Global Warming New Zealand style!

[ujoni08]

I've been thinking about the temperature -- CO2 lags in the paleo-climatological records. If true, they would seem to be a problem for the theory that atmospheric CO2 concentrations drive atmospheric warming. Of course, there is a small possibility that the current methodologies using proxies are in some way subject to a flaw that makes the record appear to have a lag, but let's take it for the moment that there is a definite, proven lag of circa 800 years. To me that would be a problem for the CO2-driven temperature theory (and of course I take the point about natural CO2 emissions from e.g. volcanic activity, etc.).

I did a bit of searching, and the answer that some scientists have given is that some as-yet-unidentified factor seems to start a warming period, which then lasts about 5 000 years. The lag is only for say the first 800 years, after which the CO2 levels rise significantly. After that, a feedback seems to operate, where the rising CO2 then accelerates the temperature rise.

http://www.realclimate.org/index.php/ar ... ice-cores/

The reason has to do with the fact that the warmings take about 5000 years to be complete. The lag is only 800 years. All that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data.

The 4200 years of warming make up about 5/6 of the total warming. So CO2 could have caused the last 5/6 of the warming, but could not have caused the first 1/6 of the warming.

It comes as no surprise that other factors besides CO2 affect climate. Changes in the amount of summer sunshine, due to changes in the Earth’s orbit around the sun that happen every 21,000 years, have long been known to affect the comings and goings of ice ages. Atlantic ocean circulation slowdowns are thought to warm Antarctica, also.

From studying all the available data (not just ice cores), the probable sequence of events at a termination goes something like this. Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a “feedback”, much like the feedback that results from putting a microphone too near to a loudspeaker.

In other words, CO2 does not initiate the warmings, but acts as an amplifier once they are underway. From model estimates, CO2 (along with other greenhouse gases CH4 and N2O) causes about half of the full glacial-to-interglacial warming.

So, in summary, the lag of CO2 behind temperature doesn’t tell us much about global warming. [But it may give us a very interesting clue about why CO2 rises at the ends of ice ages. The 800-year lag is about the amount of time required to flush out the deep ocean through natural ocean currents. So CO2 might be stored in the deep ocean during ice ages, and then get released when the climate warms.]

What do others think?

Jon

[ujoni08]

More here:

http://www.realclimate.org/index.php/ar ... p-and-co2/

This subject has been very well addressed in numerous places. Indeed, guest contributor Jeff Severinghaus addressed this in one of our very first RealClimate posts, way back in 2004. Still, the question does keep coming up, and Jeff recently received a letter asking about this. His exchange with the letter writer is reproduced in full at the end of this post. Below is my own take on the subject.

First of all, saying “historically” is misleading, because Barton is actually talking about CO2 changes on very long (glacial-interglacial) timescales. On historical timescales, CO2 has definitely led, not lagged, temperature. But in any case, it doesn’t really matter for the problem at hand (global warming). We know why CO2 is increasing now, and the direct radiative effects of CO2 on climate have been known for more than 100 years. In the absence of human intervention CO2 does rise and fall over time, due to exchanges of carbon among the biosphere, atmosphere, and ocean and, on the very longest timescales, the lithosphere (i.e. rocks, oil reservoirs, coal, carbonate rocks). The rates of those exchanges are now being completely overwhelmed by the rate at which we are extracting carbon from the latter set of reservoirs and converting it to atmospheric CO2. No discovery made with ice cores is going to change those basic facts.

Second, the idea that there might be a lag of CO2 concentrations behind temperature change (during glacial-interglacial climate changes) is hardly new to the climate science community. Indeed, Claude Lorius, Jim Hansen and others essentially predicted this finding fully 17 years ago, in a landmark paper that addressed the cause of temperature change observed in Antarctic ice core records, well before the data showed that CO2 might lag temperature. In that paper (Lorius et al., 1990), they say that:

changes in the CO2 and CH4 content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing

What is being talked about here is influence of the seasonal radiative forcing change from the earth’s wobble around the sun (the well established Milankovitch theory of ice ages), combined with the positive feedback of ice sheet albedo (less ice = less reflection of sunlight = warmer temperatures) and greenhouse gas concentrations (higher temperatures lead to more CO2 leads to warmer temperatures). Thus, both CO2 and ice volume should lag temperature somewhat, depending on the characteristic response times of these different components of the climate system. Ice volume should lag temperature by about 10,000 years, due to the relatively long time period required to grow or shrink ice sheets. CO2 might well be expected to lag temperature by about 1000 years, which is the timescale we expect from changes in ocean circulation and the strength of the “carbon pump” (i.e. marine biological photosynthesis) that transfers carbon from the atmosphere to the deep ocean.

