Glacification of the North America at 3million years (my) before present (BP) was a known fact.

No past research noted a sharp drop in CO2 level. It was almost constantly dropping since 150my BP.
http://www.geocraft.com/WVFossils/Carboniferous_climate.html

I thought the old theory was that the formation of the Isthmus of Panama by continental drift brought about a change in ocean circulation reaching the arctic ocean resulting in the glacification. This looks to me like a better explanation then the sudden drop in CO2 level which is a non-event.

http://commons.wikimedia.org/wiki/Image:65_Myr_Climate_Change.png

The climate and ice models say so - it must be true.

Southern Greenland is approximately at the same latitude as Scandanvia. It is the climate produced from prevailing winds that keep Scandanvia warmer and Greenland cooler.

However, with more CO2 in the atmosphere, there will be more warming all the way around.

No good estimate as to how long it will take for Greenland to melt, but it probably won't be in our lifetimes. However, Greenland is so large that it's presenese impacts the climate itself as it preturbs the jet stream and produces a lot more storminess that there would be other wise. So, when Greenland does melt, there will be a significant shift of climates. Much more desert like in North America.

Well, this is of no logic.
Even myself, not being a global warming skeptic, think that there is much absurd logic in this news.

The "only" thing to make Greenland freezing is "solely" a drop in CO2?
No, I don't buy into it.
What if there was some change in solar output, some unknown change in oceanic circulation, some change in cosmic rays or some small polar shift

Scientists sometimes are too narrow and absurd.
I start doubting the global warming thing, even when seeing the poles melting I remain open to whatever it may be, who knows for sure what is the cause for global warming. However I do know that pollution by oil and coal is never good.

Regarding climate researchers and CO2:

When your only tool is a hammer, everything looks like a nail.

This is really getting funny, as in stupid funny. Show me the signature of today's CO2 greenhouse gas hoax ... It should be there.

It's quite possible that Greenland was ice free 3 million years ago because the Earth's climate was a lot warmer. Were you driving around in your SUV 3 million years ago? No, so what caused the warming?

Why did the ice ages start some 3 million years ago? Who did that.

My money is on the sun driving Earth's climate.

I wonder what the effect of the earth's higher core temperature is on the ice sheet and global warming generally?

My specific questions would be as follows:

Why is the earth's core warmer than the surface? (residual heat from the big bang, nuclear reactions, etc.?)

To what part of the earth's surface temperature does core heat contribute?

Is the earth's core cooling? If so, at what rate?

Could the cooling have passed a threshold that allowed the ice sheet to form?

What is the implication of further core cooling on global warming (or cooling)?

I can't believe how someone can get away with making such a stupid statement as "the ONLY thing that can explain the transition from an ice free Greenland is a drop in CO2 etc..." The ONLY THING? Really? What about every other TRUE aspect of what causes climate change like perhaps the SUN! or changes in ocean currents, Changes in the earth's axis or orbit. But NOOO it must be CO2. the less then 1% of our atmospheric gas which is very debatable if it causes warming at all! but to totally disregard and not mention methane or water vapor KNOWN causes of warming and to solely blame CO2 is very insulting to me and should be also to anyone with half a brain or the slightest knowledge of anything weather and climate related. I am just sick and tired of every temporary warming episode being blamed on CO2. To add insult to injury is the mention of ice sheet and climate modeling, these models are barely if at all acurate to predict what could happen in a few months, but can miraculously know what happened 3 million years ago!

OK, seriously, do these "State of the Art" researchers really think they have solved the puzzle?

Does anyone think it a just a bit ODD that the study magically determines that it is "just about" the CO2 levels of present that existed when Greenland was ice free? And, more importantly, that lower CO2 levels made the ice form?

As a famed SNL character might say "How Conveeeenient!"

You see, anything else might just poke a hole in the AGW agenda.

And while there are lots of interesting ideas of why the ice sheet changes over time, did anyone else notice that the little fireball in the sky was "accidently" left off of the list?

Right, CO2. Had nothing to do with the closing of the Panama Strait or the rising of the Himalayan Mountains and the Tibetan Plateau. There is no proof that temperature follows CO2 only in the model world does temperature follow CO2.

There was an ice age during the Ordovician with CO2 levels 10X higher than today.

Using the same brilliant thinking as my BU buddies, this proves that high CO2 levels force extreme global cooling.

"The one question that scientists do not know the answer to is why was there a sudden drop in atmospheric CO2 three million years ago? "

Obviously, it was the famous tipping point they keep talking about.

High temps and high CO2 levels are very unstable. Once either one gets too high and too unstable, it cascades. We should all be enjoying our good luck right now, instead of being scared, paranoid little freaks.

"The one question that scientists do not know the answer to is why was there a sudden drop in atmospheric CO2 three million years ago?"

I'm pretty sure there is more than one. Like whether or not CO2 levels have a significant impact on climate.

this is bogus global warming is nothing more than propaganda. the earth is actually warming but we have nothing to do with it.

Thanks Brett for all the great information.

I saw this today in the BBC and though I know you keep abreast of all this, since it is part of an ongoing development some might be interested:

"Arctic ice 'is at tipping point'"
http://news.bbc.co.uk/2/hi/science/nature/7585645.stm

As I understand it, while current data show that melting is not as much as last year with a couple of weeks to go, various factors indicate that the trend is toward more, including an increase in rate and some thinning. In any case, we will all know where 2008 fits with other years soon, and I'm sure Brett will post about it.

Although I've lost interest in continuing to participate here on a regular basis because of ongoing bias and the sometimes rude/sarcastic quality of arguments, I am interested in the posts in which Brett shares his expertise to show us more in-depth information.

I am also concerned that the circular and shallow arguments of the denier/delay machine and its fans can be more convincing than they should be. Those who drop in here might think they will find a discussion of Global Warming, rather than an ongoing attempt by participants to create a consensus that majority science is full of baloney. Many of these arguments have been being put forward for several decades, and scientists have made huge efforts to include and understand the points made, get better at communicating how science works, and provide answers/improve models. I think once a point has been answered dozens or hundreds of times, repeating it only deceives those who accept assertions without checking sources.

Making insulting claims about the IPCC, Dr. Hansen, Al Gore, people here, and others is part of the democratic process; so is my claim that this is dishonest or that if you believe it you have been deceived. If you have not joined the club, these insults have the purpose of creating doubt and a little research into the actual history of these people will show quite a different picture. A general figure of about 98% to 99% of credible scientists agree that global warming is happening and perhaps a slightly lower figure agree that it is man-made.

In any case, whatever you think about CO2, it is clear that we have a number of critical issues around pollution, toxins in the environment, an ocean in crisis with pollution and overfishing, etc. It is less costly to address the causes of extreme weather events than to rescuing its victims. An excellent example brought to my mind recently is the removal of wetlands in favor of development around New Orleans, and the failure to fund adequate strengthening of levees, not only near New Orleans, but in many other locations (most recently the upper Mississippi).

The only thing that can explain it is CO2? And these guys are scientists? Wow no wonder people have a hard time accepting AGW. So many factors involved yet this is the best they could come up with. Could it be that the only ones funding them are proponents of the CO2 farce to begin with? Rock on Oz as this stuff is getting more and more comical by the day.

I'd like to make a request of those of you posting rude comments about how stupid scientists are, how CO2 has no effect on climate, etc. Would you mind terribly including in your message what education you have had in climatology, and how many years you've been working in the field? Because otherwise we're likely to conclude you're some ignorant yahoo. Thanks in advance!

Hmmm. Mars is 99%+ co2 and "they"{it} manages to have ice. Really if we stop making co2, do all these people think it would be possible to have another ice age, all my I just think of all the things I can do like...umm...uhhh..uhh..ride snowmobile, until I run out of gas and they no longer deliever due to road closure, well wait it wouldn't matter we all would eventually die from starvation, so well shoot...lets keep making that co2 if its keeping it warmer, yesterday my temp hit 58 today it nudged 60 with most of the day in the mid -upper 50's with rain,drizzle,wind, just beautiful for August, really though once again I can't even begin to imagine how cold it would have been without global warming, like yesterday, today my thanks and appreciation goes out to all you loggers, power plant workers, suv drivers, and all the co2 producers behind the scenes, without you it would be a cold world!

