{"id":145,"date":"2005-04-14T13:19:17","date_gmt":"2005-04-14T17:19:17","guid":{"rendered":"\/?p=145"},"modified":"2009-06-01T07:35:56","modified_gmt":"2009-06-01T12:35:56","slug":"ozone-depletion-and-global-warming","status":"publish","type":"post","link":"https:\/\/www.realclimate.org\/index.php\/archives\/2005\/04\/ozone-depletion-and-global-warming\/","title":{"rendered":"Ozone depletion and global warming Perte d’ozone et r\u00e9chauffement climatique<\/lang_fr> Ozon Azalmas\u0131 ve K\u00fcresel Is\u0131nma<\/lang_tk>"},"content":{"rendered":"
\n

One of the most common mistakes that we have observed in discussions of climate and atmospheric change is confusion between the rather separate concepts of ozone depletion and global warming. This isn’t necessarily surprising given the scant information that most people pick up from the media. However, for many years meteorologists have been fighting a rearguard action to persuade people that the globe isn’t warming because there is more sun coming through the ozone hole. There are however important connections between the two issues that complicate potential actions that we might take to alleviate the different problems. This week, for instance, a new IPCC report<\/a> was released that looked at the greenhouse warming potential of many of the replacement chemicals (HFCs and HCFCs) that were used to replace CFCs in aerosol cans and refrigeration units under the Montreal Protocol (and subsequent amendments).
\npar Gavin Schmidt<\/strong>, traduit par Vincent Noel<\/small><\/p>\n

Dans le d\u00e9bat sur le changement climatique, l’une des erreurs les plus courantes est la confusion entre la diminution de l’ozone et le r\u00e9chauffement plan\u00e9taire. Ceci n’est pas vraiment surprenant, compte tenu de la qualit\u00e9 discutable des informations propag\u00e9es par les medias. <\/p>\n

Depuis plusieurs ann\u00e9es maintenant, les climatologues et m\u00e9t\u00e9orologues tentent d’expliquer au public que si la plan\u00e8te se rechauffe, ce n’est pas parce qu’il y a davantage de rayonnement solaire qui passe par le trou dans la couche d’ozone. Les deux ph\u00e9nomenes sont cependant \u00e9troitement li\u00e9s, ce qui complique l’adoption d’une strat\u00e9gie pour s’attaquer \u00e0 l’un ou l’autre de ces probl\u00e8mes. Cette semaine, par exemple, un nouveau rapport de l’IPCC<\/a> s’est interess\u00e9 au possible effet de serre des produits chimiques (HCF et HCFC) utilis\u00e9s pour remplacer les CFC dans les bombes a\u00e9rosols et les syst\u00e8mes de refroidissement dans le cadre du protocole de Montr\u00e9al (et de ses amendements).<\/p>\n

(suite…)<\/a>
\n<\/lang_fr><\/p>\n


\nThe connections actually go both ways: Firstly, CFCs, HFCs etc. are greenhouse gases, while ozone is both a greenhouse gas and an absorber of solar radiation (in the UV range), and so changes to their concentrations affect the radiation transfer through the atmosphere. Secondly, the chemistry that controls ozone loss is very sensitive to the local temperature and humidity, and as that is affected by climate change, that will impact ozone depletion as well. <\/p>\n

The original CFCs were powerful greenhouse gases (about 0.34 W\/m2<\/sup> forcing since 1850), and even allowing for a cooling due to the subsequent depletion in stratospheric ozone (-0.15 W\/m2<\/sup>), they had a net warming effect. Therefore the ongoing phase-out will help both the stratospheric ozone problem and reduce the forcings leading to global warming. CFC concentrations are indeed now starting to level out and are expected to decrease further in coming decades. However, some of the replacement gases (for instance HFC-23) which are not as harmful to ozone, nonetheless have an significant greenhouse warming potential. The total forcing from these replacements is expected to be small compared to increases in CO2<\/sub>, but any reductions that can be easily made can potentially offset some increases in CO2<\/sub>. Thankfully, some other replacements exist (for instance ammonia) which neither affect ozone nor the greenhouse effect. The cure for ozone depletion has not turned out to be worse than the disease!<\/p>\n

