Ocean Heat Depth

Ocean Heat Depth

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Unknown 12/04/2015 Add Comment

Ocean heat at the equator

On November 24, 2015, equatorial waters at ≈100 m (328 ft) depth at 110-135°W were over 6°C (10.8°F) warmer than average in 1981-2000, as illustrated by above image. The animation below shows equatorial ocean heat over the past few months, illustrating that temperature anomalies greater than 6°C (10.8°F) occurred throughout this period at depths greater than 100 m (328 ft).

The danger of ocean heat destablizing clathrates in the Arctic

The danger is that ever warmer water will reach the seafloor of the Arctic Ocean and destabilize methane that is held there in sediments the form of free gas and hydrates.

So, how comparable is the situation at the equator with the situation in the Arctic? How much heating of the Arctic Ocean has taken place over the past few years?

The image on the right, produced with NOAA data, shows mean coastal sea surface temperatures of over 10°C (50°F) in some areas in the Arctic on August 22, 2007.

In shallow waters, heat can more easily reach the bottom of the sea. In 2007, strong polynya activity caused more summertime open water in the Laptev Sea, in turn causing more vertical mixing of the water column during storms in late 2007, according to this study, and bottom water temperatures on the mid-shelf increased by more than 3°C (5.4°F) compared to the long-term mean.

This study finds that drastic sea ice shrinkage causes increase in storm activities and deepening of the wind-wave-mixing layer down to depth ~50 m (164 ft) that enhance methane release from the water column to the atmosphere. Indeed, the danger is that heat will warm up sediments under the sea, containing methane in hydrates and as free gas, causing large amounts of this methane to escape rather abruptly into the atmosphere.

The image below, replotted by Leonid Yurganov from a study by Chepurin et al, shows sea water temperature at different depths in the Barents Sea, as described in an earlier post.

The image below is from a study published in Nature on November 24, 2013, showing water temperatures measurements taken in the Laptev Sea from 1999-2012.

Water temperatures in Laptev Sea. Red triangles: summer. Blue triangles: winter. Green squares: historic data.
From Shakhova et al., (2013) doi:10.1038/ngeo2007

Before drawing conclusions, let's examine some peculiarities of the Arctic Ocean more closely, specifically some special conditions in the Arctic that could lead to greater warming than elsewhere and feedbacks that could accelerate warming even more.

Amount of methane ready for release

Sediments underneath the Arctic Ocean hold vast amounts of methane. Just one part of the Arctic Ocean alone, the East Siberian Arctic Shelf (ESAS, rectangle on map below, from the methane page), holds up to 1700 Gt of methane. A sudden release of just 3% of this amount could add over 50 Gt of methane to the atmosphere, and experts consider such an amount to be ready for release at any time (see above image).



Total methane burden in the atmosphere now is 5 Gt. The 3 Gt that has been added since the 1750s accounts for almost half of the (net) total global warming caused by people. The amount of carbon stored in hydrates globally was in 1992 estimated to be 10,000 Gt (USGS), while a more recent estimate gives a figure of 63,400 Gt (Klauda & Sandler, 2005). The ESAS alone holds up to 1700 Gt of methane in the form of methane hydrates and free gas contained in sediments, of which 50 Gt is ready for abrupt release at any time.



Imagine what kind of devastation an extra 50 Gt of methane could cause. Imagine the warming that will take place if the methane in the atmosphere was suddenly multiplied by 11.

Whiteman et al. recently calculated that such an event would cause $60 trillion in damage. By comparison, the size of the world economy in 2012 was about $70 trillion.

Shallow waters in the Arctic Ocean

Shallow waters and little hydroxyl

The danger is particularly high in the shallow seas that are so prominent in the Arctic Ocean, as illustrated by the light blue areas on the image on the right, from an earlier post.

Much of the waters in the Arctic Ocean are less than 50 m deep. Being shallow makes waters prone to warm up quickly during summer temperature peaks, allowing heat to penetrate the seabed.

This can destabilize hydrates and methane rising through shallow waters will then also enter the atmosphere more quickly, as it rises abruptly and in plumes.

Elsewhere in the world, releases from hydrates underneath the seafloor will largely be oxidized by methanotroph bacteria in the water and where methane does enter the atmosphere, it will quickly be oxidized by hydroxyl. In shallow waters, however, methane released from the seabed will quickly pass through the water column.

Large abrupt releases will also quickly deplete the oxygen in the water, making it harder for bacteria to break down the methane.

