We’ve had a policy of (mostly) not commenting on the various drafts, misquotes and mistaken readings of the Fourth Assessment report (“AR4” to those in the acronym loop) of the IPCC. Now that the summary for policy makers (or “SPM”) has actually been published though, we can discuss the substance of the report without having to worry that the details will change. This post will only be our first cut at talking about the whole report. We plan on going chapter by chapter, hopefully explaining the key issues and the remaining key uncertainties over the next few months. This report will be referenced repeatedly over the next few years, and so we can take the time to do a reasonable job explaining what’s in it and why.
First of all, given the science that has been done since the Third Assessment Report (“TAR”) of 2001 – much of which has been discussed here – no one should be surprised that AR4 comes to a stronger conclusion. In particular, the report concludes that human influences on climate are ‘very likely’ (> 90% chance) already detectable in observational record; increased from ‘likely’ (> 66% chance) in the TAR. Key results here include the simulations for the 20th Century by the latest state-of-the-art climate models which demonstrate that recent trends cannot be explained without including human-related increases in greenhouse gases, and consistent evidence for ocean heating, sea ice melting, glacier melting and ecosystem shifts. This makes the projections of larger continued changes ‘in the pipeline’ (particularly under “business as usual” scenarios) essentially indisputable.
Given all of the hoopla since the TAR, many of us were curious to see what the new report would have to say about paleoclimate reconstructions of the past 1000 years. Contrarians will no doubt be disappointed here. The conclusions have been significantly strengthened relative to what was in the TAR, something that of course should have been expected given the numerous additional studies that have since been done that all point in the same direction. The conclusion that large-scale recent warmth likely exceeds the range seen in past centuries has been extended from the past 1000 years in the TAR, to the past 1300 years in the current report, and the confidence in this conclusion has been upped from “likely” in the TAR to “very likely” in the current report for the past half millennium. This is just one of the many independent lines of evidence now pointing towards a clear anthropogenic influence on climate, but given all of the others, the paleoclimate reconstructions are now even less the central pillar of evidence for the human influence on climate than they have been incorrectly portrayed to be.
The uncertainties in the science mainly involve the precise nature of the changes to be expected, particularly with respect to sea level rise, El Niño changes and regional hydrological change – drought frequency and snow pack melt, mid-latitude storms, and of course, hurricanes. It can be fun parsing the discussions on these topics (and we expect there will be substantial press comment on them), but that shouldn’t distract from the main and far more solid conclusions above.
The process of finalising the SPM (which is well described here and here) is something that can seem a little odd. Government representatives from all participating nations take the draft summary (as written by the lead authors of the individual chapters) and discuss whether the text truly reflects the underlying science in the main report. The key here is to note that what the lead authors originally came up with is not necessarily the clearest or least ambiguous language, and so the governments (for whom the report is being written) are perfectly entitled to insist that the language be modified so that the conclusions are correctly understood by them and the scientists. It is also key to note that the scientists have to be happy that the final language that is agreed conforms with the underlying science in the technical chapters. The advantage of this process is that everyone involved is absolutely clear what is meant by each sentence. Recall after the National Academies report on surface temperature reconstructions there was much discussion about the definition of ‘plausible’. That kind of thing shouldn’t happen with AR4.
The SPM process also serves a very useful political purpose. Specifically, it allows the governments involved to feel as though they ‘own’ part of the report. This makes it very difficult to later turn around and dismiss it on the basis that it was all written by someone else. This gives the governments a vested interest in making this report as good as it can be (given the uncertainties). There are in fact plenty of safeguards (not least the scientists present) to ensure that the report is not slanted in any one preferred direction. However, the downside is that it can mistakenly appear as if the whole summary is simply up for negotiation. That would be a false conclusion – the negotiations, such as they are, are in fact heavily constrained by the underlying science.
Finally, a few people have asked why the SPM is being released now while the main report is not due to be published for a couple of months. There are a number of reasons – firstly, the Paris meeting has been such a public affair that holding back the SPM until the main report is ready is probably pointless. For the main report itself, it had not yet been proof-read, and there has not yet been enough time to include observational data up until the end of 2006. One final point is that improvements in the clarity of the language from the SPM should be propagated back to the individual chapters in order to remove any superficial ambiguity. The science content will not change.
Had it been up to us, we’d have tried to get everything together so that they could be released at the same time, but maybe that would have been impossible. We note that Arctic Climate Impact Assessment in 2004 also had a similar procedure – which lead to some confusion initially since statements in the summary were not referenced.
How good have previous IPCC reports been at projecting the future? Actually, over the last 16 years (since the first report in 1990), they’ve been remarkably good for CO2 changes, temperature changes but actually underpredicted sea level changes.
When it comes to specific discussions, the two that are going to be mostly in the news are the projections of sea level rise and hurricanes. These issues contain a number of “known unknowns” – things that we know we don’t know. For sea level rise the unknown is how large an effect dynamic shifts in the ice sheets will be. These dynamic changes have already been observed, but are outside the range of what the ice sheet models can deal with (see this previous discussion). That means that their contribution to sea level rise is rather uncertain, but with the uncertainty all on the side of making things worse (see this recent paper for an assessment (Rahmstorf , Science 2007)). The language in the SPM acknowledges that stating
“Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise. Understanding of these processes is limited and there is no consensus on their magnitude.”
Note that some media have been comparing apples with pears here: they claimed IPCC has reduced its upper sea level limit from 88 to 59 cm, but the former number from the TAR did include this ice dynamics uncertainty, while the latter from the AR4 does not, precisely because this issue is now considered more uncertain and possibly more serious than before.
On the hurricane/tropical strorm issue, the language is quite nuanced, as one might expect from a consensus document. The link between SST and tropical storm intensity is clearly acknowledged, but so is the gap between model projections and analyses of cyclone observations. “The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period.”
We will address some of these issues and how well we think they did in specific posts over the next few weeks. There’s a lot of stuff here, and even we need time to digest it!
Etant donné tout le battage dans les médias depuis le TRE, nombre d’entre nous étaient curieux de voir ce que le nouveau rapport indiquerait au sujet des reconstructions paléoclimatiques des 1000 dernières années. Les « sceptiques »(euphémisme pour désigner les dernières personnes doutant encore du rôle de l’homme dans les changements climatiques récents) seront sans aucun doute déçus. Les conclusions ont été sensiblement renforcées par rapport à celles émises dans le TRE, ce qui était logiquement prévu en raison des nombreuses études additionnelles faites depuis et qui pointent toutes dans la même direction. La conclusion que le réchauffement récent à grande échelle excède « probablement » l’amplitude climatique des dix derniers siècles des 1000 dernières années dans le TRE, a été étendu aux 1300 dernières années dans ce rapport, et la confiance dans cette conclusion passe de « probablement » dans le TRE à « très probablement» dans le QRE pour les 500 dernières années. C’est juste l’un des nombreux éléments indépendants démontrant l’influence anthropique sur le climat ; certains voulaient le faire passer comme l’élément clé de l’évidence du changement climatique mais étant donné tous les autres éléments il est à présent encore moins le pilier central sur lequel repose les conclusions de l’influence humaine sur le climat.
Les incertitudes, au niveau science, impliquent principalement la nature précise des changements à prévoir, en particulier en ce qui concerne l’élévation du niveau de la mer, les changements d’El Niño et les changements hydrologiques régionaux – fréquence des sécheresses et fonte de neige, des tempêtes aux moyennes latitudes, et naturellement, des ouragans. Il peut être amusant de décortiquer les discussions sur ces sujets (et nous prévoyons qu’il y aura des commentaires substantiels dans la presse), mais celles-ci ne doivent pas occulter les conclusions principales beaucoup plus fermes.
Le processus de finalisation du SPM (qui est bien décrit ici
et là) est quelque chose qui peut sembler étrange. Les représentants de gouvernement de toutes les nations participantes prennent le résumé de l’ébauche (écrite par les auteurs principaux des différents chapitres) et discutent si le texte reflète vraiment les résultats scientifiques fondamentaux décrits dans le rapport principal. L’essentiel ici est de noter que ce qu’ont écrit au début les auteurs principaux ne l’est pas nécessairement sous la forme la plus clair ou la moins ambigüe d’un point de vue sémantique, et les gouvernements (pour qui le rapport est écrit) sont parfaitement autorisés à demander que les formulations soit modifiées de manière à que les conclusions soient correctement comprises à la fois par eux-mêmes et les scientifiques. Il est également important de noter que la formulation finale retenue doit être d’une part conforme aux résultats scientifiques fondamentaux des chapitres techniques, et d’autre part validée par les scientifiques. L’avantage de ce processus est que pour toutes les personnes impliquées, le sens de chaque phrase est parfaitement claire. Pour rappel, après la publication du rapport sur les reconstructions des températures de surface par les National Academies, de nombreuses discussions portaient sur le sens du mot « plausible ». Ce genre de chose ne devrait pas se produire avec le QRE.
Le processus du SPM a également un objectif politique très utile. Spécifiquement, il permet aux gouvernements impliqués de se sentir en partie « propriétaires» et parties prenantes du rapport. Ceci rend difficile les tergiversations ultérieures et les rejets du rapport en utilisant l’argument qu’il a été écrit par quelqu’un d’autre. Ceci oblige ainsi les gouvernements à s’impliquer pour que le rapport soit aussi bon qu’il puisse l’être (dans la marge fixée par les incertitudes). Il y a en fait de nombreuses barrières de sécurité (dont la présence des scientifiques) pour s’assurer que le rapport ne soit pas biaisé et orienté dans telle ou telle direction. Cependant, ceci peut être à tort interprété comme un processus de négociation sur l’intégralité du résumé. Ce serait une conclusion fausse – les négociations, telles qu’elles sont effectuées, sont en fait très fortement contraintes par la science fondamentale sous-jacente.
Enfin, certaines personnes se demandent pourquoi le SPM est publié maintenant alors que le rapport principal ne doit pas être publié avant le mois d’avril. Il y a un certain nombre de raisons – premièrement, la réunion de Paris a été une affaire tellement médiatisée que maintenir un embargo sur le SPM jusqu’à ce que le rapport principal soit prêt est probablement inutile. En ce qui concerne le rapport principal lui-même, il n’a pas été relu et corrigé, et les données de l’année 2006 n’ont pas encore pu être incluses dans le manuscrit. Enfin, des améliorations du SPM au niveau sémantique devraient être de nouveau répercutées au niveau des différents chapitres afin de lever toute ambiguïté. Au niveau science, le contenu ne changera pas.
