The environmental debate thread

[JohnB]

Sorry to derail for a moment, but I thought all might like a chuckle. While reading up on the GHCN datasets I came across this paper concerning the methods of adjusting the data. It comments on some of the problems and i thought this quote was a beaut.

In the process of creating GHCN, cautionary remarks were made that cast doubt on the quality of climate data. For example, a meteorologist working in a tropical country noticed one station had an unusually low variance. When he had an opportunity to visit that station, the observer proudly showed him his clean, white instrument shelter in a well cared for grass clearing.

 

Unfortunately, the observer was never sent any instruments so every day he would go up to the shelter, guess the temperature, and dutifully write it down. Another story is about a station situated next to a steep hillside. A few of meters uphill from the station was a path which students used walking to and from school. On the way home from school, boys would stop and...well, let’s just say the gauge observations were greater than the actual

rainfall.

:D

 

Swansont, I bet physicists never that particular, um, precipitation problem.

 

/derail

[Chris C]

Thank you for the response. In that case I have still not found a peer reviewed response to the McIntyre peer reviewed critique of Mann's 1998 study. THe only rebuttals I find are from Mann in the "letters to Nature" section.

 

In this case, I wouldn't be looking for a 'rebuttal' as much as a perspective on what it actually means (i.e. what was the significance of the Mann et al. error). See the analysis of the MM rebuttal at http://www.cgd.ucar.edu/ccr/ammann/millennium/refs/WahlAmmann_ClimaticChange_inPress.pdf

 

A very read, for a quick analysis and non-technical language, would be http://www.pewclimate.org/what_s_being_done/in_the_congress/7_27_06.cfm

 

Mann et al. is not alone in reconstruction of the last millennia. You can visit the free, online authoritative book by the National Academies of Science at http://books.nap.edu/catalog.php?record_id=11676 for paleoclimate perspective over the last 2,000 years or http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf starting on pg. 466.

 

To be honest, it seems that for the laymen, the whole significance of this Mann and MM thing is if a Medieval Warm Period(MWP) exists, which seems to be of different significance in the actual academic community. Right now, the literature does not give us any reason to believe a MWP that was hotter than today exists, and there is a substantial amount of work suggesting that it was a more regional phenomena than a global one (confined to Greenland, Europe, and parts of Asia), and probably as warm as the middle of the 20th century, although the error bars are large enough to get it like today, or a few tenths warmer, if you go the the very high end. There does not appear to be a strong MWP signal in the tropics, Antarctica, southern hemisphere or other areas of the northern hemisphere. The NAS report and IPCC go over this.

 

So far as we can tell, global warming is roughly 0.8 C from pre-industrial time, with the large majority of that coming from anthropogenic sources, and smaller forcings (mostly from 1900-1950) from natural variability (See Ammann et al 2007 in PNAS). Since climate is not now in equilibrium, it is likely we have about 0.5 C more "in the pipeline" that we're commited to even if GHG levels remain constant (Hansen et al.,2005). It is important to emphasize that AGW-theory does not require warming to be unprecedented; it only requires it to be caused by humans today. The existence of a medieval warm period seems, for some, to be a threat to anthropogenic global warming- though, in reality, it isn't really relevant. It is no more relevant than saying it was hotter 5 million years ago, we're just addressing the temperature or temperature change, without addressing the causes. If it turns out that the medieval times were a bit warmer than we think, this does not effect the attribution of recent warming to CO2. If anything, unmodified causes with a warmer past temperature would hint at higher climate sensitivity to an external forcing agent. Detection of climate change (now or before) simple demonstrates that climate has changed in a meaningful, statistical sense (at this point, providing a reason for that change is not necessary). Attribution of climate change is done by 1) detecting that climate has changes (is changing), 2) demonstrating consistency with known and expected relationships from greenhouse theory, such as identifying fingerprints (stratosphere cooling) or simulating the global changes in models with anthropogenic + natural forcing, and 3) demonstrating that the detected change is inconsistent with alternative explanations. This can all be done with a great deal of confidence now. A number of 'fingerprint' studies (e.g. Hegerl et al., 2000; Stott et al., 2000; Meehl et al., 2001) are out there.

