Traducido por Angela Carosio
La semana pasada propusimos una apuesta contra el pronóstico en un artículo de la revista Nature “pausa en el calentamiento global” por Keenlyside et al. y prometimos presentar nuestro caso científico en otra ocasión, y aquí está.
He aquí porque pensamos que el pronóstico no es sólido:
Figura 4 extraída de Keenlyside et al. 2008. La línea roja muestra las observaciones (información extraída de HadCURT3), la línea negra muestra un escenario típico estándar propuesto por el IPCC (Intergovernmental Panel on Climate Change, IPCC por sus siglas en inglés), derivado de forzamientos observados hasta el año 2000, y por el posterior escenario de emisiones A1B. Los puntos verdes con barras representan pronósticos individuales con temperaturas de la superficie del océano. Los datos son promedio de 10 años.
- La figura 4 muestra que un escenario típico estándar de calentamiento global propuesto por el IPCC funciona un poco mejor, para las temperaturas medias globales de los últimos 50 años, que su método con temperaturas de la superficie del océano (ver también los números de correlación en la parte superior del panel). Que el escenario típico estándar de calentamiento global funcione mejor es muy notable, ya que no incluye ningún dato observado. En la curva verde, que presenta una serie de pronósticos individuales de períodos de 10 años y que no es una sucesión temporal, cada serie temporal comienza nuevamente cerca del clima observado ya que esta inicializado con las temperaturas observadas de la superficie del océano. De esa manera, la curva verde no puede llegar muy lejos, en comparación con el escenario “libre” que marca la curva negra. Por ende, se esperaría que el pronóstico verde obtuviera mejores resultados que el pronóstico negro. El hecho que éste no es el caso, nos demuestra que la técnica de inicialización no mejora el pronóstico modelo para la temperatura global.
- Los “pronósticos de enfriamiento” no han pasado la prueba del período de los pronósticos posteriores. Las temperaturas globales promedio, en períodos de 10 años, han incrementado monótonamente durante todo el período considerado, ver la línea roja. Pero el método parece haber producido ya dos pronósticos falsos de enfriamiento: uno para la década centrada en 1970 y otro para la década centrada en 1999.
- El pronóstico no es solamente demasiado frío para 1994-2004, sino que probablemente es también demasiado frío para 2000-2010. Para que el pronóstico de 2000-2010 sea acertado, todos los meses que restan de ese período tendrían que ser tan fríos como enero del 2008, que fue de lejos y hasta ahora el mes más frío de esa década. De modo que se requeriría un enfriamiento extremo para los próximos dos años y medio.
- Tampoco la habilidad de su método para pronosticar las temperaturas europeas (la fig. 3c, no forma parte de nuestra apuesta) es notable. Su método ha pronosticado varios enfriamientos desde 1970, sin embargo las temperaturas europeas han ido incrementado en forma regular desde entonces. Recuerden que los pronósticos siempre empiezan cerca de la línea roja; casi todas las predicciones para europa han sido demasiado frías comparando con la realidad. De modo que parece haber un prejuicio sistemático en los pronósticos.
- Uno de los puntos clave del artículo es que el método permite pronosticar el comportamiento de la circulación convectiva meridional, MOC (Meridian Overturning Circulation, MOC por sus siglas en inglés). Por falta de datos, no se sabe exactamente qué es lo que estuvo haciendo la MOC, de modo que los autores diagnosticaron el estado de la MOC por las temperaturas de la superficie del océano. Para hacerlo más simple: un atlántico norte caliente significa una MOC fuerte, mientras que un atlántico norte frío corresponde a una MOC débil (aunque es, por supuesto, un poco más complejo que eso). Su método da un pequeño codazo al modelo de las temperaturas de la superficie del océano hacia las observadas antes que el pronóstico comience. ¿Pero esto induce a la respuesta correcta de la MOC? Supongamos que el modelo de la superficie del atlántico es muy fría, lo que sugiere una MOC débil. Posteriormente, se inclina hacia el modelo más cálido de las temperaturas de la superficie del océano. Pero si se hace esto, la temperatura de la superficie del océano se hace más boyante, lo que tiende a debilitar la MOC en vez de hacerla más fuerte. De modo que con este método no se puede predecir la respuesta de la MOC correctamente. Nos gustaría ver esto evaluado en un “modelo perfecto” donde se restauren las SST (temperaturas de la superficie del océano, SST por sus siglas en inglés) para tratar de llegar a un pronóstico modelo que encaje con la simulación previa (de donde se tiene mucho más información). Si no funciona para ese caso, no funcionará en el mundo real.