Si cela avait été possible, nous aurions essayé d’obtenir l’ensemble en même temps, permettant ainsi une sortie synchrone. A noter que l’Arctic Climate Impact Assessment a utilisé en 2004 une procédure similaire – ce qui a conduit à un peu de confusion étant donné que les déclarations dans le résumé n’étaient pas référencées.
Quelle fût la qualité des précédents rapports à propos de leurs projections du futur ? En fait, pour les 16 dernières années (depuis le premier rapport en 1990), elles ont été remarquablement bonnes pour les changements du CO2 ainsi que des températures mais ont par contre sous-évalué les changements du niveau marin.
En ce qui concerne les discussions spécifiques, ce sont les prévisions relatives à l’élévation du niveau marin et aux cyclones que l’on va retrouver de manière dominante dans la presse. Ces questions comportent un certain nombre d’ « inconnues connues », – c’est à dire de choses dont nous soupçonnons le rôle et l’existence mais que nous ne connaissons pas suffisament pour les inclure dans les modèles. Pour le niveau marin, l’inconnue est l’ampleur du changement dynamique des calottes polaires. Ces changements dynamiques ont déjà été observés, mais non utilisables par les modèles de calottes polaires (voir cette discussion précédente). Cela signifie que leur contribution à l’élévation du niveau marin est plutôt incertaine, mais dans tous les cas l’incertitude liée à ce processus ne fera qu’empirer la situation (voir un papier récent pour une estimation (Rahmstorf, Science 2007 ). Ceci est reconnu dans le résumé et formulé ainsi :
« Les processus dynamiques relatifs au mouvement de la glace qui ne sont pas inclus dans les modèles actuels mais suggérés par les observations récentes, peuvent accroître la vulnérabilité de la calotte glaciaire au réchauffement, ceci accentuant la future élévation du niveau marin. La compréhension de ces processus est limitée et il n’y a pas de consensus sur leur amplitude. »
A noter que quelques médias comparent des résultats non strictement comparables : ils ont déclaré que le GIEC a réduit l’ampleur maximale de 88 à 59 cm, mais le chiffre précédent du TRE incluait cette incertitude relative à la dynamique de la glace, alors que ce n’est pas le cas avec le QRE, précisément parce que cette question est maintenant considérée comme davantage incertaine et peut-être plus sérieuse qu’avant.
A propos de la problématique cyclones/tempêtes tropicales, le ton est assez nuancé, comme l’on doit s’y attendre dans un document de consensus. Le lien entre température de surface céanique et intensité des tempêtes tropicales est clairement reconnu, comme l’ est la différence entre les projections des modèles et les analyses des observations cycloniques. «L’augmentation apprente de la proportion de cyclones très intenses depuis 1970 dans quelques régions est bien plus grande que celle simulée par les modèles actuels pour cette période ».
Nous aborderons quelques unes de ces questions et nous donnerons notre avis sur la manière dont elles ont été traitées dans des articles spécifiques dans les semaines à venir. Il y a beaucoup de travail en perspective, et nous avons, nous aussi, besoin de temps pour digérer tous ces résultats !
Traduit de l’anglais par T. de Garidel et O. Daniélo
Temos tido uma política de (em geral) não comentar os vários rascunhos, citações incorretas e erros de leitura no relatório da Quarta Avaliação (“AR4” para aqueles acostumados com acrônimos) do IPCC. Agora que o sumário para tomadores de decisão (ou “SPM”) do IPCC foi enfim publicado, é possível discutir seu cerne sem nos preocupar tanto com sutilezas e detalhes do relatório. Esta postagem é somente inicial, desde que planejamos avaliar o relatório capítulo por capítulo durante os próximos meses, explicando as questões chaves e as questões ainda incertas. Este relatório será repetidamente referenciado nos próximos meses, de modo que poderemos a tempo realizar um trabalho razoável explicando seu conteúdo e motivo.
Em primeiro lugar, pelas pesquisas que vêm sendo realizadas desde o Terceiro Relatório de Avaliação (TAR) de 2001 – muitas das quais têm sido discutidas aqui – não é surpresa alguma que o AR4 traga uma forte conclusão. Em particular, o relatório conclui que as influências humanas sobre o clima são “muito possivelmente” (> 90% probabilidade) detectáveis nos dados observados; aumentado de “possivelmente” (> 66% probabilidade) no TAR. Resultados chaves apresentados aqui incluem as simulações climáticas ao longo do século XX, realizadas com os mais modernos modelos de clima, demostrando que as recentes tendências não podem ser explicadas sem a inclusão do aumento da concentração de gases de efeito estufa devido às ações humanas. Esse aumento também é consistente com o aquecimento dos oceanos, derretimento de gelo nos mares e em terra, e sinais de mudanças em ecossistemas naturais. Tal conjuntura torna irrefutáveis as projeções de grandes e contínuas mudanças ao longo do tempo, particularmente sobre o cenário business as usual (sem mudanças nos padrões globais de produção e consumo).
Tendo em vista todo o sensacionalismo desde o TAR, muitos de nós estávamos curiosos para ver o que o novo relatório iria trazer sobre as reconstruções paleoclimáticas dos últimos 1000 anos. Os ’contrários‘ irão sem dúvida ficar desapontados. As conclusões têm sido significativamente fortalecidas em relação ao que havia no TAR, o que certamente deveria ser esperado, haja vista os numerosos estudos adicionais que têm sido feitos apontando para uma mesma direção. A conclusão de que o recente aquecimento em grande escala provavelmente excede o alcance visto nos últimos séculos, foi estendido dos 1000 anos utilizados no TAR, para os últimos 1300 anos no relatório atual, e a confiança nessa conclusão foi promovida de “possivelmente” no TAR para “muito possivelmente” no relatório atual para o último meio milênio passado. Esta é apenas uma das várias e independentes linhas de evidências agora apontando em direção a uma clara influência antropogênica sobre o clima. Porém, dada todas as outras, as reconstruções paleoclimáticas são agora menos ainda o pilar central das evidências da influência humana sobre clima do que vinham incorretamente sendo consideradas.
As incertezas científicas envolvem principalmente a natureza precisa das mudanças esperadas, particularmente com respeito à elevação do nível do mar, mudanças do El Niño e em regimes hidrológicos regionais – freqüência de secas e descongelamento de coberturas de gelo, tempestades em latitudes médias, e com certeza, furacões. Pode ser divertido avaliar os pormenores das discussões nestes tópicos (e nós esperamos que haverá uma cobertura substancial da impresa sobre eles), mas isso não deve nos distrair das principais e das mais sólidas conclusões.
O processo de finalização do SPM (o qual é bem descrito aqui and aqui) pode parecer um pouco estranho. Representantes dos governos de todas as nações participantes pegam o rascunho do sumário (como escrito por um dos autores líderes de um dos capítulos individuais) e discutem se o texto reflete fielmente a ciência que está por trás do relatório principal. A chave aqui é notar que o que os autores líderes originalmente redigiram não é necessariamente a mais clara ou menos ambígua linguagem, de modo que cabe perfeitamente aos governos (para os quais o relatório está sendo escrito) insistirem que a linguagem seja modificada para que as conclusões sejam corretamente entendidas por eles e pelos cientistas. É também importante frisar que os cientistas têm que estar contentes com a linguagem final acordada, e se esta concorda com a ciência contida nos capítulos técnicos. A vantagem desse processo é que qualquer um envolvido está absolutamente consciente dos significados de cada sentença. Lembre-se que depois do National Academies report on surface temperature reconstructions” houve muita discussão sobre a definição de ‘plausível’. Este tipo de coisa não deve ocorrer no AR4.
O processo do SPM também é muito útil como uma proposta política. Especificamente, ele permite aos governos envolvidos sentirem-se ‘como parte’ do relatório. Isso torna difícil mudanças posteriores nas posições assumidas, com base no argumento de que o relatório foi escrito por outra pessoa. Isso fornece aos governos um absoluto interesse em tornar esse relatório o melhor possível (dada as incertezas). Existem de fato muitas salvaguardas (ao menos pelos cientistas presentes) para assegurar que o relatório não seja enviesado em qualquer direção preferencial. Todavia, o lado ruim é que ele pode ser erroneamente confundido como um ponto de partida para negociações. Esta pode ser uma conclusão falsa – as negociações estão, de fato, fortemente constritas pela ciência subjacente.
Finalmente, poucas pessoas têm se perguntado por que o SPM está sendo lançado agora enquanto o relatório deverá ainda ser publicado em alguns meses. Existe um número de razões – primeiramente, a reunião de Paris possui tal significado público que segurar o SPM até que o relatório principal esteja pronto torna-se sem sentido. O relatório principal propriamente dito ainda não foi corrigido na íntegra, e não houve tempo suficiente para incluir dados observacionais do fim de 2006. Uma questão final é que as melhorias na concisão da linguagem do SPM devem ser propagadas para os capítulos individuais, de modo a remover qualquer ambigüidade superficial. O conteúdo científico não deve mudar.
Se dependesse de nós, teriamos tentado colocar tudo junto de modo que eles pudessem ser lançados ao mesmo tempo, mas talvez isto não fosse possível. Notamos que o “Arctic Climate Impact Assessment” em 2004 também teve um procedimento similar – o que levou a uma certa confusão inicial, pois as afirmações contidas no sumário não estavam referenciadas.
O quão bom estavam os relatórios anteriores do IPCC quanto à antecipação do futuro? Na verdade, nos últimos 16 anos (desde o primeiro relatório em 1990), eles têm se mostrado notavelmente bons para as mudanças de CO2 e temperatura, mas com previsões não tão boas acerca das mudanças do nível do mar.