What provides the greater variation in climate on the planet today, CO2 or the oceans?

CO2 continues to plague researchers minds, making the more plausible explanations impossible for them to grasp. It doesn't take very long to find more realistic theories:

"A Short Circuit in Thermohaline Circulation: A Cause for Northern Hemisphere Glaciation?" by N. W. Driscoll, G. H. Haug.
http://www.sciencemag.org/cgi/content/abstract/282/5388/436

And an article from The Woods Hole Institution:
"How the Isthmus of Panama Put Ice in the Arctic"
http://www.whoi.edu/oceanus/viewArticle.do?id=2508

D Caldwell wrote...
....When your only tool is a hammer, everything looks like a nail...

whats your tool then?

WeatherWatcher:
Thanks for nailing down the real Issues. Everything you said is true. CO2 warms our Planet for the last 660,000 years. The planet has a concentration of CO2 at 280ppm. Then after pre-industrial times, CO2 rises to 390ppm today.
Temperatures and the rise of CO2,CH4,and N20 mirror each other. They go up and down and up again at exactly the same intervals. This was the basis of the Keeling graph. If you don't believe this then look at Venus. Venus has a large atmosphere of CO2 and is warmer than it should be for it's relative distance to the Sun. In terms of forcings, the Sun has contributed to the warming only 0.12c. The greatest feedback mechanism has been water vapor. CO2 Molecules react to IR then tumble, move faster and collide with other gases and this is called warmer. We have created the greenhouse effect. It's warming the Arctic if you haven't noticed.
Also since explaining warming to you, because you have energy that doesn't mean you should waste it. Half of the great coral reef is dying. We need regulations for over fishing, Greenpeace had to chase the Japanese out of our waters for killing whales, and you laugh at this. I don't even get the joke! If America is a great Country then prove it! Your choice.
KIPP

bill-tb, I don't understand why you think that just because something influenced the earths temps 3million yrs ago means that today, the something that's now influencing the temp can't be us!

The chemistry for CO2 causing warming by its greenhouse properties is straightforward science! We are burning tons of the stuff and forcing up the concentration.

Scientist, from even as early as 1890, and across many disciplines (IPCC) have worked out what the effect of the additional CO2 would be and this has been the observe temp rise we have seen over the period.

more and more reputable organizations are puting out statements indicating that AGW is real and very dangerous and something needs to be done. Here an impressive latest statement from the Brookings Institution
7 Years to Climate Midnight

WeatherWatcher said ...
...I've lost interest in continuing to participate here on a regular basis because of ongoing bias and the sometimes rude/sarcastic quality of arguments, I am interested in the posts in which Brett shares his expertise to show us more in-depth information...

...circular and shallow arguments of the denier/delay machine and its fans can be more convincing than they should be. Those who drop in here might think they will find a discussion of Global Warming, rather than an ongoing attempt by participants to create a consensus that majority science is full of baloney. Many of these arguments have been being put forward for several decades, and scientists have made huge efforts to include and understand the points made, get better at communicating how science works, and provide answers/improve models. I think once a point has been answered dozens or hundreds of times, repeating it only deceives those who accept assertions without checking sources.

Well said mate!

Saly: I am not a scared paranoid freak. People in denial, do so because they are in fear of reality.
People that accept reality, have a better understanding of how to act and why. Global warming is an ominous fact. We are not alarmed, not afraid or choose to be lefty's, pinko's, or weirdo's. We are Americans First. We are patriots,
workers, and Businessmen. Artists, engineers and Scientists. We enjoy respect from our peers, if we deserve it. We are people, who live in a country now divided by those who have and those that don't. I have lived in Mexico City and have seen the gross poverty along side the very wealthy. I would not wish this on anyone. Not in My country for sure. We need the middle class like never before. Who ever is really running the country now, I'm not quite sure. But values like truth, honesty, and fairness should always prevail, over the special concerns of one group over any other. One person, one vote.
KIPP

Weather watcher ... you are basically trying to make the point that because the warmers got on the stage first they cannot now be displaced whether right or wrong. Nice try but that ain't how science works. You can wrap your arguements in all the concern about toxins you wish & it doesn't give them any more weight.
Regarding this " article " it is a terrible piece of FLUFF short of everything except speculation & CO2 porn. The only intelligent morsel I found raises the issue of whether CO2 leads or follows the global temp changes & I've read arguements for both cases.
Have a good Labour / Labor day folks.
Rick.

How's this for a common sense explanation? The warm period that caused Greenland to be ice-free released CO2 from the oceans, causing high CO2 levels. When the climate cooled down and glaciers returned, the cooler oceans reabsorbed all the previously released CO2. What caused the lower temps. is open to much speculation but CO2 dropping before temperatures isn't one of them. These researcher's minds are so closed they're starved of oxygen.

One of the first things you learn in freshman geology class is that as temperatures warm, CO2 solubility in the oceans decrease. This causes more outgassing of CO2 and higher CO2 concentrations in the atmosphere - as is the pattern seen in Vostok ice cores.

In other words cause and effect is confused. Is Laurie David's elementary school textbook cited as a reference?

Forgot to mention, I flew over Greenland three weeks ago and it looked exactly the same as always. Two mile thick ice and almost no indication of any melt this summer.

I wonder why we haven't seen any Greenland melt-day headlines from EO this year?

Weatherwatcher, you seem confused about what a forum is. It is my understanding that nobody is required to think just like you at all. If 95 percent of this forum thinks much that is written about GW is bunk, they have that right to disagree and they have the right to cry foul. You find many of the posts to be insulting and frankly I find your posts to be insulting as well, but I think you have the right to babble all you want. I am only writing this reply because you swung first and the idea that anybody feels it necessary to try to censor other people's thoughts forces me to directly reply to that subtle threat.

I think these researchers are full of horse poop. Whenever I see CO2 and modeling in the same sentence, I feel the presence of an agenda driven conclusion.

Andrew:
How long to melt Greenland?

http://ex-parrot.com/~pete/greenland.html

Excerpt:
How big is the greenland ice sheet.?
Very. Wikipedia and other sources suggest about 2.85million cubic kilometres.

How long will it take to melt at current rates
So, divide, 2 850 000 000 by 220 and you get 13000 years.

So here is a novel take:

Atmospheric CO2 is caused by GloBull Warming.
Whoda thunk it.
Oh wait.

Me.

http://72.14.205.104/search?q=cache:-T7FOwrCJlIJ:www.thereporter.com/ci_10157633%3Fsource%3Dmost_viewed+John+Takeuchi+one+hot+topic&hl=en&ct=clnk&cd=1&gl=us

WeatherWatcher said:
""A general figure of about 98% to 99% of credible scientists agree that global warming is happening and perhaps a slightly lower figure agree that it is man-made.""

Let see you backup that statement.
I make it 32.5% agree with AGW

But since 72.68% of all statistice are made up on the spot, it may be out my .1 or .2 %.

Paulo: Look at my post and it will show clearly that the sun. scientifically measured was 0.12c more warm. In terms of warming the Sun has little influence in rapid climate change, and warming over the last 150 years. These are only
articles written for copy for a newspaper. Read the last IPCC report. Read the History of Global Warming by Spencer Weart. There are a lot of honest and dishonest debates. Follow your Stomach, and keep the faith. I can weather the many ideas because I know the fundamentals. No matter what good article that Brett posts, we need to pull back, take a breath, and say, what are the real honest questions. For the last 150 years it has been warming, and I can't wait to see what excuse will be applied to deny this reality. The fact that skeptics can't answer my questions adequately about CO2 is the big missing
piece, and only makes me believe in global warming more. Read the IPCC report, and don't be afraid of being called names.
KIPP

Brett: Thanks for your recent posts, I know how busy you must be, we another hurricane about to arrive. KIPP

WeatherWatcher said "A general figure of about 98% to 99% of credible scientists agree that global warming is happening and perhaps a slightly lower figure agree that it is man-made."