 

 

I fully understand that climateaudit exists, and McIntyre is obviously a very interested and dedicated individual. They can disagree with my extent of the MWP (which comes from a number of studies that McIntyre does talk about), although the literature supports the notion that today is anomalous but with some uncertainty, and there is nothing in the mainstream literature for me to be convinced otherwise. I fully support his efforts, and welcome corrections to work in the field. Although I have expressed my concern on his site to him that he decides only to "audit" papers which seem to be consistent with Mann et al. and not take the time to "audit" papers like the recent Loehle 2007 paper which received attention by realclimate, climate audit, the rest of the blogosphere, etc. His response to me was that he did not have the time to go over them. So the best I can say is that I think McIntyre is on a mission to get as much out of a medieval warm period as possible, or to extend the error in today's measurements as much as possible, but he is doing a very good job of forwarding the science in that regard. I think he is in the "skeptical" category and not in the "deceiving" category, and so his work should still receive attention. It is true, however, that he does not sit in the mainstream of research on this topic, has not done too much refereed original research on it (primarily but not exclusively blogging), and is often (rightly or not) associated with one end of the political spectrum. In my opinion, a lot of the site is simply complaining about the hockey stick and paleoclimate, but again, he is helping more than hurting the science so he can have fun with that.

[iNow]

This "Mann et al., 1998" "McIntyre" dance already occurred here:

 

http://www.scienceforums.net/forum/showthread.php?t=29265

[JohnB]

and not take the time to "audit" papers like the recent Loehle 2007 paper

Loehle 2007 has recieved a (polite) hammering here. Post 143 is quite trenchant. You may also note that even El Nino (who works on Climate constructions with Michael Mann) has obseved "Later, McIntyre started his audit and so far i am pleased to see he is not giving Loehle a free ride."

 

While the Loehle paper could have been better, and I believe that an improved version is in the pipeline it is an unusual reconstruction for two reasons. 1. It is the first reconstruction (AFAIK) that does not use tree ring proxies. and 2. It is the first reconstruction that used proxies exclusively from previously published peer reviewed papers that had already established the temperature calibration.

[swansont]

Swansont asked

 

"- do you mean sunspot number, or something else?"

 

My main reference on the relationship between sunspot activity and temperature is the Max Plank Institute who published their data from 1860 to 2000. Their data shows a really nic correlation from 1860 to about 1970. After that, it all falls apart.

 

They used a term 'reconstructed irradiance' which is a blend of sunspot number, sunspot area, and the intensity of sunspot action. This shows a clear correlation with temperature change.

 

One of their papers is at :

 

http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2004/pressRelease20040802/

 

I quote :

 

"As the scientists have reported in the renowned scientific journal, Physical Review Letters, since 1940 the mean sunspot number is higher than it has ever been in the last thousand years and two and a half times higher than the long term average."

 

I downloaded the first paper and as you've posted before, there are the graphs showing a variation in TSI of about 2.5 W/m^2. Then I noticed that a newer paper is out. Lo and behold, the variation has decreased by more than a factor of two. (I couldn't copy and paste a link, but pdfs are available. I searched on Google scholar and found a preprint)

 

Reconstruction of solar total irradiance since 1700 from the surface magnetic flux N.A. Krivova, L. Balmaceda, and S.K. Solanki

Astronomy & Astrophysics (2007)

 

Note that the 0.1% is shown in the first graph as being about 1.25 W/m^2, and the 1930-1960 variation is less than that, no matter which of their models you use, and there is a shift in the dates of the peaks and troughs. The correlation doesn't look as good now, I think.

 

There are other TSI reconstructions in the paper, but they aren't very different.

[swansont]

forgot to add:

 

The last line of their conclusion is

 

"The (delta)TSI obtained in this paper thus cover the range found

from independent recent reconstructions. However, all the values

we obtain are significantly below the (delta)TSI values deduced

from stellar data and used in older TSI reconstructions."

 

edit: (delta symbol didn't paste properly from the pdf; added text)

[SkepticLance]

To swansont

 

Nice graphs.

I am not sure how this quite relates to temperature change. Just from a visual comparison between the TSI figures as shown on your second graph, and average global temperature change, there appears to be a very good statistical correlation (not perfect - by what is?). Did the researchers attempt to relate the TSI levels to global temperature? Some kind of conversion formula?

[swansont]

To swansont

 

Nice graphs.

I am not sure how this quite relates to temperature change. Just from a visual comparison between the TSI figures as shown on your second graph, and average global temperature change, there appears to be a very good statistical correlation (not perfect - by what is?). Did the researchers attempt to relate the TSI levels to global temperature? Some kind of conversion formula?

 

I didn't see any temperature plots; the axes here are TSI, which was one of the axes in the plots from the other paper. You should be able to directly compare them.

 

Since the TSI increase in the recent plots post-date the early/mid-century temperature increase by ~20 years (1930-1960 vs 1910-1940, i.e. almost two full sunspot cycles), I have a hard time accepting a characterization that the correlation is "good." The solar increase should precede the temperature increase it's causing, right? I suspect that's why the authors didn't present that correlation. If they said anything I missed it in scanning over the paper.