Com relação às discussões específicas, os dois temas mais cobertos pelos jornais são as projeções de aumento do nível do mar e os furacões. Essas questões contêm um número de “ignorâncias conhecidas” – coisas que nós sabemos que não sabemos. Para o aumento do nível do mar, o desconhecimento é quão grande será o efeito de alterações na dinâmica das superfícies de gelo. Tais mudanças dinâmicas já foram observadas, mas estão fora do alcance da capacidade dos modelos atuais de superfícies de gelo (veja esta discussão anterior). Isso significa que suas contribuições para o aumento do nível do mar são bastante incertas, mas com todas as incertezas pendendo para o pior cenário (veja este recente artigo para uma avaliação (Rahmstorf , Science 2007)). A linguagem no SPM ressalta isso dizendo
“Processos dinãmicos relacionados à movimentação de gelo não incluídos nos modelos correntes mas sugeridos por observações recentes podem ampliar a vulnerabilidade das superfícies de gelo ao aquecimento, aumentando a futura elevação do mar. A compreensão desses processos é limitada e não há consenso sobre sua magnitude.”
Note que alguns órgãos da mídia têm comparado maçãs com peras: eles argumentam que o IPCC reduziu seu limite superior do nível do mar de 88 para 59 cm, mas o primeiro número do TAR incluiu a incerteza da dinâmica do gelo, enquanto que o último do AR4 não inclui, precisamente porque essa questão é agora considerada mais incerta e possivelmente mais séria que antes.
No caso das tempestades tropicais/furacões, a linguagem é muito suave, como pode-se esperar do um documento de consenso. A ligação entre SST e a intensidade de tempestades tropicais é claramente reconhecida, mas também a distância entre as projeções de modelos e as análises das observações de ciclones. “O aumento aparente da porporção de eventos muito intensos desde 1970 em algumas regiões é muito maior que o simulado pelo modelos atuais para este período”.
Iremos focalizar algumas dessas questões em postagens específicas durante as próximas semanas. Existe muita coisa aqui, e o nós precisaremos de tempo para digerir tudo!
Traduzido do inglês por Ivan B. T. Lima e Fernando M. Ramos.
Ingilizce’den çeviren: Figen Mekik
Uluslararası Iklim Değişikliği Görevgücü (UIDG) dördüncü değerlendirme raporunun (4DR) çeşitli müsveddelerini ve hakkındaki doğru veya yanlış yargıları burada konu etmemeyi politika edinmiştik. Ancak, şimdi politika belirliyiciler için özeti (PBÖ) yayınlandığından, raporun içeriğini değişikliğe uğrayacağı endişesi olamadan tartışabiliriz. Bu yazımız tüm raporun tartışmasındaki ilk adımımız olacak. Önümüzdeki aylarda raporu ve içindeki önemli konuları, kavramları ve belirsizlikleri teker teker işlemeyi düşünüyoruz. Önümüzdeki bir kaç sene içinde bu rapora pek çok atıf yapılacağı muhakkak; bu yüzden raporun içeriğini ve içinde yazılanların sebeplerini detaylı olarak ele almamız gerekli.
Ilkin, Üçüncü Değerlendirme Raporunun (3DR) 2001’de yayınlanmasından beri (bu konuyu çok tartıştık burada) ilerleyen bilim sayesinde 4DR’nin daha sağlam sonuçlara varmış olması kimseyi şaşırtmamalı. Özellikle 4DR şu sonuca varmış: insanların küresel iklim üzerindeki etkisinin ölçülebilir izler bırakıyor olma olasılığı yüzde 90’ın üzerinde. Bu 3DR’de sadece yüzde 66 olarak belirlenmişti. Buradaki önemli sonuçlardan biri en yeni bilgisayar modelleriyle yapılan 20inci yüzyıl iklim benzetimlerinde son yıllarda iklimde gözlemlenen eğilimlerin insan-dışı etkenlerle açıklanamaması, ve bu trendleri açıklayabilmek için modellere muhakkak insanlardan kaynaklanan sera gazlarındaki artış, düzenli olarak deniz sularının ısınması, deniz buzlarının erimesi, buzulların erimesi ve ekosistem kaymaları eklenmesi gerekmektedir. Bu da, “her-zamanki-gibi-iş-başında” (business as usual) tutumundan sonuçlanacak daha büyük iklim değişikliklerinin olacağını tartışmasız kabul edilecek hale getiriyor.
3DR’nin yarattığı tartışmalardan sonra, 4DR’nin, geçen 1000 yıl için yapılan geçmiş-iklim geriçatmaları hakkında ne yazdığını çok merak ettik. Karşı çıkanlar burada muhakkak hayal kırıklığına uğrayacaklar. 3DR’deki sonuçlara göre yeni rapordakiler çok daha güçlendirilmiş vaziyette. Tabii bu beklenen bir gelişme çünkü üçüncü rapordan bu yana pek çok bilimsel çalışma yapıldı ve tüm bu çalışmalar hep aynı yönde sonuçlara vardılar. Güncel geniş yöresel ısınmanın herhalde geçtiğimiz yüzyıllarda görülen ısınmadan daha fazla olduğu vargısı, üçüncü raporda “geçmiş binyıl’a göre’ye” çıkarılmıştı ve herhalde yerine olasılıkla denilmişti; ve şimdi yeni raporda bu ısınmanın büyük olasılıkla geçmiş 1300 yılda gözlemlenenden daha çok olduğu belirlendi. Pek çok bağımsız ve somut delil kullanımı yoluyla da görüyoruz ki iklim üzerinde insan-kaynaklı net bir etki var. Ancak, diğer tüm delilleri göz önünde bulundurursak, artık insan-kaynaklı iklim değişimi savında geçmiş-iklim geriçatmaları daha az önem taşıyor; zaten bu geriçatmalar yanlış vurgulanmıştı.
Bu bilim dalındaki belirsizliklerin çoğu olabilecek değişikliklerin tam karakterini kestirememe çerçevesinde yoğunlaşıyor, özellikle deniz seviyesindeki artışlar, El Nino ile ilgili ve bölgesel hidrolojik değişimler (mesela, kuraklık sıklığı ve yoğun kar erimesi, orta enlem fırtınaları ,ve tabbi ki kasırgalar). Her ne kadar bu konuları tartışmak çok zevkli olacaksa da (herhalde medya bu konuda çok tartışmaya meydan tutacaktır), raporun yukarıda bahsettiğimiz daha sağlam ve önemli diğer sonuçlarını gözardı etmemeliyiz.
PBÖ’nün son haline getirilmesi süreci biraz tuhaf gelebilir (ki burada ve burada tarifleri var). Ilgili tüm devletlerin temsilcileri bu özetin bir kopyasını alıp (ki bu özetler rapordaki her bolümünün önde gelen yazarları tarafından hazırlanıyor), ana rapordaki metnin gerçekten arkasındaki bilimi yansıtıp yansıtmadığını tartıştılar. Burada dikkat edilen husus şu: önde gelen yazarların ilkin hazirladiği özetteki ifade olabilecek en net ve kesin anlatımla yazılmamış olabilir. Dolayısıyla bu devletlerin temsilcileri (ki zaten bu kişiler için bu rapor hazırlanıyor) bu raporda istedikleri değişiklerin yapılmasında israr etmeye yüzde yüz hak sahibi oluyorlar ki raporu, hem kendileri hem de yazan bilim insanları rahatlıkla anlayabilsinler. Bir diğer husus da şu ki bu metni hazırlayan ve düzelten bilim insanları yeni metinden memnun ve raporun arkasinda yatan bilimsel sonuçlarla bağdaştığından emin olmalılar. Bu süreci olumlu yanı bu konuyla uğraşan herkesin her cümledeki manayı açıkça anlayabilmesidir. Hatırlarsanız Milli Akademi’nin (National Academies) yüzey ısı geriçatması raporundaki “muhtemel” kelimesi çok tartışma yaratmıştı. 4DR’de bunun engellenmesi isteniyor.
PBÖ sürecinin ayrıca son derece değerli bir siyasi amacı da var: ilgili devletlerin rapora sahip çıkmasını sağlıyor. Bu, ileride raporun “başkasi yazdı” mazeretiyle ört bas edilmesine engel olacaktır. Raporun olabileceği en iyi hale gelmesinde (belirsizlikler dahilinde) bu devletlerin de çıkarı oluyor dolayısıyla. Hatta burada raporun herhangi bir eğilime tabi olmasını engelleyecek pek çok koruyucu unsur mevcut. Ancak, bu tutum yanlış algılanabilir; tüm raporun tartışmaya açık olduğu izlenimini verebilir. Bu doğru bir yargı olmaz çünkü raporla ilgili tartişmalar çok sağlam bilimsel gerçeklere dayanmaktadır.
Son olarak, pek çok kişi PBÖ’nün neden ana rapordan aylar once yayınlandığını sordu. Bunun bir kaç sebebi var: ilk olarak, Paris toplantisi o kadar aleni bir olay oldu ki, PBÖ’yü ana rapor yayınlanana kadar tutmak anlamsızlaştı. Ana rapora gelince, henüz detaylı bir şekilde okunup düzeltilmedi ve 2006 yılının sonuna kadar gözlemlenen ve ölçülen veriler henüz rapora dahil edilemedi. Ve bir diğer husus da PBÖ’nün yazım dilinde yapılan düzeltmeler rapordaki ait oldukları bölumlere aktarılmalı, ve açıkça ifade edilememiş öyeler düzeltilmeli. Ama raporun bilimsel içeriği değismeyecek.
Bize kalsaydı, biz herseyi bir arada hazırlayıp sunmayı isterdik, ama belki bu mümkün olamadı. 2004’deki Arktik Iklim Etkisi Değerlendirmesinde de benzeri bir sürecin yaşandığını gördük, ve bu süreç bazı yanlış anlaşılmalara sebep oldu çünkü özetteki bazı yazılanlar raporla desteklenememişti.
Geçmiş UIDG raporları geleceği tahmin etmekte ne kadar başarılı oldu? Aslında, son 16 yıldır (ilk rapor 1990’da yayınlandı), atmosferdeki CO 2 ve ısı değişimlerini belirlemekte başarılıydılar ama deniz seviyesi hesapları gerçekte gözlemlenenden az oldu.