On the other hand, some of the climate change effects on ozone were discussed previously<\/a> in connection with Arctic ozone levels. These effects are both chemical and dynamical. The chemical impacts relate mainly to increasing levels of methane and stratospheric water vapour directly affecting the local chemistry. Additionally, stratospheric cooling (caused by increasing CO2<\/sub> as well) has an indirect effect on the rates of many of the ozone-destroying reactions (accelerating ozone loss). Dynamically, planetary and gravity wave activity, (related to convection and the jet streams, for instance) all affect the momentum balance in the stratosphere and control the Brewer-Dobson<\/a> overturning circulation. Therefore changes to those can potentially affect the stratospheric circulation and thus change stratospheric winds and stability. These dynamic effects can often lead to local changes of temperature (particularly in high latitudes) much greater than any radiative change e.g through possibly changes to the strength of the polar vortex (Shindell et al, 1998<\/a>).<\/p>\n

So, as we learn more about stratospheric ozone and climate change, what were once two separate problems have become more and more entwined. It therefore appears unlikely that meteorologists are going to get a break anytime soon from explaining exactly how the two issues do, and don’t, connect. <\/p>\n

La d\u00e9pendance climat \/ ozone a lieu dans les deux sens : Tout d’abord, les CFC, HFC, etc sont des gaz \u00e0 effet de serre, tout comme l’ozone (qui de plus absorbe les radiations solaires dans l’UV). Un changement dans la concentration de ces gaz affecterait le transfert des radiations \u00e0 travers l’atmosph\u00e8re, et donc le climat. D’autre part, les processus chimiques qui contr\u00f4lent la perte d’ozone sont tr\u00e8s sensibles \u00e0 la temp\u00e9rature et l’humidit\u00e9 \u00e0 l’\u00e9chelle locale. Comme le changement climatique affecte directement ces propri\u00e9t\u00e9s, il affectera \u00e9galement la perte d’ozone.<\/p>\n

Les CFC d’origine sont des gaz \u00e0 fort effet de serre (leur for\u00e7age repr\u00e9sente \u00e0 peu pr\u00e8s 0.34 W\/m2<\/sup> depuis 1850), et m\u00eame en tenant compte du refroidissement cr\u00e9\u00e9 par la perte simultan\u00e9e d’ozone stratosph\u00e9rique (-0.15 W\/m2<\/sup>), l’effet moyen reste le r\u00e9chauffement. La suppression des CFC contribue donc \u00e0 r\u00e9duire en m\u00eame temps la perte d’ozone stratosph\u00e9rique, et le for\u00e7age radiatif \u00e0 l’origine du r\u00e9chauffement climatique. A l’heure actuelle la concentration en CFC se stabilise, et on pr\u00e9voit qu’elle devrait diminuer dans les d\u00e9cades \u00e0 venir. Cependant, bien que les gaz utilis\u00e9s en remplacement des CFC (par exemple le HFC-23) n’affectent pas l’ozone, leur effet de serre reste potentiellement important. On estime le for\u00e7age total de ces gaz faible par rapport \u00e0 l’augmentation du CO2<\/sub>, mais toute r\u00e9duction dans ce for\u00e7age reste bonne a prendre, car elle aiderait \u00e0 contre-balancer l’impact du CO2<\/sub>. Heureusement, certains gaz de remplacement (par exemple l’ammoniaque) n’affectent ni l’ozone, ni l’effet de serre. Le rem\u00e8de contre la perte de l’ozone n’est finalement pas pire que le mal !<\/p>\n

D’un autre c\u00f4t\u00e9, dans l’Arctique les effets du changement climatique sur l’ozone sont \u00e0 la fois chimiques et dynamiques (voir ici)<\/a>. D’une part, l’augmentation du niveau de m\u00e9thane et d’humidit\u00e9 stratosph\u00e9rique affecte directement la chimie locale. De plus, le refroidissement stratosph\u00e9rique (provenant de l’augmentation du niveau de CO2<\/sub>) acc\u00e9l\u00e8re indirectement la perte d’ozone, en affectant la vitesse des r\u00e9actions chimiques destructrices. Au niveau dynamique, l’activit\u00e9 des ondes plan\u00e9taires et de gravit\u00e9 (reli\u00e9es a la convection ou au courants jets, par exemple) affectent l’\u00e9quilibre stratosph\u00e9rique et controlent la circulation de Brewer-Dobson<\/a>. Des changements dans cet \u00e9quilibre pourraient modifier la circulation et la stabilit\u00e9 des vents stratosph\u00e9riques. De tels effets dynamiques peuvent mener a des changements locaux de temp\u00e9rature (surtout aux hautes latitudes) plus importants qu’aucun changement d’origine radiative, en jouant notamment sur l’intensit\u00e9 du vortex polaire (Shindell et al, 1998<\/a>).<\/p>\n

Alors que nous en apprenons toujours plus sur l’ozone stratosph\u00e9rique et le changement climatique, ces deux probl\u00e8mes \u00e0 l’origine clairement distincts deviennent de plus en plus dependants l’un de l’autre. Il semble clair que les climatologues devront s’habituer a expliquer comment les deux probl\u00e8mes interagissent.
\n<\/lang_fr><\/p>\n


