Brett: I believe you linked the wrong video.
Reply: yes you are right. I have no idea how that happened.

Dr. Keller said that changes in solar irradiance due to variations in the orbit of the earth drive the large scale changes in the earth's climate seen over time. Sounds convincing to me.

I heard him say a few months ago that we would likely be headed into another ice age, if not for AG CO2 warming things up. If so, AGW is a gift to the entire human race. 80% reductions in CO2 emissions would not only starve us, but might freeze us too.

Brett you linked to Katie's previous video. I did see the correct one on katie's page. Reply: Thanks, it's fixed now.

One thing I noticed is the good Dr. didn't answer the questions asked, especially the last one.

I apologize for the video screw up. I swear I posted the new one earlier in the day and somehow last weeks got in there. It has been corrected now with the new video online. Brett.

SM,

He did acually answer the first half of the question. If the US and Canada cut their emissions significantly, whilethe rest of theworld continued to grow, then the impacts of the measures would be minimal. Although he didn't come out and say it, you can conclude from his answer that the cost-effectiveness of the US and Canada takign such measures alone would be minimal.

Patrick Henry,

I think you take too much liberty with Dr. Keller's answer. He stated that the cause of the patter s on CO2/temp records in question (I assume the question was refering to the antartic ice core records that go back several hundred thousand years) were caused by a feed-back mechanism initiated by orbital forcing. he did not imply that nothing other than orbital forcing can be a main driver in large scale climate change.

the pattern ....caused by a feed-back mechanism

cmbclean,

If you think about that concept, it doesn't make any sense. Feedback is by definition a response, not a driver.

Remember that ice ages start when CO2 is at a maximum, and they end when CO2 is at a minimum. This is completely inconsistent with GHG theory, and shows that ice ages happen in spite of CO2, not because of it.

Off topic .. sorry but it is very interesting:
Excerpt:
THE GREAT PACIFIC CLIMATE SHIFT II?
Back in 1977, the Pacific Ocean underwent a major transformation in sea surface temperature patterns that was called the Great Pacific Climate Shift. Suddenly warm water replaced cold water that had dominated for most of the prior three decades near the west coast of North America and along the equatorial eastern Pacific.

Just a coincidence that it started getting warmer in 1978 and leveled off at 1999 and is coling now?

http://icecap.us/images/uploads/THE_GREAT_PACIFIC_CLIMATE_SHIFT_II.pdf

cbm or PH , can one of you explain what this orbital feedback he was talking about is?

ON the historical CO2/temp:

It appears that Hansen actually predicted the lag before it was discovered, so any claim that the lag does not fit in with current theory is simply wrong. Hopefully this is the nail in the coffin for this silly argument.

http://www.nature.com/nature/journal/v347/n6289/abs/347139a0.html

Dave,

This is a decent explanation-
http://en.wikipedia.org/wiki/Milankovitch_cycles

Boris,

The Vostok core data was measured in the 1950s when Hansen was still a baby. The response and lag is due to the fact that CO2 solubility is lower in warm water and responds to changes in ocean temperature. That principle has been understood for hundreds of years.

PH,

A feedback mechanism is a result, but it can also be a driver. There is no restriction on a feed-back mechanism being the driver of something else. Also, while CO2, does lag temps, I think that stating that temps and CO2 are 180 degress out of phase is an exaggeration.

Dave,
The current widely accepted hypothesis as to the origin of the CO2 temperature lag is this (as far as I understand it):

The Milankovitch cycle changes Northern Hemisphere insolation in a positive direction. (This increase in insolation would not, in itself, be enough to end an ice age.) However, as the increase in insolation causes ocean temps to rise, more CO2 is released into the atmosphere. This increased CO2 further increases temperatures, which further increases CO2 concentration, which further increases temperatures and so on. Thus, while the main driver for the end of an ice age is CO2 concentration, the factor that initiates the cycle is increased insolation.

I would like to note that the science on what causes and ends an ice age is by no means settled.
The Milkanovitch theory of ice ages has some problems. One of the main ones is described as the "100,000 year problem." Over the last million years or so, glaciation seems to operate on roughly 100,000 year cycles. However, the 100,000 eccentrictiy cycle is much weaker than the 21,000 year precession cycle and the 41,000 year obliquity cycle. For a good introduction to Milankovitch cycles go to wikipedia at
http://en.wikipedia.org/wiki/Milankovitch_cycles

cmbclean,

I think that stating that temps and CO2 are 180 degress out of phase is an exaggeration.

Nobody said anything like that.

Look at the Vostok graph. Assume 0 phase shift between Temps and CO2. Ice ages begin when CO2 is high. They end when CO2 is low. There is nothing complex about this. When CO2 is at a peak, that is when temperatures start to decline. Obviously this is happening in spite of CO2 feedback.

