Ocean Heat Overwhelming North Atlantic

Ocean Heat Overwhelming North Atlantic

Arctic sea ice extent on June 19, 2016, was at a record low for the time of the year, as the (updated) image below shows.

[ image from JAXA ]
Not only is Arctic sea ice extent at record low for time of year, the sea ice is also rapidly getting thinner, more fractured, lower in concentration and darker in color. 

[ Cracks in sea ice north of Greenland on June 19, 2016, created with Arctic-io image ]
On the morning of June 20, 2016, strong methane releases were recorded over the water north of Greenland, as well as east of Greenland, as illustrated by the image below.

The image below shows that on the morning of June 20, 2016, mean global methane levels had increased be several parts per billion over a large altitude range, compared to the two previous days. Methane levels at selected altitudes on days in July 2015 and December 2015 are added for reference.
[ click on images to enlarge ]
Temperatures in the Arctic are rising, as illustrated by the image below, showing that on June 19, 2016, temperatures were as high as 31.4°C or 88.4°F over the Mackenzie River (green circle) which ends in
the Arctic Ocean (and thus warms up the Arctic Ocean there).


On June 20, 2016, the Sun will reach its highest point (Solstice), and the Arctic will have 24 hours sunlight, i.e. on the Arctic Circle (latitude 66.56° north) or higher. The Arctic is about 20,000,000 square km (7,700,000 square miles) in size and covers roughly 4% of Earth's surface. Insolation during the months June and July is higher in the Arctic than anywhere else on Earth, as illustrated by the image below, by Pidwirny (2006).


Sea surface temperature near Svalbard was as high as 55°F (or 12.8°C, at the green circle) on June 14, 2016, an anomaly of 19.6 °F (or 10.9°C) from 1981-2011, as illustrated by the image below.


[ click on images to enlarge ]
Above image, created with nullschool.net, further shows that the cold lid that had been growing so prominently in extent over the North Atlantic over the past few years, has shrunk substantially. By comparison, the cold area over the North Pacific has grown larger. This is further confirmed by the image on the right, created with NASA maps and showing ocean temperature anomalies for May 2016.

Plenty of meltwater has run off from Greenland in 2016, as illustrated by the NSIDC.gov image on the right. The run-off from Alaska and Siberia into the Pacific seems less by comparison than the run-off into the North Atlantic. So, how could it be that the cold area in the North Pacific has grown larger than the cold area in the North Atlantic?
[ click on images to enlarge ]

Could there be another factor influencing the size of these cold areas in the North Atlantic and the North Pacific?

The image below, created with NOAA images, gives a comparison between the situation on June 1, 2015 (top), and June 1, 2016 (bottom), showing anomalies from 1961-1990.


The difference is striking, especially when considering the strength of the colder anomalies (from 1961-1990). Besides meltwater, something else must be influencing the size and strength of these anomalies in the North Atlantic and the North Pacific in different ways. Quite likely, the difference is caused by the Global Ocean Conveyor Belt (or thermohaline circulation), which is carrying warm water into the North Atlantic, while carrying cold water out of the North Atlantic. In the North Pacific, it is doing the opposite, i.e. carrying cold water in, while carrying warm water out of the North Pacific.

[ Note that this animation is a 2.3 MB file that make take some time to fully load ]
In conclusion, there are several factors that are influencing the situation, including the influence El Niño has had and the impact La Niña will have, and changes to ocean currents. Even if the Conveyor Belt may slow down, more important than its speed is how much heat it will carry into Arctic Ocean. The image below shows a trend pointing at the water on the Northern Hemisphere getting 2 degrees Celsius warmer well before the year 2030, compared to the 20th century average.

If such trends continue or even strengthen, ever warmer water will be carried from the North Atlantic into the Arctic Ocean, overwhelming possible cooling due to meltwater run-off. Since the Atlantic inflow is about 10 times greater in volume than the Pacific inflow, the net result will be further speeding up of the warming of the Arctic Ocean.

A warmer Arctic Ocean will speed up decline of the sea ice, causing more sunlight to be absorbed by the Arctic Ocean, as one of the feedbacks that are further accelerating warming of the Arctic Ocean. Feedback #14 refers to (latent) heat that previously went into melting. With the demise of the sea ice, an increasing proportion of the ocean heat gets absorbed by the Arctic Ocean.

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 sea ice is in a bad shape, as also illustrated by the above concentration comparison, between June 24, 2012, and a forecast for June 24, 2016.


As above comparison shows, the sea ice is now also much thinner than it was in 2012. 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
The danger is that heat will reach the seafloor and will destabilize methane hydrates contained in sediments at the seafloor of the Arctic Ocean.

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


Links

- NASA Study Finds Atlantic 'Conveyor Belt' Not Slowing (March 25, 2010)
jpl.nasa.gov/news/news.php?release=2010-101

- Arctic Ocean Circulation: Going Around At the Top Of the World, by Rebecca Woodgate (2013)
nature.com/scitable/knowledge/library/arctic-ocean-circulation-going-around-at-the-102811553

- Pidwirny, M. (2006). "Earth-Sun Relationships and Insolation". Fundamentals of Physical Geography, 2nd Edition. 
physicalgeography.net/fundamentals/6i.html
Next
« Prev Post
Previous
Next Post »