Belirli tartışma konularına gelince, başında en çok ele alınacak iki unsur var: deniz seviyesindeki değişiklikler ve kasırgalar. Bu unsurların bir kaç tane “bilinen bilinmeyenleri” var – yani hakkinda fazla bilgimizin olmadığını bildiğimiz şeyler. Deniz seviyesindeki değişiklikler için kestirmediğimiz unsur buzul levhalarındaki dinamik değişimlerin deniz seviyesini nasıl etkilediği. Bu dinamik değişiklikler gözlemlendi, ama gözlemlerimiz buzul levhası modellerinin kapasitesi dışında oldu (daha önceki tartışmamızı burada okuyun). Bu da buzul levhalarının dinamiğinin deniz seviyesi üzerinde etkisinin henüz belirsiz olmasından kaynaklanıyor; ancak bu belirsizliğin çapı deniz seviyesindeki artışı daha da vahim yapacak doğrultuda (bu konuyu değerlendirmek için yeni yayınlanmış şu makaleye bakabilirsiniz (Rahmstorf, Science 2007)). PBO bu konuyu şöyle dile getiriyor:
“Güncel modellere dahil edilmeyen ancak yakın zaman içinde gözlemlenmiş olan buzul akışıyla ilgili dinamik süreçler, buzul levhalarını küresel ısınmaya karşı daha da hassaslastırabilir, ve ileride deniz seviyesinde daha fazla artışa sebep olabilir. Bu süreçlerin anlaşılabilirliği sınırlıdır ve boyutu hakkında bir ortak kanı henüz yoktur.”
Burada şuna dikkatinizi çekelim: bu konuda bazı medyacılar elmalarla armutları kıyaslamaktalar: Diyorlar ki UIDG deniz seviyesi artışı tahmininin üst sınırını 88 den 59 cm’e indirdi. Ancak, 3DR bu buzul dinamiği belirsizliğini hesaba katmıştı; 4DR katmadı çünkü özellikle bu unsur şimdi daha az kesin tespit edilebilir bulunuyor ve muhtemelen eskiden olduğundan daha ciddi kabul ediliyor.
Kasırga/tropik fırtına konusuna gelince, rapordaki uslupta çok nuans var, ve bir ortak karar belgesinden bu beklenir. Deniz üstü ısısı ile tropik fırtına sıklığı arasındaki iliski açıkça kabul görmüş vaziyette, ancak aynı açıklıkla görülen bir diğer şey de model tahminleri ile kasirga analizleri arasindaki büyük farklar. “1970’den beri bazı bölgelerde görülen güçlü kasrıgalarda sıklık (artıs) modellerin tahminin çok üstünde.”
Önümüzdeki haftalarda bu konuları ve PBÖ’nün başarısını tartısacağız. Burada çok malzeme var ve hazmetmek için bizim de zamana ihtiyacımız var!
Traducido por Covadonga Escandon
Hemos seguido un política de (casi) no comentar los distintos borradores, citas erróneas y lecturas equivocadas del Cuarto informe de evaluación (AR4 por sus siglas en inglés) del Grupo Intergubernamental de Expertos sobre Cambio Climático (IPCC). Sin embargo, ahora que ya ha sido publicado el resumen para responsables de políticas (o SPM), podemos discutir los contenidos del reporte sin tener que preocuparnos de que los detalles vayan a cambiar. Este artículo será el primero en el que hablaremos sobre el reporte completo. Planeamos ir capítulo por capítulo y esperamos explicar los puntos clave y las dudas claves que aún quedan durante los próximos meses. Este reporte será citado repetidamente durante los próximos años así que podemos tomarnos el tiempo necesario para explicar bien qué contiene y por qué.
En primer lugar, dada la ciencia que se ha llevado a cabo desde el Tercer informe de evaluación (TAR) en 2001 -gran parte del cual ha sido discutido aquí- nadie debería sorprenderse de que el AR4 llegue a una conclusión más firme. En particular, el reporte llega a la conclusión de es “muy factible” (> 90% de probabilidad) que las influencias humanas sobre el clima ya sean detectables en los registros de observaciones; en el TAR esto se consideraba como “factible” (> 66% de probabilidad). Los resultados claves aquí incluyen las simulaciones para el siglo XX usando modelos climáticos punteros que demuestran que las tendencias recientes no pueden ser explicadas si no se incluyen incrementos de gases de invernadero relacionados con los humanos así como evidencia consistente del calentamiento oceánico, del derretimiento de hielo marino y de glaciares y cambios en los ecosistemas. Esto hace que las proyecciones de mayores y continuados cambios ya iniciados (especialmente bajo escenarios “no cambiemos nada”) sean esencialmente indisputables.
Dado todo el sensacionalismo que ha habido desde el TAR, muchos de nosotros teníamos curiosidad por ver qué diría el nuevo reporte sobre reconstrucciones paleoclimáticas de los últimos mil años. Los detractores quedaran sin duda decepcionados en este sentido. Las conclusiones han sido significativamente fortalecidas con respecto a lo que estaba en el TAR, algo que era de esperarse dado el número de estudios adicionales que se han hecho desde entonces y que apuntan todos en la misma dirección. La conclusión de que el calentamiento reciente a gran escala factiblemente sobrepasa el rango observado durante los siglos anteriores ha sido ampliada de los últimos 1000 años en el TAR a los últimos 1300 años en el reporte actual y la confianza en esta conclusión se ha incrementado de “factible” en el TAR a “muy factible” para el último milenio en el nuevo reporte. Ésta es solamente una de las muchas líneas independientes de evidencia que apuntan ahora hacia una clara influencia antropogénica sobre el clima; pero, dadas todas las demás, las reconstrucciones
paleoclimáticas son ahora todavía menos el pilar central de evidencia sobre la influencia humana sobre el clima, que es lo que incorrectamente se ha hecho creer.
Las incertidumbres en la ciencia involucran principalmente la naturaleza exacta de los cambios que deben esperarse, particularmente con respecto al incremento del nivel del mar, cambios en El Niño y cambios hidrológicos regionales -frecuencia de las sequías y derretimiento de la cubierta nivosa, tormentas en latitudes medias y, por supuesto, huracanes. Puede ser interesante analizar en detalle las discusiones sobre estos temas (y esperamos que haya numerosos comentarios sobre ellos en la prensa), pero esto no debe distraernos de las principales y más sólidas conclusiones mencionadas arriba.
El proceso para terminar el SPM (que está descrito aquí y aquí) es algo que puede parecer un poco extraño. Representantes gubernamentales de todas las naciones participantes toman el borrador del resumen (tal y como lo escriben los autores principales de los capítulos) y discuten si el texto refleja realmente la ciencia que sustenta el reporte principal o no. Lo importante aquí es señalar que lo escrito por los autores principales originalmente no es necesariamente el lenguaje más claro posible ni el menos ambiguo, por ello los gobiernos (para quienes se escribe el reporte) tienen todo el derecho de insistir en que el lenguaje sea modificado de tal modo que las conclusiones sean entendidas correctamente por ellos y por los científicos. También es importante hacer notar que los científicos tienen que estar contentos con que el lenguaje final acordado se corresponde con la ciencia de los capítulos técnicos. La ventaja de este proceso es que todos los involucrados tiene perfectamente claro qué significa cada frase. Hay que recordar que después del reporte de las Academias Nacionales sobre las reconstrucciones de la temperatura de la superficie hubo una gran discusión sobre la definición de ‘plausible’. Este tipo de cosas no deberían pasar con el AR4.
El proceso para el SPM también sirve a un muy útil propósito político. Específicamente, permite que los gobiernos involucrados sientan como que parte del reporte “les pertenece” a ellos. Esto dificulta mucho que después algunos cambien de opinión y lo rechacen sobre la base de que fue escrito por alguien más. Esto hace que los gobiernos tengan un especial interés en que el reporte sea tan bueno como sea posible (dadas las incertidumbres). Hay de hecho gran cantidad de salvaguardas (empezando por los científicos presentes) para asegurar que el reporte no esté sesgado hacia alguna dirección concreta. Sin embargo, un aspecto negativo es que puede parecer erróneamente como si el resumen entero simplemente pudiera negociarse.
Esta sería una conclusión falsa: las negociaciones, tal y como están, se encuentran de hecho fuertemente restringidas por los hechos científicos. Finalmente, unas cuantas personas han preguntado porqué el SPM se hace público ahora mientras que el reporte completo no será publicado hasta dentro de un par de meses.
Hay varias razones: primero, el encuentro de París ha sido un asunto tan público que guardar el SPM hasta que esté listo el reporte principal probablemente no tiene sentido. En lo que respecta al reporte mismo, todavía no había sido revisado y aún no ha habido suficiente tiempo para incluir datos de observación de finales del 2006. Un último punto es que las mejoras en la claridad del lenguaje del SPM deben propagarse hacia los capítulos específicos de tal modo que desaparezca cualquier ambigüedad superficial. El contenido científico no cambiará.
Si hubiéramos podido decidir nosotros, hubiéramos tratado de tenerlo todo junto de tal manera que pudieran ser hecho públicos simultáneamente pero esto talvez hubiera sido imposible. Notamos que en el 2004, para la Evaluación de impactos climáticos del Ártico se siguió un procedimiento similar, lo que produjo algo de confusión inicialmente ya que algunas afirmaciones del resumen no tenían las citas correspondientes.
¿Qué tan buenos han resultado los anteriores reportes del IPCC haciendo proyecciones a futuro? De hecho, a lo largo de los últimos 16 años (desde el primer reporte en 1990), han resultado extraordinariamente buenos para cambios en el CO2 y cambios en la temperatura pero subestimaron los cambios en el nivel del mar.
En lo que se refiere a discusiones específicas, las dos que van a estar mayormente en las noticias son las proyecciones del aumento del nivel del mar y los huracanes. Estos temas contienen algunas “incógnitas conocidas” (cosas que sabemos que ignoramos). Para el incremento del nivel del mar, la incógnita es qué tan grande será el efecto de cambios dinámicos en las placas de hielo continentales. Estos cambios dinámicos ya han sido observados pero están fuera del rango con el que pueden lidiar los modelos para placas de hielo (ver esta discusión previa). Esto significa que su contribución al aumento en el nivel del mar es más bien incierta pero esta incertidumbre yace totalmente del lado que empeoraría las cosas (ver este reciente artículo para una evaluación: Rahmstorf, Science 2007). El lenguaje en el SPM reconoce dicha afirmación.
“Los procesos dinámicos relacionados con el flujo de hielo que no están incluidos en los modelos actuales pero que son sugeridos por observaciones recientes, incrementarían la vulnerabilidad de las placas de hielo al calentamiento, aumentando el futuro incremento en el nivel del mar. La comprensión de estos procesos es limitada y no hay un consenso sobre su magnitud.”