- Cuando los modelos cambian de ser conducidos por temperaturas de la superficie del océano observadas, a calcular libremente la temperatura del océano, sufren de algo llamado “shock de empalme”. Esto es extremadamente difícil, quizás imposible, de evitar, como han mostrado anteriormente otros “modelos perfectos” (ej. Rahmstorf, Climate Dynamics 1995). Este problema presenta un gran desafío para el tipo de pronóstico intentado por Keenlyside et al., en donde sucede un cambio hacia la liberación de la temperatura de la superficie del océano al principio del pronóstico. En respuesta al “shock de empalme” en un modelo, la oscilación típica de la MOC en las próximas décadas es de magnitud similar a aquella encontrada en las simulaciones de Keenslyside et al. Sospechamos que este “shock de empalme”, que no es una variante realista del clima sino un mero artefacto del modelo, pudo haber jugado un rol importante en esas simulaciones. Una forma de verificarlo sería un modelo perfecto como el que mencionamos anteriormente, o un análisis del presupuesto de radiación neta en las pruebas libres y restauradas. Una diferencia significativa puede explicar mucho.
- Para corroborar como ejecuta la MOC el modelo de Keenlyside et al., podríamos fijarnos en su mapa de habilidad en la Fig. 1a. Ésta muestra áreas color azul en el mar del Labrador, el mar de Groenlandia, Islandia y Noruega, y en la región de la Corriente del Golfo. Las áreas en azul muestran “habilidades negativas”, esto significa que en su método de asimilación de datos, las zonas azules empeoran la situación en vez de mejorar el pronóstico. Estas son las regiones críticas para la MOC, y ello indica que por alguna de las dos razones en 5 y 6, su método no puede predecir las variaciones de la MOC correctamente. No obstante, este método demuestra ser útil (muestra aptitudes) en algunas áreas, esto es importante y útil. Sin embargo, esta aptitud proviene de la advección de las anomalías en la temperatura de la superficie por la circulación oceánica media, más que de las variaciones en la MOC. Este también sería un tema interesante para investigar en el futuro.
- Todos los modelos climáticos usados por el IPCC (Grupo intergubernamental de expertos sobre el cambio climático, IPCC por sus siglas en inglés), públicamente disponibles en el archivo de modelo CMIP3, incluyen variabilidades intrínsecas tanto de la MOC como de la variabilidad de las corrientes del pacífico tropical y la Oscilación del Atlántico Norte. Alguno de esos modelos también incluyen una estimación de la variación solar en el forzante. De modo que, en principio, todos estos modelos debieran reflejar el enfriamiento encontrado por Keenlyside et al., excepto que estos modelos debieran mostrarlo al azar en un punto en el tiempo, y no en un punto específico en el tiempo. El punto específico es la innovación buscada en este estudio. El problema es que los otros modelos muestran que el enfriamiento en la media de una década con respecto a la otra, en un escenario razonable de calentamiento global es extremadamente improbable, y casi nunca ocurre (ver el correo de ayer). Esto sugiere que el pronóstico de enfriamiento global de Keenlyside et at. se encuentra fuera de la variabilidad natural encontrada en modelos climáticos, y probablemente en el mundo real también, y es quizás un artefacto del método de inicialización.
Nuestro juicio puede ser erróneo, tuvimos que confiar en el material publicado, mientras que Keenlyside et al. tienen acceso a modelos de datos completos y estuvieron trabajando con él durante meses. Pero lo interesante de éste pronóstico es que sabremos la respuesta dentro de unos pocos años, porque estas son predicciones que se podrán evaluar a corto plazo, y nos agrada leerlas.
