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Long lived CFC’s, Methane – Nitrous Oxide uptake and the destruction of the northern hemisphere Ozone Layer

by on January 24, 2012

Arctic Ozone Hole 2011 - March 2011: This shows strongly reduced ozone values (left, dark blue) and significantly increased concentration of chlorine monoxide (right, red) that is directly involved in ozone degradation.

Low temperatures enhance ozone degradation above the Arctic

Extraordinarily cold temperatures in the winter of 2010/2011 caused the most massive destruction of the ozone layer above the Arctic so far: The mechanisms leading to the first ozone hole above the North Pole were studied by scientists of the KIT Institute of Meteorology and Climate Research (IMK). According to these studies, further cooling of the ozone layer may enhance the influence of ozone-destroying substances, e.g. chlorofluorocarbons (CFC), such that repeated occurrence of an ozone hole above the Arctic has to be expected.

About a year ago, IMK scientists, together with colleagues from Oxford, detected that ozone degradation above the Arctic for the first time reached an extent comparable to that of the ozone hole above the South Pole. Then, the KIT researchers studied the mechanisms behind. Their results have now been published in the journal Geophysical Research Letters.

According to IMK studies, occurrence of the Arctic ozone hole was mainly due to the extraordinarily cold temperatures in the ozone layer that is located at about 18 km height in the stratosphere, i.e. the second layer of the earth’s atmosphere. There, chlorine compounds originating from chlorofluorocarbons (CFC, e.g. greenhouse gases and refrigerants) and other pollutants are converted chemically at temperatures below -78°C. These chemical conversion products attack the ozone layer and destroy it partly. One of the main statements in the study: If the trend to colder temperatures in the stratosphere observed in the past decades will continue, repeated occurrence of an Arctic ozone hole has to be expected.

We found that further decrease in temperature by just 1°C would be sufficient to cause a nearly complete destruction of the Arctic ozone layer in certain areas,” says Dr. Björn-Martin Sinnhuber, main author of the study. Observations over the past thirty years indicate that the stratosphere in cold Arctic winters cooled down by about 1°C per decade on the average. According to Sinnhuber, further development of the ozone layer will consequently be influenced also by climate change. He points out that the increase in carbon dioxide and other greenhouse gases will warm up the bottom air layers near the ground due to the reflection of part of the thermal radiation by the bottom layer of the atmosphere towards the earth’s surface, but also result in a cooling of the air layers of the stratosphere above, where the ozone layer is located.

After the first discovery of the Antarctic ozone hole in the mid-1980s, CFCs were rapidly identified to be the cause and their use was prohibited by the Montreal Protocol of 1987. However, it will take decades until these substances will have been removed completely from the atmosphere. “Future cooling of the stratosphere would enhance and extend the impacts of these substances on the ozone layer,” says Dr. Björn-Martin Sinnhuber. It is now necessary to study potential feedbacks on climate change. Science Codex

An Arctic ozone hole is thus predicted to occur in years 2010-2019, in spite of anticipated decreases of CFC concentrations because of the implementation of the Montreal protocol.

The possibility of an Arctic ozone hole is a very disturbing development with strong political and social implications. In contrast to the Antarctic ozone hole, an Arctic ozone hole would affect heavily populated parts of the Northern Hemisphere. Source University Waterloo

To make this clear, the Antarctic ozone lose was predicted back in 1998 by Shindell et al., based upon GCM modeling. This show how precisely accurate scientist are able to predict future changes, with the help of models.

Second Hole in the Ozone Layer opened over the Artic North Pole in 2011 – Could be Harmful to People

In addition to the annual ozone hole which has been opening over Antarctica for decades, an new hole which scientists have been tracking also opened at the top of the Earth over the Artic in 2011.

The new tear in the layer of the atmosphere which protects us from the Sun’s harmful UV radiation, is currently smaller than that of the hole over Antarctica. However, the Arctic polar vortex, a persistent large-scale cyclone within which the ozone loss takes place is highly mobile in comparison to the Antarctic vortex.

This means that the Artic Ozone hole has a greater chance of occurring over densely populated northern areas on the earth, as opposed to the virtually unpopulated surface of Antarctica. Source

“At low latitudes, methane in the stratosphere breaks down into hydrogen oxides, which attack ozone. Nitrous oxide can decompose to form ozone-eating nitrogen oxides.” – D. Shindell, 2002 –

related “Water vapor breaks down in the stratosphere, releasing reactive hydrogen oxide molecules that destroy ozone. These molecules also react with chlorine containing gases, converting them into forms that destroy ozone as well. So a wetter stratosphere will have less ozone.

Observations of ozone show a thinning of the Earth’s protective stratospheric ozone layer by about 3 to 8% overall since the 1970s. In the upper stratosphere, ozone depletion has been from 15 to 20%. Again, the model is better able to reproduce these values when increased water vapor is included. This is especially true in the upper stratosphere, where ozone is most sensitive to water. The model indicates that increased water vapor accounts for about 40% of the ozone loss in the upper stratosphere, and about 20% of the overall loss to date.

There are two driving forces behind the change in stratospheric moisture. Increasing emissions of methane are transformed into water in the stratosphere by chemical reactions. This can account for about a third of the observed increase in moisture there.” Source: NASA  Reaction of Ozone and Climate to Increasing Stratospheric Water Vapor

This means that we not only have to phase out CFC’s, but Greenhouse gases like methane and nitrous oxide too, if we plan to rescue the ozone layer! However, the exact impact from these Greenhouse gases must be quantified and potential large scale excursions modeled in respect to the destruction of the ozone layer and impacts on atmospheric circulations and civilization.