\nIngilizce\u2019den \u00e7eviren Figen Mekik<\/small><\/p>\n

Iklimsel ve havak\u00fcreyle ilgili tart\u0131\u015fmalarda en s\u0131kl\u0131kla g\u00f6r\u00fclen yanl\u0131\u015f alg\u0131lama, asl\u0131nda iki ayr\u0131 konu olan ozon azalmas\u0131 ve k\u00fcresel \u0131s\u0131nman\u0131n ayn\u0131 zannedilmesi oluyor. Insanlar\u0131n medya\u2019dan edindi\u011fi bilgi azl\u0131\u011f\u0131 g\u00f6z \u00f6n\u00fcnde bulundurulursa, bu da \u00e7ok \u015fa\u015f\u0131rt\u0131c\u0131 bir \u015fey de\u011fil. Fakat pek \u00e7ok senedir meteorologlar, ozon deli\u011finden g\u00fcne\u015f \u0131s\u0131s\u0131 girdi\u011fi i\u00e7in d\u00fcnyan\u0131n \u0131s\u0131nmad\u0131\u011f\u0131n\u0131 anlatmaya \u00e7al\u0131\u015f\u0131yorlar. Ancak bu iki konu aras\u0131nda baz\u0131 \u00f6nemli ba\u011flant\u0131lar yok de\u011fil. Ve bu ba\u011flant\u0131lar iki sorunu da \u00e7\u00f6zmek i\u00e7in ataca\u011f\u0131m\u0131z ad\u0131mlar\u0131 olumsuz y\u00f6nde etkileyebilir. Mesel\u00e2 bu hafta Uluslararas\u0131 Iklim De\u011fi\u015fikli\u011fi G\u00f6revg\u00fcc\u00fc\u2019n\u00fcn yeni raporu<\/a> yay\u0131nland\u0131. Bu raporda Montreal Protokol\u00fc (ve pek \u00e7ok eklemeleri) gere\u011fi, buzdolaplar\u0131nda ve spreylerde kullan\u0131lan CFC\u2019lerin yerine kullan\u0131lacak pek \u00e7ok gaz\u0131n (HFC ve HCFC) seragaz\u0131 olma potansiyeli ele al\u0131n\u0131yor. <\/p>\n

Asl\u0131nda aradaki ili\u015fkiler iki y\u00f6nl\u00fc. \u00d6ncelikle, CFC ve HFCler seragaz\u0131 niteli\u011finde; ozon hem seragaz\u0131 \u00f6zellikleri ta\u015f\u0131yor hem de g\u00fcne\u015ften gelen \u00fcltraviole \u0131\u015f\u0131nlar\u0131n\u0131 emebiliyor. Dolay\u0131s\u0131yla bu gazlar\u0131n havak\u00fcredeki yo\u011funlu\u011fu artt\u0131k\u00e7a, atmosferin \u0131s\u0131n\u0131m iletme \u00f6zelli\u011fi etkileniyor. Ikinci konu ise, ozon azalmas\u0131n\u0131 denetleyen kimyasal \u00f6zellikler yerel \u0131s\u0131 ve nemden \u00e7ok etkileniyor. Yani, iklim de\u011fi\u015fikli\u011fi ozon tabakas\u0131n\u0131 da etkileyecektir.<\/p>\n