¿Por qué hemos hecho una apuesta con este pronóstico? Básicamente porque nos preocupaba el seguimiento de los medios masivos de comunicación, que dieron a entender que una pausa en el calentamiento global era inminente en vez de ser un pronóstico experimental. Esto puede resultar como un tiro por la culata contra toda la comunidad científica climática si el pronóstico resulta erróneo. Aún hoy, se sigue usando el hecho de que algunos científicos predijeron un enfriamiento global en los años 70 para desautorizar la credibilidad de la ciencia del clima, aún cuando se trató de unos pocos científicos que nunca lograron convencer a sus pares. Si distintos grupos de científicos hace una apuesta pública sobre éste pronóstico, señalaría al público en general que el pronóstico no está siendo ampliamente aceptado en la comunidad científica, en contraste con los informes del IPCC (sobre los cuales estamos en completo acuerdo con Keenlyside y sus colegas). Algunos artículos en los medios de comunicación incluso sugirieron que los escenarios planteados por el IPCC estaban siendo suplantados por este pronóstico “mejorado”.
Poner esto en el formato de una apuesta también ayuda a clarificar qué fue exactamente pronosticado y qué datos podrían falsear este pronóstico. Esto no estaba muy claro en el artículo y nos llevó un intercambio de correspondencia con los autores para clarificarlo. Esto también permite al autor decir: ‘Un momento, esto no es lo que queríamos decir con el pronóstico, pero estaríamos dispuestos a apostar por un pronóstico modificado como sigue…’ A propósito, estamos dispuestos a negociar qué es lo que apostamos, no hacemos esto por dinero. Estaríamos dispuestos a apostar, por ejemplo, una donación a un proyecto para preservar la selva tropical, o para retirar cien toneladas de CO2 del mercado europeo de negociaciones de emisiones.
Esperamos entonces que esta discusión sirva para aclarar estos temas, e invitamos a Keenlyside et al. a que publique un correo aquí (y en KlimaLounge) con su opinión sobre el tema.
And let’s not forget that the media largely misreported the results of this study because the authors use a very strained definition of the term “next decade.”
http://climateprogress.org/2008/05/02/nature-article-on-cooling-confuses-revkin-media-deniers-next-decade-may-see-rapid-warming/
As I explain, the Nature study is consistent with the following statements:
* The “coming decade” (2010 to 2020) is poised to be the warmest on record, globally.
* The coming decade is poised to see faster temperature rise than any decade since the authors’ calculations began in 1960.
* The fast warming would likely begin early in the next decade — similar to the 2007 prediction by the Hadley Center in Science (see http://climateprogress.org/2007/08/15/climate-forecast-hot-and-then-very-hot/).
* The mean North American temperature for the decade from 2005 to 2015 is projected to be slightly warmer than the actual average temperature of the decade from 1993 to 2003
I just heard the Keenlyside cooling prediction used on the radio to argue that
there is no such thing as a climate crisis (by a guy from the office of Sen.
James Inhofe, he of the hoax comment). Thanks for making this a betting matter,
RC. It gives the question a higher profile. Scientific American says that ice
sheets are sliding faster toward the sea. I’d say that’s a crisis .
So the Chaiten eruption isn’t going to get big enough to call off the bet?
[Response: Doesn’t look like it. Not enough SO2. – gavin]
[Response: And as I pointed out in response to an earlier similar comment, extratropical eruptions like this rarely give rise to a significant global mean cooling. – mike]
Re the Chaiten eruption, from what I’ve read, a volcano needs to emit at least 1 million tons of sulfur dioxide into the stratosphere to have an effect on global temperature. Chaiten has only emitted an estimated few thousand tons of sulfur dioxide:
http://ap.google.com/article/ALeqM5h6XCGT4X37OvMVvC6CA6UaDMeriAD90GHEFO0
Very interesting thanks.
Recent evidence suggests that CO2 has now reached the level of 387 parts per million – what is the total figure for CO2 equivalents – probably more significant?
Are we yet at a tipping point?
Thank you very much for these 2 articles. I used the first 4000 characters of the first one on alternet.org/environment already.
All bachelors level degrees, including journalism and English, should require the engineering and science core curriculum. Journalists do the journalism thing to sell papers. The journalism thing is exactly the wrong thing to do when reporting science. RealClimate needs to be read by the whole world. You are often too mathematical for almost everybody. Your concepts are mathematical. Nonetheless, RealClimate should be what everybody reads directly for themselves, if they can. A wager is a good idea and I think it is working for those who come in contact with your story in some way.
Last week I criticised your bet as I thought it trivialised the issues involved but I understand your rationale better now.
