Showing posts with label meltwater. Show all posts
Showing posts with label meltwater. Show all posts

Thursday, June 11, 2015

Gulf Stream brings ever warmer water into Arctic Ocean


The image below shows sea surface temperature anomalies in the Arctic as at June 9, 2015.


The image below shows the Arctic from a 180° rotated angle, while also showing the high sea surface temperature anomalies that are so prominent in the North Pacific (note also that the scale of sea surface temperature anomalies differs).



One may wonder why sea surface temperature anomalies below zero are visible in the North Atlantic, given that ocean heat is rising rapidly. As the IPCC said in AR5, more than 60% of the net energy increase in the climate system is stored in the upper ocean (0–700 m) during the relatively well-sampled 40-year period from 1971 to 2010, and about 30% is stored in the ocean below 700 m.

Global heat content at 0-2000 m is rising even faster than at 0-700 m 
The image below further pictures the situation as at June 9, 2015, with large blue and purple areas showing in the North Atlantic where meltwater from the Arctic has spread over time.



Indeed, the accumulation of meltwater over time has created a huge area with relatively cold water that tends to float at the surface, rather than sink, as the meltwater's salt content is very low.

In other words, the ocean underneath the meltwater at the sea surface is much warmer than the temperatures shown on above images. This can be illustrated by the situation near Svalbard. The image below shows the depth of Barents Sea, which is relatively shallow around Svalbard,


As the image shows, cold meltwater with low salt content floats around Svalbard where the water is most shallow. A 'polar front' separates cold and warm water, following the borders of the area where the seafloor is high. Warm, salty water is carried by the Gulf Stream from the (much deeper) Atlantic Ocean into the Arctic Ocean. This warm water collides with cold water east of Svalbard where the seafloor rises steeply, making this warm water come to the surface. 

Warm water from the Atlantic also comes to the surface west of Svalbard, where warm and cold water are similarly separated by the height of the seafloor. 

The image below shows that on June 8, 2015, sea surface temperatures as high as 11.4°C (52.52°F) were recorded to the south-east of Svalbard (a 9.8°C or 17.64°F anomaly), while sea surface temperatures as high as 7.4°C (45.32°F) were recorded to the west of Svalbard (a 3.5°C or 6.3°F anomaly). 

Sea surface temperatures (top) and sea surface temperature anomalies (bottom) on June 8, 2015.
The image below shows the situation on June 21, 2015, when sea surface temperatures as high as 12.5°C (54.5°F) were recorded to the south-east of Svalbard (a 10.2°C or 18.4°F anomaly), while sea surface temperatures as high as 8.5°C (47.3°F) were recorded to the west of Svalbard (a 3.7°C or 6.7°F anomaly) and as high as 7.3°C (45.1°F) further west of Svalbard (a 3.7°C or 6.7°F anomaly).

Sea surface temperatures (top) and sea surface temperature anomalies (bottom) on June 21, 2015.
These spots where warm water comes to the surface give an indication of how high temperatures of the water are below the surface. As more than 90% of the extra heat caused by people's emissions continues to go into oceans, ever warmer water will be carried by the Gulf Stream into the Arctic Ocean, with the danger that this will warm up sediments under the Arctic Ocean seafloor, triggering huge methane eruptions with gigantic warming potential.

The above images picture the situation as at June 8 and June 21, 2015, when summer on the Northern Hemisphere had just started. In other words, temperatures will rise over the next few months. To get an idea of what can be expected, the image below shows the situation as at September 1, 2014, when sea surface temperatures near Svalbard were as high as 17.5°C (or 63.5°F), an anomaly of 11.9°C (or 21.42°F)

Sea surface temperatures (top) and sea surface temperature anomalies (bottom) on September 1, 2014.
On the combination image below, the image on the left shows large areas (red circles) where warmer water is visible through the sea ice, indicating the presence of even warmer water at greater depth in the Arctic Ocean. The image on the right (from an earlier post) roughly shows how ocean heat can be carried by the Gulf Stream from the Atlantic Ocean off the coast of North America into the Arctic Ocean, diving under the sea ice somewhere between Greenland and Svalbard.


Then, there is also the impact of the heat wave in Russia warming up the Arctic Ocean, as indicated by the red circle on the image below.