Hay que mencionar que algunos medios han estado comparando peras con manzanas en esto: afirmaron que el IPCC ha reducido su límite superior para el nivel del mar de 88 a 59 cm, pero la primera cifra dada en el TAR sí incluía esta incertidumbre de la dinámica del hielo mientras que la segunda dada en el AR4 no la incluye, justo porque a este tema se le considera ahora más incierto y posiblemente más serio que antes.
Sobre el tema de los huracanes/tormentas tropicales, el lenguaje está muy matizado, como es de esperarse en documento que refleja un consenso. La liga entre la temperatura de la superficie del mar (TSM) y la intensidad de las tormentas tropicales se admite claramente pero también se acepta la distancia entre las proyecciones de los modelos y los análisis de las observaciones de ciclones. “El aparente aumento en la proporción de las tormentas muy intensas desde 1970 en algunas regiones es mucho mayor de lo que simulan los modelos actuales para ese periodo.”
Abordaremos algunas de estas cuestiones y qué tan bien creemos que resultaron en artículos específicos durante las próximas semanas. ¡Hay mucho material aquí y nosotros también necesitamos tiempo para digerirlo!
#15, thanks, Spencer, for that clarification. I had thought that 1.5-4 degree C range must have been the climate sensitivity range for 2X CO2, because 4 degrees didn’t seem like the worse-case human emissions scenario (at highest sensitivity). And I believe TAR had the upper figure (of worse case scenario) at 5.8 degrees C. So the AR4 figure would be an increase — am I right? But the media have been jumping around these past few months saying AR4 indicates GW will not be so bad, bec they’ve ratcheted down the warming figures.
#16, Jake, I’m also concerned with natural GHG emissions increasing due to the warming that the human emissions have caused. I do hope AR4 deals with that, even though such positive feedbacks entail a lot of uncertainty.
So my question then would be, is 6.4 degrees C the upper end only for the worst case of human emissions (at the highest sensitivity), and thus leaves out the positive feedbacks (nature emitting due to the warming, lower albedo from melting ice)? I mean, is there a possibility of even a higher temp when both human emissions and positive feedbacks are considered.
From what I understand, positive feedbacks (e.g., from melting permafrost & clathrates, & reduced albedo) are not included in the models.
#17, I do think a 3 degree increase would be pretty disasterous, esp for the poor peoples of the world (& it would make the rich a lot poorer); it’s sort of like the reichter scale – the change from a 6 to a 7 involves a lot more danger & harm than from a 5 to a 6, so a rise from 2 to 3 degrees C with GW would probably entail a lot more harms than a 1 to 2 degree increase, with a 5 to 6 degree increase extremely bad. You don’t want to go there. I’m just waiting to get Mark Lynas’s SIX DEGREES when it comes out in March; in lay language he takes us through each degree increase — 1, 2, 3, 4, 5, 6 degrees — and what each degree increase would mean re effects and harms.
Just today the opposition (CNSNews.com) is claiming that language such as “One final point is that improvements in the clarity of the language from the SPM should be propagated back to the individual chapters in order to remove any superficial ambiguity. The science content will not change.” is simple proof that making the science fit the summary is what is being done. The idea that a negotiated political “summary” should propagate it’s language back to the detailed science is very suspicious to many people for whom global warming as a result of human activity is NOT a clear fact.
#43: Sean, I’m pretty sure that it’s mm/year in both Greenland and Antarctic ice sheets numbers 1961-2003 (like in 1993-2003 numbers). So in metres/century: 0.042+0.050+0.005+0.014=0.111, or approx 0.11.
This is extremely shameless. Steven Milloy at http://www.junkscience.com has released the draft of the working group 1. How desperate will these political puppets get?
Re #15: Maybe just a typo but the SPM defines “very likely” as 90% to 95% certain, “Extremely likely” covers 95% to 99% certain. Very glad to to see the precise definitions of terms that still carry an effective qualitative message.
re 19:
Will Al Gore adapt his sea level projection for The Netherlands?
http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=5609&start=1
I personally believe that the biggest issue related appears to be the rate of CO2 increase and hence the time that it takes for 2 C of warming to take place. Currently annual emissions increases are 2 ppmv but recent years have seen 2.6 and 2.5 ppmv increases, if that accelerates to 3 ppmv somehow then we could be out of time as 100 ppmv increase to 480 ppmv which would take 50 years at 2 ppmv will only take 33 years at 3ppmv.
i wonder what the latest 2006 annual increase rates are and whether this is set to increase?
I just put up a new post summarizing what (I noticed) has changed in the IPCC from TAR to AR4.
IPCC SPM- So What’s New?
Cheers,
Sean
(If my comment is not suitable for posting, please email me and explain why, thank you.)
I had asked in the previous blog post (comment was not posted):
Do we have some sort of numerical representation for the greenhouse effect? In other words, a measurement of total solar energy which reaches the surface, and what percent is direct sunlight versus what percent is the greenhouse effect. Do we have such a number, and have we tracked changes in it (and for how long?
Thank you.
Off topic, but …
The American Solar Energy Society today released a 200 page report, “Tackling Climate Change in the US: Potential U.S. Carbon Emissions Reductions from Renewable Energy and Energy Efficiency by 2030” which outlines how the USA can reduce its carbon emissions by 60 to 80 percent by 2030 with improvements in efficiency and deployment of existing clean, renewable energy technologies.
The 60 to 80 percent reduction is in line with what is needed to keep CO2 concentrations below 450 to 500 ppm, which is what most scientists believe is necessary to prevent the worst effects of global warming.
Fifty-seven percent of the carbon reductions are from energy efficiency improvements, and forty-three percent are from renewables. No expansion of nuclear power is included in the proposal.
I know that many frequent contributors to these comment pages are very interested in solutions to the problem of reducing US carbon emissions, and will find this report useful.
Dr Rajendra Pachauri, IPCC chairman and DG, The Energy and Resources Institute & Chair IPCC: “A number of scientists say Siachen should be made a protected area, a heritage site of sorts, and that there should be no army presence on either side. For purely ecological reasons, this *might* be a good idea. But I *don’t* see why there would be melting as a result of military presence and activity.” The *s show a vagueness unworthy of an environment leader who ought to ask for withdrawal of all troops immediately! Click to see the view of chairman IPCC
http://www.dnaindia.com/report.asp?NewsID=1076589
So, we should not expect a lot from IPCC, currently head by Dr Rajendra Pachauri, as his biased, unprofessional remarked already appeared in news paper and enough to say that it would be another media hype and noting else.
Walt Bennett wrote: “Do we have some sort of numerical representation for the greenhouse effect? In other words, a measurement of total solar energy which reaches the surface, and what percent is direct sunlight versus what percent is the greenhouse effect. Do we have such a number, and have we tracked changes in it (and for how long?”
Yes, NOAA tracks that, and reports on it every year in the Annual Greenhouse Gas Index, using 1990 as the baseline.
NOAA’s May 2006 report, for 2005, found that the total “greenhouse effect” had increased by 21 percent since 1990.
In the SPM-0 table, in the 1993-2003 column, not only do the central values not add up, but the errors don’t compute either. If the Antarctic uncertainty was 0.35m/century, that would dominate the uncertainty in the sum which would therefore have to be much larger than 0.07m/century.
Pretty surprising to see elementary errors like this in such a profoundly important document. Too many late nights? It’s still broken as of right now.
[Response: It’s a simple unit conversion error, some values (including their error bars) are accidentally in mm/yr, not in m/century, hence they are a factor of 10 too large. -stefan]
More evidence of global warming:
#52: Walt: Figure SPM-2 in the new summary shows the (direct) anthropogenic contribution to the greenhouse effect of 1.6 W/m2 (0.6 to 2.4 W/m2 bounds). One presumes there would be a further indirect effect of increased water vapor forcing and albedo change from melting ice that aren’t quantified here (though they do quantify albedo change from black carbon in snow and land use).
This compares to: average sunlight: about 240 W/m2 (that’s 1368 W/m2 divided by 4 for surface area of a sphere vs. a circle times 0.7 for earth’s albedo) (said insolation keeps us at 255 K), plus natural greenhouse of about 150 W/m2 (bringing us to 288 K). With about 0.1 W/m2 solar increase since 1750.
They don’t report the increased forcing from the 6 SRES scenarios, but I would guess (looking at temperature changes) that the direct forcing increases range from 3.5 W/m2 to maybe 12 W/m2 above preindustrial.
So perhaps 8 W/m2 direct anthropogenic forcing, with additional forcing from water vapor/cloud and ice albedo changes of perhaps 3 times the direct effect (a rough estimate based on a climate sensitivity of 3), means 32 W/m2 human caused forcing, which would be equal to an increase of 20% in natural forcing or a 13% increase in the Sun, or an 8% increase in all forcing. That’s pretty big (enough for 6 degrees C above preindustrial at equilibrium). Obviously, changes in climate sensitivity estimates or emissions forecast can increase or decrease that number by a lot.
(RC moderators, please correct me if I’ve made any calculation errors)
re:53. “How desperate will these political puppets get?”
Money talks a lot for the likes of them.
Re 49 … a lot of extra precpitation looking for somewhere to go. Where will it all end up?
A lot of the extra precipitation will end up falling as rain in the higher latitude regions.
The increase in humidity will increase latent heat.
The significance of latent heat for snowmelt has been described by Dunne and Leopold (1978):
�If water from moist air condenses on a snowpack, 590 calories of heat are released by each gram of condensate. This is enough energy to melt approximately 7.5 gm of ice, which when added to the condensate yields a total of 8.5 gm of potential runoff�.
http://www.mnforsustain.org/climate_snowmelt_dewpoints_minnesota_neuman.htm
Re: 59 – Excellent URL with good, pragmatic information. IMHO I don’t think it is realistic to assume 60 to 80% alt energy is achievable without nuclear. While I can’t speak for the other sources, I know from work experience that solar has major challenges, and even the authors of the article don’t describe potential outcomes as “likely”. But any amount would be an excellent start.
BTW, secularanimist, go lite on us conservatives(ala 34 and other comments on RC) that don’t always agree with you.
“The major natural greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (not including clouds); carbon dioxide, which causes 9-26%; methane, which causes 4-9%, and ozone, which causes 3-7%. It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive.” Greenhouse Gas via Wikipedia.
Well what is it for CO2? 9% or 26%? That looks to me a pretty big margin of error. A multitude of 3 margin of error, ouch.
http://en.wikipedia.org/wiki/Greenhouse_gas
______________________________
99 ppm added CO2 from pre-industrial to 2007.