This post is exactly why this site is so popular for lay-people: it provides a clear explanation of climate change science and informed debate on current topics. Your best posts, like this one, allow lay-people to “see inside the heads” of how climate scientists think. For any objective, critical thinker reading your work the explanations of the assumptions you are making and the sources of error you identify both explain the issues involved and build confidence to accept your conclusions.
As you say, your “assessment could of course be wrong” but a critical thinker reading your work is looking for the evidence and reasons you present to support your argument.
Well done and thanks.
Dear group,
It seems a pity that you have had to use this hammer to crack a nut; but it works!!!
If only… If only they had let their paper speak for itself and had left out the big claim. The sadness is that if we bury this and I suspect you, others and simply the passage of time will. The interesting part (can and how oscillations be predicticted) will be buried alongside the headline result.
To me it seems such a pity for them and all of us.
Best Wishes
Alex Harvey
Why not propose your bet to Inhofe? The guy is utterly shameless.
RE:#6,
I have a journalism degree technically, but I have three times as many science credits in environmental biology, physical science, and work as an endangered species biologist for the US Forest Service and others. It’s a good point though since most top reporters come from Ivy league schools where no such requirement exists. Not so at public universities. Since graduating a couple of years ago, (non-traditional) I’ve not landed so much as an interview for a reporting job. Editors are science averse like that guy in Ely, Nevada! It’s a real problem.
Evidence shows that CO2 is going up at over 3% per year…Faster than in the highest IPCC scenario. Interesting to see if it continues at this rate…and what is causing it…drought?
Good thing for the bet that there is a lag time.
[Response: Emissions are rising 3% a year, concentrations at just over 0.5% a year (~2ppm). – gavin]
Two excellent posts regarding Keenlyside, et al. As others have said, the paper is already being used to excuse denialists’ delusions despite the fact that the authors, themselves, say clearly that their paper does not contradict AGW and should not be used to assert it does. Rapid Climate Change is a real and present danger that short-sighted denialists/industrialists pay scant attention to. The delays in action created by the lies, distortions and muzzling done by Exxon and the Bush administration have already put the world into a percarious position given that climate changes are happening all over at far faster rates than ever considered possible just a year ago. Too many of the citizens of the US and Britain still believe there is substantive scientific uncertainty about climate change – even as George Bush lives in a “green,” off-grid home and now says climate change is real.
One change I’m sure the Keenlyside authors couldn’t have considered is the much-more-rapid-than-expected release of methane in the Arctic that was reported in the last week or so. (Can’t find link now, but the results will do: http://www.csmonitor.com/2008/0428/p01s04-wogi.html )
Keep up the good fight with good science.
Cheers
“Thanks for making this a betting matter, RC. It gives the question a higher profile.” I agree, but I wonder why RC does, as the higher profile gives the lie to the notion that there is universal scientific consensus on AGW. Granted Keenlyside predicts only a temporary reprieve before AGW predominates again, I doubt that nuance will make to the coverage of a Warming vs. Not Warming bet. RC fears the media is making an issue of Keenlyside temperature flattening — I see the media in comfortable lockstep with AGW proponents regardless of an occasional Keenlyside blip on the screen. AGW sells more papers, so to speak, than its absence. I admire the courage of RC’s convictions, then, because it has nothing to gain if the bet is won and everything to lose if the bet is lost.
#13, wmanny that is such an disingenious, inaccurate, and lazy post.
There is broad scientific consensus on the reality of anthropogenic climate change but there still a huge amount of ongoing research into many of the details. Keenlyside and his colleagues deal with some of the details but expressly state they not doubt the broad consensus view on the reality of anthropogenic climate change.
Your suggestion that the bet offered by RealClimate “gives the lie to the notion that there is universal scientific consensus on AGW” is just plain wrong.
Your comments about RealClimate’s motives and your suggestion that they are driven by “convictions” rather than good science indicate you are too lazy to engage them in a debate based on science and evidence.
If you want to do some background reading on the scientific consensus statements (you seem in real need of it), there is a good compilation of them (with links) at http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change .
Re #13 “media in comfortable lockstep with AGW proponents” might have less to do with comfort and more to do with honest reporting. After all, they spent 20 years “comfortably” reporting the debate about AGW, but that debate is finally over, so the media have simply moved with the news. Can’t expect anything less, nor anything more, than that from the media.
I guess I’m of two minds about this whole affair. Sure, let’s not let the “debate” thing derail us again just because a couple guys with a model think there might be a flat spot in the warming trend, if you hold the chart up to the light just so and squint.
