25th Anniversary of Ozone Hole Discovery

25 years ago in May 1985, scientists from the British Antarctic Survey (BAS) officially discovered the now controversial hole in Earth's ozone layer. The feature, which has expanded and contracted since its discovery, has been responsible for large losses of ozone in Earth's atmosphere over Antarctica.

The discovery of the ozone hole alerted the world to a major environmental threat as the accumulation of chlorofluorocarbons (CFCs) used in industrial solvents were found to deplete the protective layer of ozone that surrounds the Earth.

Action by governments around the world led to the 1987 Montreal Protocol and its amendments, which ensured that production and consumption of CFCs, halons and carbon tetrachloride were phased out by 2000, and methyl chloroform by 2005. All members of the United Nations have now signed the Montreal Protocol.

In good news, the ozone layer depletion seems to be on a dramatic upswing and levels of ozone are expected to continue to reach safer levels in the coming decades.

Another Giant Antarctic Iceberg Crash

Satellite images reveal that a giant crash earlier this month between Antarctica's Mertz glacier's giant floating tongue of ice and another iceberg has resulted in a new iceberg (the size of Luxembourg) to break off the continental shelf.



Yet another instance of "ice calving" that may be related to climate change (refer to previous blog post on January 14), the occurrence is feared by scientists to ultimately affect ocean circulation patterns.

Exactly how would that happen? Well the collision halved the size of the tongue that drains ice from the vast East Antarctic ice sheet into the Southern Ocean. The removal of this tongue of floating ice would reduce the size of that area of open water, which would slow down the rate of salinity input into the ocean, which would also slow down the rate of Antarctic bottom water formation.

Oceans act like a giant flywheel for the planet's climate by shifting heat around the globe via myriad currents above and below the surface. When such instances disrupt this process the end result could prove quite significant as it relates to our evolving climate.

Now that's an Iceberg!

Within the past couple days a massive piece of ice broke off of Antarctica's Filchner Ice Shelf. The images above taken on January 12 and January 13 by NASA’s Terra and Aqua satellites captured the huge piece of ice as it was breaking away. At about 150 kilometers long by 25 kilometers wide, the piece of the ice shelf that broke away was larger than the state of Rhode Island.

The ice shelf is a portion of Antarctica’s expansive ice sheets that extend over the ocean. As fresh snow falls on the ice sheet, the weight compresses it out like pancake batter spreading on a pan. The ice shelf grows out until waves and ocean currents break off the edge, forming a new iceberg.

This process is known as "ice calving" -- a sudden release and breaking away of a mass of ice from an iceberg, ice shelf or glacier. Although calving can be caused by tidal and seismic events, periodic calving and disintegration of ice masses are considered normal geological processes.