 

They admit that the previous analysis was too large, and this analysis agrees with other independent work. Energy should correlate with temperature; if the TSI change was half of the previous study (and it's actually less), it stands to reason that the associated temperature increase is similarly smaller, which puts it pretty much in agreement with all the other studies.

[Chris C]

I calculate a forcing of 0.33 W/m-2 for ΔTSI of +0.14%. That is around 0.2 K in temperature response after equilibrium. This is near the high end of the IPCC forcings chart, but the IPCC is relative to 1750 which was a bit higher than 1700 so 0.14% is a high number. Aerosols also offset this by a factor of at least 2, so that leaves quite a lot of warming to be explained by other things.

 

[SkepticLance]

To swansont

 

Re your TSI graphs.

 

The correlation with average global temperature is not perfect. This simply shows something we already agree about - that there are other important factors influencing temperature. However, there still seems to be a pattern.

 

The TSI is dropping from 1870 to 1910, which is a net global cooling period. It is rising from 1910 to 1950. The extra from 1940 to 1950 is a bit of a surprise to me, but that's OK, if we allow for other factors.

 

With the proviso that there are other factors, would you agree that sunspot activity is an important influence on global warming/cooling?

[iNow]

To skepticlance

 

How is a "perfect correlation" defined? I've never heard of such a thing through all my years of statistics, research, and publication, so your assistance in defining this term would be helpful. Thanks in advance.

[SkepticLance]

iNow.

Correlation is quantified by the correlation coefficient. If this reaches 1, then the correlation is 'perfect'. However, the term 'perfect correlation' is not scientific jargon, and perhaps I should not have used it. Not that it matters, since I am sure my meaning was clear.

 

Sadly, your question really is not a contribution to the discussion, more a distraction. How about some science?

[iNow]

iNow.

Correlation is quantified by the correlation coefficient. If this reaches 1, then the correlation is 'perfect'. However, the term 'perfect correlation' is not scientific jargon, and perhaps I should not have used it. Not that it matters, since I am sure my meaning was clear.

 

Sadly, your question really is not a contribution to the discussion, more a distraction. How about some science?

 

[inappropriate comment removed by mod] I was asking you to clarify something you said.

 

I've shared lots of science, which you handily dismissed as "opinion." I'm done wasting my time with you.

[SkepticLance]

iNow

 

You really should learn to modify your language on the forum on those occasions when you get annoyed. In my opinion, which could be wrong, my meaning when I said 'perfect correlation' was clear, and I know you are reasonably intelligent and educated. Thus, I canot see you being baffled by such an obvious term, even if it is not correct jargon. Thus, my conclusion that your question was intended as a distraction, rather than a contribution. Am I wrong?

[CDarwin]

Yes, I deliberately left out the statement that the inability to predict the effects of clouds could result in the coming situation being worse. The reason I left it out is because it is meaningless. It is a 'glass half full or glass half empty' situation. If you don't know what's going to happen, then you don't know whether what will happen is better or worse than your prediction. Not very helpful.

 

I know I'm waay behind on this debate, but I saw this scanning the "Aliens" thread and it just bothered me a bit, so I thought I'd interject concerning it.

 

Regardless of every argument made about the relative certainty climate modelers have about the effects of aerosols, this argument is contrary to basic risk analysis. Risk takes into account both probability and potential consequences. If something is unlikely but catastrophic, it still may pay to take measures against it.

 

You seem to be accepting that humans are driving anthropogenic climate change, and that models can accurately predict that change minus the effect of aerosols. Well, like you say, we may be underestimating their effect and the consequences may be less catastrophic, or we may be overestimating their effect and the consequences may be more catastrophic.

 

The possibility of the worse scenario, even if the situation is as uncertain as you say it is, itself justifies action.

[foodchain]

iNow

 

You really should learn to modify your language on the forum on those occasions when you get annoyed. In my opinion, which could be wrong, my meaning when I said 'perfect correlation' was clear, and I know you are reasonably intelligent and educated. Thus, I canot see you being baffled by such an obvious term, even if it is not correct jargon. Thus, my conclusion that your question was intended as a distraction, rather than a contribution. Am I wrong?

 

 

 

 

What I don’t get is the reality that science does indeed know that humans are indeed changing the environment in a multitude of ways. Now most of these systems are critical in regards to supporting life as we know. Ultimately changing these variables in time is going to change the environment. To coincide with any major change in the environment historically speaking has always lead to mass extinctions as far as I know of.

 

So maybe its simply the reality that large scale ecological change is lethal to life because life is entangled with such in the form of natural selection/evolution.

 

So with an ever growing source of change which is human population density/behavior/technology concentration and use only continues to be that in time it means just that much more change. Yet this change is rather rapid in some ways. It might not seem rapid to an individual lifetime as much as its rapid in being just a few hundred year global change.