Several recent papers have indeed established that there is lag of CO2 behind temperature. We don’t really know the magnitude of that lag as well as Barton implies we do, because it is very challenging to put CO2 records from ice cores on the same timescale as temperature records from those same ice cores, due to the time delay in trapping the atmosphere as the snow is compressed into ice (the ice at any time will always be younger older than the gas bubbles it encloses, and the age difference is inherently uncertain). Still, the best published calculations do show values similar to those quoted by Barton (presumably, taken from this paper by Monnin et al. (2001), or this one by Caillon et al. (2003)). But the calculations can only be done well when the temperature change is large, notably at glacial terminations (the gradual change from cold glacial climate to warm interglacial climate). Importantly, it takes more than 5000 years for this change to occur, of which the lag is only a small fraction (indeed, one recently submitted paper I’m aware of suggests that the lag is even less than 200 years). So it is not as if the temperature increase has already ended when CO2 starts to rise. Rather, they go very much hand in hand, with the temperature continuing to rise as the the CO2 goes up. In other words, CO2 acts as an amplifier, just as Lorius, Hansen and colleagues suggested. [...]

.

Just putting this in for discussion.

Jon

[snow hope]

Jon, no matter what way the AGW theory believers try to justify it, there is no way to get away from the FACT that Temperatures are seen to rise before CO2 rises (anywhere between 800 years and 1500 years) according to the detailed analysis of ice cores and past climates.

As you have said yourself, "To me that would be a problem for the CO2-driven temperature theory". It seems that you are coming to realise the inconvenient truth....... but of course the AGWers will find any means they can to try and get around this FACT.

I know it may be hard to accept this, if you 'believe' that we are causing the earth's climate to warm. But can I ask you to sit there and honestly ask yourself, do we really have the ability to cause the climate of the planet to warm, when we are so insignificant compared to the power of our local star, the sun? The heat sink of the vast oceans? The power of the clouds, storms, monsoons, hurricaines and cyclones, etc. Even on land, mankind's towns and cities still occupy less than 1% of the actual land coverage.

It is strongly my opinion that the impact we make compared to the other major natural global parameters that drive our climate, are similar to pissing into the sea. Yes, it must warm the sea, but in my opinion it is insignificant...... I probably won't change your mind, but all I can do is say what I think.

[An Inspector Calls]

ujoni08
I have just read your link to Realclimate, in particular this crucial early paragraph:

First of all, saying “historically” is misleading, because Barton is actually talking about CO2 changes on very long (glacial-interglacial) timescales. On historical timescales, CO2 has definitely led, not lagged, temperature. But in any case, it doesn’t really matter for the problem at hand (global warming). We know why CO2 is increasing now, and the direct radiative effects of CO2 on climate have been known for more than 100 years. In the absence of human intervention CO2 does rise and fall over time, due to exchanges of carbon among the biosphere, atmosphere, and ocean and, on the very longest timescales, the lithosphere (i.e. rocks, oil reservoirs, coal, carbonate rocks). The rates of those exchanges are now being completely overwhelmed by the rate at which we are extracting carbon from the latter set of reservoirs and converting it to atmospheric CO2. No discovery made with ice cores is going to change those basic facts.

There are so many sweeping statements there that are supposed to be taken as given.

The argument that CO2 leads temperature on historic timescales but not on archaeological timescales must be somewhat torturous, I imagine, but that point is side-stepped!

The direct effects of CO2 on climate have been know qualitatively for a 100 years, and to reasonable quantitative accuracy for perhaps the last 50. They don't amount to a great deal, which is why CO2 was never considered a problem until, perhaps, the mid 70s.

Then the flight of fancy begins:
"We know why CO2 is increasing now, and the direct radiative effects of CO2 on climate have been known for more than 100 years. In the absence of human intervention CO2 does rise and fall over time, due to exchanges of carbon among the biosphere, atmosphere, and ocean and, on the very longest timescales, the lithosphere (i.e. rocks, oil reservoirs, coal, carbonate rocks). The rates of those exchanges are now being completely overwhelmed by the rate at which we are extracting carbon from the latter set of reservoirs and converting it to atmospheric CO2."

These, the author claims, are basic FACTS!!!!

Does the author really know the full size of the natural sources and sinks of CO2?;

Does he know that they are huge compared to anthropogenic emissions?

Does he know by how much the sources and sinks vary over time?

Can he really make any claim that anthropogenic CO2 dominates the changes in the natural sink and source flows?

[ujoni08]

Thanks for the replies. Snow, at the moment, based upon my readings, I am of the opinion that we are contributing something to CC, but my mind is not closed. As Chris Martenson puts it (he was writing about the exponential debt problem): this is my current opinion, and I reserve the right to change my opinion should new facts come to light. I always stayed away from discussing CC, because I felt it was much more complicated than energy depletion.

