CR
Cryospheric Sciences

Sea-ice

Image of the Week – For each tonne of CO2 emitted, Arctic sea ice shrinks by 3m² in summer

January 20, 2017
Image of the Week – For each tonne of CO2 emitted, Arctic sea ice shrinks by 3m² in summer
Mean area of Arctic September sea ice lost by CO2 emissions of each citizen for each country of the world in 2013. These results are based on the observed trend of 3 m² sea-ice area loss per tonne of CO2 emitted [Credit: adapted from Notz and Stroeve (2016), Fig.S1]

Declining sea ice in the Arctic is definitely one of the most iconic consequences of climate change. In a study recently published in Science, Dirk Notz and Julienne Stroeve find a linear relationship between carbon dioxide (CO2) emissions and loss of Arctic sea-ice area in summer. Our image of this week is based on these results and shows the area of September Arctic sea ice lost per inhabitant d ...[Read More]

Image of the Week – Sea Ice Floes!

December 2, 2016
Image of the Week – Sea Ice Floes!
Left: Floes in the Southern Ocean surrounding the Nathaniel Palmer, taken by a multi-rotor drone. The length of the Nathaniel Palmer, about 100 m, is shown for comparison [Credit: EOS]. Right: Floes in the Bering Strait in May, 2000 from the MODIS satellite. Arrow shows the width of the Bering Strait, 85 km, for comparison [Credit: NASA Earth Observatory].

The polar regions are covered by a thin sheet of sea ice – frozen water that forms out of the same ocean water it floats on. Often, portrayals of Earth’s sea ice cover show it as a great, white, sheet. Looking more closely, however reveals the sea ice cover to be a varied and jumbled collection of floating pieces of ice, known as floes. The distribution and size of these floes is vitally imp ...[Read More]

Image of the Week – What an ice hole!

November 25, 2016
Image of the Week – What an ice hole!
A schematic representation of what causes polynyas to open [Credit: Céline Heuzé]

Over the summer, I got excited… the Weddell Polynya was seemingly re-opening! ”The what?” asked my new colleagues. So today, after brief mentions in past posts, it is time to explain what a polynya is. Put it simply, a polynya, from the Russian word for “ice hole”, is a hole in the sea-ice cover. That means that in the middle of winter, the sea ice locally and naturally opens and reveals the ocean ...[Read More]

Image of the Week – Goodness gracious, great balls of ice!

November 18, 2016
Image of the Week – Goodness gracious, great balls of ice!
Ice balls on Stroomi beach, Estonia. [Credit: Aleksandr Abrosimov, Wikimedia ].

At first glance our image of the week may look like an ordinary stoney beach…but if you look more closely you will see that this beach is not, in fact, covered in stones or pebbles but balls of ice! We have written posts about many different weird and wonderful ice formations and phenomena (e.g. hair ice or ice tsunamis) here at the EGU Cryosphere blog and here is another one to add to the l ...[Read More]

Image of the Week – The Polar Hole!

October 14, 2016
Image of the Week – The Polar Hole!
Figure 1: Mean sea-ice thickness for November 2010 from CryoSat-2 satellite measurements. [Credit: The data processing of CryoSat-2 sea-ice thickness is funded by the German Federal Ministry for Economic Affairs and Energy (Funding: 50EE1008) and data of November 2010 are provided by meereisportal.de (Funding: REKLIM-2013-04) ].

Have you ever stumbled upon a satellite picture showing observations of the Arctic or Antarctic? You often see a circle where there is no data around the exact location of the geographic pole – as you can see in our Image of the Week. A few days ago, I wanted to explain this to one of my friends and turned to my favourite search engine for help. My search turned up a tremendous amount of sto ...[Read More]

Image of the Week — ice tsunamis !

September 23, 2016
Image of the Week — ice tsunamis !
A pile-up ice shove at Brighton Beach, Winsconsin, in March 2009. [Credit: bigcityal via Wikimedia ]

“Tsunami“ is a word that became world famous after the so-called Christmas tsunami in 2004, when enormous waves hit the shores around the Indian Ocean with disastrous consequences for countries such as Sri Lanka, Thailand, Somalia and many others. But did you know that tsunamis can be icy? An ice tsunami is one of the many names associated with ice shoves (or ivu, shore ice override, i ...[Read More]

Image of the Week – Satellite Measurements of Arctic Sea Ice

September 16, 2016
Image of the Week – Satellite Measurements of Arctic Sea Ice
The map above shows the region around Fram Strait that separates Greenland and Svalbard (Spreen et al., 2009) . The colours show the amount (volume flux) of sea ice that was moving from the Artic Basin and south in October/November 2006 as measured by satellites. The arrows show the direction of sea ice.

Sea ice is an important part of the Earth’s climate system. When sea ice forms, it releases heat and salt. When sea ice melts, it takes up heat and adds freshwater to the salty ocean water. It is also important for the exchange of energy between the atmosphere and the ocean surface, and for the ocean currents that transport warm and cold water from the equator to the poles and back. The main route ...[Read More]

Image of the week – Our salty seas and how this affects sea ice growth

August 5, 2016
Image of the week – Our salty seas and how this affects sea ice growth
Lines of constant density for sea water . Black lines show lines of constant density as a function of temperature (y-axis) and salinity (x-axis). The dashed black line indicates, for a given salinity, the temperature at which the water will freeze. Figure adapted from Timmermans and Jayne (2016) - with permission.

Earth’s oceans are not simply just water, they are a complicated multi-component fluid consisting of water and dissolved salts (ask anyone who has tried to drink it!). The existence of these salts has a significant impact on global ocean circulation. Nowhere is this more significant than in the polar oceans where it is one of the key factors influencing sea ice formation. In this week’s imag ...[Read More]

Image of the week — The warming effect of the decline of Arctic Sea Ice

June 10, 2016
Image of the week — The warming effect of the decline of Arctic Sea Ice
Decreasing sea ice and its effect on the albedo in the Arctic (credit: I. Eisenman, K. Pistone, V. Ramanathan, and NASA/GSFC Scientific Visualization Studio)

One of the most dramatic signals of Earth’s recent warming has been the precipitous decline of the Arctic sea ice. While the sea-ice decline is in response to warming ocean and atmosphere, it also has an important feed-back on the climate itself. Solar radiation and albedo Earth’s main energy source is solar radiation. This solar radiation is either absorbed in the atmosphere or at the ...[Read More]

Image of the Week – See How Seasonal Sea Ice Decline Differs!

May 13, 2016
Image of the Week – See How Seasonal Sea Ice Decline Differs!
Figure 1: Arctic sea-ice area (75°N to 90°N) VS global annual mean surface air temperature for the complex model MPI-ESM-LR. Red dots represent a seasonal average over autumn (September/October/November) and blue dots over spring (March/April/May) of a particular year in the historical and future (RCP8.5) simulations. The dotted black lines result from a linear orthogonal regression in the ice area regime with the steepest change (Credit: subset of fig 2 from Bathiany et al, 2016 ).

Why do we care about sea ice in the first place? Sea ice is important for several components of the climate system. Due to its high albedo, sea ice reflects a high amount of the incoming solar radiation and is therefore relevant for the Earth’s energy budget. Sea ice inhibits the exchange of heat, moisture and momentum between ocean and atmosphere, which usually occur at the sea surface. Whe ...[Read More]