temperature in July was 1.47°C above the 20thcentury average on the Northern Hemisphere in 2015. A polynomial trendline based on these data points at yet another degree Celsius rise by 2030, on top of the current level, which could make it 3.27°C warmer than in 1750 for most people on Earth by the year 2030, as illustrated by the image below.

Will it be 3.27°C warmer by the year 2030?
The image below shows a non-linear trend that is contained in the temperature data that NASA has gathered over the years, as described in an earlier post. A polynomial trendline points at global temperature anomalies of over 4°C by 2060. Even worse, a polynomial trend for the Arctic shows temperature anomalies of over 4°C by 2020, 6°C by 2030 and 15°C by 2050, threatening to cause major feedbacks to kick in, including albedo changes and methane releases that will trigger runaway global warming that looks set to eventually catch up with accelerated warming in the Arctic and result in global temperature anomalies of 16°C by 2052.
[ click on image to enlarge ]
The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.



In the Arctic Ocean, the more salty newly-arriving warm water will tend to dive under the freshwater that has formed...
Posted by Sam Carana on Friday, September 25, 2015