On the other hand… who gives a poop anymore? Seriously, it’s getting to the point where anyone who stands up in a crowd and says “my dog knows more about climate than Jim Hansen” is not going to like the reaction he gets. People in the streets are reading the reports carefully now, and what they are finding there gives little comfort. Setting aside the price of oil and its immediate impact on food, there is still enough going on with climate change and related water and agriculture issues to cause a prudent soul to glance around for an exit.
Well we’re 7 billion prudent folk all glancing around nervous, and I’m not the first to point this out. And going forward, anyone says all this is just smoke and mirrors to get grants to study tree rings is advised not be standing under a sturdy limb and holding a rope when he’s saying it. If you follow my meaning.
I love that “monotonously”! Maybe monotonically? Or is this another example of the transAtlantic divide in language?
John
[Response: Thanks John, fixed that. Not transAtlantic, but we’re not all born native speakers of the global language of science. -stefan]
[Response: Actually, I almost changed that when were editing, but I thought monotonously was a little more apt…. – gavin]
Latif’s group does not have much experience in modelling the MOC. But how could they (and the Nature reviewers) have overlooked so many obvious red flags? The fact that the hindcasts with their method perform worse than a standard IPCC scenario, the number of failed previous cooling predictions, the negative skill in the Gulf Stream and deep-water formation regions… should these not have cautioned them against going to the media to forecast a pause in global warming? Your bet does a good service, but I fear that it cannot undo the damage that they have already done in confusing the media public about global warming.
Gavin, you responded at #11 that emissions are rising at 3% per year while concentrations only rise at 0.5% per year. That is somewhat logical because there was already some concentration before we started any emissions. However there is another phenomenon that I have been unable to understand, and I would like to know if there is any theory that explains it.
Between the 80’s and the 90’s, man-made emissions of carbon from fosil fuels increased from about 5 billion tons per year to about 6.5 billion tons per year, which means a 30% increase in how much CO2 we put into the atmosphere yearly. However, the ratio at which CO2 concentration increases in the atmosphere slowed down between the 80’s and the 90’s, from 1.6 ppm/year to 1.5 ppm/year. Is there an explanation for that? Do you think it could be related to the rising temperatures and how it affects the Earth’s capability to sequester atmospheric CO2 by natural processes like the photosintesis of the plants? Or is there something else? And whatever the cause may be, is it predicted in the models?
Thanks.
“Even today, the fact that a few scientists predicted a global cooling in the 1970s is still used to undermine the credibility of climate science”
Why does the HadCRU3 temperature data not show the cooling in the 1970s? Does the forecast of Keenlyside et al for this period, of a cooling, reflect the cooling in the 70s from other datasets?
Re: coupling shock
Nice summary. I read the paper as saying that they are restoring to SST anomalies rather than the raw SSTs themselves – does this make a difference?
[Response: Not to the coupling shock problem. -stefan]
There is no need to bet when you stick to the science (and measured data and observations as much as possible). The green line “forecast” for the period 1995-2000 in the graph above is well below actual observations for the same period. This speaks for itself.
Also, evidence of the affects of global warming from many parts of the world speaks for itself – melting ice, droughts, increasing water supply problems in big cities like Barcelona etc.
What causes doubt and confusion is that the effects of global warming are not uniform around the globe and there are always weather fluctuations (that may even increase in scale and predictability) as global warming progresses. Global circulation patterns are very complex and the effects of any changes are so difficult to predict on a local, regional level. This is why we need a focus on regional and local studies, observations, and assessment that do not depend so heavily on models.
Professor Molina, Nobel Prize (chemistry) issued a stark warning recently (April, 2008) by suggesting that, “…long before we run out of oil, we will run out of atmosphere”. Professor Santilli (nominationed for the Nobel Prize in chemistry and physics) has raised the issue of atmospheric oxygen depletion – particularly in some of our largest cities around the world. The Chinese, for example, have planted a forest twice the size of New York’s Central Park on a 1,750-acre site north of the Olympic village in Beijing, to raise oxygen levels. Nearly a dozen factories are also closing or relocating outside Beijing, and factories hundreds of kilometres away will suspend operations for the duration of the olympics.
