Scientists that switch from Climate Advocates to Climate Skeptics

[Snow_Miser]

I thought I would start a list of all of the scientists that have switched from advocates to skeptics.

http://climaterealis...dex.php?id=6050

Physicist Dr. Denis Rancourt, a former professor and environmental science researcher at the University of Ottawa, has officially bailed out of the man-made global warming movement.

In a hard-hitting and exclusive new exclusive video just released by Climate Depot, Dr. Rancourt declares that the entire man-made global warming movement is nothing more than a “corrupt social phenomenon.” “It is as much psychological and social phenomenon as anything else,” Rancourt, who has published peer-reviewed research, explained in a June 8, 2010 essay.

http://www.canada.co...05-fc28f14da388

Claude Allegre, one of France's leading socialists and among her most celebrated scientists, was among the first to sound the alarm about the dangers of global warming.

His break with what he now sees as environmental cant on climate change came in September, in an article entitled "The Snows of Kilimanjaro" in l' Express, the French weekly. His article cited evidence that Antarctica is gaining ice and that Kilimanjaro's retreating snow caps, among other global-warming concerns, come from natural causes. "The cause of this climate change is unknown," he states matter of factly. There is no basis for saying, as most do, that the "science is settled."

http://www.climatechangedispatch.com/climate-reports/8158-another-top-international-scientist-jumps-off-global-warming-titanic

A top East European climatologist, who shared the Nobel Peace Prize with UN global warming colleagues, jumps a sinking ship as ocean data signals a cooler climate.

Dr. Lucka Kajfež Bogataj left cold clear water between herself and her former UN shipmates by declaring that rising levels of airborne carbon dioxide probably don’t cause global temperatures to rise. The news scuppers hopes for a change in fortune for the beleagured UN climate agency. Their doomed ‘ship,’ the Intergovernmental Panel on Climate Change (IPCC) has been sailing on an ill wind ever since it was struck by that Climategate ‘torpedo’ last year.

http://www.aim.org/d...global-warming/

The evidence was not conclusive, but why wait until we were certain when it appeared we needed to act quickly? Soon government and the scientific community were working together and lots of science research jobs were created. We scientists had political support, the ear of government, big budgets, and we felt fairly important and useful (well, I did anyway). It was great. We were working to save the planet.

But since 1999 new evidence has seriously weakened the case that carbon emissions are the main cause of global warming, and by 2007 the evidence was pretty conclusive that carbon played only a minor role and was not the main cause of the recent global warming. As Lord Keynes famously said, “When the facts change, I change my mind. What do you do, sir?”

http://www.nature.co...s.2010.577.html

For most of her career, Curry, who heads the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, has been known for her work on hurricanes, Arctic ice dynamics and other climate-related topics. But over the past year or so she has become better known for something that annoys, even infuriates, many of her scientific colleagues. Curry has been engaging actively with the climate change skeptic community, largely by participating on outsider blogs such as Climate Audit, the Air Vent and the Black¬board.

[skierinvermont]

After skimming this it appears that none of the people are actual climate scientists and several of them rest their arguments upon blatant falsehoods.

For example, one of them claims there is no tropospheric hot spot. There is. Such blatant falsehoods dispel whatever credibility he might have had.

http://www.skeptical...ot-advanced.htm

The only one who is a climatologist, Judish Curry, understands and has helped demonstrate the strong evidence for AGW but simply believes other climatologists are "haughty." Doesn't really belong on you list.

[skierinvermont]

One of the examples on your list is blatantly fabricated. As far as I know Dr. Lucka Kajfež Bogataj of Slovenia has not jumped ship. You link us to a shoddy source that provides no evidence that she has jumped ship. The only thing the link you gave us says is that she recently explained in Slovenian publication that over the last 3 million years temperature rise has preceded not followed CO2 rise. This is a universally acknowledged fact. You don't need to go translating some Slovenian publication to find that out. You could have read that easily in the IPCC report or any other mainstream climate publication. Her statement is not evidence that she has suddenly become a skeptic. In fact, it is evidence that she remains a mainstream climatologist.

