Ozone Hole Opened Over The Arctic

Ozone Layer cartoon

Ozone is Earth's natural sunscreen, shielding life from excessive amounts of ultraviolet radiation. But Earth's ozone layer has been damaged by well-intentioned chemicals - chlorofluorocarbons, used for refrigerants and aerosol spray-cans - that have the unintended consequence of destroying ozone molecules.


A huge Arctic ozone hole opened up over the Northern Hemisphere for the first time this year, an international research team.


The hole covered 2 million square kilometres - about twice the size of Ontario - and allowed high levels of harmful ultraviolet radiation to hit large swaths of northern Canada, Europe and Russia, the 29 scientists say.


The discovery of the "unprecedented" hole comes as the Canadian government is moving to reduce staff in what Environment Minister Peter Kent calls the "streamlining" of its ozone monitoring network.


Environment Canada scientists say the "chemical ozone destruction over the Arctic in early 2011 was - for the first time in the observation record - comparable to that in the Antarctic ozone hole."


It also highlights the importance of Environment Canada's ozone networks, which scientists have warned could be drastically reduced. Department officials say ozone monitoring will continue but will be "streamlined" to eliminate "redundancy."


The scientists say maintaining "comprehensive" data is "critical" to understanding Arctic ozone depletion and the threats it poses.


They used U.S. and European satellites, along with ground stations and scientific balloons - including those operated by Environment Canada - to find and track the hole. "The satellites, ground stations and balloons each provide a piece of the puzzle", says co-author Kaley Walker, at the University of Toronto. "It is important to have them all."

The peak of the Ozone Layer in late March

The hole formed over the Arctic in February and March, then swung across northern Canada, northern Europe and Central Russia to northern Asia, prompting scientists to issue warnings this spring about excess radiation.


A report shows just how big and remarkable the hole was and how it moved. It also points to what scientists are calling "ominous" changes in the Arctic stratosphere, about 20 kilometres above the surface, which may be linked to climate change and increasing greenhouse gas emissions.


The ozone-destroying chlorine compounds have been banned internationally, but they are so "long-lived" the scientists expect them to stay in the atmosphere for decades. Scietists say it will likely be about 70 years - "a full generation of humans" - before the chlorine compounds disappear from the atmosphere. Meantime a cooling trend in the stratosphere, which is thought to be tied to increasing greenhouse gases like carbon dioxide, could create more ozone holes.


They also say "more acute Arctic ozone destruction could exacerbate biological risks from increased ultraviolet radiation exposure, especially if the vortex shifted over densely populated midlatitudes, as it did in April 2011." The "polar vortex" is the frigid air mass that circles the polar region in winter and can dip as far south as New York and Rome.

I love the Ozone Layer sticker

The lowest value (deepest hole) ever recorded was 73 Dobson Units on September 30, 1994, while the broadest hole occurred on September 29, 2000, when the ozone-depleted area stretched 29.9 million square kilometers. The record for mean size of the ozone hole - the greatest extent over a one-month window - was September 7 to October 13, 2006, when the hole reached 26.2 million square kilometers. The mean ozone hole in 2010 was 22.2 million square kilometers.




In 2010 report, the science advisers to the Montreal Protocol found that:


- Global ozone and ozone in the Arctic and Antarctic is no longer decreasing, but is not yet increasing.


- The ozone layer outside the Polar Regions is projected to recover to its pre-1980 levels some time before the middle of this century. The recovery might be accelerated by greenhouse gas-induced cooling of the upper stratosphere.


- The ozone hole over the Antarctic is expected to recover much later.


- The impact of the Antarctic ozone hole on surface climate is becoming evident in surface temperature and wind patterns.


- At mid-latitudes, surface ultraviolet radiation has been about constant over the last decade.




Ozone hole 2011, compared to previous years:

Is The Planet Gliese 581d Really Habitable?

Yahoo : A rocky alien planet called Gliese 581d may be the first known world beyond Earth capable of supporting life as we know it, a new study suggests.

Astronomers performing a new atmospheric-modeling study have found that the planet likely lies in the "habitable zone" of its host star — that just-right range of distances that allow liquid water to exist. The alien world could be Earth-like in key ways, harboring oceans, clouds and rainfall, according to the research.

This conclusion is consistent with several other recent modeling studies. But it does not definitively establish that life-sustaining water flows across the planet's surface.

The new study assumes that Gliese 581d, which is about seven times as massive as Earth, has a thick, carbon-dioxide-based atmosphere. That's very possible on a planet so large, researchers said, but it's not a given. [Video: Life-Sustaining "Super Earth" Gliese 581d]

The Gliese 581 system: Worlds of possibilities

Gliese 581d's parent star, known as Gliese 581, is a red dwarf located 20 light-years from Earth, just a stone's throw in the cosmic scheme of things. So far, astronomers have detected six planets orbiting the star, and Gliese 581d is not the only one intriguing to scientists thinking about the possibility of life beyond Earth.

Another planet in the system, called Gliese 581g, is about three times as massive as Earth, and it's also most likely a rocky world. This planet received a lot of attention when its discovery was announced in September 2010, because it's located right in the middle of the habitable zone. That makes 581g a prime candidate for liquid water and life as we know it — if the planet exists.

Some researchers question the analysis used to discover the planet, and say they cannot confirm 581g in follow-up studies. The planet's discoverers, however, are standing by their find. [The Strangest Alien Planets]

Gliese 581d orbits outside of 581g, far enough away from its star that researchers first thought it too cold for life when it was originally discovered in 2007. But a strong greenhouse effect may warm 581d up substantially, perhaps enough to support liquid water.

That's the tentative conclusion of the new study, as well as several other recent studies by different research teams that also modeled Gliese 581d's possible atmosphere.

Modeling an alien atmosphere

The planet Gliese 581d receives less than a third of the solar energy that Earth does from our sun, and it may be tidally locked (a situation in which one side of the world always faces its sun — a permanent day — and the other faces away, producing eternal night).

After Gliese 581d's discovery, it was generally believed that any atmosphere thick enough to keep the planet warm would become cold enough on the night side to freeze out entirely, ruining any prospects for a habitable climate, researchers said.

The research team tested that possibility in the new study, developing a new kind of computer model that simulates alien planets' atmospheres and surfaces in three dimensions. The model is similar to those used to study climate change on Earth.

When the team ran the model, they found that Gliese 581d probably can indeed host liquid water if it has a dense carbon dioxide atmosphere. Even though the planet is relatively far away from its dim red dwarf parent star, it could be warmed by a greenhouse effect, with daytime heat circulated around the planet by the atmosphere.

The team, led by scientists from the Laboratoire de Métrologie Dynamique (CNRS/UPMC/ENS/Ecole Polytechnique) at the Institut Pierre Simon Laplace in Paris, France, published their results in The Astrophysical Journal Letters.

The work remains speculative.

To determine conclusively if Gliese 581d is truly habitable, future work will probably have to detect and characterize its atmosphere directly. And that is likely years off, since it requires the development of new and advanced telescopes. Human-made probes won't be getting to the planet anytime soon; with current technology, it would take spacecraft hundreds of thousands of years to make the 20-light-year trek.