Feedback is by definition a response, not a driver.

I'd like Patrick Henry to try a simple experiment that anybody with a microphone, amplifier and speakers can try.

Turn the "input gain" and "output volume" knobs all the way down. Put the microphone in front of the speakers. Turn on the system. Now start frobbing the dials.

ALERT: This experiment is exquisitely sensitive to speakers, room acoustics, and phase-of-moon. For best results, start with the output volume low.

The "input gain" adjusts the positive feedback. I think you'll find that for each position of the "output volume" knob, you'll find a critical setting of the "input gain" knob -- below which nothing much happens, and above which you get a loud high-pitched squeal.

I also think you'll be able to find a setting, just below that threshold, where the speakers sort of "ring" when any sound hits the mike.

I'd like Patrick to adjust the system to that setting, and then shout into the microphone, and see what happens.

Experiment 1:
Turn the input gain knob lower -- reducing the positive feedback -- and try again.

First time, loud squeal. Second time, no squeal.

Experiment 2:

Adjust the system so that it is a loud as possible without squeal. Now move the mike closer to the speaker. What happens?

If you're trying to avoid the "squeal", I'd like Patrick to answer the question of whether or not the positive feedback is or is not a "driver" of the system.

Just one preliminary comment on Dr. Keller's reaction to my question on the paleoclimatological record on warming and CO2 and what causes what:

I won't let Dr. Keller get away with this kind of very unsteady answer to this extremely fundamental problem for the whole of the AGW scenario which could lead to a roll-back of the industrial age as we know it.

The whole AGW charade has one single fundamental tenet and that's the ideological position that CO2 drives the warming. Period. I've never, as long as I've been watching this thermodynamical soap opera unfold, heard anything detailed about any other temperature driving factor from that camp.

As soon as any non-AGW type causative factor (such as Milankovitch configurations) is put forward as the main driver of a development towards a climate optimum (as observed in the ice core proxy data sets) the AGW'ers invariably respond by inventing ad hoc scenarios like Dr. Keller just did in the video...

A lot of impofrtant new research is currently being done on Milankovitch's hypothesis and I expect that we'll know much more in the future about insolation events and details of long-time climate cycles.

You AGW'ers just seem to be so pessimistic about future climate science. Science always evolves in unexpected directions. We're sure to know much more about the complex interplay between glacials and interglacials. In the meantime we'd better not roll back modern society because of a wobbly and possibly irrelevant idea about the role of humans in the large-scale evolution of terrestrial climate.

I'll just put my finger on Dr. Keller's concept of the CO2 positive feedback mechanism: does this mean that CO2 doesn't drive the modern warming of ~0.6C (+/-0.2C) but just happens to be around in the atmosphere when a positive feedback mechanism is desperately needed to construe the hypothesis/theory of Anthropogenic Global Warming? And then there's the entire set of spurious auxiliray AGW concepts like, e.g., the tipping point of climate development that's being put forward by Jim Hansen but I guess that's just GISS-work...

When looking at the paleoclimatology of those ice core proxy data, it doesn't look like CO2 covaries with temperature in any other way than being triggered by the warming event. I can detect no positive feedback mechanism; CO2 rises and falls in response to warming for the last ~700K years BP. If I'm too myopic to detect very small-scale positive feedback events in the paleoclimatological record, well, that's on the house.

Since neither the IPCC nor Al Gore never mention, in any explicit way, the fundamental role of the astronomy in the long-time glacial/interglacial shifts on record the general public must go home with the false impression that the anthropogenic component of the CO2 portion of the atmosphere has got to be all there is and that anthropogenic CO2 is going to lead to the dystopic world of Global Frying.

Just one small example: in the October issue of the National Geographic Magazine there's a multicolored poster on CO2 "pollution". The text on the poster says correctly that the rise in CO2 follows warming #historically" but the graph continues to feed the unsuspecting lay reader with the bawdlerized information that the rise in CO2 precedes the rise in temperature. This is fraudulent and pathetic.

I never thought much of graphology, my loss no doubt, but after watching the AGW graphology, i.e. the way these people use botched-up climate graphs, for quite some time now I strongly feel that this kind of graphology must be a vital area in psychosociological research if there is such a thing. I'm sure someone could apply successfully for a grant.

This is more of a political question than a global climate question. Why has the U.N. not even tried to consol other countries that are increasing their CO2 output? Common sense would tell you try to find cleaner ways to make energy. A good example is the MagnaTrain, NO CARBON DIOXIDE OUTPUT. We need to save our children this is the only planet that we can stay in as is; without spending all of the Earth's money to make it hold just about 1 million people. If I am mistaken please tell me. I have been watching these posts for a while so I will see it there.