You need to learn how to differentiate legitimate sources from manipulative shoddy ones. Otherwise you're going to keep getting duped like this.

[Snow_Miser]

The only thing the link you gave us says is that she recently explained in Slovenian publication that over the last 3 million years temperature rise has preceded not followed CO2 rise. This is a universally acknowledged fact. You don't need to go translating some Slovenian publication to find that out. You could have read that easily in the IPCC report or any other mainstream climate publication. Her statement is not evidence that she has suddenly become a skeptic. In fact, it is evidence that she remains a mainstream climatologist.

Seems to me like you're trying to reassure yourself... but that's just the impression I got, since this post seems fairly agressive.

From the article:

"A detailed comparison of temperature data and the quantity of carbon dioxide captured in the ice shows, that sometimes it warmed up first and then the concentration of carbon dioxide increased, and sometimes vice versa, but on average the temperature changed first and some 700 years later a change in aerial content of carbon dioxide followed."

If co2 never drove climate, skier, and this is an "accepted fact" then why do CAGW proponents keep on insisting that co2 must have created the temperature rise, since the co2 and temperature correlate so well?

There's also this from the translator:

"She is still regarded as an eminent scientist (inter alia, she is the adviser to the president), so she has a lot to lose if she were to persist on the IPCC Titanic for too long. She's a political survivor, so next she'll pretend that she always knew! "

So if she still believes that co2 drives climate, then why does she state that co2 increase came after temperature rise?

[skierinvermont]

So if she still believes that co2 drives climate, then why does she state that co2 increase came after temperature rise?

That's an excellent question! I am glad you asked!

The large majority of temperature fluctuations in the past, for example the fluctuations between ice ages and interglacials, were not driven by CO2. The temperature increases clearly precede the CO2 increase. Likewise the temperature cooling clearly precedes the CO2 decrease. The exact causes of the initial temperature increase or decrease are probably at least significantly related to Milankovitch cycles. But it's quite clear that the initial warming impetus sets off a positive feedback whereby CO2 increase and ice albedo decrease cause further warming.

In addition, there are more isolated examples where it appears a mass exodus of CO2 did initiate a short rapid warming event. The PETM (Paleocene-Eocene Thermal Maximum) is sited as one such example. At the start of the PETM CO2 rapidly spiked and warming ensued.

But the fact is there are few examples of CO2 initiating warming events because the carbon cycle is generally fairly stable. We are now altering it by taking carbon which has been stored as fossil fuels for millions of years and burning it. So although there are few examples of CO2 increases initiating (and thus preceding) the temperature increase, it is quite clear that CO2 increases have amplified previous warming periods.

So you see your article's assumption that because she acknowledges temperature increases preceded CO2 increases she has become a skeptic, is entirely incorrect. It only reveals how completely oblivious the author is to the most basic tenets of climate science.

[ORH_wxman]

Going "skeptic" has become more common in recent years partly (IMHO) because of the media hype and alarmist attitude toward GW/AGW. It tries to paint a catastrophic picture in a 100 year period because of GHGs. It simply doesn't really add up.

Sensationalizing the Little Ice Age climate and telling us that every inch of glacial retreat since 1850 is a sign of doom and gloom is absolutely ridiculous. If they really want to see catastrophe, then a return to the LIA climate would do just that. The famine with the current world population would be astounding.

Obviously I'm not a climate scientist so my opinion means very little, but at least being an atmospheric scientist helps me see how twisted some of the propaganda is. I also think "Skeptic" is a term that many AGW supporters grossly misrepresent or lump into all one category with the pathetically demeaning term "deniers". Its a childish tactic that's really a turn-off and embarrassing for science. A "skeptic" doesn't mean you don't believe in global warming or in man-made global warming, it just means you might be skeptical of what the IPCC and the "consensus" is trying to sell at the moment. There's a lot of factors we still don't know a lot about (a lot of it is solar...multi-decade max/min, cloud feedback, etc)

And for me and others, it also means that the doom and gloom is exaggerated. Peer review is only part of the science and not everyone sees peer review, even people who have to make important decisions with respect to climate change.

