Sunday, 15 March 2015

Strong Winds And Waves Batter Arctic Sea Ice

As Earth warms, the intensity of storms is rising across the globe. At least eight people died in Vanuatu, as it was hit by Cyclone Pam. "It hit Port Vila at an incredible 340 kilometres an hour", mentions a recent news report. The left part of the image below shows Cyclone Pam reaching speeds as high as 144 kilometers an hour (89.48 mph, green circle) on March 12, 2015, 1500Z, while three further cyclones feature on the Southern Hemisphere. 

At the same time, on the Northern Hemisphere, winds reached speeds as high as 101 km/h (62.76 mph, bottom green circle), 120 km/h (74.56 mph, middle green circle) and 112 km/h (69.59 mph, top green circle), as shown on the right part of above image.

The image on the right shows winds with speeds as high as 125 km/h (77.67 mph) batter the coast of Greenland on March 13, 2015 (green circle).

The image below shows strong winds moving from the North Atlantic into the Arctic Ocean on March 13, 2015. 

The video below, with forecasts for March 13 - 20, 2015, shows strong winds battering the Arctic Ocean at both the Pacific and Atlantic ends.

The combination image below shows winds around Greenland (top) and winds penetrating the Arctic Ocean (bottom).

Waves as high as 41.5 ft (12.65 m) were recorded between Svalbard and Norway on March 13, 2015 (green circle on the left part of the image below), while waves as high as 23.13 ft (7.05 m) were recorded close to the edge of the sea ice on March 15, 2015 (green circle on the right part of the image below).

The updated image below shows waves higher than 10 m (33 ft) near Svalbard close to the edge of the sea ice on March 16, 2015 (green circle).

Meanwhile, it more and more looks like the 2015 sea ice extent maximum was reached on February 25, as illustrated by the image below.

The image below (added later, ed.) shows Arctic sea ice area up to March 18, 2015 (top), and Arctic sea ice extent up to March 20, 2015 (bottom). Briefly, the difference between area and extent could be compared to Swiss cheese. Area is the cheese without the holes, while extent measures the cheese in addition to the holes. For more on this, see this NSIDC FAQ.

Strong winds can cause high waves that can break up the sea ice. At the same time, strong winds can speed up currents that push sea ice out of the Arctic Ocean, while bringing warmer water into the Arctic Ocean, as illustrated by the image below.

The image below shows sea surface temperatures of 20.9°C (69.62°F, green circle left) recorded off the coast of North America on March 14, 2015, an anomaly of 12.3°C or 26.54°F.

[ click on image to enlarge ]
The image below shows sea surface temperature anomalies in the Arctic Ocean on March 15, 2015.

The big danger is that warm water will trigger further releases of methane from the seafloor of the Arctic Ocean. Peak daily methane levels recorded in early 2015 averaged a very high 2370 parts per billion, as illustrated by the image below.

Natalia Shakhova et al. estimate the accumulated methane potential for the Eastern Siberian Arctic Shelf (ESAS, rectangle on image right) alone as follows:
- organic carbon in permafrost of about 500 Gt;
- about 1000 Gt in hydrate deposits; and
- about 700 Gt in free gas beneath the gas hydrate stability zone.

Hydrates can become destabilized by pressure changes that can be caused by earthquakes and resulting shockwaves and landslides, or that can be caused by wild temperature swings.

Hydrates can also become destabilized by a small temperature rise that can be caused by influx of warmer water from outside the Arctic Ocean or by warm surface water being mixed down by storms.

Waters in the ESAS are quite shallow, averaging less than 50 m depth over its 2x10ˆ6 km2 area, while methane hydrates in the ESAS can exist at depths as shallow as 20 m.

Where heat is able to penetrate the sediment along cracks, some hydrate destabilization can occur, which in turn can trigger larger destabilization, as methane escaping from a hydrate expands to 160 times its earlier volume; this explosive expansion can cause further destabilization of sediments containing methane in the form of hydrates and free gas.

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


Strong Winds And Waves Batter Arctic Sea Ice
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