Ilk kullan\u0131lan CFC\u2019ler g\u00fc\u00e7l\u00fc seragazlar\u0131d\u0131r (a\u015fa\u011f\u0131 yukar\u0131 0.34W\/m2<\/sup>\u2019lik bir zorlama 1850\u2019den beri), ve stratosferdeki ozonun azalmas\u0131n\u0131n sa\u011flad\u0131\u011f\u0131 so\u011fuma etkisine ra\u011fmen (-0.15 W\/m2<\/sup>), bunlardan havak\u00fcrede net bir \u0131s\u0131nma etkisi oldu. Dolay\u0131s\u0131yla bu gazlar\u0131n kullan\u0131lmas\u0131na son verilmesi hem ozon azalmas\u0131na engel olacak, hem de k\u00fcresel \u0131s\u0131nmay\u0131 azaltacakt\u0131r. Hatta \u015fimdiden CFC yo\u011funlu\u011fu azalmaya ba\u015flad\u0131 bile, ve \u00f6n\u00fcm\u00fczdeki ony\u0131llarda iyice azal\u0131ca\u011f\u0131na ina\u0131lmakta. Ancak, CFC\u2019lerin yerine kullan\u0131lan baz\u0131 gazlar (mesel\u00e2 HFC-23) ozona bir zarar\u0131 olmad\u0131\u011f\u0131 halde, k\u00fcresel \u0131s\u0131nmay\u0131 art\u0131rma konusunda b\u00fcy\u00fck potansiyel ta\u015f\u0131yorlar. Bu gazlardan meydana gelen toplam zorlaman\u0131n, CO2<\/sub>\u2019den olana k\u0131yasla k\u00fc\u00e7\u00fck olmas\u0131 bekleniyor, ama ne kadar az seragaz\u0131 olursa havak\u00fcrede, CO2<\/sub>\u2019nin verdi\u011fi zarar o kadar azalt\u0131labilir. \u00c7ok \u015f\u00fck\u00fcr ki, ba\u015fka gazlar da var CFC\u2019lerin yerine ge\u00e7ebilecek, (mesel\u00e2 amonyak gibi) ve bu gazlar\u0131n ne ozon deli\u011fine ne de k\u00fcresel \u0131s\u0131nmaya olumsuz bir katk\u0131s\u0131 yok. Ozon azalmas\u0131n\u0131n \u00e7aresi belas\u0131ndan beter de\u011fil neyse ki. <\/p>\n

Di\u011fer yandan, iklimsel de\u011fi\u015fimin ozon \u00fczerindeki etkilerini daha once<\/a> Arktik ozon seviyelerini tart\u0131\u015f\u0131rken konu\u015fmu\u015ftuk. Bu ektiler hem kimyasal hem de dinamik. Kimyasal etkilerin \u00f6z\u00fcnde, stratosferdeki metan ve su buhar\u0131 yo\u011funlu\u011funun artmas\u0131ndan y\u00f6resel havak\u00fcre kimyas\u0131n\u0131n de\u011fi\u015fmesi yat\u0131yor. Ayr\u0131ca, stratosferin so\u011fumas\u0131 (havada CO2\u2019nin artmas\u0131ndan kaynaklan\u0131yor bu da) ozonu azaltan reaksyonlar\u0131n \u00fczerinde dolayl\u0131 bir etki yarat\u0131yor (ozon azalmas\u0131n\u0131 h\u0131zland\u0131r\u0131yor yani). Dinamik olarak, gezegensel ve yer\u00e7ekimi dalga hareketi (\u0131s\u0131yayma ve jet streamle ilgili) stratosferdeki moment dengesini bozuyor ve Brewer-Dobson<\/a> devirimli dola\u015f\u0131m\u0131n\u0131 denetliyor. Dolay\u0131s\u0131yla, bu tip de\u011fi\u015fiklikler ileride stratosferik hava dola\u015f\u0131m\u0131n\u0131 etkileyip, stratosferik r\u00fczg\u00e2rlar\u0131 ve stratosferin genel dengesini bozabilir. Bu dinamik etkiler \u00e7o\u011fu zaman g\u00fcne\u015ften gelecek herhangi bir etkiden daha fazla yerel \u0131s\u0131 de\u011fi\u015fikliklerine (\u00f6zellikle y\u00fcksek enlemlerde) yol a\u00e7abilir. Mesel\u00e2, kutupsal girdab\u0131n g\u00fcc\u00fcn\u00fc de\u011fi\u015ftirmek gibi (Shindell et al., 1998<\/a>). <\/p>\n

Stratosferdeki ozon ve iklim de\u011fi\u015fimi hakk\u0131ndaki bilgilerimiz artt\u0131k\u00e7a, bir zamanlar iki ayr\u0131 sorun olan \u015fey gittik\u00e7e birbirine kar\u0131\u015fmaya ba\u015fl\u0131yor. Yani, yak\u0131n gelecekte, bu konular\u0131n aras\u0131nda ne kadar ba\u011flant\u0131n\u0131n olup olmad\u0131\u011f\u0131n\u0131 anlatan meterologlara kurtulu\u015f g\u00f6r\u00fcnm\u00fcyor.
\n<\/lang_tk><\/lang_tk><\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

One of the most common mistakes that we have observed in discussions of climate and atmospheric change is confusion between the rather separate concepts of ozone depletion and global warming. This isn’t necessarily surprising given the scant information that most people pick up from the media. However, for many years meteorologists have been fighting a […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[1,3],"tags":[],"class_list":{"0":"post-145","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-climate-science","7":"category-greenhouse-gases","8":"entry"},"aioseo_notices":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/145","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/comments?post=145"}],"version-history":[{"count":0,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/145\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/media?parent=145"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/categories?post=145"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/tags?post=145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}