[OSUmetstud]

Kerry Emanuel gave a talk about hurricanes in a globally warmed world at the NESC in March 2005. It was very alarmist. He had issues with the AMO smoothing etc. The talks that I have seen of his lately are much more reserved. The recent work he published in BAMS in 2008? showed that Atlantic Hurricanes would decrease in a globally warmed world due to a more persistent El NIno like state. He used synthetic cyclones to approximate development in the different climate states.

[tacoman25]

Kerry Emanuel gave a talk about hurricanes in a globally warmed world at the NESC in March 2005. It was very alarmist. He had issues with the AMO smoothing etc. The talks that I have seen of his lately are much more reserved. The recent work he published in BAMS in 2008? showed that Atlantic Hurricanes would decrease in a globally warmed world due to a more persistent El NIno like state. He used synthetic cyclones to approximate development in the different climate states.

I have to wonder about this. Just because waters are warmer doesn't mean the atmosphere/ocean are behaving like El Nino. Since we entered the latest -PDO phase, -ENSO state has been dominant, countering the idea that AGW is causing El Ninos to become more common/dominant.

[Mallow]

Going "skeptic" has become more common in recent years partly (IMHO) because of the media hype and alarmist attitude toward GW/AGW. It tries to paint a catastrophic picture in a 100 year period because of GHGs. It simply doesn't really add up.

Sensationalizing the Little Ice Age climate and telling us that every inch of glacial retreat since 1850 is a sign of doom and gloom is absolutely ridiculous. If they really want to see catastrophe, then a return to the LIA climate would do just that. The famine with the current world population would be astounding.

Obviously I'm not a climate scientist so my opinion means very little, but at least being an atmospheric scientist helps me see how twisted some of the propaganda is. I also think "Skeptic" is a term that many AGW supporters grossly misrepresent or lump into all one category with the pathetically demeaning term "deniers". Its a childish tactic that's really a turn-off and embarrassing for science. A "skeptic" doesn't mean you don't believe in global warming or in man-made global warming, it just means you might be skeptical of what the IPCC and the "consensus" is trying to sell at the moment. There's a lot of factors we still don't know a lot about (a lot of it is solar...multi-decade max/min, cloud feedback, etc)

And for me and others, it also means that the doom and gloom is exaggerated. Peer review is only part of the science and not everyone sees peer review, even people who have to make important decisions with respect to climate change.

At the same time, implying that the IPCC and other AGW "supporters" (like "skeptic", a misnomer) are out to lunch or trying to "sell" some crackpot theory (when it's generally mainstream science) as you're doing here only serves to feed those who have little to no knowledge on the issue and just like to regurgitate what they're told, whether it has any sound basis in reality or not (see Bethesda and snowlover, who have clearly demonstrated time and time again that they don't understand very basic and well-documented aspects of global climate and climate science).

Will, you have to realize that while your intentions aren't to discredit all of AGW science, posts like this make it seem like you tacitly support a group of people who have just as little understanding of climate science as those who say we're doomed within our children's lifetime. This is what bothers me about some "skeptics" (that misnomer is annoying to me as well since I consider myself a "skeptic", as a scientist)... they're perfectly content acknowledging the know-nothings on the "warmist" side of things, but refrain from saying any bad about the crackpots on their own side. It goes both ways, but since I'm on the "alarmist" side (as some would say, which, I might add, is the "pathetically demeaning" term used by the "deniers" side), I of course get irked more by the underhanded insults I feel are directed at me.

[VAwxman]

I have to wonder about this. Just because waters are warmer doesn't mean the atmosphere/ocean are behaving like El Nino. Since we entered the latest -PDO phase, -ENSO state has been dominant, countering the idea that AGW is causing El Ninos to become more common/dominant.

The theory though is that, since AGW argues for more warmth at the poles relative to the tropics, the north-south temperature gradient weakens, which leaves circulations in a more nino-like state. And that is what should occur, if the AGW theory is correct. I'm not saying it is or isn't though. We will have to wait and see what reality is, and of course even if it is right, it is being fought off right now by the natural signals... PDO, etc.

