Global Earth: Arctic Sea Ice Steep Decline Continues

Steep decline of the Arctic sea ice continues. The yellow line on the image below follows 2014 sea ice area up to June 5 and shows that sea ice area now is close to a record low for the time of the year.

[ click on image to enlarge ]

The Naval Research Laboratory image below compares sea ice concentration on May 14, 2014 (left) with the sea ice concentration forecast for June 15, 2014 (run on June 7, 2014, on the right).

Above image shows falling sea ice concentration, with low sea ice concentration extending to the center of the Arctic Ocean.

Low sea ice concentration at the center of the Arctic Ocean is an ominous sign; at last year's minimum, very little sea ice was left close to the North Pole, as discussed in an earlier post.

On the right is an image of the University of Bremen showing sea ice concentration on June 8, 2014 (click on the images to enlarge them).

Arctic sea ice already is very thin, as discussed in recent posts. The image below shows that the sea ice volume trend down to zero was confirmed for the months April and May 2014.

[ image by Andy Lee Robinson based on PIOMAS data, click on image to enlarge ]

The lowest sea ice volume for 2014 is expected to be reached in September, and - given the shape the ice is in now - will likely be one of the lowest minima on record. In fact, there is a chance that there will be no ice left whatsoever later this year. As illustrated by the image by Wipneus below, an exponential curve based on annual minima from 1979 points at zero ice volume end 2016, with the lower limit of the 95% confidence interval pointing at zero ice end of 2014.

As the sea ice disappears, a lot more heat will be absorbed by the Arctic Ocean. Sea ice reflects 50% to 70% of the incoming energy, describes NSIDC.org, but thick sea ice covered with snow reflects as much as 90% of the incoming solar radiation. Melting of snow creates melt ponds on the ice and because shallow melt ponds have an albedo of approximately 0.2 to 0.4, the surface albedo drops to about 0.75. As melt ponds grow and deepen, the surface albedo can drop to 0.15. The ocean reflects only 6% of the incoming solar radiation and absorbs the rest. Snow and ice decline comes with a further feedback in that all the energy that during the melt went into transforming ice into water will - in the absence of ice - now be absorbed by the ocean as well.

Accelerated Warming in the Arctic

[ from the post Near-Term Human Extinction ]

Such feedbacks are causing warming to accelerate in the Arctic Ocean, as depicted in above image and described in the earlier post Feedbacks in the Arctic. Much of the Arctic Ocean is very shallow and the seafloor is thus vulnerable to warming. The Gulf Stream can be expected to keep carrying warmer water into the Arctic Ocean, so the situation is dire, while extreme weather events such as heatwaves and cyclones can make the situation even worse.

The NOAA image below shows huge sea surface temperature anomalies all over the Northern Hemisphere on June 8, 2014.

[ click on image to enlarge ]

Large areas with sea surface temperature anomalies up to 8°C and higher show up in and around the Arctic Ocean, as further illustrated by the image below.

[ click on image to enlarge ]

The image below shows high sea surface temperature anomalies from February 21, 2014, up to June 9, 2014, on the Northern Hemisphere (red bars), next to global average anomalies (orange/shaded bars).

The global sea surface temperature anomaly is worrying (a 1.25°C anomaly was reached on May 22, 2014). See the NOAA website to compare this with earlier months. Note that on specific spots the anomaly is much higher, as illustrated by the images further above.

Warm surface waters in the Arctic sea ice spell bad news, given that the sea ice is already at or close to record lows, in terms of area and volume.

And as ocean heat threatens to melt the sea ice from beneath, the sun is now strongly warming up the ice from above. Insolation in the Arctic is at its highest at this time of year, as Earth reaches its maximum axial tilt toward the sun of 23° 26'. In fact, insolation during the months June and July is higher in the Arctic than anywhere else on Earth, as discussed at this earlier post.

The diminishing temperature difference between the equator and the North Pole reduces the speed at which the Jet Stream circumnavigates Earth and it makes the Jet Stream become wavier, increasing opportunities for cold air to escape from the Arctic and for warm air to move in. More extreme weather increases the chance of intense and prolonged heatwaves and fierce cyclones, storms and winds to hit the Arctic Ocean.

Making things even worsen, there is the prospect of an El Niño event, projected to occur later this year. According to NOAA (June 5, 2014), the chance of El Niño is 70% during the Northern Hemisphere summer and reaches 80% during the fall and winter. El Niño odds are even higher than this, according to this post at the Wunderground blog.

Methane

Temperature rises of the water close to the seafloor of the Arctic Ocean are very dangerous, as heat can penetrate sediments and cause hydrate destabilization. Huge amounts of methane are held in sediments at the seafloor, in the form of free gas and hydrates. In shallow waters, methane released from the seafloor can more easily enter the atmosphere without getting broken down by microbes in the water.

Methane levels are already very high. On June 6, 2014, mean global methane reached levels as high as 1809 ppb, with peaks as high as 2516 ppb.

Methane release from the seafloor of the Arctic Ocean will warm up the Arctic even further, triggering even more methane releases, heatwaves, wildfires and further feedbacks, in a spiral of runaway warming, threatening to cause starvation, destruction and extintion at massive scale across the globe.

Earthquakes

Earthquakes are a further worry. A huge amount of melting takes place in Greenland, as described in the post Ten Cubic Kilometers of Ice Lost From Jakobshavn Glacier in Less than One Month. As the ice disappears, a large weight is lefted from Greenland, causing the Earth's crust there to be lifted in a phenomenon referred to as isostatic rebound. This can cause earthquakes to occur on the seafloor of the waters around Greenland, as illustrated by the image below.

[ click on image to enlarge ]

As the image below shows, the faultline alongside Greenland crosses the Arctic Ocean and extends into the Laptev Sea and Siberia, an area recently hit by two large earthquakes.

[ click on image to enlarge ]

Global Earth

Iklan

Search Engine

Monday, June 9, 2014

Arctic Sea Ice Steep Decline Continues

No comments:

Post a Comment