Anyway, I have now started reading more about CC, and agree about the complexity and number of factors operating, e.g. clouds, albedo, other greenhouse gases, natural emitters and sinks of CO2, etc. I'd like to contact a few scientists and pose some questions to them about it.

Nevertheless, I still think that we should be embarking on a massive power down anyway, because of the health risks of all these emissions, and because of looming energy depletion, pollution of ecosystems, etc.

Jon

[clv101]

AIC, we do know, as well as we know anything in science, why CO2 is increasing now. You're a smart chap, to question this just demonstrates your disingenuity.

Snow, no one is trying to get away from the fact that past Quaternary temperature rises led CO2 rises. Why would anyone the evidence is clear. It is also perfectly consistent with increased CO2 concentrations today driving temperature changes today. I don't see the issue.

I know it may be hard to accept this, if you 'believe' that we are causing the earth's climate to warm. But can I ask you to sit there and honestly ask yourself, do we really have the ability to cause the climate of the planet to warm, when we are so insignificant compared to the power of our local star, the sun? The heat sink of the vast oceans? The power of the clouds, storms, monsoons, hurricaines and cyclones, etc. Even on land, mankind's towns and cities still occupy less than 1% of the actual land coverage.

This is a subjective point of view, we are small so can't have much impact. It doesn't bare scrutiny for a moment though - human civilisation has had a huge impact on the planet, the 40% hike in atmospheric CO2 is one, another is the fact that the blue whale population has fallen some 99% since we started whaling. How about the fact half of the world's tropical forests have been cut down since 1947 or the fact that humans now appropriated over half the terrestrial bioproductivity of the planet for our own purposes. To suggest "we are small" is just nonsensical.

[An Inspector Calls]

AIC, we do know, as well as we know anything in science, why CO2 is increasing now. You're a smart chap, to question this just demonstrates your disingenuity.

Just like you dad, can't resist an insult.

Try this for size:
http://www.drroyspencer.com/2009/05/glo ... ple-model/

and
http://www.thesydneyinstitute.com.au/po ... l-sources/

I doubt your claim that we know why CO2 is increasing.

[marknorthfield]

It's very easy to parade vaguely intellectual sounding contrarianism on a forum containing a bunch of interested amateurs, isn't it?

AIC, seeing as you feel so strongly about this, I presume you have at some point contributed your thoroughly researched points on Realclimate, Skeptical Science or similar? Could you point us to a debate where you have contributed and successfully convinced others either working in (or with substantial interest in) the mainstream climate science field of at least one of their major errors? I would be interested to read that exchange.

Btw, I have a good long-standing friend who is very anti-AGW (and, coincidentally, rather right-wing). I often get the impression that he gets a kick out of deliberately going against the grain, revelling in the status of 'intellectual outsider' setting out to put the world to rights, one blog post at a time. He likes to have the last word in any argument. He is also extremely witty and musically very talented, which is at least partly why we've remained good friends for many years. As a human being, I love him dearly. I think he's also quite lonely, and that this somehow contributes to his desire to set himself apart from mainstream opinion.

I mention this because it reminds me that strongly held opinions are not necessarily driven by a fair appraisal of the best evidence available, but rather by what the opinion-holder wants to be true.

[biffvernon]

a forum containing a bunch of interested amateurs,

but also some professional earth systems scientists.

[snow hope]

Thanks for the replies. Snow, at the moment, based upon my readings, I am of the opinion that we are contributing something to CC, but my mind is not closed. As Chris Martenson puts it (he was writing about the exponential debt problem): this is my current opinion, and I reserve the right to change my opinion should new facts come to light. I always stayed away from discussing CC, because I felt it was much more complicated than energy depletion.

Anyway, I have now started reading more about CC, and agree about the complexity and number of factors operating, e.g. clouds, albedo, other greenhouse gases, natural emitters and sinks of CO2, etc. I'd like to contact a few scientists and pose some questions to them about it.

Nevertheless, I still think that we should be embarking on a massive power down anyway, because of the health risks of all these emissions, and because of looming energy depletion, pollution of ecosystems, etc.

Jon

Well that sounds like a fair assesment and a reasonable approach. I particulalry agree with the last paragraph re general pollution of our environment.

I also agree we are contributing to climate change although I think the CO2 part of it is a minor aspect, compared to the natural climate forcings. There is no doubt that the towns and cities we build and live in cause urban heat islands. There is no doubt that we have caused major impact to significant parts of the earths surface, as Chris rightly points out, over hundreds and probably thousands of years, cutting down forests for agriculture all over the world. But thats what such a successful species as the homo sapian is good at.......

[clv101]

AIC, we do know, as well as we know anything in science, why CO2 is increasing now. You're a smart chap, to question this just demonstrates your disingenuity.

Just like you dad, can't resist an insult.