[ORH_wxman]

At the same time, implying that the IPCC and other AGW "supporters" (like "skeptic", a misnomer) are out to lunch or trying to "sell" some crackpot theory (when it's generally mainstream science) as you're doing here only serves to feed those who have little to no knowledge on the issue and just like to regurgitate what they're told, whether it has any sound basis in reality or not (see Bethesda and snowlover, who have clearly demonstrated time and time again that they don't understand very basic and well-documented aspects of global climate and climate science).

Will, you have to realize that while your intentions aren't to discredit all of AGW science, posts like this make it seem like you tacitly support a group of people who have just as little understanding of climate science as those who say we're doomed within our children's lifetime. This is what bothers me about some "skeptics" (that misnomer is annoying to me as well since I consider myself a "skeptic", as a scientist)... they're perfectly content acknowledging the know-nothings on the "warmist" side of things, but refrain from saying any bad about the crackpots on their own side. It goes both ways, but since I'm on the "alarmist" side (as some would say, which, I might add, is the "pathetically demeaning" term used by the "deniers" side), I of course get irked more by the underhanded insults I feel are directed at me.

Agreed, its definitely a problem on both sides. I think a lot of it is that people lump the groups as one. There are definitely "denier" skeptics and definitely "alarmist" AGWers...but I think both represent a minority portion of each side of the argument.

I was giving my viewpoint, and you did a good job showing yours on the other side of the coin. Its too bad that it has become like this because its really hurting the actual science IMHO.

[OSUmetstud]

I have to wonder about this. Just because waters are warmer doesn't mean the atmosphere/ocean are behaving like El Nino. Since we entered the latest -PDO phase, -ENSO state has been dominant, countering the idea that AGW is causing El Ninos to become more common/dominant.

I believe the IPCC is on board with a similar conclusion. Emanuel's climate model ran the IPCC temperature scenarios and all showed increased wind shear in the Tropical Atlantic in a warmed world.

[BethesdaWX]

(see Bethesda and snowlover, who have clearly demonstrated time and time again that they don't understand very basic and well-documented aspects of global climate and climate science).

I of course get irked more by the underhanded insults I feel are directed at me.

Read these two sentences over...... If this is the way you go about this, Mr Hypocrite, you deserve to be insulted, repeatedly (in my view). I feel insulted by this, not only because you have not backed up this argument, but you've underhandedly (as you said), directed an insult at me, behind my back, hoping I wouldn't see it. This is what makes the AGW argument look bad. I'll explain my reasoning and position on AGW below, which you have apparently mis-interpreted.

How is my belief that humans have caused ~ 10-15% of the warming seen since 1850... "not understanding the science"? You better realize that "AGW" as the cause of the warming since 1850, is hypothesis based on limited understanding of the climate system & its mechanisms, and is not the least bit settled or understood, for that matter. So if it is my "doubting" that has motivated you to punch a Jab at me like that... then you're a joke who should not feel "irked" by insults. Humans have changed the Climate through Land Use Changes, Deforestations(etc), Release of excessive CO2 emmissions, urbanization, etc. This much is true, but the extent is not at all understood, it can't be when we have poor understanding of mechanisms within the Climate system. I'll get into that below.

As for why I'm skeptical of thise whole Mass AGW thing:.....

Throughout the Holocene, as evidenced in ALL Ice core Proxies from both poles, using DO18 isotopes with high resolution, there have been warmings and coolings as high or higher than what we haver seen since the Industrial revolution.... We're talking of 1-2C changes over 200yr timespans, evidenced in Volstok & Greenland Ice Cores. By today's methods put in Climate Models, (CO2 being the dominator, with Slight contributions from TSI and Volcanism)... those warmings and coolings cannot be explained!

What needs to be understood before we can assume how Much warming CO2 has caused, is what caused those warmings in the Past. The Only Plausible explanation, from what we know, is Changes in GCC (global cloud cover) driven by some aspect/driver. Only a minor 3% GCC change corresponds to a radiative net change of 0.5 W/m² compared with the IPCC estimate of 1.6 W/m² for the total effect of all recognized climatic drivers 1750-2006, including release of greenhouse gasses from the burning of fossil fuels. The Climate System is capable of seeing reduced GCC by >5%, Likely driven by GCR's, at least in part....and this is just one of Many Aspects here.

