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Tag Archives: feedback loop

Greenland Ice, Changing Albedo, and a Feedback Loop

The BBC reports: Sea Level Fears as Greenland Darkens. The article discusses a possible feedback loop where as temperatures warm algae growth may flourish, which darkens the surface and changes the albedo to increase melting.

One concern now is that rising temperatures will allow algae to flourish not only on the slopes of the narrow margins of the ice-sheet but also on the flat areas in the far larger interior where melting could happen on a much bigger scale.

We joined the latest phase of research in which scientists set up camp on the ice-sheet to gather accurate measurements of the “albedo” or the amount of solar radiation reflected by the surface.

White snow reflects up to 90% of solar radiation while dark patches of algae will only reflect about 35% or even as little as 1% in the blackest spots.

Other highlights from the article include:

Currently the Greenland ice sheet is adding up to 1mm a year to the rise in the global average level of the oceans.

It is the largest mass of ice in the northern hemisphere covering an area about seven times the size of the United Kingdom and reaching up to 3km (2 miles) in thickness.

This means that the average sea level would rise around the world by about seven metres, more than 20ft, if it all melted.

You can get Greenland Ice Data from NASA’s Vital Signs of the Planet page as noted in a past post.

Oceans as a Heat Sink: Possible Feedback Loop

Ocean currents are a complex mechanism that contribute to absorbing CO2 and heat. The NASA article, NASA-MIT study evaluates efficiency of oceans as heat sink – atmospheric gases sponge, discusses the role of ocean currents as part of climate change. The possible feedback loop is suggested by this:

In addition, they found that in scenarios where the ocean current slows down due to the addition of heat, the ocean absorbs less of both atmospheric gases and heat, though its ability to absorb heat is more greatly reduced.

The article includes this must see 40 seconds animation of ocean currents and a engaging 3D graph with the depth of the ocean as the z-axis:

Arctic Ice and Global Warming

An article from this past February, Rapid warming and disintegrating polar ice set the stage for ‘societal collapse’ – Carbon pollution is destabilizing both the Arctic and Antarctic, provides a nice overview of issues of warming and ice. For instance, there is the albedo feedback loop:

Climate models have long predicted that if we keep using the atmosphere as an open sewer for carbon pollution, the ice cap would eventually enter into a death spiral because of Arctic amplification — a vicious cycle where higher temperatures melt reflective white ice and snow, which is replaced by the dark land or blue sea, which both absorb more solar energy, leading to more melting.

The graph here is historical January Arctic ice extent and the data can be downloaded from the National Snow and Ice Data Center Sea Ice Data and Analysis Tools page.  Go to Sea ice analysis data spreadsheets and then to monthly data by year. As you’ll see there is other data there worth exploring. There are projects using Arctic ice data on both the calculus and statistics pages on this blog. If you are a real ice junkie take a look at the interactive sea ice graph and keep track of the current ice extent.  Finally, as a reader of this blog you know that you can make your own global temperature maps like the one in the article from reading April Second Warmest on Record.



A Feedback Loop: The Alaska Tundra

A recent NASA report Alaska tundra source of early-winter carbon emissions provides another example of a feedback loop. Global warming has slowed the refreezing of the Alaska tundra allowing for increased CO2 releases.

A new paper led by Roisin Commane, an atmospheric researcher at Harvard University in Cambridge, Massachusetts, finds the amount of carbon dioxide emitted from northern tundra areas between October and December each year has increased 70 percent since 1975.

“In the past, refreezing of soils may have taken a month or so, but with warmer temperatures in recent years, there are locations in Alaska where tundra soils now take more than three months to freeze completely,” said Commane. “We are seeing emissions of carbon dioxide from soils continue all the way through this early winter period.”

How much carbon is stored in the frozen soils. According to the report

The soils that encircle the high northern reaches of the Arctic (above 60 degrees North latitude) hold vast amounts of carbon in the form of undecayed organic matter from dead vegetation. This vast store, accumulated over thousands of years, contains enough carbon to double the current amount of carbon dioxide in Earth’s atmosphere.

Methane Bubbles – A Feedback Loop

The Siberian Times brings us this article: 7,000 underground gas bubbles poised to ‘explode’ in Arctic

Their appearance at such high latitudes is most likely linked to thawing permafrost which in is in turn linked to overall rise of temperature on the north of Eurasia during last several decades,’ said a spokesman.

The summer was abnormally hot for the Yamal peninsula, with the air temperature reaching 35C.

This heat impacted on the depth of seasonal thawing which grew both deeper  spread wider than in the past, so causing the formation of new lakes and a noticeable change in the regional tundra landscape.

Scientists are simultaneously observing the sudden formation of the large craters, evidently caused by eruptions or explosions of methane gas which has melted below the surface.

This is another situation where warming permafrost is related to the release of the greenhouse gas methane, which then adds to warming. In other words, a positive feedback loop. There are some excellent photos in the article.

Melting Permafrost and a Feedback Loop

The BBC has a great article on a Siberian crater, the Batagaika crater, that is growing quickly due to melting permafrost. Excerpt from the article:

As more permafrost thaws, more and more carbon is exposed to microbes. The microbes consume the carbon, producing methane and carbon dioxide as waste products. These greenhouse gases are then released into the atmosphere, accelerating warming further.

“This is what we call positive feedback,” says Günther. “Warming accelerates warming, and these features may develop in other places. It’s not only a threat to infrastructure. Nobody can stop this development. There’s no engineering solution to stop these craters developing.”

The article provides some great context in understanding the impacts of global warming.