Where's the insult? I believe you are being disingenuous to suggest we don't know why CO2 is increasing now.

[snow hope]

Snow, no one is trying to get away from the fact that past Quaternary temperature rises led CO2 rises. Why would anyone the evidence is clear. It is also perfectly consistent with increased CO2 concentrations today driving temperature changes today. I don't see the issue.

Oh contraire, The Inconvenient Truth did not accept that.....

If temperature rises caused CO2 to rise in the past, why would it be "perfectally consistent with increased CO2 concentrations today driving temperature changes today" ?

This is a subjective point of view, we are small so can't have much impact. It doesn't bare scrutiny for a moment though - human civilisation has had a huge impact on the planet, the 40% hike in atmospheric CO2 is one, another is the fact that the blue whale population has fallen some 99% since we started whaling. How about the fact half of the world's tropical forests have been cut down since 1947 or the fact that humans now appropriated over half the terrestrial bioproductivity of the planet for our own purposes. To suggest "we are small" is just nonsensical.

I agree with most of what you say Chris. But my point was that we have little impact on the climate, the warmth of the air/atmosphere, the warmth of the oceans and seas, compared to the impact the sun has, the impact of clouds, the impact of water vapour, the impact of the albedo effect, our understanding of the carbon cycle, which is not well understood despite what some may think.

Other natural climatic factors such as the Pacific Decadel Oscillation (PDO), the Arctic Oscillation (AO), Atlantic Multi-decadel Oscillation (AMO) El Nino/La Nina, which we are only recently starting to be understand. And of course the big one, the Thermohaline Circulation which takes hundreds/thousands of years to complete a cycle and could be playing a significant part in recent CO2 increases in the atmosphere. http://en.wikipedia.org/wiki/Thermohaline_circulation

So I am not suggesting we are small, there are practically seven billion of us (as you well know). I am suggesting we may not be having the impact that you are being led to believe we are having.

And I don't believe we know "why CO2 is increasing now as well as we know anything in science" and I am somwhat surprised you really believe that..... to my knowledge we don't have that degree of surety and confidence at all.

But hey, who really knows.....

[biffvernon]

I agree with most of what you say Chris. But my point was that we have little impact on the climate, the warmth of the air/atmosphere, the warmth of the oceans and seas, compared to the impact the sun has, the impact of clouds, the impact of water vapour, the impact of the albedo effect,

I wonder whether the problem in understanding lies in the difference between 'little effect' and 'a little effect'?

'Little effect' means it won't change much. In the case of our CO2 emissions that's wrong.

'A little effect' means the force is small though it may have a colossal effect. A large boulder perched precariously on a cliff-top may be dislodged by the little effect of a finger.

The anthropogenic greenhouse gasses produce a warming of only about a Watt per square metre across the whole globe, trivial in dimension compared to the Sun and the other things you list, Snowhope, but it is enough to send the climate out of the Holocene equilibrium and into the Anthropocene.

[Ludwig]

I wonder whether the problem in understanding lies in the difference between 'little effect' and 'a little effect'?

'Little effect' means it won't change much. In the case of our CO2 emissions that's wrong.

'A little effect' means the force is small though it may have a colossal effect. A large boulder perched precariously on a cliff-top may be dislodged by the little effect of a finger.

Sorry to be pedantic Biff, but what you're talking about is the cause, not the effect. The cause is little, the effect is large. (But as usual, there is no single cause: you have to factor in what placed the boulder on a cliff-top and consider all the potential energy it holds by virtue of being there.)

[An Inspector Calls]

It's very easy to parade vaguely intellectual sounding contrarianism on a forum containing a bunch of interested amateurs, isn't it?

Well, I can't do anything about the quality of the interested amateurs. But the vague intellectual contrarianism:

If you're referring here to the work of Roy Spencer, then it's published work, and he's a well established climate scientist: Roy W. Spencer is a climatologist and a Principal Research Scientist for the University of Alabama in Huntsville, as well as the U.S. Science Team Leader for the Advanced Microwave Scanning Radiometer (AMSR-E) on NASA’s Aqua satellite. He has served as senior scientist for climate studies at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

The other reference I quoted was to Murry Salby's work. He is the Climate Chair, Macquarie University.

You might (although I doubt it), be interested in Judith Curry's response to his paper (she's an American climatologist and chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology):
http://judithcurry.com/2011/08/04/carbo ... questions/

I see nothing wrong in posting work from authors of such calibre for the delection of a bunch of interested amateurs, It's just a pity several of them seem not to have taken the trouble to read them before responding.

clv101. I've now linked you twice to the work of the above authors. Both of them speak about natural sources being the cause of the recent rise in CO2 levels in the atmosphere. Yet you continue to characterise my attitude as disingenuous. There has been no response to the science therein. I can only think you are being deliberately obtuse.