The image below shows May Northern Hemisphere ocean temperature anomalies with respect to the period 1901-2000, based on NOAA data and with a polynomial trendline added.



ACCELERATED WARMING IN ARCTIC CAUSING MORE CIRRUS CLOUDS

As oceans warm, the atmosphere can be expected to carry more water vapor. This conclusion is supported by studies such as this one. With more water vapor in the atmosphere, storms can be expected to strike with greater intensity. This conclusion is supported by studies such as this one. This situation gets worse as weather gets more extreme.

What makes things even worse is that, as the Gulf Stream keeps bringing ever warmer water into the Arctic Ocean, loss of sea ice in the Arctic Ocean and more open water will be the result. More open water means more opportunity for storms to develop and for water to evaporate into the atmosphere. The combination of more open water, more extreme weather, and more water vapor in the atmosphere leads to ever more severe storms that can come with destructive winds and that can suddenly unleash massive amounts of precipitation.

Studies such as this one warn that plumes above the anvils of severe storms can bring water vapor up into the stratosphere, contributing to the formation of cirrus clouds that block a lot of heat that would otherwise be radiated away, from Earth into space.

More cirrus clouds thus is another self-reinforcing feedback loop of accelerated warming in the Arctic. As the Gulf Stream keeps bringing ever warmer water into the Arctic Ocean, such feedbacks will further speed up warming, as discussed at the feedbacks page.

Are there geoengineering methods to reduce cirrus clouds? Seeding of high altitude clouds with ice may be able to do this, resulting in more longwave radiation escaping into space, as discussed in this study.

The text in this box was also posted at the Geoengineering group at facebook

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


on June 8, 2015, sea surface temperatures as high as 11.4°C (52.52°F) were recorded to the south-east of Svalbard (a 9.8...
Posted by Sam Carana on Thursday, June 11, 2015

Monday, May 25, 2015

Sleeping Giant in the Arctic



Huge amounts of carbon are contained in sediments, soils and vegetation in the Arctic. Rising temperatures in the Arctic threaten to cause much of this carbon to be released to the atmosphere.

On May 23, 2015, temperatures in Alaska were as high as 91°F (32.78°C), as illustrated by the image below.

[ image credit: US National Weather Service Alaska ]
High temperatures were reached at the city of Eagle, located on the southern bank of the Yukon River, at an elevation of 853 ft (260 m). High temperatures at such a location will cause meltwater, aggravating the situation well beyond the local area.
A bank of permafrost thaws near the Kolyma
River in Siberia. Credit: University of Georgia

Carbon contained in soils will thus become increasingly exposed under the combined impact of rising temperatures and the associated growing amounts of meltwater. The meltwater can additionally cause erosion further downstream, thus making carbon at many locations become more prone to be consumed by microbes and released into the atmosphere in the form of carbon dioxide and methane.

A recent study found that, at a location where the Kolyma river in Siberia carved into the permafrost and exposed the carbon, microbes converted 60% of the carbon into carbon dioxide in two weeks time.

Gary Houser, who recently launched the movie Sleeping Giant in the Arctic, elaborates on the threat of emissions from thawing permafrost:
This immense release would likely feed on itself, raising temperatures that continue melting more and more permafrost in a vicious, frightening, and unstoppable cycle. A tipping point could well be crossed, at which time human intervention is no longer possible. Temperatures across the planet could soar, setting in motion catastrophic levels of drought and food shortage. All life support systems on earth and life forms themselves could be placed under severe stress.

The colossal scale of the danger - and the observation of those factors lining up that could trigger it - demand that humanity exercise the precautionary principle. All political decision-making related to carbon emissions must be based on the understanding that a catastrophic consequence is looming, and the window of time for prevention quickly diminishing.
SLEEPING GIANT IN THE ARCTIC:
Can Thawing Permafrost Cause Runaway Global Heating?
by Gary Houser



Sources: 

US National Weather Service Alaska

University of Georgia

Sleeping Giant in the Arctic


Sleeping Giant in the Arctic http://arctic-news.blogspot.com/2015/05/sleeping-giant-in-the-arctic.html

Posted by Sam Carana on Monday, May 25, 2015