Differing spectrums of energy from the Sun, such as UVA and UVB rays, penetrate deep into the oceans and any body of matter, and vary much more heavily than TSI. And adding in the Fact that The Ozone Layer lost a significant amount of its luster due to CFC emmisions, Major Volcanic Eruptions, and Changes in GCR's would allow more of these UV ray at a very high spectrum to penetrate into the atmosphere, and oceans and warm them significantly.

And... we also have Oceanic Oscillations, that, since the mid 1970's, have contributed to warming through an already Very Warm OHC globally. So that is an enhancer as well. Drivers such as the PDO, AMO, IOD, to name a few, and their effect on Global Sea Ice, Cloud Cover, and the climate system in general, need to be taken into account.

So we have Large uncertainty, with other possible contributors to the warming we've seen. Nature has, on its own, replicated warmings faster and greater than those of today, so it needs to be accepted, based on what we've observed, that at least part of the warming seen is likely natural. CO2 hs indeed, based on sound science, contributed a certain amount of this warming, but the amount may be very significant, or too small to accurately measure, dependant on forcings/feedbacks within the climate system. I'm on the low end of the AGW spectrum, to be honest, but my opinion may change over time, it depends what happens.

Our understanding of these natural aspects would be improved through better measurement, analysis, and non biased science.

[Mallow]

Read these two sentences over...... If this is the way you go about this, Mr Hypocrite, you deserve to be insulted, repeatedly (in my view). I feel insulted by this, not only because you have not backed up this argument, but you've underhandedly (as you said), directed an insult at me, behind my back, hoping I wouldn't see it. This is what makes the AGW argument look bad. I'll explain my reasoning and position on AGW below, which you have apparently mis-interpreted.

I frankly didn't care whether you read it one way or the other, and indeed I figured you would.

FWIW, I believe that you do a lot of reading on the subject and that your intentions are honest. But your posts often betray your lack of understanding of certain basic aspects of climate science. You've been learning on the job, so to speak, and you're building your knowledge base as you go... But one of your biggest flaws (imo) is that you lack the background to judge whether many of the articles you post are reasonable, or if they can be easily debunked. It makes you look bad when you post a silly article you found on a blog and ask "could this disprove agw?", when a pretty quick skimming of said article would have the flaws jumping out at anyone with the physics background to intelligently discuss climate change. But when those silly flaws are pointed out, you tend to have a habit of defending the silliness before you gradually back out and latch on to another argument.

These are just my observations, and from my perspective, but that's why I included you in that parenthetical. I should've just kept my mouth shut in the first place... These arguments always bring out the worst in me.

[tacoman25]

At the same time, implying that the IPCC and other AGW "supporters" (like "skeptic", a misnomer) are out to lunch or trying to "sell" some crackpot theory (when it's generally mainstream science) as you're doing here only serves to feed those who have little to no knowledge on the issue and just like to regurgitate what they're told, whether it has any sound basis in reality or not (see Bethesda and snowlover, who have clearly demonstrated time and time again that they don't understand very basic and well-documented aspects of global climate and climate science).

Will, you have to realize that while your intentions aren't to discredit all of AGW science, posts like this make it seem like you tacitly support a group of people who have just as little understanding of climate science as those who say we're doomed within our children's lifetime. This is what bothers me about some "skeptics" (that misnomer is annoying to me as well since I consider myself a "skeptic", as a scientist)... they're perfectly content acknowledging the know-nothings on the "warmist" side of things, but refrain from saying any bad about the crackpots on their own side. It goes both ways, but since I'm on the "alarmist" side (as some would say, which, I might add, is the "pathetically demeaning" term used by the "deniers" side), I of course get irked more by the underhanded insults I feel are directed at me.