This recent paper has lots and lots of evidence that there has been global warming since the end of the Little Ice Age:
http://people.iarc.uaf.edu/~sakasofu/pdf/Earth_recovering_from_LIA_R.pdf

There's not much argument over past warming, the argument is over what comes next. Runaway warming, more of the same, or the big chill.
The science isn't settled. I'd like to see the survey of "credible scientists" that says it is.

It is well known that CO2 can cause the greenhouse effect, so it is natural to hypothesize that CO2
is one of the causes of the present warming trend. However, it is not appropriate to conclude that
the 0.6�C rise is mostly due to human causes without carefully subtracting the contributions of
natural changes. This point is missing in the IPCC study on global warming.


(from the above mentioned paper)

Patrick,

There was an ice age during the Ordovician with CO2 levels 10X higher than today.

Using the same brilliant thinking as my BU buddies, this proves that high CO2 levels force extreme global cooling.

The ice age at the end of the Ordovician happened in much different conditions than we have today, so we can not directly compare cause-effect relationships such as CO2 levels. Continents were in very different places than they are today, which means very different ocean circulations and climate patterns. Climate would respond differently to ANY forcing in that situation, even solar forcing.

Your comparison is ill-informed, or at least ill-supported. Show me that all other climate factors responded the same back then as they do today. Show me that the ENSO cycle existed, that there was such a thing as the PDO, or that the Gulf Stream kept Europe warm. When you can do that, you can claim that CO2's effect then is exactly the same as its effect now.

Brett, Just been going round looking at various climate changes position statements.

Reading Accuweather's, it does not seem to really state an actual position. Isn't it time that this was reviewed...things have moved along quite a bit since it was posted...

"The one question that scientists do not know the answer to is why was there a sudden drop in atmospheric CO2 three million years ago?"

Don't you guys get it? Too many f----g trees, used up all the CO2 :-)

Off topic but important . Whether you are a proponent of , or a skeptic of AGW is irrelavant . Gustav is looking to be a really bad one. I speak only for myself but I think there are many who would agree with me that prayers are going out to all of you folks down along the Gulf Coast. May the Good Lord watch out for all of you and protect you from harm. And I mean it !!!

According to a tv news report last night, a man has just set off on an attempt to canoe to the North Pole, to 'prove' to the world that the Arctic ice is melting due to climate change.

These are things that should cause us to question our premises regarding global warming. Since we have only started tracking this type of thing in the recent past (of earths "history"), does it cause us to question that perhaps the "global warming" we are seeing is not something to fear but actually a season of the life-cycle of an "old" earth.

The answer to the Greenland question - ALIENS.

Thanks skeptic for the link to that great web site. Very interesting. I've always been a fan of Michael Shermer. Lots of good information there. If you are a true skeptic though, then I don't understand how you can say that GW is propaganda. A skeptic would be open to all possibilities.

WeatherWatcher - My sentiments exactly.

I agree with this statement of yours:

Although I've lost interest in continuing to participate here on a regular basis because of ongoing bias and the sometimes rude/sarcastic quality of arguments, I am interested in the posts in which Brett shares his expertise to show us more in-depth information.

Couldn't have said it better myself.

Thanks Brett for all that you do here to advance our understanding of this issue.

Good grief. I am reminded again why I mostly stopped reading the comments on this blog.

If the commenters here spent half the time reading actual science that they do making ignorant snarky comments, they might actually learn something about the climate.

If you read the press release Brett linked, you will find that the researchers did not ignore solar effects, changes in ocean currents, orbital shifts, etc. They explicitly considered them. They found that those changes did contribute to the glaciation, but not as much as the drop in CO2 levels did.

Better yet, skip the press release and read the paper.

Anyone here who thinks another theory is right should be prepared to actually defend that theory and state the scientific evidence in its favor, not just sneer at models in general as if that implies some other theory is correct. (Bonus points: if you hate models, defend your pet theory without appealing to them. Clue: you can't produce a quantitative calculation without a model of some kind.)

For instance, if you think that Pliocene Greenland glaciation was due to the Sun instead of CO2, present your calculation which shows that the effect of the former is (a) larger than the latter during the time period under consideration and (b) large enough to explain the Greenland glaciation. Check that (c) your theory is consistent with climates of other periods, e.g. the Paleocene-Eocene, Ogliocene, Pleistocene, and Holocene. Be sure to also (d) explain what is wrong with the calculation in the Nature paper. (Hint: (d) without (a) and (b) and (c) doesn't constitute evidence in favor of your theory. And no, repeating tired old erroneous logic about 10x CO2 levels and CO2 lead-lags doesn't count.)

This is a new paper, so it's not the last word on the subject, but farcical pseudoscientific "skepticism" from the posters here is certainly not going to invalidate it.

i propose that we should call the current epoch MODELocene or COMPUTERALARMocene...so here are some dudes, choosing to ignore the natural causes of the mumerous glacial periods during the pleistocene, the recent past, and why greenland is covered in ice: earth's orbital eccentricity, earth's wobble on its axis, variable decadal global oceanic circulation, variable solar output, plate tectonics and the interaction between all of the above, and instead, choose to blame co2 while ignoring that ice cores show co2 concentrations follow temperature...the pleistocene has some of the best milankovitch cycle correlations yet these dudes choose instead to invoke the co2 card...i just want to know one thing, prior to us humans running around the globe expelling copious amounts of co2, just what exactly caused the rise and fall of co2 that purportedly caused the cyclic glaciation during the pleistocene as well as the cyclic glacial evidence occuring on greenland in the recent past? if c02 is to blame, why are temperatures dropping today while co2 continues to rise? the answer at the back of the page is it isnt co2, but that big ball of fire 100 times the size of earth...i wish the dudes would go outside and look up, instead of spending all day long squinting at some invented algorithms to explain what ought to be obvious is frying the top of their melons...or is it simply a matter of funding?......have a nice day, dudes!!!

Bob Tisdale,

"CO2 continues to plague researchers minds, making the more plausible explanations impossible for them to grasp."

And then you proceed to immediately contradict yourself by demonstrating that researchers consider plenty of other explanations.

So what you're really saying is that competing scientific explanations are okay, as long as none of those explanations include CO2. Because the only possible justification for explaining anything using CO2 is irrational AGW alarmism and investigator bias.

Got it.

This new study didn't just ignore other explanations. They explicitly considered the competing theories you find "more plausible", and gave new reasons why they appear to be inadequate explanations, even in the absence of the effects of CO2. That is, they didn't just simply say that CO2 can explain it, they also presented other arguments for why the competing theories can't explain it. Even if you don't think it's CO2, you still need to address those arguments if you think it's something else.

So perhaps you'd like to start by explaining why those reasons are wrong. This will require (gasp) actually reading the study. Maybe even (double gasp) reading some of the other background literature.

It is certainly possible that this paper is wrong and some other explanation is right. Personally I think the El Nino theory is interesting. We need to wait to see if the proponents of competing theories can refute it. But to justify another theory you have to actually give an argument in favor of that theory. You can't just sit in an armchair and make insinuations about closeminded scientists any time someone appeals to the greenhouse effect.

A. L.:

First off, I am saddened that you think that any comment questioning the researchers on their statements should be interpreted as being rude or that they are just stupid. Frankly, I think they are bright but are just merely attempting to prove a theory or an agenda by using methods that are not in accordance with the time honored and accepted scientific process. Time and time again we see studies in which the investigation process is geared to solely prove one cause-effect scenario namely being human activity induced CO2 emissions. All other potential issues are discounted at the outset.

Secondly, the science behind climate studies is a mere 30 to 40 years old. How much background do even the most learned individuals have that we should solely believe in them? For example, metereology as a science and study has been around for several hundred years and yet they still have nearly no true idea of what will occur more than about 3 days in the future. It seems that at least in the atmospheric sciences, familiarity with the process does not necessarily lead to better divination of the outcome.