Our emissions to the atmosphere impact on natural processes, the environment, and health in very many ways – the ozone hole was the first big warning. It is so important that we learn, inform and educate on the basis of the best known science – illiminating guesswork (and certainly no bets)!
Re: RMS error and correlation skill
The supplementary information to the paper has an interesting figure – Supp. Fig. 2c shows the difference in RMS (root mean square) error (as compared to the correlation maps shown in the main paper) between the hindcasts and non-initialised cases. There it demonstrates that the RMS error in the Atlantic is worse in the forecast cases compared to the non-initialised cases. There are a few regions where the forecast appears more skillful in this metric of skill, which could be viewed as more relevant when making forecasts.
You are always very polite and diplomatic. The guts of this story is really quite funny: a group of climate scientists manages to sell a weird model result, most likely an artifact due to an inadequate modeling technique, as a sensational forecast to Nature and the world media…
I think the lesson of this story is that it is rather problematic that new climate science papers are now all over the media within hours of appearing in a journal, with political implications being discussed before the scientific community had time to properly assess and discuss the new study.
Brilliant article review, I hope I can capture some of the magic in the paper I am reviewing today. I understand the gist of coupling shock, but can you provide an example of how it would play out, and what can be done to identify and quantify this result.
Re #22, yes the media has to learn that peer review is not the end of the scientific process but part of an ongoing process of validation and verification before it is allowed into the hallowed halls of scientific truths.
Whilst bets are of no use in determining the underlying physical reality, they are very useful in sorting out people’s real level of confidence in their predictions. This can be a useful indicator how strongly we lay-people should factor them into out considerations.
I do hope Keenlyside’s team post here, their take would be interesting. From a policy and adaptation point of view such efforts to make more accurate short-term predictions could be valuable, if time bears out their predictions.
#5 Martin Pierard,
I wouldn’t think of a single global tipping point as such, what’s important in this respect are the different climate subsystems. In that respect you may find this page interesting:
http://www.pik-potsdam.de/infodesk/tipping-points
#17 Nylo,
Those CO2 increments seem all over the place to me, when viewed on a short term basis:
http://www.esrl.noaa.gov/gmd/ccgg/trends/ scroll down to global average.
1998 is interesting, but without looking at what’s happening regionally I wouldn’t read too much into most of the year-to year variance. What is apparent is that on a multi-year basis the ppm/year increase is going up, try something like a 5 year moving average to filter inter-annual difference for the full record.
With regards CO2 emissions uptake, have you read David Archer’s post on this? https://www.realclimate.org/index.php/archives/2007/11/is-the-ocean-carbon-sink-sinking/
#19 Gareth John Evans,
Out of interest, the Arctic Oscillation/North Atlantic Oscillation (which are intrinsically linked) seem to have a key role in both the Arctic ice loss (outflushing through the Fram Strait) – Rigor/Wallace) and the Mediterranean drying e.g. Figen Mekik’s post at RC https://www.realclimate.org/index.php/archives/2007/10/sweatin-the-mediterranean-heat/
Mmmmm, I’m far from convinced.
wmanny #13–Let’s get one thing straight. The consensus of scientists on climate change is that humans, by releasing massive amounts of the greenhouse gas, CO2, into the atmosphere, are largely responsible for the current epoch of warming. Keenlyside et al. is part of that consensus, not a challenge to it.
You say, “I see the media in comfortable lockstep with AGW proponents… ”
Well, I’ve always found the truth to be more comfortable than any lie. Actually, the media lag far behind the scientists in terms of the level of consensus. If they really understood the science, then the occasional outbursts by denialists would generate no more notice than a fart in polite company–a little embarassment for the offender, but no overt comment.
Re #10
” It’s a good point though since most top reporters come from Ivy league schools where no such requirement exists.”
That’s certainly not true of the one where I teach.
It is true that old fears of a new ice age did not originate with climate scientists [edit – no nonsense please] and I confess to being someone who worried about such things at that time. But was I wrong? When estimates of a possible return of an ice age still vary between this week and 50,000 years why should I be confident that the guys with tenure and titles have a handle on it?
In that large, mysterious (to me, anyway) context, listening to climate scientists boldly predict changes or non-changes in the range of tenths of degrees over a mere 10 or 20 years strikes me as more than just a tad beyond hubris and more like a standard deviation or two into the delusional range. One volcanic burp, one solar belch, a passing cosmic cloud or some butterfly flapping its wings in New Jersey and entire models can become just really bad computer games.