Just a couple of points. When asked the first question Dr Keller states that orbital changes cause the earth to warm, which in turn causes the rise in CO2, mostly from the oceans. This fact seems to be accepted by most. If we are to also believe that CO2 drives temperature, we have a little problem on our hands. If the earth warms, CO2 is produced. Wouldn't that also mean that the rise in CO2 would further warm the earth, thereby creating a cycle? Earth warms, CO2 produced. Co2 warms earth more, more CO2 produced. Where does it end? Where's the reversal mechanism? Clearly the earth has warmed before. "Orbital variations" I believe Keller said, but why didn't that lead to an out of control greenhouse effect? I guess I see a contradiction here. I'm sure someone here knows this; at what points in the past was CO2 high and temperatures low? If we accept that as the earth warms CO2 is produced, to me, it brings into question how much of a temperature driver CO2 is or could be. Any thoughts?

"The Vostok core data was measured in the 1950s when Hansen was still a baby."

Not with the resolution to identify a lag.

"I can detect no positive feedback mechanism"

It would be hard to detect with everything going on in the graphs. Luckily we have over a century of experimentation and observation that shows CO2 is a greenhouse gas and holds more heat closer to the surface.

Iceman, you've just described the positive feedback that leads to the various AGW scenarios.

Co2 warms earth more, more CO2 produced. Where does it end? Where's the reversal mechanism?

Some other component in the system kicks in to limit the phenomena. In my speaker feedback example above, the amplifier has a limited power output. So the amplitude of the squeal rapidly goes to that level, and that stops -- it just can't any louder.

My understanding is that similar mechanisms govern the maximum attainable atmospheric temperature.

iceman,

If the amplifying effect of all feedbacks was greater than the underlying driver, it would go out of control and be irreversible. However, this is not the case on earth, as can be seen in the Vostok cores.

For most of the history of life on earth, CO2 levels have been much, much higher than now. As much as 10-20x higher. Incontrovertible evidence that the idea of a "tipping point" from burning fossil fuels can not happen.

As someone who is totally frustrated by the agenda of The Weather Channel, it is great to find that your site that gives both sides of the GW debate.

Reply: Thanks for the nice comment John. Brett

BT & PH,
Thanks for the info. Just wondering, more for you BT, what are your feelings on the Robert H. Essenhigh article I've linked below.

http://pubs.acs.org/subscribe/journals/ci/31/special/may01_viewpoint.html

A few things we/I can do now:
I will turn off a few extra lights.
I will not water my lawn in the winter.
I will drive a slower until I buy an electric car.
I will plant two trees this year.
I will flush my toilet less. If it is yellow, let it mellow, if it's brown send it down.

I will re-post this comment 3 times.

superhero,

Two more suggestions. Turn off your computer permanently and flush your toilets before they release too much methane.

Thanks for the info. Just wondering, more for you BT, what are your feelings on the Robert H. Essenhigh article I've linked below.

At my first read, this piece appears to raise fair and legitimate questions that merit reasonable and informed response. The climatological community seems to be doing just that -- the piece is cited multiple times, and various participants in the discussion (on both sides) make reference to it.

The focus of his argument is beyond my expertise, and I'll defer to commentary from other sources who have more familiarity with the relevant science than me.

(Off-topic alert)

By the way, iceman, while looking for commentary on the Essenhigh piece you cite, I found a provocative and interesting theory he offers on the sinking of the Titanic: Titanic Disaster: New Theory Fingers Coal Fire, apparently published in 2004.

He speculates that a coal fire was underway in the bunkers of the Titanic, and that the crew was burning as much coal as possible in order to bring it under control (this was, apparently, recommended practice at the time). The ship was steaming at full speed in order to uncover the coal and reach port as quickly as possible.

His presentation is, sadly, apparently not available online; I would like to see it (I'm a bit of a Titanic-buff).

Essenhigh does the calculation for the contribution of water vapor to the greenhouse effect improperly. Although he uses "U.S. Standard Atmosphere profiles for the variation of temperature, pressure, and air density with elevation", he does not include the variation of water vapor with elevation. He also does not consider the overlap between the absorption bands of water and CO2. Also, the spectral range used in his calculation is implied to be 5.6�7.6�m, which corresponds to a temperature of 383 - 523 K, whereas IR radiation from the Earth is emitted at about 285 K (10.2�m). Nor does Essenhigh appear to consider radiation from altitudes above Earth's surface. That is why radiative transfer models are needed to perform accurate calculations on the atmosphere.