Third, many skeptics, or deniers as some like to acuse, have backgrounds in physical sciences not necessarily in climatology. Myself, I have 20 years experience in physical sciences. Please recall that the leading voices in AGW agendas often are not climatologists but rather have backgrounds as diverse as astronomy, politics or social studies.

paulm:

Sure the science of how CO2 traps heat might be settled. But please remember, those are controlled experiments in a research beaker. To extrapolate those results to the globe is not science based but rather agenda based.

Tell me again why global warming is VERY dangerous.

WW:

Let me get this straight, 98 to 99% of CREDIBLE scientists agree about AGW right?

So, what you are saying is that anyone who disagrees with the agenda is not credible right?

sammy k,

"so here are some dudes, choosing to ignore the natural causes of the mumerous glacial periods"

How do you know? Because you carefully read the article Brett linked, and the scientific paper it's based on? I think not.

In fact, they explicitly considered a number of natural causes. CO2 is a natural cause in the Pliocene, by the way. They also considered closure of the Panama seaway, El Nino, and tectonic uplift.

Why people feel compelled to shoot their mouth off about studies they didn't even read, I don't know.

"the pleistocene has some of the best milankovitch cycle correlations"

They're not talking about the Pleistocene, they're talking about the Late Pliocene. In other words, they're talking about why did the most recent glacial cycles start in the first place. Milankovitch cycles existed before the Pliocene, after all, but we haven't always had glacial-interglacial cycles.

"just what exactly caused the rise and fall of co2 that purportedly caused the cyclic glaciation during the pleistocene as well as the cyclic glacial evidence occuring on greenland in the recent past?"

CO2 didn't cause cyclic glaciation, it just amplified it. There are a number of factors which likely contributed to the carbon cycle to one extent or another, including the ocean physical pump due to warming, the biological pump due to a number of different factors (warming, iron fertilization from dust, changes in upwelling and runoff), reef growth and burial, and still other contributors.

And what does your question have to do with any of the points you're trying to make, anyway? What caused CO2 changes is independent of what effect the CO2 had on the climate.

"the answer at the back of the page is it isnt co2, but that big ball of fire 100 times the size of earth..."

Please demonstrate this scientifically. Be quantitative: show that solar behavior agrees in rate, magnitude, and timing with the observed climate changes. (Don't forget to divide total solar irradiance by four to get surface averaged radiative forcing.) Bonus points for doing it without using any model, since you hate them so much. (It will be interesting to see how you calculate the temperature change due to the Sun without using a physical model.)

Darren,

"First off, I am saddened that you think that any comment questioning the researchers on their statements should be interpreted as being rude or that they are just stupid."

No, "any" comment is not automatically rude. Many of the actual comments here, however, have been rude. Yours is an example: instead of coming up with a scientific flaw in their study, you resort to claiming that they're biased and unscientific.

"Time and time again we see studies in which the investigation process is geared to solely prove one cause-effect scenario namely being human activity induced CO2 emissions. All other potential issues are discounted at the outset."

That's also a rude statement. In this study, the researchers considered several other theories and gave reasons why they're wrong. If you think there's something wrong with those reasons, say what it is. But claiming that they're unscientifically ignoring competing hypotheses without even addressing their arguments is, well, rude.

"Please recall that the leading voices in AGW agendas often are not climatologists but rather have backgrounds as diverse as astronomy, politics or social studies."

Pretty much all of the leading voices in AGW science have backgrounds in climate science.

Speaking as a physicist, I can't believe the stupid things that many people trained in the physical sciences, but not climate science, say about the climate. Physics arrogance outside one's discipline is a classic disease. I don't claim to be an expert in climate dynamics, and armchair physical scientists shouldn't either.

"But please remember, those are controlled experiments in a research beaker. To extrapolate those results to the globe is not science based but rather agenda based."

If you think that results in a lab can't be scientifically applied to phenomena outside a lab, I question your "20 years experience in the physical sciences". For one, you're dismissing pretty much the entire field of astronomy.

Furthermore, please explain why atomic physics stops working outside the lab. Because that's what you're pretty much claiming. Also explain how to account for the Earth's current temperature without the greenhouse effect. Also the cooling of the stratosphere.

paulm wrote:
"whats your tool then?"

Since I'm not claiming to know exactly what caused Greenland to freeze 3 million years ago, I have no need of any tools related to this subject.

It's just that I'm skeptical that anyone can know enough about the global climate 3 million years ago to confidently eliminate, through climate modeling, all possible forcings except for changes in CO2.

I believe that an open-minded investigation into this issue should have generated at least another couple of scenarios that could explain the glaciation just as well as increased CO2.

But since their minds were already made up before the study began .... all roads lead to Rome.

D Caldwell,

"It's just that I'm skeptical that anyone can know enough about the global climate 3 million years ago to confidently eliminate, through climate modeling, all possible forcings except for changes in CO2."

You can't eliminate all possible forcings. You can in principle eliminate all postulated forcings. How successfully they did that remains to be seen.

"I believe that an open-minded investigation into this issue should have generated at least another couple of scenarios that could explain the glaciation just as well as increased CO2."

They already considered several alternate scenarios. How many more "should" they have considered? (Let me guess: "more".) What scenarios did they leave out that they should have included?

"But since their minds were already made up before the study began"

Yet another example of how ideologically driven the "open-minded" so-called "skeptical" commenters here really are.

You have no idea what they were thinking before the study. You have no factual basis for asserting anything about their motivations or thoughts on the matter. Your accusations in say far more about your close mindedness than theirs: in the absence of any supporting facts, you nonetheless "know" that their minds were made up before even starting the study.

An honest skeptic wouldn't be slinging around accusations of bias. They'd be reading the paper, the background literature, and the evidence for and against each of the hypotheses.

If somebody came out with a study pointing the figure at some non-CO2 cause you wouldn't accuse them of bias. But any time someone mentions CO2, the only possibility is that they're prejudiced. It can't possibly be because there is evidential support for that theory, or a lack of support for alternative theories.

PI they left out the opening of the Antarctic circulation when South America separated. This is what they think cause Antarctica to be as cold as it is today. You take that and increase the albedo effect causes further cooling. I just don't like when they make CO2 the end all be all for their theories. The Pleistocene CO2 is one of the only times that CO2 and temperature somewhat correlate. Why don't you try correlating CO2 to UAH or RSS. you would get a R2 of like .15 which means no correlation at all. If you like there is a thread over at Climate Audit which specifically discusses this time period and no one there did find the exact reason for the start of glaciations.

PI - All I can say is - AMEN.

Finally someone who knows what he/she is talking about.

My guess is that you will see the same tired old responses, that YOU are the one who must prove YOUR theory of man made GW. Then, when you offer proof, if it goes against what the majority believe here, you will be ridiculed, labelled and driven away.

It's not about science you know - scientists are all corrupt, data manipulating, Al Gore worshipers. The models and data are not viable - it's all about getting funding.

It is obvious, after reading the articles, that the scientists considered a multitude of factors before making this conclusion. My biggest question, is why Greenland has such a large ice sheet, when it is farther south than many other land masses that don't have a miles thick ice sheet on them.

Patrick H - how did you measure the thickness of the Greenland ice sheet when you flew over it? What altitude were you at? I'm assuming that you flew over at the standard commercial flight altitude, 35,000 ft. From that elevation, how could you see if there was melting ice or not? Was it cloud free when you flew over? Did your plane circle the continent while you took measurements? What kind of instruments do you need to take those kinds of measurements? Is that in your elementary school Geology book too?

Great observation, but totally insignificant scientifically.

Reply: I was wondering how it was possible that he saw all of Greenland.

Whether you believe Al Gore or not, Al Gore's movie was the worst thing that ever happened to climate science. Because he convinced almost everyone, especially non-scientists, that the cause of global warming was simple. Well, it's not simple. Maybe it's not quite as hard as generating power from fusion or curing cancer, but it's right up there.

CO2 has a known, small effect. The claim that it has a large effect is not even a theory, it is just a speculation. It's plausible, but not proven. So scientifically it's about even with the Sun-comic-ray-clouds idea. Plausible, but not proven. The bottom line is that nobody understands how the climate works. More science is needed, less bickering.

Doesn't this describe what is happening in this debate?
http://en.wikipedia.org/wiki/Color_of_the_bikeshed

Thank you, PI.