I admire the creativity and genius in climate modeling and the insights it can provide but when you guys start thinking it’s real, maybe it’s time to back away from the keyboard for a bit.
Without the ugly constraints of the overarching politicized death struggle, there is a beauty even in the uncertainties of this pursuit. To minimize or even fail to investigate uncertainties lest it give comfort to the denialist foe is no way to live.
#29 – the phenomenon of greenhouse gases retaining heat at the surface of the earth operates on decadal scales, and the orbital variations (Milankovitch cycles) which cause the waxing and waning of the ice ages operate on millennial scales, and both are fundamental physical processes, and are not elucidated by computer models. Nothing is going to change those results, short of a complete refutation of fundamental physics – unlikely.
The computer models deal with the actual energy and matter flows within, and in and out of the system, and do not account for random geological or cosmological events, such as volcanic eruptions or asteroid impacts, solar disturbances, etc. However, these computer models are also based in fundamental physics, and the random events can be modelled as well, if not predicted in advance.
This begs a question. Should you lose the bet, what ramifications does that have for AGW theory? How many years of cooling will it take before AGW theory is debunked? Let’s see a commitment from RC staff on this. How many years of continued cooling will it take for AGW theory to be rejected? You like bets, then place one on that.
[Response: None. About 20. Like I said. Lot’s of bets have been offered – few taken. – gavin]
CarbonSink51, Spoken like a man who doesn’t understand the science. Look, the GCMs are complicated, and yes there are uncertainties, but the fundamental reality, the 800 pound gorilla in the room is the fact that CO2 traps outgoing infrared radiation. Since such radiation is the only way energy escapes the climate system, that has to heat things up. Since the only escape clause is some magical negative feedback that kicks in to keep climate from warming above its current level, and since there is no such mechanism known and further since climate has warmed above this level in the distant past, I’d say this is pretty darned unlikely. Those who look to such a mechanism are appealing to Disney’s first law–Wishing will make it so.
Sad to say, I keep hearing people — and these are bright people — say “I don’t believe in global warming.” I don’t know how to get away from paralyzing fear that must be the driver of this sort of comment — they don’t want to believe it.
I’m writing a novel with a denier in it, and tried to come up with a carp about the GW science that hasn’t been used. Just my luck, I decide the denier announces that global cooling has begun! reality imitating art…
> 21, Gareth
Molina was talking about climate change.
Santilli? Look him up. Utterly off topic.
You don’t have permission to access /~stefan/Publications/Journals/rahmstorf_climdyn95.pdf on this server.
[Response: I made a local version you shouldn’t have a problem with (link above). – gavin]
[Response: Emissions are rising 3% a year, concentrations at just over 0.5% a year (~2ppm). – gavin]
Hi Gavin,
I clearly heard the exact phrase “over 3%” deliberately and clearly stated yesterday at a government-funded research institute in Boulder at a presentation by a visiting publishing scientist using the latest sources who is researching the latest CO2 trend anomalies.
Of course, this is my own personal opinion, the researcher might have been exagerating (I doubt it..the researcher would have been crucified by other publishing experts present..not to mention their reputation) and my statement is not in any way connected to any single institution.
This is nice, that climate scientists have reached consensus. If you want to convice the general public to the “tipping point” that we actually as a society begin to do something about it. You must preserve your credibility, and resist the temptation to say, every time that there is a hot day or a hurricane “see-it is global warming”. Because surely then when there is a cold day or a calm season, you have taught the deniers.
And when the arctic ice melts – faster than the models predict – who can say this is AGW?
Alien (Only art, no science)
[Response: If you care to look, we have been remarkably consistent on that point. – gavin]
Re #36: Possibly a reference to the increase in the rate?
Why do you think it’s melting? Global cooling?
You know, when somebody introduces themselves as “veritas” or Mr. Friendly the used automobile salesman, I reflexively reach for my wallet.
RE#38 I think that we are in deep doo doo a’la AGW. I am just pointing out that if the speed of arctic ice melting is outside the parameters that are predicted by the model, then the model might be wrong.
Alien
As one that repeatedly asked that you rescind your bet in favor of a gentleman’s bet, I commend you for agreeing to a non-financial bet. I still believe that the wager is too high but it will be interesting if Keenlyside et. al. will respond with terms that are more fitting with science and its discussion – perhaps a year’s subscription to Nature magazine for the inner city high school of the winner’s choice.