Excerpts from the wikipedia entry about Ozone depletion:  http://en.wikipedia.org/wiki/Ozone_depletion

Arctic ozone hole

On March 15, 2011, a record ozone layer loss was observed, with about half of the ozone present over the Arctic having been destroyed.[69][70][71][72] The change was attributed to increasingly cold winters in the Arctic stratosphere at an altitude of approximately 20 km (12 mi), a change associated with global warming in a relationship that is still under investigation.[73] By March 25, the ozone loss had become the largest compared to that observed in all previous winters with the possibility that it would become an ozone hole.[74] This would require that the quantities of ozone to fall below 200 Dobson units, from the 250 recorded over central Siberia.[74] It is predicted that the thinning layer would affect parts of Scandinavia and Eastern Europe on March 30–31.[74]

On 2 October 2011, a study was published in the journal Nature, which said that between December 2010 and March 2011 up to 80% of the ozone in the atmosphere at about 20 kilometres (12 mi) above the surface was destroyed.[75] The level of ozone depletion was severe enough that scientists said it could be compared to the ozone hole that forms over Antarctica every winter.[75] According to the study, “for the first time, sufficient loss occurred to reasonably be described as an Arctic ozone hole.”[75] The study analyzed data from theAura and CALIPSO satellites, and determined that the larger-than-normal ozone loss was due to an unusually long period of cold weather in the Arctic, some 30 days more than typical, which allowed for more ozone-destroying chlorine compounds to be created.[76] According to Lamont Poole, a co-author of the study, cloud and aerosol particles on which the chlorine compounds are found “were abundant in the Arctic until mid March 2011—much later than usual—with average amounts at some altitudes similar to those observed in the Antarctic, and dramatically larger than the near-zero values seen in March in most Arctic winters.”[76]

Tibet ozone hole

As winters that are colder are more affected, at times there is an ozone hole over Tibet. In 2006, a 2.5 million square kilometer ozone hole was detected over Tibet.[77] Also again in 2011 an ozone hole appeared over mountainous regions of TibetXinjiangQinghai and the Hindu Kush, along with an unprecedented hole over the Arctic, though the Tibet one is far less intense than the ones over the Arctic or Antarctic

Effects

Weather/Climate

Study Links Ozone Hole to Weather Shifts

The hole in the Earth’s ozone layer over the South Pole has affected atmospheric circulation in the Southern Hemisphere all the way to the equator, and a new study says this has led to increased rainfall in the subtropics. The study [pdf], which appears in the April 21 issue of the leading journal Science, is the first time that ozone depletion has been linked to climate change over such a wide area. Columbia

Humans

The most common forms of skin cancer in humans, basal and squamous cell carcinomas, have been strongly linked to UVB exposure. The mechanism by which UVB induces these cancers is well understood—absorption of UVB radiation causes the pyrimidine bases in the DNA molecule to form dimers, resulting in transcription errors when the DNA replicates. By combining epidemiological data with results of animal studies, scientists have estimated that a one percent decrease in stratospheric ozone would increase the incidence of these cancers by 2%.

A study showed that a 10% increase in UVB radiation was associated with a 19% increase in melanomas for men and 16% for women. A study of people in Punta Arenas, at the southern tip of Chile, showed a 56% increase in melanoma and a 46% increase in nonmelanoma skin cancer over a period of seven years, along with decreased ozone and increased UVB levels.

Studies are suggestive of an association between ocular cortical cataracts and UV-B exposure

Animals

A study photographed and took skin biopsies from over 150 whales in the Gulf of California and found “widespread evidence of epidermal damage commonly associated with acute and severe sunburn,” having cells which form when the DNA is damaged by UV radiation. The findings suggest “rising UV levels as a result of ozone depletion are to blame for the observed skin damage, in the same way that human skin cancer rates have been on the increase in recent decades.

Plants

An increase of UV radiation would be expected to affect crops.

Deliberate false Denial  (Crimes against Humanity)

The Chair of the Board of DuPont was quoted as saying that ozone depletion theory is “a science fiction tale…a load of rubbish…utter nonsense”

Related

Increased polar stratospheric ozone losses and delayed eventual recovery owing to increasing greenhouse-gas concentrations

Abstract

The chemical reactions responsible for stratospheric ozone depletion are extremely sensitive to temperature1. Greenhouse gases warm the Earth’s surface but cool the stratosphere radiatively2, 3, 4, 5 and therefore affect ozone depletion. Here we investigate the interplay between projected future emissions of greenhouse gases and levels of ozone-depleting halogen species using a global climate model that incorporates simplified ozone-depletion chemistry. Temperature and wind changes induced by the increasing greenhouse-gas concentrations alter planetary-wave propagation in our model, reducing the frequency of sudden stratospheric warmings in the Northern Hemisphere4. This results in a more stable Arctic polar vortex, with significantly colder temperatures in the lower stratosphere and concomitantly increased ozone depletion. Increased concentrations of greenhouse gases might therefore be at least partly responsible for the very large Arctic ozone losses observed in recent winters6, 7, 8, 9. Arctic losses reach a maximum in the decade 2010 to 2019 in our model, roughly a decade after the maximum in stratospheric chlorine abundance. The mean losses are about the same as those over the Antarctic during the early 1990s, with geographically localized losses of up to two-thirds of the Arctic ozone column in the worst years. The severity and the duration of the Antarctic ozone hole are also predicted to increase because of greenhouse-gas-induced stratospheric cooling over the coming decades. Source Increased polar stratospheric ozone losses and delayed eventual recovery owing to increasing greenhouse-gas concentrations

Nature Aerosols make methane more potent , An emissions-based view of climate forcing by methane and tropospheric ozone

Unprecedented Arctic ozone loss in 2011

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