Very little hydroxyl is present in the atmosphere over the poles, as illustrated by the image on the right, showing global hydroxyl levels, from an earlier post.

In case of a large abrupt methane release from the Arctic Ocean, the little hydroxyl that is present in the atmosphere over the Arctic will therefore be quickly depleted, and the methane will hang around for much longer locally than elsewhere on Earth.

Shallow waters make the Arctic Ocean more prone to methane releases, while low hydroxyl levels make that methane that enters the atmosphere in the Arctic will contribute significantly to local warming and threaten to trigger further methane releases.

High levels of insolation in summer in the Arctic

Furthermore, the amount of solar radiation received by the Arctic at the June Solstice is higher than anywhere else on Earth, as illustrated by the image below, showing insolation on the Northern Hemisphere by month and latitude, in Watt per square meter, from an earlier post.

Warm water enters Arctic Ocean from Atlantic and Pacific Oceans

What further makes the situation in the Arctic particularly dangerous is that waters are not merely warmed up from the top down by sunlight that is especially strong over the Arctic Ocean in summer on the Northern Hemisphere, but also by warm water that flows into the Arctic Ocean from rivers and by warm water that enters the Arctic Ocean through the Bering Strait and through the North Atlantic Ocean. The latter danger is illustrated by the image below, from an earlier post.

Feedbacks

Furthermore, there are feedbacks that can rapidly accelerate warming in the Arctic, such as albedo losses due to loss of sea ice and snow cover on land, and changes to the jet stream resulting in more extreme weather. These feedbacks, described in more details at this page, are depicted in the image below.

Methane

Above image shows that methane levels on December 3, 2015, were as high as 2445 parts per billion (ppb) at 469 millibars, which corresponds to an altitude of 19,810 feet or 6,041 m.

The solid magenta-colored areas (levels over 1950 ppb) that show up over a large part of the Arctic Ocean indicate very strong methane releases.

Note there are many grey areas on above image. These are areas where no measurements could be taken, which is likely due to the strength of winds, rain, clouds and the jet stream, as also illustrated by the more recent (December 5, 2015) images on the right.

The polar jet stream on the Northern Hemisphere shows great strength, with speeds as high as 243 mph or 391 km/h (over a location over japan marked by green circle) on December 5, 2015.

So, high methane levels may well have been present in these grey areas, but didn't show up due to the weather conditions of the moment.

Furthermore, the white geometric areas are due the way the satellite takes measurements, resulting in areas that are not covered.

Finally, it should be noted that much of the methane will have been broken down in the water, before entering the atmosphere, so what shows up in the atmosphere over the Arctic is only part of the total amount of methane that is released from the seafloor.

In conclusion, the high methane levels showing up over the Arctic indicate strong methane releases from the seafloor due to warm waters destabilizing sediments that contain huge amounts of methane in the form of free gas and hydrates.

Climate Plan

As global warming continues, the risk increases that greater ocean heat will reach the Arctic Ocean and will cause methane to be released in large quantities from the Arctic Ocean seafloor. The 2015 El Niño has shown that a huge amounts of ocean heat can accumulate at a depth greater than 100 m (328 ft). Conditions in the Arctic and feedbacks make that methane threatens to be released there abruptly and in large quantities as warming continues.

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

On November 24, 2015, equatorial waters at ≈100 m (328 ft) depth at 110-135°W were over 6°C (10.8°F) warmer than average...
Posted by Sam Carana on Friday, December 4, 2015

Ocean Heat

Ocean Heat

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Unknown 11/09/2015 Add Comment

Sea Surface Temperatures

Sea surface temperatures were as high as 15.8°C or 60.4°F near Svalbard on November 7, 2015, a 13.7°C or 24.7°F anomaly. Let this sink in for a moment. The water used to be close to freezing point near Svalbard around this time of year, and the water now is warmer by as much as 13.7°C or 24.7°F.

[ click on image to enlarge ]

Above image further shows that sea surface temperature anomalies as high as 6.7°C or 12.1°F were recorded on November 7, 2015, off the coast of North America, while anomalies as high as 6°C or 10.9°F were recorded in the Bering Strait.

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 ]

How did temperatures get so high near Svalbard? The answer is that ocean currents are moving warm water from the Atlantic Ocean into the Arctic Ocean. The ocean is warmer underneath the sea surface and at that location near Svalbard warm water from below the surface emerges at the surface.