D Caldwell, there's a big difference between the paper's finding that the CO2 drop was the dominant cause of the glaciation and your assertion that all other causes were "confidently eliminate(d)." CO2 is a gas and doesn't just move itself around the climate system. One or more of those "eliminated" factors (forcings) moved the CO2. With any luck, future work will reveal the details.

All of this bears some similarity to the problem of the mechanism for the Pleistocene deglaciations. For a couple of decades, it was known that Milankovitch cycles started it off and that CO2 had to be involved (since calculations showed that the Milankovitch cycles weren't enough by themselves), but how the Miliankovitch cycles acted to release the CO2 and where the CO2 came from remained a mystery. The fact that not all of the pieces of the puzzle were known didn't mean that there was anything wrong with the pieces that were known. Now the problem has been solved. Isn't the scientific process great?

D Caldwell,

Well said. We don't really have much idea about, for example, the real extent of Arctic sea ice over the last 300 years never mind what conditions were like 3 million years ago.

The problem is the models, for computers never lie. This seems to be a truism for many, especially younger, scientists who try to input all the parameters they think are relevant but then accept the model's results almost without question. They don't seem to appreciate that the results are often only 'informed speculation'.

PI: I will accept the drumming down for my knee-jerk reaction and for the incompleteness of my comment. The present fixation of many papers (not all papers) on greenhouse gases as the driver of climate provoked my comment. No disagreement from me on that point.

Darren --- Actually, climatology is over 150 years old. Read "The Discovery of Global Warming" by Spencer Weart:

http://www.aip.org/history/climate/index.html

Review of above:

http://query.nytimes.com/gst/fullpage.html?res=9F04E7DF153DF936A35753C1A9659C8B63

PI,
These kind of speculative studies accomplish nothing. What we are looking at is current or recent data, which cannot begin to model current atmpospheric climate trends based on changes in CO2 and other GHG concentrations. Still waiting for the GCMs to forecast with precision the next change in ENSO. CO2 driven models fall short every time.

MIGUEL: Yes,man,Yes. At this time we knew that things were starting to settle down, and forests were lush. The biosphere, and ocean life was shifting from trilobites to bigger organisms. So carbon sinks could capture 80% of all CO2. Although the biosphere existed before this time when it finally became one land mass this could be a huge factor. You make one million $$$$$$$$$.
KIPP

Pl wrote:
"You have no idea what they were thinking before the study. You have no factual basis for asserting anything about their motivations or thoughts on the matter. Your accusations in say far more about your close mindedness than theirs: in the absence of any supporting facts, you nonetheless "know" that their minds were made up before even starting the study."

Consider this:
Many leaders in the climate research community (perhaps not these particular U of B guys) have made statements like "the science is settled", "the debate is over", "if we pursue any further debate, it will only serve to delay needed action", and so on. By and large, the alarmist community minds are made up regarding AGW, no?

I, of course, cannot really know what's in their minds. I do, however, have good reason to wonder.

For an interesting alternative source for ice epochs, see:

http://www.sciencebits.com/ice-ages

About 2 pages down is a fascinating little chart (that is a bit hard to figure out at first glance). It has galactic arm position of the solar system, galactic cosmic ray flux, ice epoch, and some other data all on the same timeline. While it's mostly just illustrating a correlation, it's interesting to look at the way the greater cosmos might be involved.

On a millions of years scale, it argues for our leaving an ice epoch at this time (so ice ages ought to be getting less severe, and interglacials ought to be warmer too). Not that this should matter much in the 100,000 year time scale... but all things must end some day...

My personal speculation about Greenland would be focused on the ocean currents about the island. At present, arctic water keeps the air cool. But was this always so? A minor shift in the path of the Gulf Stream and Greenland could suddenly be getting warmer air off shore. Do we really know exactly how the ocean currents circulated, how deep the arctic ocean was, what the ice depth was, what the salinity was, etc. What would it take to get a shift of arctic water into the pacific and pull gulf stream water north? And if that was the initial condition, what would it take to shift it to where it is today?

Could it be that when 'enough' arctic ice forms, it blocks warm water intrusion into the arctic ocean and the feedback loop gives you a frozen Greenland. And that if the arctic melts 'enough' we end up with a switch back the other way and it all stays melted? This is not clear at all. Did they account for this?

Last minor nit to pick: You get lots of ice accumulation when you have lots of water in the air. That takes warm water and air. Then you cool it and it drops loads of snow. So maybe Greenland has all that ice because the gulf stream got close enough to bring water vapor north, but not so close as to keep it warm. See Antarctica for an example of a very cold place in the interior with very little ice. The air is dried out via cold before it can reach the interior. It's not enough to say "it got cold", you also have to account for the relatively warmer wetter air supply.

FWIW, this page: http://www.sciencebits.com/CO2orSolar

make an interesting argument about CO2 vs Solar as causal. It uses the IPCC data and skips all the harping about thermometer quality and model accuracy and... Jumps right to a simple point. Using IPCC data you can't say if people are making the world warmer or cooler. The error band on the forcing from things like particulates is larger than the effect of CO2, so we might be net making it warmer, or cooler, even accepting all IPCC data as truth. We don't know which dominates, our CO2 or our particulates!

This has caused me to speculate on a way to "fix" AGW (iif it is real) via particulates: Take all the sulphur we are removing from our gasoline and diesel. Put it in special Jet-A1 fuel (call it Jet-A1+S). Most long distance air flights have several fuel tanks. Use Jet-A1 for takeoff and landing, but shift to the Jet-A1+S tanks when at altitude and fly very high. This would load the stratosphere with sulphate particulates and thus lead to cooling.

Given how brown the L.A. basin used to be (and many other cities too!) and how much cleaner they are now; it's clearly the case ;-) that we can put 'enough' smog in the stratosphere via sulphates to make it shadier here on earth. Since this would still be far less SO4 than a big volcano spews, it ought not to harm the global ecology (any more than natural volcanos do).

While this is a bit tongue in cheek, I do think it would work. I just don't think anyone would ever want to try to sell the idea to a world conditioned to think of sulphate smog as only evil.

PI: Better yet, skip the press release and read the paper.

Quoting from the paper's abstract:

Here we use a fully coupled atmosphere ocean general circulation model and an ice-sheet model to assess the impact of the proposed driving mechanisms for glaciation and the influence of orbital variations on the development of the Greenland ice sheet in particular.

So the faith we have in the paper is dependent on the faith we have in the accuracy of GCMs. I, myself, am extremely skeptical of GCMs, and therefore equally skeptical of the paper's conclusions.

Jim Arndt,

"they left out the opening of the Antarctic circulation when South America separated."

That happened ~25 million years ago. It's not an explanation for Greenland glaciation 2.7 million years ago.

"You take that and increase the albedo effect causes further cooling."

Antarctica was already pretty much fully glaciated at the end of the Pliocene; there hadn't been a significant increase in albedo there at the onset of the Greenland glaciation.

"I just don't like when they make CO2 the end all be all for their theories."

Why? If they said it was the ocean circulation, or the Sun, or whatever, you wouldn't be complaining. It's only when someone brings up CO2 that you are inexplicably dissatisfied.

And they didn't make CO2 "the end all be all". They considered several other theories, found that they had some effect, but that the effect wasn't as strong as CO2.

"The Pleistocene CO2 is one of the only times that CO2 and temperature somewhat correlate."

That's not true either; there are plenty of times when changes in CO2 level coincide with greenhouse/icehouse periods. (And I hope you're not basing your opinion on Nahle's infamous homebrewed graph, the one that floats around on skeptic sites with "geocraft.com" on it ... the last time I saw that checked out, he had shifted some key data by tens of millions of years...)

"Why don't you try correlating CO2 to UAH or RSS. you would get a R2 of like .15 which means no correlation at all."

That's an incredibly terrible statistical argument.

