[getsmart-l] What's happening to the ozonehole? It might affect warming in the southern hemisphere
gboxen at rogers.com
Wed Aug 18 15:28:30 EDT 2010
If the ozone hole is closing why have our uv radiation readings gone up every
summer? It seems to me that the scale has increased for the last 3 summers as
the highs are higher and that the sunlight levels at 5:00 pm in July were higher
than I remember previously- that they resembled those of a midsummer afternoon.
Ozone Hole Healing Could Cause Further Climate Warming
Total Antarctic ozone - September 2009. (Credit: NOAA)
ScienceDaily (Jan. 26, 2010) — The hole in the ozone layer is now steadily
closing, but its repair could actually increase warming in the southern
hemisphere, according to scientists at the University of Leeds.
The Antarctic ozone hole was once regarded as one of the biggest environmental
threats, but the discovery of a previously undiscovered feedback shows that it
has instead helped to shield this region from carbon-induced warming over the
past two decades.
High-speed winds in the area beneath the hole have led to the formation of
brighter summertime clouds, which reflect more of the sun's powerful rays.
"These clouds have acted like a mirror to the sun's rays, reflecting the sun's
heat away from the surface to the extent that warming from rising carbon
emissions has effectively been cancelled out in this region during the
summertime," said Professor Ken Carslaw of the University of Leeds who
co-authored the research.
"If, as seems likely, these winds die down, rising CO2 emissions could then
cause the warming of the southern hemisphere to accelerate, which would have an
impact on future climate predictions," he added.
The key to this newly-discovered feedback is aerosol -- tiny reflective
particles suspended within the air that are known by experts to have a huge
impact on climate.
Greenhouses gases absorb infrared radiation from the Earth and release it back
into the atmosphere as heat, causing the planet to warm up over time. Aerosol
works against this by reflecting heat from the sun back into space, cooling the
planet as it does so.
Beneath the Antarctic ozone hole, high-speed winds whip up large amounts of sea
spray, which contains millions of tiny salt particles. This spray then forms
droplets and eventually clouds, and the increased spray over the last two
decades has made these clouds brighter and more reflective.
As the ozone layer recovers it is believed that this feedback mechanism could
decline in effectiveness, or even be reversed, leading to accelerated warming
in the southern hemisphere.
"Our research highlights the value of today's state-of- the-art models and
long-term datasets that enable such unexpected and complex climate feedbacks to
be detected and accounted for in our future predictions," added Professor
The Leeds team made their prediction using a state-of-the-art global model of
aerosols and two decades of meteorological data. The research was funded by the
Natural Environment Research Council's Surface Ocean-Lower Atmosphere Study (UK
SOLAS) and the Academy of Finland Centre of Excellence Programme.
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The above story is reprinted (with editorial adaptations by ScienceDaily staff)
from materials provided by University of Leeds, via EurekAlert!, a service of
1. . Aerosol climate feedback due to decadal increases in southern hemisphere
wind speeds. Geophysical Research Letters, 2010; (in press)
Need to cite this story in your essay, paper, or report? Use one of the
University of Leeds (2010, January 26). Ozone hole healing could cause further
climate warming. ScienceDaily. Retrieved August 17, 2010, from
Note: If no author is given, the source is cited instead.
for National Geographic News
Published May 5, 2010
Background information is given
...Ozone Recovery to Warm Antarctica?
Meanwhile, some scientists say the environmental triumph of a recovering ozone
layer could have a troubling side effect: boosting global warming, at least in
the Antarctic region.
Ozone itself is a greenhouse gas. A thinner ozone layer not only reduced heat
trapped over the region, it helped stir circumpolar winds, which in turn
created sea spray that formed reflective, cooling clouds.
"It's very difficult to quantify the impact on a global scale, but I think the
evidence suggests filling the hole will have a regional effect on the
Antarctic, possibly leading to more warming for the bulk of the Antarctic,"
Shanklin said. "That could drastically change predictions about global sea
Ken Carslaw of the U.K.'s University of Leeds was a co-author on the study that
suggested closing the ozone hole would lead to a bump in Antarctic warming.
Still, he thinks that any warming mitigation produced by the ozone hole was
merely a side effect and not a net gain.
"I wouldn't say that these discoveries [of possible warming] suggest the
formation of the ozone hole was a good thing," he said.
NASA's Newman agreed: "The consequences of unabated CFC growth were disastrous
for life," he said.
"So at some point you had to act, and fortunately they acted before it became
a really severe problem. We never got to the level of an environmental
"It really is a testament to the good science that went into [understanding]
the ozone hole and the nerve of the politicians to act on that science."
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