So how much more thermal energy is added to earth per square kilometer, with 99 more ppm, and how much would that theoretically raise the temperature of the earth in total? Theoretically speaking. No need to adjust for clouds, water vapor, etc, just how much more thermal energy is added.
http://www.ipcc.ch/SPM2feb07.pdf
[Response: Funny guy. You should probably investigate where that information came from – I’m sure it’s reputable and they’ll probably explain what the range means…. (hint) – gavin]
RepublicanGuy: 9% to 26% is not _margin of error_ it is a fundamental difficulty in assigning a number. The number you get by taking a vacuum and adding 270 ppm of CO2 is a lot different than the number you get by taking the preindustrial atmosphere and subtracting 270 ppm CO2 (I would guess that 26% is the first approach and 9 % the second). This occurs because the various gases have overlapping spectra.
The SPM states that the increase in CO2 leads to a 1.66 W/m2 increase in forcing. I know that doubled CO2 (4 W/m2) has about a 0.8 degree C direct contribution to temperature (along with .7 to 3.7 degrees feedback), so 1.66 W/2 would be about 0.3 degree C, with 0.3 to 1.4 degree additional feedback expected. We’ve seen 0.8 degrees of warming, and expect 0.6 degrees more, which falls within that range.
Does that answer your question?
The current scientific consensus is (found in comparing AR-4 to TAR) based on far greater certainty that global warming is due to human actions, that the sharp rise in heat trapping gases since the 1950s is not a natural cycle, and this condition will not soon go away. The evidence is clear that actions must be taken soon because the rates at which carbon dioxide, methane and nitric oxide are increasing are unprecedented. Present levels of carbon dioxide in the atmosphere have not been detected on earth for over 600,000 years.
Because of these facts, ocean chemistry and temperature are undergoing an accelerating change. Levels of rainfall are increasing in the polar latitudes. Heavy precipitation events occur more frequently and rapid runoff of rainwater increases the rate of erosion. In the sub-tropics there is less rainfall predicted. Given such trends, our inability to manage water, protect low-lying coastal areas and reduce the loss of topsoil should promote widespread caution.
These facts make it clear that actions needed to cap and then reduce the rate of heat trapping gas emissions will have greater impact if taken sooner, than if we stall in efforts to be more energy efficient. Because warmer oceans and land areas will persist for decades, if not centuries, institutional changes must be encouraged now to assist the most vulnerable and curb inherent inefficiencies in power consumption and transportation.
As the U.K. government campaign is fond of saying tomorrow’s climate depends on today’s actions.
Does anyone have any insight as to how Richard Lindzen developed views that are so far out of the scientific mainstream? Is he just kissing the hand that feeds him or are his views of climate change part of a monetary (Grover Norquist-like) or religious (rapture – obsessed) conservative ideology?
[Response: Somebody else can figure out the psychology of Lindzen’s denialism, but it’s not really important. What’s important is whether he has any arguments that bear scrutiny. The last actual argument he published was the IRIS cloud feedback mechanism, a good many years back, which did not stand up to scrutiny. All of his earlier arguments (cumulus drying, super-lapse-rate feedback) were demonstrably wrong. So far as I can tell he has stopped making scientific arguments. That’s what counts. He’s playing his MIT professorship for all that it’s worth, but that’s all he’s got going for him right now. –raypierre]
I think Lindzen’s always been a maverick and because of that has asked questions about what others just assumed to be true. This approach may be wrong 99% of the time, but it’s the 1% that wins scientific awards. Hopefully he’ll stop wallowing in the 99% soon and move on.
I’ve got to ask — what is the deal? I posted (#8), and my colleague (#64, and others) posted on how the AR4 math is wrong, showing that global sea level rise is not well accounted for in the publicly released document.
I am forced to ask — considering some “Freudian Slip” situation — how the release of this long-awaited 2007 document could both 1) do the math wrong and 2) discount current sea-level rise trends from the big ice sheets in Greenland and W. Antarctica.
I eagerly await some reponse — or “rationalization” — as to how this can be explained.
#71 Sorry that you disliked my post sufficiently to zap it, Dan. I’m retired, but I was a successful and (I think) respected scientist for almost 40 years. I do know a little bit about what constitutes science. Computers have made our work immeasurably easier, but they haven’t yet replaced the ability of human beings to think logically and collect data objectively. Clever computer programming is a valuable skill, but it isn’t science.
#61. Thanks very much for the link to this report! It does indeed talk about renewables and energy efficiency, as carbon mitigation measures for the U.S. and proposes we can reduce carbon emissions by 60-80 percent this way. Unfortunately, the report is a theoretical treatise–its authors were asked what they thought could be potentially accomplished, given resource assessments and technological capabilities. No consideration is given to many real world aspects, such as the politics of land use and ownership, full costs of deployment and existing power plant replacement, grid adjustments, ecological problems (due to the very large land requirements for large scale solar and wind), and much much more. These sorts of pie in the sky studies have plagued renewables from the beginning and torture us with the prospect of revolutionary change, but they do a disservice to an industry that is now in the throws of real practical expansion, due to both high energy prices and climate change worries. But these forces have their limits, as do renewables themselves. As presently conceived, renewable sources will not run the world, or even a large portion of it. They are currently less than 1 percent of global energy use, and though very important for a range of countries, from Iceland to India, they are far from equal to the task of turning over the 12 trillion dollar fossil fuel system. The future lies with energy diversity, an expanding and increasingly flexible portfolio of sources. Technology won’t solve it all, by any means, but it will help enormously. For a good discussion of energy issues related to climate change, see John Holdrens article The Energy Innovation Imperative, at http://bcsia.ksg.harvard.edu/BCSIA_content/documents/Innovations_The_Imperative_6_06.pdf
The future lies with a diversity of sources
Doing some late night reading on this subject as a result of the vast media coverage of the IPCC report. I personally haven’t really had any doubts about the human impact on global warming, but I am merely a student of Computing and have no deep scientific understanding of the subject (one tries though).
This is just a thank you to the authors for this blog.
To the editors:
According to The Guardian, the AEI (American Enterprise Institute) thinktank is offering $10,000 to anyone who will cast doubt on the report, scientists and economists included.
I suggest you get a copy of that letter and publish it here, together with who funds the AEI.
#37 Pat, Rebound has been continuous process since the last ice age, quite severe in the Arctic, where you find very old Bow head whale skeletons, ancient half burried walruss skeletal heads 160 meters above sea level! Present rate around where I live is about 2 cm a year, where raised beach ridges are a common shoreline sight..
What recent GW does to rebound is a very good question…
I blogged on the new IPCC report and my take here. Take a look and let me know what you think.
[Response: Hi, Andrew. I think this is a very nice summary of the highlights of the report. I’ll leave it to Mike Mann to comment on your take on whether the nuances of the NAS statement on climate of the past millennium is significantly different from what the SPM says. It all comes down to details of how one estimates the uncertainty in reconstructions of medieval warmth. Nobody can say that the Medieval was definitely warmer (hemispherically) than the present, but some might say that the error bars are large enough that one cannot rule out the possibility. In some sense you are right that there were no real scientific breakthroughs reported in this round. The improvements were incremental, and the big news was in how fast the Earth’s climate is changing. The SAR, in contrast, introduced a breakthrough in the aerosol connection to interrupted warming, whereas the TAR had some breakthroughs in coupled ocean-atmosphere modelling. The timing of AR4 just missed the next big breakthrough — which will be in improved and coupled modelling of glacier dynamics, including fracture mechanics, ice shelves and all that stuff. I think one mustn’t discount a breakthrough of a technological sort in AR4 though: The number of model runs exploring more of scenario and parameter space is vastly increased, and more importantly, it is available in a coherent archive to the full research community for the first time. The amount of good science that will be done with this archive in the next several years is likely to have a significant impact on our understanding of climate. –raypierre]
[Response: One clarification on the point made by Ray P above. Actually, the IPCC statement is stronger than what Ray suggests. The careful choice of wording by the IPCC on this indicates that they did think we can rule out the possibility that Medieval large-scale warmth was comparable to the present at a moderately (likely=67%) high level of confidence, and that is of course taking into account the fact that there are uncertainties. –mike]
[Response: As we note in the piece above, the NRC did endorse the key conclusions of IPCC (2001) with regard to millennial reconstructions, hence news reports in e.g. Nature such as “Academy Affirms Hockey-Stick Graph”. Nonetheless, the NRC report was a rush job, was forced to ignore key papers in the pipeline, and had limited representation of experts in paleoclimatology (perhaps seeking breadth but sacrificing depth in this key area in their selection of panel members). By contrast, the IPCC was a long, careful, deliberate process, based on several years of thorough assessment of the literature, the IPCC paleoclimate chapter was written by leading experts in the field of paleoclimatology, and input was solicited from essentially every leading expert in the field. It should be unsurprising that they came to a somewhat different (and in my view, more accurate) bottom line. I hope that answers the question for you Andrew? –mike]
Neal Boortz is on the attack :
25 Reasons to blah, blah, blah ……
http://boortz.com/nuze/index.html
What are your thoughts regarding Christopher Monckton’s analysis of the 4AR?
http://ff.org/centers/csspp/pdf/20070201_monckton.pdf
Bodman et al. Embrace IPCC Report Sort Of
After the IPCC Committee delivered its report, officials from the U.S. government gave their take on it. Energy Secretary Sam Bodman, NOAA Administrator Conrad Lautenbacher and EPA Administrator Stephen Johnson each made remarks and answered questions. (shown on CSPAN2).
They said that they and the Bush Administration embraced the IPCC report and that without the funding for scientific research sought for and received by the president starting in 2002, the IPCC would not have been able to deliver its final product. In other words, U.S. government funded research was responsible for much of the scientific content in the report.
Bodman cited 7 DOE supercomputers funded by the Bush administration as key elements in generating this scientific work.
All three repeatedly referred to the $29 billion spent by the Bush administration over the last 6 years on climate change research and greenhouse gas mitigation.
So where did this figure of $29 billion originate? Only a few years ago the White House was claiming that it spent $2 billion a year on climate research and then $3 billion and now the $29 billion figure so frequently quoted by administration spokesmen today.
That would work out to about $5 billion per year and indeed seems be consistent with the numbers in a WH press release from last year. See below.