1. You shouldn't be comparing CO2, but log CO2.
2. You shouldn't be comparing log CO2 to temperature either, but rather total radiative forcing, including other anthropogenic and natural sources of warming and cooling.
3. Since radiative forcing is modulated by feedbacks and a big time lag, what you want to compare is feedback-scaled and time-integrated radiative forcing to temperature. That is, you have to force a climate model, even a simple one.
4. You need to take into account the uncertainty in the forcing and the response, otherwise your conclusions (one way or the other) will be overconfident.
5. It helps if you compare to several climate indicators, such as surface temperature and ocean heat content. That helps pin it down.

This is what actual scientists do. Look in the IPCC AR4 WG1 report at the end of chapter 9 for a survey of the observational estimates of climate sensitivity to CO2, and read the papers for their methodology.

"If you like there is a thread over at Climate Audit which specifically discusses this time period and no one there did find the exact reason for the start of glaciations."

That's because it's only been under active scientific debate for about 10 years, and hasn't been fully resolved yet. The paper discussed here is gives new evidence for the CO2 theory and against other theories.

As I said above, it remains to be seen whether this new evidence holds up. Frankly, I think it's quite possible that someone will come up with an effective rebuttal, at least at first. Not because there's anything wrong with the CO2 hypothesis a priori, but because it's rare for new theories to be decisively established with a single paper, especially when the scientific argument itself hasn't been around for that long. But you can't dismiss the study simply because you don't like CO2. You need an actual scientific argument.

Dave Andrews,

Geologists actually know quite a bit about what conditions were like 3 million years ago. Especially when evaluating hypotheses like "What change does tectonics have?" We certainly know where the continents and the mountains were.

"This seems to be a truism for many, especially younger, scientists who try to input all the parameters they think are relevant but then accept the model's results almost without question."

In the absence of telepathy, perhaps you shouldn't speculate as to how much "scientists" question model results.

Bob,

Ok. I think the comments here would be useful if people stuck to discussing the scientific evidence, and not making sarcastic comments about scientists and their motivations.

If you look in the paleoclimate literature, you will find that it is by no means "fixed" on greenhouse gases as "the driver of climate". GHGs played a major role in many of the greenhouse/icehouse events in the past, but so did tectonics and ocean circulation, among other mechanisms. You see a lot of GHG papers regarding the modern climate, because CO2 has been the largest recent forcing, but it's much more mixed in the past.

JP,

"These kind of speculative studies accomplish nothing."

They are not particularly speculative, and they accomplish much in ranking the relative contribution of major climate drivers.

"What we are looking at is current or recent data, which cannot begin to model current atmpospheric climate trends based on changes in CO2 and other GHG concentrations."

Modern models get atmospheric trends pretty accurately on the broad zonal and continental scales, to within the precision of the error bars on the predictions and on the data itself.

"Still waiting for the GCMs to forecast with precision the next change in ENSO."

This is the usual weather-climate confusion. Specific ENSO events are probably never going to be predictable beyond a year or so — see, e.g., the work of Mat Collins here — and this has nothing to do with the skill of GCMs to forecast climatic averages.

The ability of GCMs to get the statistics of ENSO is does have some effect (e.g., does ENSO get stronger or weaker on average, and more or less frequent). There the models are indeed weak.

(It's one reason why the study being discussed here should be taken with a grain of salt, because ENSO is one of the competing theories. On the other hand, you can reliably say some broad things about ENSO behavior without a fancy model, and that may be adequate for answering questions like "does Greenland end up with ice sheets". I have not read the paper, so I haven't evaluated their argument there.)

That doesn't have a huge effect on temperature projections, but it does prove problematic for regional precipitation projections in areas teleconnected to ENSO, especially for extreme events more than averages per se.

I've heard rumors that the NCAR CCSM may have recently solved the split-ITCZ problem which should go a long way to remedying that.

"CO2 driven models fall short every time."

It has nothing to do with "CO2 driven" or not. Drive any model, no matter how high resolution, with any forcing you want, natural or anthropogenic, and you're still not going to predict specific chaotic events past a very limited horizon.

Anonymous,

You are confusing two bodies of work. There is a large body of evidence implicating CO2 as a first-order forcing of the modern climate. That is entirely different from the question of what caused the Late Pliocene glaciation in the Northern Hemisphere, which is less well understood.

MJW,

"I, myself, am extremely skeptical of GCMs, and therefore equally skeptical of the paper's conclusions."

Upon what basis are you "extremely skeptical of the GCMs" when it comes to predicting global temperature? Especially as applied to these very gross paleoclimate forcings? GCMs aren't perfect, but they certainly do reproduce the major oceanic circulation patterns, they handle orographic effects on atmospheric dynamics, etc. — all the factors which were considered as hypotheses regarding the Greenland glaciation, and all of which are much less subtle than the nuances of decadal scale climate. As I said above, their ability to reproduce El Nino is their major weakness with respect to this paper, but CO2 and tectonics can be reasonably evaluated with a GCM.

Actually, I've looked a bit more at the study and I don't think it relies ability of GCMs to predict sustained change in El Nino behavior. Rather, they simply prescribe such a sustained change by fiat, and see if its effects on Greenland are large enough to explain the glaciation. (Their conclusion is "no", but as I've said, this is probably not yet the last word on the matter.)

Anonymous,

Cosmic ray correlations with climate are intriguing, but it's actually a lot more speculative than CO2, whose physical effect can be calculated much better. And when you turn to modern climate, the hypothesis becomes much more problematic as the trends in cosmic ray activity don't coincide with the climate trend for a fairly long period, like 50+ years. If it was just a 10 year misfit or even maybe 20 you might be able to explain that with natural variability, but such a sustained disagreement casts a lot of doubt on the mechanism.

As for ocean circulation and Greenland glaciation, you might be surprised by how much geologists can reconstruct about past climate, including temperatures, salinities, glacial advance and retreat, etc. However, I'm not very familiar with this particular question, so I can't tell you how much is actually known.

The particular hypothesis you advance appears to include a change in the meriodinal overturning circulation reducing heat transport to Greenland. The authors of this study did consider such a possibility (due to the Panama isthmus closure). As for your "ice barrier" proposal, I don't know much about the sea ice dynamics, but the authors did at least look at ice albedo feedbacks.

It's not correct to say that, using the IPCC data, you can't say whether people are making the world warmer or cooler. If you ramp the particulate cooling up to its largest allowable value — which is unlikely but possible; it is more likely near the central estimate — then you can almost cancel the CO2 forcing, but there are still other anthropogenic GHGs which you can't cancel, which are about 50% of the CO2 warming. You also can't ignore the opposite possibility, which is that aerosol cooling is much smaller than the central estimate, and CO2 warming is even stronger.

In short, if you take forcing uncertainty into account, then estimates of CO2 climate sensitivity become more uncertain. However, very low climate sensitivities are still excluded with high probability. You can see this in the IPCC ch. 9 section I mentioned in an earlier comment. (You have to be a little careful, since a few of those studies didn't take aerosol uncertainty into account, but most of them did.)

The idea of cooling the climate by sulfate aerosol "geoengineering" has been proposed many times. It's an incredibly dangerous idea, for a number of reasons. It's worth keeping on the table, but probably only as an emergency last resort if we're about to cross some extreme climate threshold like Greenland ice sheet disintegration, and have no other mitigation option.

The reasons why aerosol geoengineering is problematic include:

1. You're committed to it. If you do it for N years and then stop doing it for some reason, the aerosols precipitate out quickly and you get N years worth of global warming within the span of just a few years — far worse than the worst "alarmist" scenario anyone has ever floated. Can we really be sure that we'll stick to it for the centuries needed to scrub the CO2 from the atmosphere?

2. CO2 warming is not perfectly canceled by aerosol cooling, either in space or time. They distribute themselves in different ways. So while you might keep the global average temperature the same, some local regions will still experience some pretty large changes.

3. There are environmental side effects of geoengineering on a scale necessary to counteract global warming, including acid rain and other health/ecology impacts, and shifts in precipitation zones (see point 2). (A big volcano from time to time is rather different from having the equivalent of a big volcano every year.)

4. Even if it fixed the climate, it doesn't do anything about the increasingly problematic ocean acidification from increasing CO2 levels.