One question on your logic that I don’t quite understand (and perhaps I am misinterpreting the chart at the top of the article). You state in point 2 that since there are two false cooling forecasts that the model is suspect. While I grant you that the large gap in the late 90s is of huge concern, isn’t that same concern warranted with the large continuous gap from actual in the IPCC hindcast from 1965 to 1985?
“You know, when somebody introduces themselves as “veritas” or Mr. Friendly the used automobile salesman, I reflexively reach for my wallet.”
No biggie, but Gavin I’m sure has my two IP addresses. One of them is rather blatent and has been so for the two years or so that I’ve been posting on this blog.
Re #42 Sean O,
No there isn’t a concern about the IPCC model and the small deviations from the measured temperature evolution during the period around 1970-1985. The IPCC models make no claim to reproduce every variation in the temperature evolution in response to enhanced greenhouse forcing. That’s the whole point, of course. Everyone recognises that the Earth undergoes a warming response to enhanced greenhouse forcing. In general it’s recognised that prediction of the so far unpredictable phenomena (El Nino’s, La Nina’s, the fine details of ocean circulation oscillations, volcanos and any solar variation outwith the 11 year solar cycle) that provide short term modulation of any trend is likley to be unfruitful at present.
However Keenleyside et al are claiming to be able to predict the trend incorporating these short term modulations. Therefore Keenleyside’s assertions concerning the short term should be subject to the degree of scrutiny commensurate with their particular claim. That doesn’t apply to the IPCC simulations since they make no such claim of being able to predict short term modulations of the long term trend. That’s obvious isn’t it?
Re #18: Nylo says “Gavin, you responded at #11 that emissions are rising at 3% per year while concentrations only rise at 0.5% per year. That is somewhat logical because there was already some concentration before we started any emissions.” Actually, you are trying to compare two numbers that have completely different meanings…It is an apples-to-oranges comparison. The 3% per year is the amount by which the emissions are increasing…and (assuming that the fraction of this that stays in the atmosphere is constant) this would then be essentially proportional to the second derivative of the concentration of CO2 in the atmosphere with respect to time. However, the 0.5% per year is the rate at which the concentration of CO2 in the atmosphere is increasing…i.e., it is essentially the first derivative of the concentration of CO2 in the atmosphere with respect to time.
Thus, whether this 0.5% value is less than, greater than, or equal to the 3% value is irrelevant. It is sort of like trying to figure out if my weight in pounds is less than my height in centimeters and attaching some deep meaning to it.
#1
“As I explain, the Nature study is consistent with the following statements:
* The “coming decade” (2010 to 2020) is poised to be the warmest on record, globally.
* The coming decade is poised to see faster temperature rise than any decade since the authors’ calculations began in 1960.
* The fast warming would likely begin early in the next decade — similar to the 2007 prediction by the Hadley Center in Science”
If 2005-2015 turns out to be cooler than 1995-2005, do you think that would be cause to question the projected warming for 2010 to 2020? What about longer projections? I guess my main question is: what projections of warming can be accurately assessed for their true accuracy in the short term (next ten years or so)?
#44
“Everyone recognises that the Earth undergoes a warming response to enhanced greenhouse forcing.”
But what is debatable is the degree of that warming response, and what amount of forcing correlates into how much warming. And how much of the warming seen in the past century is conclusively due to GHG.
> debatable
Wrong concept, for scientific work.
Try for publishable. It’s harder, but it’s useful.
Re: 27
“Actually, the media lag far behind the scientists in terms of the level of consensus.”
No doubt. Generally, the public forms views by what it sees in the media and internet (not peer-reviewed journals, academia, scientific conferences, or the consensus from the major science academies) and what I see in the general media a pretty even mix, with many outlets covering contrarians exclusively (such as the WSJ op-ed columns to name one of many). The result is that the same handful of contrarian names get constantly recycled to the point where they have long reached virtual celebrity status. It’s a little disconcerting.
RC is an outstanding site and I’m amazed at the patience the scientists express here, but for every site of this quality there seem to be several junkscience.coms.
Why did GISSTEMP for March fall from 0.81 deg to 0.68 deg?
http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt
This makes the first 4 months of 2008 the coolest since 2000.
PJ