From 2001 To The End Of 2006, The Federal Government Will Have Devoted Over $29 Billion To Climate Programs, More Than Any Other Nation. The President�s 2007 Budget proposes $6.5 billion for climate change activities.
http://www.whitehouse.gov/news/releases/2006/07/20060711-7.html
However, others, including the National Environmental Trust, the GAO and AAAS haven’t had much success in verifying these numbers.
http://www.net.org/proactive/newsroom/release.vtml?id=29017
http://www.net.org/proactive/newsroom/release.vtml?id=29048
http://www.aaas.org/spp/rd/cctp06p.pdf
Some people, like James Hansen, for example, have openly complained about budget cuts in monitoring programs. What then is the true story of the $29 billion? The link below to the USAID provides a breakdown by agency and area.
http://www.usaid.gov/our_work/environment/docs/fy07_climate_change.pdf
The money spent in 2006 was about as follows:
Climate Science $1.9 billion of which $1.3 was from NASA.
Climate Change Technology Program $2.8 billion of which $2.5 was from DOE
Tax Credits $1 billion
The proposed increase in 2007 is mostly due to a big increase in the tax credits, while the science funding drops off.
EPA and NOAA’s funding are less than $200 million each, although Lautenbacher and Johnson did not seem concerned about this.
Of the DOE’s budget, around $1.2 billion is in the category Energy Efficiency and Renewable Energy. Somewhere between $500 million and $1 billion is associated with carbon capture and sequestration.
The biggest complaint about these numbers is that the Bush administration has continually broadened the definition of what constitutes climate change research and mitigation, thus making it appear that the funding for this area is skyrocketing when in fact it is actually going down in some categories.
Bodman also said that the U.S. would not adopt a GHG cap unilaterally, out of concern this would drive jobs overseas to countries with no caps and lax air pollution standards, thereby making the overall problem worse.
A reporter then pointed out that Germany has had caps in place for several years and has experienced job growth. Bodman said he was sure someone would perform an economic analysis that would clarify this.
Another reporter asked that since California now has its own version of a GHG cap in place, wouldn’t it be expected to lose jobs? Bodman said he thought this would be the outcome.
One hopeful note. Bodman said that U.S. scientists would be made available to talk to the media about the IPCC report. Of course, he didn’t say which scientists and under what circumstances. After all, buried somewhere in the $29 billion is a line item titled Salaries.
(Re: 2
Could tectonic rebound from ice loss on Greenland and Antarctic result in additional significant increases in sea level? )
However there are not the observed temperature changes in the Antartic, so isn’t that
putting the cart before the horse? ….
“Climate Change 2007: The Physical Science Basis Summary for Policymakers
Working Group I”
IPCC WGI Fourth Assessment Report, (Feb 2007)
http://www.ipcc.ch/SPM2feb07.pdf report
…..”Some aspects of climate have not been observed to change. {3.2, 3.8, 4.4, 5.3}
“â?¢ Antarctic sea ice extent continues to show inter-annual variability and localized changes but no statistically
significant average trends, consistent with the lack of warming reflected in atmospheric temperatures
averaged across the region. {3.2, 4.4} “….
…”It is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica (see Figure SPM-4).”….
…”â?¢ Global average sea level in the last interglacial period (about 125,000 years ago) was likely 4 to 6 m higher than during the 20th century, mainly due to the retreat of polar ice. Ice core data indicate that average polar temperatures at that time were 3 to 5°C higher than present, because of differences in the Earthâ??s orbit. The Greenland ice sheet and other Arctic ice fields likely contributed no more than 4 m of the observed sea level
rise. There may also have been a contribution from Antarctica. {6.4}”…
…”Current global model studies project that the Antarctic ice sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall. However, net loss of ice mass could occur if dynamical ice discharge dominates the ice sheet mass balance. {10.7}”…
and one could refer to any of the following as well for other science on the matter
ECORD: IODP Expedition 310-Tahiti Sea Level
http://www.ecord.org/exp/tahiti/310.html
“So far, the only sea-level record that encompasses the whole deglaciation is based on offshore drilling of Barbados coral reefs which overlie an active subduction zone and was located close to the former ice sheets during the Last Deglaciation. Vertical tectonic movements in such areas may be large and are often discontinuous, implying that apparent sea level records may be biased by variations in the rates of uplift. Hence, there is a clear need to study sea level changes in tectonically stable regions or in areas where vertical movements are slow and/or regular. Furthermore, the eustatic function is best estimated from sea level data collected far from the former ice margins where the the influence of glacio-isostatic rebound is minimized”…
Volcanic and tectonic processes coinciding with glaciation and crustal rebound: an early Holocene rhyolitic eruption in the Dyngjufjöll volcanic centre and the formation of the Askja caldera, north Iceland
Bulletin of Volcanology 64 (3-4), 192 (2002)
http://dx.doi.org/10.1007/s00445-002-0204-7
“A pronounced volcanic production maximum on the rift zones through Iceland coincided with rapid crustal rebound during and after glacier melting at the Pleistocene/Holocene boundary. At peak glaciation, ice thickness over central Iceland may have reached 1,500-2,000 m, causing 400-500-m depression of the crust. Rapid climatic improvement caused glacier melting and removal of the ice load within about 1,000 years. Low mantle viscosity resulted in rapid crustal rebound which was completed in about 1,000 years, with an average rate of uplift on the order of nearly half a metre per year over central Iceland.”..”A model is proposed involving uplift of tectonically well-defined crustal blocks to the north and west of the Askja caldera, combined with downsagging caused by voluminous outpouring of basaltic lava. The southern and eastern borders of the caldera are remnants of a subsidence following the 10-ka Plinian eruption, partly reactivated by the 1875 A.D. Plinian eruption. The model provides a satisfactory explanation for the enigmatic Ã?skjuop pass, and it is in agreement with a gravity survey of the Dyngjufjöll centre. The uplift coincided with rapid crustal rebound which was amplified by crustal deformation (doming) of the volcanic centre caused by high magmatic pressure in the plumbing system of the volcano. This is supported by emission of very large lava flows produced in the first millennia of the Holocene. ”
Decontaminating tide gauge records for the influence of glacial isostatic adjustment: The potential impact of 3-D Earth structure
Geophysical Research Letters 33 (24), 24318 (30 Dec 2006)
doi:10.1029/2006gl028448
http://dx.doi.org/10.1029/2006gl028448
Observation of glacial isostatic adjustment in â??stableâ?? North America with GPS
G F Sella et al.
Geophys. Res. Lett 34 (L02306), (26 Jan 2007)
http://dx.doi.org/10.1029/2006gl027081
_____________________________________________
RE: (51. …”Yet the report forecasts droughts and reductions in rainfall most places.”)
“Climate Change 2007: The Physical Science Basis Summary for Policymakers
Working Group I”
IPCC WGI Fourth Assessment Report, (Feb 2007)
http://www.ipcc.ch/SPM2feb07.pdf
..”â?¢ The frequency of heavy precipitation events has increased over most land areas, consistent with warming
and observed increases of atmospheric water vapour. {3.8, 3.9}”…
_______________________________________________
RE: (46. Where is the discussion of natural variability in all this?”)
“Climate Change 2007: The Physical Science Basis Summary for Policymakers
Working Group I”
IPCC WGI Fourth Assessment Report, (Feb 2007)
http://www.ipcc.ch/SPM2feb07.pdf
….”â?¢ Difficulties remain in reliably simulating and attributing observed temperature changes at smaller scales.
On these scales, natural climate variability is relatively larger making it harder to distinguish changes
expected due to external forcings. Uncertainties in local forcings and feedbacks also make it difficult to
estimate the contribution of greenhouse gas increases to observed small-scale temperature changes. {8.3,
9.4}”….
and the footnote
“1 Climate change in IPCC usage refers to any change in climate over time, whether due to natural variability or as a result of human activity. This usage differs
from that in the Framework Convention on Climate Change, where climate change refers to a change of climate that is attributed directly or indirectly to human
activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods.”
why to the IPCC use the “Virtually certain”, “Extremely likely”, “Very likely”, “Likely”, “More likely than not”, “Unlikely”, “Very unlikely” and “Extremely unlikely” qualifiers? it makes it difficult to read. it would make much more sense to just use a range of likelyhoods – “it is 90-99% likely that x will happen.” much easier to read, and also less restrictive, as figures such as 85-95% could be used, or specific figures with uncertainties: 90% ±4%. this would make the entire report that little bit more accurate, and MUCH, MUCH easier to read.
the same could go for the “High Confidence” etc.
#26: absolutely classic. I haven’t heard a comment so backwards for years! I’m gonna have fun with comments like these in the next few weeks.
A quick question for the RC crew or any other scientist re Polar cap changes. ‘Are there any studies about the possibility of a orbital shift for the planet with the change in mass from ice to water?”. I note a recent private published book by Prof Lance Endersby who suggests that such orbital shifts may have been induced by glacial change in the past. A suddent orbital shift would be more than catastrophic it would suggest a major extinction event. Any responses would be appreciated
I gather that this prelim policy laymen’s type of summary report is not the actual technical bling-bling we should expect of the IPCC AR4 coupled climate models, because according to LLNL, such will be released in chapter 8?
As far as a sense of homogeneity across the models, what actual number of modeling input factors (ex: Co2, solar, clouds) would encompass the said physical sciences of “atmosphere, land surface, ocean and sea ice” that were submitted specifically to the IPCC AR4 for consideration? Ten ? More, less?
Additionally, will the release of chapter eight further quantify the uncertainties, bias, differences and so forth in relation to the various model versions simulations, within their range and scope, in consideration to their ability to reproduce, replicate, and or be in some form of a consensus data output agreement?
Or will we have diverging model outputs that persist in diverging projected climatic opinions or lack of certaintities? Excusing of course the nonlinearity factors of the natural climate systems which will always, I assume, interject its whims; especially at the shorter intervals versus longer climate patterns; further compounding the matter for modelers.