Ocean Heat

The oceans are warming up rapidly, especially the waters below the sea surface. 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.

NOAA's ocean heat content figures for 0-2000 m are very worrying, as illustrated by the image below.

The image below was created with data for January through to March, while adding non-linear trendlines for ocean heat at depths of 0-700 m and 0-2000 m. For growth of ocean heat content for 0-700 m, a polynomial trend is added, while for growth of ocean heat content for 0-2000 m an exponential trend is added.

[ click on images to enlarge ]

The image below shows a polynomial trend based on all available quarterly data for ocean heat content from 0 to 2000 m. The trendline shows even faster growth.

The danger is that, as ocean heat continues to grow, ocean currents will keep carrying ever warmer water from the Atlantic and Pacific Oceans into the Arctic Ocean.

Merely watching temperatures at the surface of the ocean may underestimate the warming that is taking place below the sea surface. At the sea surface, evaporation takes place that cools the water. Furthermore, melting of sea ice and glaciers will make that a layer of cold freshwater spreads at the surface, preventing much transfer of heat from the ocean to the atmosphere, as discussed at this earlier post. The blue-colored areas on the Northern Hemisphere on the top image are partly the result of this meltwater. There is another reason why these areas are relatively cool, i.e. sulfates, as further discussed in the section below.

Aerosols

Particulates, in particular sulfate, can provide short-term cooling of the sea surface. Large amounts of sulfate are emitted from industrial areas in the east of North America and in East Asia. On the Northern Hemisphere, the Coriolis effect makes that such emissions will typically reach areas over the nearby ocean to the east of such industrial areas, resulting in the sea surface there being cooled substantially, until the particulates have fallen out of the sky. Since the sulfate is emitted on an ongoing basis, the cooling effect continues without much interruption.

[ click on image to enlarge ]

This sulfate has a cooling effect on areas of the sea surface where ocean currents are moving warm water toward the Arctic Ocean. Because the sea surface gets colder, there is less evaporation, and thus less heat transfer from the ocean to the atmosphere during the time it takes for the water to reach the Arctic Ocean. As a result, water below the sea surface remains warmer as it moves toward the Arctic Ocean.

Similarly, as illustrated by above image, sulfur dioxide emitted in industrial areas in North America and East Asia can extend over the oceans, cooling the surface water of currents that are moving water toward the Arctic Ocean.

Methane

The image below shows that atmospheric methane levels in 2014 were 1833 parts per billion (WMO data) or 254% the pre-industrial level. WMO data are for 1984-2014 and are marked in red, while IPCC data (AR5) are for the years 1755-2011 and are marked in blue.

The image below shows the rise of methane levels from 1984 created with World Metereological Organization (WMO) data. The square marks a high mean 2015 level, from NOAA's MetOp-2 satellite images, and it is added for comparison, so it does not influence the trendline, yet it does illustrate the direction of rise of methane levels and the threat that global mean methane levels will double well before the year 2040.

The image below illustrates the danger that large amounts of methane will erupt from the Arctic Ocean, particularly in East Siberian Arctic Shelf, where the sea is quite shallow, so much of the methane can reach the atmosphere without being broken down by microbes on the way up through the water column.

The video below shows how methane concentrations start to rise close to sea level, and how concentrations strengthen at higher altitudes, and to eventually get lower at even higher altitudes.

The Threat

Ocean heat threatens to increasingly reach the seafloor of the Arctic Ocean 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 ]

The image below gives an indication of the ocean heat that is pushed by the Gulf Stream toward the Arctic Ocean. Note that this image shows the situation on November 15, 2015. Water off the east coast of North America is even warmer at the peak of the Northern Hemisphere summer and it is this water that is now arriving in the Arctic Ocean.

Below is a radio version of this post, roughly as read by Debba Kale Earnshaw at this episode and the next episode of extinctionradio.org

Malcolm Light comments:

To a geologist-oceanographer, the increasing rate of heat gain in the deep water seems obvious. Massive quantities of heat are generated in the earth's interior by radioactivity and find their way to the surface in rising convection systems to erupt along mid-ocean ridges as basaltic lava flows, pushing the plates apart. Under normal circumstances, prior to the arrival of civilized man, the plates cooled as they expanded by passing their heat into the oceans, which then was radiated into space.