Personally, I only call someone an "alarmist" if they clearly preach catastrophic global warming and tend to make claims/predictions that are on the extreme side of things (like James Hansen or Al Gore, for instance). There are many, like myself, who believe AGW is definitely a factor...but are very skeptical about catastrophic global warming. So that's why I get so irked about all skeptics being lumped together as "deniers" (people who deny AGW as a factor), and I also am careful not to lump everyone who believes AGW is a factor into the "alarmist" category.

[tacoman25]

The theory though is that, since AGW argues for more warmth at the poles relative to the tropics, the north-south temperature gradient weakens, which leaves circulations in a more nino-like state. And that is what should occur, if the AGW theory is correct. I'm not saying it is or isn't though. We will have to wait and see what reality is, and of course even if it is right, it is being fought off right now by the natural signals... PDO, etc.

Yes, I just think that is a premature assumption, since we don't even know what exactly drives PDO/ENSO/etc.

[OHSnow]

A lot more climate scientists have switched from skeptics to proponents of the theory. I think today some 97% of climate scientists support the AGW theory.

[tacoman25]

A lot more climate scientists have switched from skeptics to proponents of the theory. I think today some 97% of climate scientists support the AGW theory.

Depends again on how you define "skeptic" or "proponent". Are they skeptical of AGW altogether, or just catastrophic AGW?

[WeatherRusty]

Depends again on how you define "skeptic" or "proponent". Are they skeptical of AGW altogether, or just catastrophic AGW?

Does accepting the current understanding of equalibrium climate sensitivity to fall within the range of 2 - 4.5C place me in the catastrophic category? Don't you think that kind of warming would seriously alter living conditions planet wide?

[skierinvermont]

Yes, I just think that is a premature assumption, since we don't even know what exactly drives PDO/ENSO/etc.

It's not an assumption. It is the general result of climate models.

Note that the atmosphere being in a Nino-like state is different than there being more El Ninos. I guess this is why atlantic hurricane activity is predicted to decrease. More El Nino "like" shear.

[tacoman25]

Does accepting the current understanding of equalibrium climate sensitivity to fall within the range of 2 - 4.5C place me in the catastrophic category? Don't you think that kind of warming would seriously alter living conditions planet wide?

Depends on how quickly it happened, how much it actually warmed, and how the warming was distributed.

Alarmists, in my opinion, are those that assume the worst will happen and only see terrible, catastrophic results of warming. Part of this mindset, I believe, comes from the fact that humans are behind AGW - so AGW/climate change is put in the same box as man-made environmental damage.

[tacoman25]

It's not an assumption. It is the general result of climate models.

Note that the atmosphere being in a Nino-like state is different than there being more El Ninos. I guess this is why atlantic hurricane activity is predicted to decrease. More El Nino "like" shear.

It's still an assumption. Climate models have to be built on certain assumptions.

Perhaps, but some scientists have actually predicted more El Ninos.

[WeatherRusty]

Depends on how quickly it happened, how much it actually warmed, and how the warming was distributed.

Alarmists, in my opinion, are those that assume the worst will happen and only see terrible, catastrophic results of warming. Part of this mindset, I believe, comes from the fact that humans are behind AGW - so AGW/climate change is put in the same box as man-made environmental damage.

Well without going into detail, I expect that any significant change in climate on regional and global scales and either toward warmer or cooler conditions will burden many facets of modern technological societies as well as being devastating to the world's poorer populations. We are vulnerable in ways that most of us are oblivious to. We take for granted our supplies of food and water. We take for granted our technologies will be capable of overcoming most any obstacle we face. We will soon be in for a rude awakening when the support systems we have developed begin to fail for more and more of the soon to be over 7 billion humans made possible by favorable climate, technology and abundant resources to support it all. A significant change in climate will stress our tenuous hold on prosperity to the breaking point. We can see it coming, but rather than face up to the challenge we bury our collective heads in the sand. Arnold's sex life is of more interest and concern to people.