About IPCC Model Output
http://www-pcmdi.llnl.gov/ipcc/about_ipcc.php
…”the PCMDI is archiving coupled ocean-atmosphere general circulation model output to support the Working Group 1 component of the IPCC’s 4th Assessment Report. The data archived by the PCMDI from each participating coupled ocean-atmosphere model is a subset of that model’s output. Working Group 1 of the IPCC focuses on the physical climate system — atmosphere, land surface, ocean and sea ice — “…
Important Information for Analysts and Authors
http://www-pcmdi.llnl.gov/ipcc/info_for_analysts.php
..” The overall purpose of Chapter 8 of the AR4 is to assess the ability of the global climate models to make projections of future climate change.”…
IPCC Climate Model Documentation, References, and Links
http://www-pcmdi.llnl.gov/ipcc/model_documentation/ipcc_model_documentation.php
(RE:2 ..”Greenland glaciers finally melt (either slowly or in a big whoosh) tectonic rebound will probably increase the frequency and magnitude of earthquakes around the world.”…)
If the thought intrigues you, there are research papers out there
discussing the topic and or similar trains of thoughts.
RETREATING GLACIERS SPUR ALASKAN EARTHQUAKES
http://www.nasa.gov/centers/goddard/news/topstory/2004/0715glacierquakes.html (08/02/200)
“In a new study, NASA and United States Geological Survey
(USGS) scientists found that retreating glaciers in southern
Alaska may be opening the way for future earthquakes.”…”Even though shrinking glaciers make it easier for earthquakes
to occur, the forcing together of tectonic plates is the main
reason behind major earthquakes.”…
“Earthquakes in Greenland: Are They Related to Postglacial Rebound?”
Chung, W. AGU 2000 Spring Meeting
http://www.agu.org/cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=sm00&database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Fsm00%2Fsm00&maxhits=200&=“S32A”
“An intriguing observation in Greenland is a clear spatial correlation between seismicity and deglaciated areas along passive continental margins, a piece of evidence of earthquake triggering due to postglacial rebound. Another piece of evidence of induced seismicity due to deglaciation is from earthquake source mechanisms.”…”These and two prior events support the theory that the shallow part of the lithosphere beneath the deglaciated margins is under horizontal extension. The observed stress field can be explained as flexural stresses due to removal of ice loads and surface loads by glacial erosion. These local extensional stresses are further enhanced by the spreading stress of continental crust and reactivate preexisting faults. Earthquake characteristics observed from Greenland may be typical of those along the deglaciated passive margins elsewhere. ”
Lateral viscosity variations beneath Antarctica and their implications on regional rebound motions and seismotectonics
Wu, P. P.; Kaufmann, G.; Ivins, E. R. American Geophysical Union, Spring Meeting 2004, abstract #G33A-13 (05/2004)
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004AGUSM.G33A..13W&db_key=PHY&data_type=HTML&format=&high=42d4f8714c16259
…”Fault stability is predicted over much of Antarctica today, indicating that the seismically quite state is probably due to the presence of the thick ice. At the site of the 1998 Balleny Island Earthquake (Mw=8.1), the induced fracture stresses are relatively small by comparison, and interestingly become more prone to stress failure when a three-dimensional earth model is assumed.”
Glacial isostatic stress shadowing by the Antarctic ice sheet
Ivins, Erik R.; James, Thomas S.; Klemann, Volker Journal of Geophysical Research, Volume 108, Issue B12, pp. ETG 4-1, CiteID 2560, DOI 10.1029/2002JB002182 (12/2003)
http://dx.doi.org/10.1029/2002JB002182
“Numerous examples of fault slip that offset late Quaternary glacial deposits and bedrock polish support the idea that the glacial loading cycle causes earthquakes in the upper crust. A semianalytical scheme is presented for quantifying glacial and postglacial lithospheric fault reactivation using contemporary rock fracture prediction methods”…”A thick lithosphere, of the order of 150-240 km, augments stress shadowing by a late melting (middle-late Holocene) coastal East Antarctic ice complex and could cause present-day earthquakes many hundreds of kilometers seaward of the former Last Glacial Maximum grounding line.”
Re #74: Dave, obviously the arithmetic error in the table is a bit embarrassing, but it’s really just another sign that the just-released document was itself still somewhat a draft. The point is that the substance of the document isn’t affected. I’m sure they’ll fix the problem pronto.
Regarding your specific concern, I think the SPM made it clear that all that can be done now is to allow for sea level rise from 1) thermal expansion, 2) melt in place and 3) a more or less linear extrapolation of the small amount of dynamical melting that has been observed so far. While it is the expert judgement of many glaciologists that dynamical melting will accelerate very rapidly, there aren’t the needed models or terrain surveys in place as yet to be able to do more than make educated guesses. As a result, all that could really go into the AR4 was the vague statement to the effect that dynamical melting could make things much worse. Really I’m just re-stating what was said toward the end of the post, but hopefully I’ve made things a bit more clear.
One other small point, we do not have anywhere near enough fossil fuels reserves to achieve the higher and hence more alarmist scenarios unless we invoke large scale positive feedback loops for large releases of CO2 from natural sources such as the siberian permafrost, or rain forests etc and as RC are always telling us the Science does not tell us that until temps reach 3 C above now. By 2030 Oil and Gas would have peaked and coal cannot scale to take there place so the REALITY of the climate situation is that we are going to get around 1 to a 2 C rise in temps as a maximum.
So lets not get too alarmist about the doomed world.
[Response: Would that this were true. There is more than enough coal to go to at least 4xCO2, depending somewhat on how fast you burn it, and if they figure out how to tap into seafloor methane clathrates, it could go even higher. What’s the support for your statement that “coal cannot scale to get there”? –raypierre]
–
Excerpt from interview transcript posted at Climate Science Watch website regarding sea level issue, BBC World News, February 2, 2007.
–
… Interview with Sharon Hays, Associate Director/Deputy Director for Science [OSTP] at the White House Office of Science and Technology Policy, leading the United States delegation, and Rick Piltz, Director, Climate Science Watch.
BBC interviewer in Paris: �[Sharon Hays] told me what she learned:
…
BBC: And the sea level rise is one of the issues that is most contentious through the week. Many people have said, many people are saying that, what you�ve agreed is effectively too conservative, it�s too low, that sea level is rising quicker than what is reflected in this report.
Hays: Right. What happened with this report is that the model projections we know don�t fully take into account the melting of the ice that we are seeing. And I think that the report dealt with this issue in a very a satisfactory way in that it reported the projections that the models have put out�and I should note that those models now have less certainty than they did in the previous report�but it deals with the fact that this ice is melting at a faster rate than we expected and is not accounted for in the models, by simply stating that. And it states it in the report very clearly and makes it clear that the projections are a baseline, so to speak, that we expect the melting to be greater.
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http://www.climatesciencewatch.org/index.php/csw/details/bbc-ipcc-interview/
pete best (now #57) said:
Last 10 years annual mean CO2 rise (ppmv), from NOAA’s ERSL, global monitoring division :
Note the Mauna Loa results at the top of the same page have slightly higher numbers for some years:
But for this purpose, point samples should not be used alone when global averages are available.
This is not to say that 3 ppmv global annual increases are not possible, but there has not been anything above 2.5 since 1998.
What is the potential albedo effect relating to increased desertification, has anyone researched the potential of desert albedo to offset global warming, and due to the higher angle of incidence would this have more or less effectthan the melting of the artic per unit area(assuming the desert is near the equator)? Do you think I could convince Lindzen that this is his next big idea?
It seems that CO2 cycle feedback are, in AR4, included.
It’s said in this report that this feedback explains till +1°C for the high value of the range(for A1F1).
Were this effect also included in TAR?
It is interesting to me that so-called skeptics have chosen to attack the climate change issue based on the science, when in reality the source of their opposition is clearly the economic consequences that may result from combatting climate change. My experience is that they often understand economics much better than they understand climate science. I think there is a constructive role in the debate for conservative economic opinion. We certainly will not be able to address climate change if our economy is weakened. Continuing to attack the science at this point is merely a recipe for moving yourself to the margins of the debate.
Could someone elucidate the section on page 10 under the “projections of future climate changes” heading? I’m looking at the part about “even if all concentrations of ghgs and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1 c per decade would be expected.” Am I right in reading that to mean that if, for example, we’d gone to work hard in 1988 and done everything we needed to do to stop emissions growth by 2000 we’d now be seeing increases in temperature at about half the current rate? I think it’s interesting if that’s the correct reading, because it should give us some sense of the scale of change that real efforts could produce. But I’m not sure I’m reading it correctly (and I have to say that this SPM is not as well-written as the TAR)
[Response: Thanks for stopping by Bill, its an honor. Your read on this is correct, its the so-called ‘commitment to warming’ rearing its head once again. The mid and deep ocean continue to warm for decades in response to any given perturbation in greenhouse gas concentrations. This makes stabilizing global mean surface temperature a bit like steering a supertanker. This is why many, such as Jim Hansen, have indicated we don’t have much time to act (a decade perhaps) if we are to avoid crossing thresholds that may represent ‘dangerous anthropogenic interference with the climate’. –mike]
Re: We should also be aware of less absorption of atmospheric CO2 by oceans as the waters keep warming and out-gassing of CO2 from some shallower and warmer sea regions.
junkscience.com are so upset at what they see as political interference in the IPCC scientists’ report that they have leaked the full drafts of the fourth assessment:
http://www.junkscience.com/draft_AR4/
RE #45 & natural climate variability. I see it like this, the ocean has waves, up & down, and ebb & flood tides. But then something outside this system happens, an ocean earthquake, and we get a tsunami.
We all felt very bad re the tsunami victims, that they didn’t even know what was coming though the signs (to the knowledgeable) were there. Let’s become wise, listen to the knowledgeable & act now to avoid disaster.
As Sen. McCain recently said, the debate is over; it’s time to act. Something I was saying 17 years ago, before science reached scientific certainty on this. Would a person take poison because it was only 94% likely to kill, and not 95% certain? Would a doctor tell a patient they won’t remove the lump because it’s only 94% certain to be cancerous, so come back in a year & see if it reaches 95% certainty?
Re: #95
I agree. But I don’t think the attacks on the science are coming from those who are truly economic conservatives.
There’s a vast difference between economic conservatives and robber-barons. The present U.S. administration serves the latter, while paying lip service to the former. What kind of true economic conservative gives us the biggest federal budget deficits in the history of the world — isn’t paying your bills fundamental to sound economic conservatism? It’s high time we (the voting public) stopped accepting plain old greed as “economic conservatism.”
Perhaps the best analysis of global warming from an economic standpoint is the Stern report. And the so-called conseratives (actual robber-barons) are about as angry about that, as they are about the IPCC report.