5. You also have to consider the political, military, and moral consequences of widespread deployment of a tool which can potentially alter regional climates within a few-year time span.

Alan Robock has an interesting essay on "20 reasons why geoengineering may be a bad idea". As I said, I don't think it's a credible alternative to emissions abatement, but it might be held in reserve for the biggest emergencies.

Don't Panic:

"So scientifically [CO2 is] about even with the Sun-comic-ray-clouds idea."

Not even remotely. Nobody can really calculate yet the effect of cosmic-ray mediated solar variability on clouds even in principle, and the solar and cosmic ray trends agree rather poorly with most of the modern warming.

I think the solar-cosmic ray link is interesting, and it may prove to be larger than is currently thought, but the evidence is already against it being a dominant factor in explaining climate in the industrial era. And it is extremely poorly understood relative to the radiative dynamics of the greenhouse effect.

And by the way, in response to a previous comment: "it is not appropriate to conclude that the 0.6 C rise is mostly due to human causes without carefully subtracting the contributions of natural changes. This point is missing in the IPCC study on global warming."

The IPCC rather explicitly considers the effects on the climate of pure natural, pure anthropogenic, and the combination of natural and anthropogenic forcings. If you would like to argue that they subtracted wrong, go ahead, but it's not true that they failed to do the subtraction.

Gary B,

"My biggest question, is why Greenland has such a large ice sheet, when it is farther south than many other land masses that don't have a miles thick ice sheet on them."

I don't know, and I don't think anyone knows for sure. I found some discussion of your question when reading some of the news coverage of this study. If you read this, one of the co-authors speculates as follows:

"The answer is most likely related to the fact that underneath the ice on Greenland are some high-altitude mountains on the east coast, which are high enough to be cold enough that ice can form, which then flows slowly down the slopes and eventually covers the entire island," Lunt explained. "In certain time periods [for example about 20,000 years ago], when the Earth's orbit is aligned in a certain way, ice does start to form in Canada and Siberia � for example in the last Ice Age."

PI:

Point me to the studies,(apart from Stainforth et al, Phil Trans. R. Soc A (2007)365, 2145-2161) that point to the scientists questions about the models and I will read them

David Benson:I always get history, and Weart's
description of rapid climate change, and it's effect on climate very relevant. GREAT book.
Good Labor,KIPP

Kipp wrote "If you don't believe this then look at Venus. Venus has a large atmosphere of CO2 and is warmer than it should be for it's relative distance to the Sun."

How can this be proven? Mercury has no atmosphere, if it did would it be warmer or cooler, than Venus? than it is right now? If Venus' atmosphere was a different composition would it be warmer or cooler? If Venus had no atmosphere would it be warmer or cooler? If someone could answer these questions with some type of proof I would appreciate it.

Mike B.

PI:
I am a Photographer learning Science. Learning from books, reading reports, and just studying climate science. I don't get the denial attached to CO2 as a forcing. Where is the balance. El Nino could be a big factor today as other forces have been a factor in the past. Why is AGW a religion, a conspiracy, or alarmist. I have seen pictures of the Earth, through the Carl Zeiss lens of a satellite. Infrared pictures, of the IR, and yes Ghgs enshroud our Earth. There is this fear of discovery and wonder, a compelling
silence, a need to conform to the past, dirty tricks, and the fierce loyalty to special interests, that defy logic, and make America much less then it could be. If we were really smart we could jump into the new green economy, instead of having China make the solar panels for us.
Happy Labor,KIPP

PI wrote "For instance, if you think that Pliocene Greenland glaciation was due to the Sun instead of CO2, present your calculation which shows that the effect of the former is..."

Could you prove to me that CO2 caused the Pliocene Greenland glaciation? I'm pretty sure that the best way to convince someone that something happened is to provide evidence first, to your standards of course, and unlike another poster stated I will not ridicule you for the proof you provide.

PI:Following your logic, why can't you compensate
for chaotic events, in a forcing like the El Nino,
by observing it's history, and effects in the Southern Atlantic, 16 months later, and the pattern of the observed oscillations. Aren't there factors like temperature, the wind circulation patterns in the antarctic, the PMO, and PO, the gulf stream, the AMO, telling us already the difference between the El Nino and the La Nina. I read that scientists can't say whether La Nina will stay for two more years or not. I thought you could have a quality of determinism through the chaos. Or inspite of choas? Could you help me with this. KIPP

pi,

accusing me of not reading the article shows how weak your defense of it is...typical AGW style tactics of attacking character first...i see you conveniently avoided that ice cores shows co2 concentrations follow temperatures not the other way around...simply stating that co2 amplifies glaciation is once again an argument with no proof except in some biased algorithm...avoiding the historical context of the pleistocene and the causes of its glacial cycles is again an attempt to avoid the earth's geologic history of glaciation prior to the idea that co2 is a driver of climate...so my question remains, pi, what proof do you have that co2 amplifies glaciation when there have been periods in earth's history when glacial events were occurring when co2 percentages were an order of magnitude greater than they are today?...and dont forget about the ice cores, bonus points if you can admit to yourself temperatures drive co2 concentration...

PI: Modern models get atmospheric trends pretty accurately on the broad zonal and continental scales, to within the precision of the error bars on the predictions and on the data itself.

What is the reference for this claim? Or, more specifically, what is the supporting evidence, keeping in mind that only agreement between predictions and later measured data counts as evidence; hindcasts don't. Also, you might clarify what you mean by "within the precision of the error bars on the predictions." How are the error bars defined for the predictions, and how wide are they? Obviously, if the error bars are, say, +/-20 degrees C, the claim would be true but meaningless.

PI: I ate crow once on this thread. I have no intention of doing it again or of letting you continue your pompous preaching without comment. Today I have the time to respond. The other day I didn't.

Lunt et al looked separately at four hypotheses for Greenland glaciation: tectonic uplift, the closing of the Panama isthmus, the end of the permanent El Nino state, and the drop in CO2 levels. Did it occur to them that the changes might be interdependent on one another? I find no mention of a simulation on the interaction between the three non-CO2 hypotheses. Could the tectonic uplift have caused the closure of the Panama seaway? Could the closure of the Panama seaway have altered oceanic circulation and initiated the end of the permanent El Nino state? They also fail to relate, at least in the abstract and the supplemental data, how any of those three impacted CO2 levels. (See below.) How did they assure the effects of the closure of the Panama seaway and end of the permanent El Nino were isolated? How did they assure the effects of the reduction in CO2 were isolated from the other three hypotheses, meaning did they fix the CO2 levels of the other three or did they allow the CO2 levels to drop as a result of the cooling and glaciations, which would have added positive feedback?

Did Lunt et al include the following papers in their references? Did they assure the additional hypotheses presented by Haug et al and Sigman et al were taken into account by their models?
Haug et al, 1999, "Onset of Permanent Stratification in the Subarctic Pacific Ocean", Nature.
Haug et al, 2005, "North Pacific Seasonality and the Glaciation of North America 2.7 million years ago", Nature.
Sigman et al, 2004, "Polar Ocean Stratification in a Cold Climate", Nature.

Or did they assume the output of the models represented all hypotheses for the cooling and for the decline in CO2 levels?

Did Lunt et al handle that hand-off between the GCM and the Ice Sheet Model correctly?

In "Late Pliocene Greenland Glaciation Controlled By A Decline In Atmospheric CO2 Levels", Lunt et al assume their sensitivities and their models are correct. I can't join them in those assumptions. There are so many, too many, unknowns.

I began my initial comment on this thread with, What provides the greater variation in climate on the planet today, CO2 or the oceans?

