Atmospheric chemistry

Depletion of the Ozone Layer in the 21st Century

A paper in Angewandte Chemie suggests that models predict that climate change will lead to an accelerated recovery of the ozone layer. However, reliable predictions are complicated by the ozone-depleting effect of N2O. If emissions of this greenhouse gas remain at current levels, by 2050 they could account for 30% of the ozone-destroying effects of chlorofluorocarbons at their peak.1

It is concluded that "the regulation of N2O levels in the atmosphere is not only important for the protection of Earth's climate (Kyoto Protocol) but also for the future evolution of the stratospheric ozone layer (Montreal Protocol). A reduction of N2O emissions would decrease the anthropogenic greenhouse effect and it would have a positive impact on the recovery of the ozone layer."

Depletion of the Ozone Layer in the 21st Century

Depletion of the Ozone Layer in the 21st Century, Dameris, Martin , Angewandte Chemie International Edition, Volume 9999, Number 9999, p.NA, (2009)

On the Constitution of the Atmosphere.

On the Constitution of the Atmosphere., Dalton, John , Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London (1800-1843), 1/1815, Volume 2, Issue 1, p.267 - 268, (1815)

Soot climate forcing via snow and ice albedos

Abstract: plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The “efficacy” of this forcing is ∼2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future.

Soot climate forcing via snow and ice albedos, Hansen, J. , Proceedings of the National Academy of Sciences, 01/2004, Volume 101, Issue 2, p.423 - 428, (2004)

The Great Global Warming Swindle

Here in the UK, Channel 4 just screened an interesting documentary. Good viewing and challenges what seems to have become the accepted view that global warming is caused by man-made CO2 emissions. Instead, the programme points out that climate change has always been with us (including a medieval warm period, even balmier than today, and a mini ice-age in the seventeenth century when the River Thames froze so solid that fairs were regularly held on the ice). The programme presents some evidence to suggest that the rise in carbon dioxide lags behind temperature rises by 800 years and therefore can't be the cause of it. It also suggests that man-made sources of carbon dioxide are dwarfed by natural sources and that the source of variation in temperature is really linked to variations in sun activity.

The programme suggests that we can hardly be surprised when "environmental journalists" whose continued employment requires publication of stories produce newsworthy doom-laden stories. After all, why would the media publish stories from such journalists the gist of which is there is no need to panic because climate variation is nothing to do with us.

Anyway, if you are able, see the programme again in the UK on More4 (Monday 12 March 2007, 10.00pm): "Polemical film challenging the consensus that man-made CO2 is heating up the earth. Featuring leading academics, the film questions the science behind the accepted reasons for global warming and argues other explanations for climate change are not being properly aired".

Record ozone loss over South Pole

OzoneOzoneOzone measurements made by the European Space Agency Envisat satellite reveal the ozone loss of 40 million tons by 2 October in 2006 and that this exceeds the record ozone loss of about 39 million tons for the whole of 2000. The size of this year's ozone hole is 28 million square km.

The Ozone layer is a protective layer found about 25 kilometres above us mostly in the stratospheric stratum of the atmosphere that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays. Over the last few years the effective thickness of the ozone layer declined, increasing the risk of skin cancers, cataracts and harm to marine life. The thinning of the ozone layer is caused by the presence of pollutants in the atmosphere originating from, for instance, chlorofluorocarbons (CFCs), which have still not vanished from the air although banned under the 1987 Montreal Protocol.

"Such significant ozone loss requires very low temperatures in the stratosphere combined with sunlight. This year’s extreme loss of ozone can be explained by the temperatures above Antarctica reaching the lowest recorded in the area since 1979," European Space Agency Atmospheric Engineer Claus Zehner said.

Background Information

Ozone (O3) is another allotrope of oxygen. It is bent with a O-O-O angle of about 123° It is formed from electrical discharges or ultraviolet light acting on O2. It is an important component of the atmosphere (in total amounting to the equivalent of a layer about 3 mm thick at ordinary pressures and temperatures) which is vital in preventing harmful ultraviolet rays of the sun from reaching the earth's surface. Aerosols in the atmosphere have a detrimental effect on the ozone layer. Large holes in the ozone layer are forming over the polar regions and these are increasing in size annually. Paradoxically, ozone is toxic! Undiluted ozone is bluish in colour. Liquid ozone is bluish-black, and solid ozone is violet-black.

For chemical robots

IUPAC Name: ozone
Canonical SMILES: [O-][O+]=O
InChI: InChI=1/O3/c1-3-2

Why is there so much methane on Titan?

This Cassini-Huygens article ponders the abundance of methane on Titan. Titan's atmosphere is mostly nitrogen but there are also methane and many other organic compounds. On Earth, life refreshes the methane supply as it is a by-product of metabolism. This is not likely to be the source of methane on Titan but if, as on Earth, sunlight is continuously destroying methane, how is methane getting into Titan's atmosphere?

Soot major culprit of global warming?

The observation that soot makes global warming "worse" is well covered today. The BBC covers this - largely because it appears that soot is more important for global warming than realised earlier. Dr James Hansen and Larissa Nazarenko, (Goddard Institute for Space Studies, NASA, and Columbia University Earth Institute) suggest that trying to reduce the amount of soot produced would be easier than cutting carbon dioxide and other greenhouse gas emissions. Concentrations of soot are often high over China and India, where coal and organic fuels are used domestically, and over Europe and North America, where the main source is diesel oil.1

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Copyright 1993-2011 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.