Montreal-protokollens 20-års-jubilæum

Artiklen (i tidsskriftet Nature maj 1985) viste, at tykkelsen af ozonlaget over Antarktis i de sydpolare forårsmåneder var aftaget fra mere end 300 Dobson enheder til mindre end 200. Vi lærte fænomenet at kende som det antarktiske ozonhul og det blev knyttet sammen med stigende koncentrationer af menneskeskabte CFC-gasser

Ozonlagets udtyndning førte i 1987 til, at FN udarbejdede Montreal-protokollen, som begrænser udledningerne af ozon-nedbrydende stoffer

virkningerne af Montreal-protokollen fører til en genopretning af ozonlaget i løbet af 2. halvdel af det 21. århundrede.

Forskningen har vist, at ozonnedbrydningen i de arktiske områder er direkte afhængig af vintertemperaturerne i det arktiske ozonlag. I vintre med meget lave temperaturer ser vi en kraftig ozonnedbrydning. På grund af den forøgede koncentration af drivhusgasser forventer vi, at temperaturerne i atmosfæren nærmest jordoverfladen stiger, mens den falder højere oppe. Det har betydning i den arktiske stratosfære, hvor temperaturen fortsætter med at aftage, hvilket i en årrække fremover kan føre til vintre med kraftigere ozonnedbrydning

Dette mønster har været observeret, og nævnt i IPCCs sidste rapport:
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf
(side 11)

jeg ser da intet om, at tropopausen skulle flytte sig (opefter)! ??

stratosfæren afkøles (grundet ozonsvind)

The same CO2 radiative forcing that produces near-surface global warming is expected (perhaps surprisingly) to cool the stratosphere. This cooling, in turn, is expected to produce a relative increase in ozone (O3) depletion and the frequency of ozone holes.

One of the strongest predictions of the greenhouse effect theory is that the stratosphere will cool. Although this cooling has been observed, it is not trivial to separate the effects of changes in the concentration of greenhouse gases and ozone depletion since both will lead to cooling. However, this can be done by numerical stratospheric modeling. Results from the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory show that above 20 km..the greenhouse gases dominate the cooling

tropopausen skulle flytte sig (opefter)! ??

Earlier research has shown that increases in the height of the tropopause over the past two decades are directly linked to stratospheric ozone depletion and increased greenhouse gases. The new research uses climate model results to provide more quantitative estimates of the relative contributions of natural and human influences to overall tropopause height changes. This work indicates that 80 percent of the roughly 200 meter increase in tropopause height from 1979 to 1999 is directly linked to human activities. Smaller tropopause height increases over the first half of the 20th century were largely caused by natural variations in volcanic aerosols and solar irradiance.

3. Så er der den mulighed at problemet kan rettes på et eller andet tidspunkt uden at det går helt galt.

hip hip hurra: Nu hører vi så, at ozonhullet måske kan være fyldt ud efter 2050; forudsat altså, at ikke 'noget andet går galt' i mellemtiden!

Jeg funderer over, om de oplæg til Montreal-aftalen, som i firserne blev præsenteret for beslutningstagerne mon 'huskede' at præcisere, at den (mulige) bedring lå ~65 år ude i fremtiden??

But new laboratory work on the cross sections of ClOOCl suggest that its photolysis under polar stratospheric winter/spring conditions is nearly an order of magnitude slower than what would be required to explain the observations of ozone loss and ClO in the atmosphere and a factor of six slower than a value based on the current recommendations. We show the impact of these new results on our understanding of polar ozone chemistry.

Det var et heldigt tilfælde, som dog har været mere uheldigt for udviklingslandene, da de i starten ikke havde råd til de dyrere alternativer til freon.

Lad os håbe at fornuften i CO2 sammenhængene vil sejre og udviklingslandene ikke kommer til at betale den tåbeliges pris.

Rick_uk ved du overhovedet hvad de frivilige CO2 kvote-penge bliver brugt til i udviklingslandene?

to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.

Nothing currently suggests that the role of CFCs must be called into question, Rex stresses. "Overwhelming evidence still suggests that anthropogenic emissions of CFCs and halons are the reason for the ozone loss. But we would be on much firmer ground if we could write down the correct chemical reactions."

Of course, it may be that Rex's research has gone wrong somehow or that another chemical mechanism involving CFCs will turn out to be chiefly responsible for ozone depletion. Nevertheless, it is good to keep in mind that all scientific results are provisional and may change in the light of new evidence.

By the way, for anyone who cares about my own take on the ozone hole/CFC issue, in chapter 8 of my 1993 book, Eco-Scam: The False Prophets of Ecological Apocalypse, I concluded:

Despite a great deal of continuing scientific uncertainty, it appears that CFCs do contribute to the creation of the Antarctic ozone hole and perhaps to a tiny amount of global ozone depletion. If CFCs were allowed to build up in the atmosphere during the next century, ozone depletion might eventually entail significant costs. More ultraviolet light reaching the surface would require adaptation—switching to new crop varieties, for example—and it might boost the incidence of nonfatal skin cancer. In light of these costs, it makes sense to phase out the use of CFCs.

Nevertheless, it is good to keep in mind that all scientific results are provisional and may change in the light of new evidence.

Og den temp. stigning kan vi nok heller ikke holde det til

For increases in global average temperature exceeding 1.5-2.5 grader and in concomitant (forbunden) atmospheric carbon dioxide concentrations, there are projected to be major changes in ecosystem structure and function, species' ecological interactions, and species geographical ranges, with predominantly negative consequences for biodiversity, and ecosystem goods and services e.g. water and food supply.

Aftalen udløber i 2012. Med dens beskedne mål (selv om de bliver opnået, hvilket er endnu ikke sikkert) kan aftalen på ingen måde begrænse jordens drivhusgas udslip i en omfang der har en noget som helst praktisk betydning.

Copenhagen-aftalen (som vil løbe fra 2012) bliver den rigtige stor prøve. Den må knække verdens CO2 kurv indenfor 2 år (inden 2015) og sikrer at tendensen fortsætter nedad i hele dens levetid.

A potentially serious inconsistency has been identified in the tropics, the area in which tropospheric amplification should be seen. Section 1.1 of the CCSP report says:

"In the tropics, the agreement between models and observations depends on the time scale considered. For month-to-month and year-to-year variations, models and observations both show amplification (i.e., the month-to-month and year-to-year variations are larger aloft than at the surface). This is a consequence of relatively simple physics, the effects of the release of latent heat as air rises and condenses in clouds. The magnitude of this amplification is very similar in models and observations. On decadal and longer time scales, however, while almost all model simulations show greater warming aloft (reflecting the same physical processes that operate on the monthly and annual time scales), most observations show greater warming at the surface.

"These results could arise either because "real world" amplification effects on short and long time scales are controlled by different physical mechanisms, and models fail to capture such behavior; or because non-climatic influences remaining in some or all of the observed tropospheric data sets lead to biased long-term trends; or a combination of these factors. The new evidence in this Report favors the second explanation[min fremhævning, CBH]."

Mig bekendt er det netop en af problemerne for klimamodellerne, at de forudsiger en STØRRE opvarmning over troperne ifht. overflademålingerne, end der rent faktisk kan konstateres, mens at overflademålingerne faktisk viser markant opvarmning.....?

Jeg tvivler ikke på at chlor radikale er ansvarlige for en del af ozonnedbrydelsen