[ORH_wxman]

Well without going into detail, I expect that any significant change in climate on regional and global scales and either toward warmer or cooler conditions will burden many facets of modern technological societies as well as being devastating to the world's poorer populations. We are vulnerable in ways that most of us are oblivious to. We take for granted our supplies of food and water. We take for granted our technologies will be capable of overcoming most any obstacle we face. We will soon be in for a rude awakening when the support systems we have developed begin to fail for more and more of the soon to be over 7 billion humans made possible by favorable climate, technology and abundant resources to support it all. A significant change in climate will stress our tenuous hold on prosperity to the breaking point. We can see it coming, but rather than face up to the challenge we bury our collective heads in the sand. Arnold's sex life is of more interest and concern to people.

The world is over populated. This population is unsustainable unless we get lucky enough to keep the current climate within a very small window. That simply isn't even natural...nevermind man made AGW. If we even returned to LIA conditions of 200 years ago, it would be disastrous.

[skierinvermont]

It's still an assumption. Climate models have to be built on certain assumptions.

Perhaps, but some scientists have actually predicted more El Ninos.

No they are built on theoretical physics and empirical observations.

[LakeEffectKing]

No they are built on theoretical physics and empirical observations.

And approximations....

[WeatherRusty]

Both Skier and myself should be considered skeptics, but skeptical in a sense which does not seek to deny the validity of AGW science within the bounds of its inherent uncertainty. The science does not claim to understand every nuance of the climate system to the point of being able to predict a general outcome beyond a range of probability. That range of uncertainty is wide enough to encompass outcomes which include mild disruption to catastrophic effects on wild life and human civilization.

Whether one chooses to embrace a catastrophic scenario or one of much less impact, both positions and everywhere in between are supported by the state of understanding as it stands today. Regardless, even a shift of 0.5C toward warmer or cooler conditions world wide will be somewhat disruptive. The LIA was not much more a shift than that, what would warming of 2.0 to 4.5C mean to our world? We may be on a course to finding out even if it takes 100 to 300 years to get there.

[tacoman25]

No they are built on theoretical physics and empirical observations.

Right, those are what form the assumptions. But if you tweak the assumptions only a bit, the model results can vary wildly. Which is why global warming estimates have ranged all over the place.

My original point was that since so little is known about what drives ocean circulations and ENSO/PDO, I think it's a little assumptive to try to predict (with or without climate models) how AGW would effect these aspects of climate.

[tacoman25]

Both Skier and myself should be considered skeptics, but skeptical in a sense which does not seek to deny the validity of AGW science within the bounds of its inherent uncertainty. The science does not claim to understand every nuance of the climate system to the point of being able to predict a general outcome beyond a range of probability. That range of uncertainty is wide enough to encompass outcomes which include mild disruption to catastrophic effects on wild life and human civilization.

Whether one chooses to embrace a catastrophic scenario or one of much less impact, both positions and everywhere in between are supported by the state of understanding as it stands today. Regardless, even a shift of 0.5C toward warmer or cooler conditions world wide will be somewhat disruptive. The LIA was not much more a shift than that, what would warming of 2.0 to 4.5C mean to our world? We may be on a course to finding out even if it takes 100 to 300 years to get there.

I guess you could be considered a skeptic; however, neither one of you seem very skeptical towards the mainstream, "consensus" viewpoint on AGW. I think skeptics are usually considered those who are skeptical about the mainstream viewpoint, or at least certain aspects of it.

[Mallow]

I guess you could be considered a skeptic; however, neither one of you seem very skeptical towards the mainstream, "consensus" viewpoint on AGW. I think skeptics are usually considered those who are skeptical about the mainstream viewpoint, or at least certain aspects of it.

In the climate science field, the "skeptics" have given themselves that name in an attempt to legitimize their position as "the scientific position". In general, all scientists should be natural "skeptics". Often in other fields, the position that is considered the mainstream scientific position is also the "skeptical" position (see debates of science vs pseudoscience).

I'm skeptical that the slowing of warming over the past decade means anything either way for the debate at hand (too short a time period), whereas some "skeptics" seem to think (for no sound scientific reason) that it disproves that AGW is a "significant" climate driver. I believe my position on that specific aspect, for example, is the more "skeptical" position.