Now, with the fast evolving atmospheric greenhouse Arctic methane global warming veil. the heat is simply being reflected back into the oceans and onto the land. Therefore, just like a pressure cooker, the Earth's interior heat is becoming trapped more and more and of course the end result will be a final blow-out. The more than 400 thousand years of ice core data show that we can expect a massive atmospheric methane peak caused by destabilization of the Arctic subsea methane hydrates very soon (8 to 16 years away) and it will produce a Permian style extinction event with a temperature increase of some 8 to 10 degrees C.

Climate Plan

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

Sea surface temperatures were as high as 15.8°C or 60.4°F near Svalbard on November 7, 2015, a 13.7°C or 24.7°F anomaly....
Posted by Sam Carana on Monday, November 9, 2015

Arctic Sea Ice 2015 - update 11

Arctic Sea Ice 2015 - update 11

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Unknown 10/10/2015 Add Comment

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.

[ from the earlier post: August 2015 Had Highest Sea Surface Temperature on Record ]

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

Cyclones continue to hit Northern Hemisphere

Cyclones continue to hit Northern Hemisphere

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Unknown 10/01/2015 Add Comment

As the 2015 El Niño gets stronger, the Northern Hemisphere continues to get hit by strong winds and cyclones. The image below shows strong winds over the Arctic Ocean, as hurricane Joaquin approaches the coast of North America.



On above image, hurricane Joaquin is clocked at a speed of 79 mph (127 km/h) on October 1, 2015. NOAA warned that on that day the maximum sustained wind speed had increased to near 120 mph (195 km/h) with higher gusts.

For reference, NOAA uses four categories:
D: Tropical Depression – wind speed less than 39 mph (63 km/h)
S: Tropical Storm – wind speed between 39 mph and 73 mph (63 km/h - 118 km/h)
H: Hurricane – wind speed between 74 mph and 110 mph (118 km/h - 177 km/h)
M: Major Hurricane – wind speed greater than 110 mph (over 177 km/h)

NOAA issued the image below on September 30, 2015, warning that Hurricane Joaquin is likely to cause wind damage across a large part of the eastern coast of North America.

The NOAA animation below gives an idea of the strength of hurricane Joaquin.

[ click on image to enlarge, note that this is a 1.4 MB file that may take some time to fully load ]

Meanwhile, sea surface temperatures off the North American coast, as well as in the Arctic Ocean, are very high, as illustrated with the image on the right.

In the Arctic Ocean, the sea ice in many places is now less thick than it was in 2012, as illustrated by the image further below, showing sea ice thickness on October 7, 2012 (panel left) and a forecast for October 7, 2015 (panel right).

The water in the Arctic Ocean was already very warm this year. The main factor causing both these strong winds and the dramatic decrease in thickness of the multi-year sea ice is ocean heat, as also illustrated by the image below, showing high sea surface temperature anomalies in the Arctic as at September 30, 2015.

As the image below shows, nearly all the thick (over 3 m) multi-year sea ice has now disappeared, setting up a dangerous situation for the future that is much more dangerous than the situation was back in 2012. 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 more open water will go hand in hand with stronger winds and waves. In case of such a collapse, 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.

The water of the Arctic Ocean is very warm, not only at the surface, but even more so underneath the surface. The danger is that strong winds will mix warm water all the way down to the seafloor, where it could destabilize sediments that can contain huge amounts of methane in the form of hydrates and free gas.

[ click on image to enlarge ]

The image on the right illustrates the impact of winds over the East Siberian Arctic Shelf on September 26, 2015.

NSIDC specialist Julienne Stroeve recently warned: "In 2007 more than 3m of bottom melt was recorded by [an] ice mass balance buoy in the region, which was primarily attributed to earlier development of open water that allowed for warming of the ocean mixed layer. But perhaps some of this is also a result of ocean mixing."

As discussed in an earlier post, sea surface anomalies of over 5°C were recorded in August 2007 in the Arctic Ocean. Strong polynya activity caused more summertime open water in the Laptev Sea, in turn causing more vertical mixing of the water column during storms in late 2007 and bottom water temperatures on the mid-shelf increased by more than 3 degrees Celsius compared to the long-term mean.

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

As the 2015 El Niño gets stronger, the Northern Hemisphere continues to get hit by strong winds and cyclones. The image...
Posted by Sam Carana on Thursday, October 1, 2015

Warming Arctic Ocean Seafloor Threatens To Cause Huge Methane Eruptions

Warming Arctic Ocean Seafloor Threatens To Cause Huge Methane Eruptions

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Unknown 9/25/2015 Add Comment

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