Just published in Nature Geoscience are new results showing that the current Greenland ice sheet could disappear very quickly. Recall that just a few years ago it was widely assumed that it would be impossible for that to happen in much less than a thousand years. Full text here. Title/abstract:

"Rapid early Holocene deglaciation of the Laurentide ice sheet

"The demise of the Laurentide ice sheet during the early Holocene epoch is the most recent and best constrained disappearance of a large ice sheet in the Northern Hemisphere, and thus allows an assessment of rates of ice-sheet decay as well as attendant contributions to sea level rise. Here, we use terrestrial and marine records of the deglaciation to identify two periods of rapid melting during the final demise of the Laurentide ice sheet, when melting ice contributed about 1.3 and 0.7 cm of sea level rise per year, respectively. Our simulations with a fully coupled ocean-atmosphere model suggest that increased ablation due to enhanced early Holocene boreal summer insolation was the predominant cause of Laurentide ice-sheet retreat. Although the surface radiative forcing in boreal summer during the early Holocene is twice as large as the greenhouse-gas forcing expected by the year 2100, the associated increase in summer surface air temperatures is very similar. We conclude that our geologic evidence for a rapid retreat of the Laurentide ice sheet may therefore describe a prehistoric precedent for mass balance changes of the Greenland ice sheet over the coming century."

Steve Bloom,

Recall also, MBH and the 'hockey stick' were published in Nature.
They were the poster boys of the climate science community for a few years (now trying to reform and tour again) but if you post about their shortcomings on RC and Open Mind etc you are constantly told that it is time to move on.

Mike B | August 30, 2008 3:11 PM --- Read both pages of

http://members.aol.com/bpl1960/Greenhouse101.html

for Venus, Earth and Mars.

PI: You left out my "plausible, not proven" comments. Urban legends work because they are plausible. They are not true, yet they are believable. That's why we need science. Politics and religion can't sort this out.

All of the scenarios about current climate changes have problems. Too much is still unknown. I think the answer, when we finally figure it out, will be "none of the above". Or "all of the above, and more".

PI:

Thanks for taking so much time to respond to a number of people here. You seem to have a bone to pick with most.

I especially like how you are able to take shots at others, whom you know nothing about, in kinda a backhanded manner.

While you mention that I don't comment upon a scientific flaw, and therefore are being rude, I would submit that the study in itself is flawed and therefore is not rude. My comments relate to the fundamental statement that the study is geared to prove CO2 as the driver and nothing else.

Of the other ideas put forth for the presence of ice, I found it humorous at best that they reviewed them using models. Surely they can accurately model climate changes due to ocean currents and tectonic shifts much easier than they can forecast the weather next week right?

Give me a break. Umm, what about ole sol?

Seems to me that they went into the study with a CO2 bias.

Never said I'm a climate scientist or expert. But I do know enough to be skeptical of how others are researching the topic. I would like to also say that if the the leading scientists are climate experts, they sure as heck are doing a crappy job. You would think that if they know what will happen in 50 years, that 5 years should be a given. I don't really need to tell you why that is do I?

I just love this next one....

"If you think that results in a lab can't be scientifically applied to phenomena outside a lab, I question your "20 years experience in the physical sciences". For one, you're dismissing pretty much the entire field of astronomy."

Really? Please tell me what astronomy experiment is conducted in a lab. Did someone create a star in the lab? You'd think that that would have been announced somewhere.

Even better...

"Furthermore, please explain why atomic physics stops working outside the lab. Because that's what you're pretty much claiming. Also explain how to account for the Earth's current temperature without the greenhouse effect. Also the cooling of the stratosphere."

Never claimed that, but frankly put, are you seriously comparing atomic scale events to global scale events? There's a bit of a disconnect there if ask me.

Also, more importantly, never said that the greenhouse effect didn't occur or is occurring. I just don't think that human induced inputs mean anything significant to it.

Stratospheric cooling probably means nothing to this issue and more importantly, our historical perspective is so limited that no real substantive conclusions can be deduced.

Darren - Atomic physics, atmospheric physics are interrelated.

I still don't understand your statement. Why are results from the lab not reliable when it concerns the climate? The 5 day forecast and the 50 year forecast use different model parameters. I doubt that feedbacks, albedo, ocean currents/temps, ice extent, TSI and many other factors used in a climate model are used in the computer modeled 5 day forecast.

You must also consider the forecasters skill used in the whole process. The scientists in question have extensive training and years of experience. Joe Bastardi is an example. Would you say that Joe provides a good long range forecast? Or not? What are you basing your comments on?

How can you make a judgment that the leading climate scientists are doing a crappy job, especially if you don't understand the physics behind it?

Humans wouldn't enjoy a "modern" lifestyle without computer models or lab experiments. They are used for practically everything. Even oil exploration.

Atomic spectra, as one example, is studied in Astronomy and many experiments can be conducted in the lab using various instruments, such as a spectrometer, and those results can then be applied to the real world, such as measuring infrared absorbtion bands of various greenhouse gases.

No offense, but you should study a little more before you open your mouth and insert foot.

Regards

Before it should be proved wrong, it first needs to be proved right. Thats why us "skeptics","deniers", can observe where the gwers are coming from from there articles and the articles sources. Is there science involved? Sometimes yes, is there science left out because it might change belief{religion}? I think yes, wait I know yes...... Sun controlling ocean currents which affects ocean temps, less active sun leads to cooler oceans, right? Cooler oceans changes currents,right? Reading out of the Old Farmers Almanac, {not the winter forecast}, yes it is science without a political agenda and go green driven, they say that sun cycle 25 could be the quietest, thus coolest in centuries, have you ever heard a gwer mention that something like this is possible, no mention of it, none, why because there are marketing global warming, otherwise if it was about science this would be bound to be brought up, but no. We "skeptics" see the global warmers reasoning and argue it with another reasoning in which they do not argue back, they only will go back to co2, and who knows in the end maybe that co2 will prevent the next ice age...I Hope!

Apparently climatologists do not have much grounding in how feedback works. Unaware of their ignorance, they invoke net positive feedback in their GCMs. This causes the GCMs to predict significant �enhanced global warming�. Anyone who has the ability and interest to look at the NOAA data from Vostok Ice Cores for the last glaciation (and prior glaciations) will discover that, repeatedly, a temperature increasing trend changed to a decreasing trend with the carbon dioxide level higher than it had been when the temperature was increasing. Those who understand how feedback works will know that this temperature trend reversal is not possible with significant net positive feedback. Thus, as far as global climate is concerned and contrary to the assumption in the GCMs, significant net positive feedback does not exist.

Gary B:

Your right, I do tend to type first and think later sometimes.

I would like to point out that while many people merely accept the statements that are presented by experts as "facts", I choose to recognize that they are often "educated guesses". That is no fault to any of the experts but simply put, their statements are often moving targets in lieu of true fact. I strongly believe that just like in many things, climate change is one of those moving targets. Except that with climate change, there is money to be made and agendas to be advanced and that changes everything.

I guess you can make the argument that atomic physics and atmospheric physics are interrelated I understand that. But, I believe to extrapolate lab results to the climate breaks down because of the immensely chaotic nature of the atmosphere. Really, to be precise, the physics is the same but our ability to accurately model it is limited right now. That said, our ability to model it now, is worlds above where it was a mere 20 years ago. I would suspect that in 2028, our ability to model the atmosphere will be better.

I know that 5 day models are different than long range models and that the operator experience and skill plays into the forecasted results. Sure, JBs long range forecasting is one of the best around. However, I would point out, and I think he would agree, his results are nothing more than guidance and direction not a real forecast. What I have a real issue with in climate modeling is when there is a prediction of some tenths of a degree change. The precision is above the skill level of the model. Essentially, it is my opinion that the modeler is allowing bias to form the precision of their prediction.

I know why this is done. In today's world, the public wants hard numbers. Ranges are seen as incorrect or worthless or better yet, inactionable.

Good point on spectral analysis. I stand corrected. But, I would point out that modifications to basic understanding of astronomical events is continuous due to precision gains in measuring over time.

Were the earlier results wrong? Or just not the complete truth?

And I want to make sure you understand, if at some point in the future, it is shown accurately that CO2 emmissions directly cause warming, then I would sign on to whatever changes are needed. Now is not the proper time yet to make that conclusion.

Darren | September 3, 2008 9:53 AM --- No computer programs are required, just physics:

http://members.aol.com/bpl1960/Greenhouse101.html

David B Benson,

It must be so comforting to trust in Spencer Weart and 'physics'. Gospel, so to speak

David:

Thanks for the info.

It is well written and explains the effect well.