 

More and more studies coming from peer reviewed sources currently held as sound by the powers that be are supporting the reality of global climate change. The atmosphere is absolutely vital to life, and in changing this to any large extent certainly cannot be beneficial. Even in light that current consensus on global warming is not 100% absolute down to the scale of being able to predict where and for how long it will rain does not mean what we are learning should simply be ignored. Realistically its like playing Russian roulette but with only one empty chamber. I do not see what could truly lend itself as support to make such a decision as to play that a game.

 

See. I don’t need everything really to be absolute down to the entropy of a few atom system light years away. What I need to know is if humans can and are changing the environmental globally, and the current answer to that is yes but we should have known that from the simple aspect of CFCs and the ozone layer to species going extinct.

[SkepticLance]

To CDarwin

 

I think you may have missed the point a bit. That is not unusual. Half the people on this thread seem to do the same.

 

We had a discussion about the accuracy of predictions on future climate. My point was that those predictions were not accurate. There was no value judgement attached to that. I pointed out that the inability to model cloud formation made future predictions uncertain. The error could be either way - making predictions less catastropic than reality or more. The point was simply the uncertainty. Whether the uncertainty caused error one way or the other we cannot tell. I was just pointing out how uncertain predictions are.

 

To foodchain

 

The human species is changing the environment globally. Sure. What should we do about it? That is the question. And it is not an easy question. I do not believe that we should be making panic decisions based on incomplete information. We need to get out facts straight.

 

The world is warming, and humans are largely responsible due to greenhouse gas increase. That is accepted. Should we panic? There are those who will insist that the answer is yes.

 

Personally, I will always say no. The response to global warming should be :

 

1. Get the facts. To date, we still do not fully understand what is going on. Hysterical communications such as Al Gore's horrible movie do not help. Computer simulations that are incomplete and inaccurate do not help. We need to understand what is going on, without exaggeration.

 

2. Manage the changes. No panic actions. No idiots dropping millions of tonnes of iron into the ocean to stimulate plankton growth, or NASA firing mirrors into space. We need careful action designed to preserve the environment and preserve matters of humanitarian concern.

 

3. Design the alternatives. No morons telling me and millions of others that they must trade their cars in for bicycles. That is a sure recipe for a lynch mob(s). We must have alternative in place BEFORE the rules are set. If we have to give up cars, then a suitable alternative must be ready. By that, I mean a car that will run on battery power, fuel cells, hydrogen gas, or biofuel.

 

4. Focus on the real problem. There are numerous idiots who will try to attack and destroy the oil industry, totally failing to see that is not the problem. Oil will run out in 20 to 60 years. it will contribute a further 20 ppm to atmospheric CO2. Big deal! That is not the problem. The real problem is deforestation and coal.

 

Coal exists in enormous reserves - enough to contribute more than 1000 ppm to atmospheric CO2. Stop the mining and burning of coal.

 

What this means is that we have to develop new technologies. Yet I see very little in the news media about that. Instead we have all sorts of details about new taxes and restrictions. Come on guys - get real. The future is about new technology - not new taxes. Our respective governments no doubt are rubbing their hands in glee. More tax money to use to buy more votes. We should not stand for that.

[jryan]

I know I'm waay behind on this debate, but I saw this scanning the "Aliens" thread and it just bothered me a bit, so I thought I'd interject concerning it.

 

Regardless of every argument made about the relative certainty climate modelers have about the effects of aerosols, this argument is contrary to basic risk analysis. Risk takes into account both probability and potential consequences. If something is unlikely but catastrophic, it still may pay to take measures against it.

 

You seem to be accepting that humans are driving anthropogenic climate change, and that models can accurately predict that change minus the effect of aerosols. Well, like you say, we may be underestimating their effect and the consequences may be less catastrophic, or we may be overestimating their effect and the consequences may be more catastrophic.

 

The possibility of the worse scenario, even if the situation is as uncertain as you say it is, itself justifies action.

 

 

Well, then why not think about a few other potential catastrophes? On the off chance that the supervolcano in Yellowstone will blow in the next 100 years, should we mandate fallout shelters in all homes around the world? It would cetainly assist in survival. But of course we won't because the cost<-->benefit connection simply isn't there.

 

In the same way, if AGW isn't the primary driver, or an insignificant driver in GW (due to some yet seen or quantified forcing) then what is the alternative benefit of CO2 reduction? And is that alternative worth the cost?

[swansont]

To swansont

 

Re your TSI graphs.

 

The correlation with average global temperature is not perfect. This simply shows something we already agree about - that there are other important factors influencing temperature. However, there still seems to be a pattern.

 

The TSI is dropping from 1870 to 1910, which is a net global cooling period. It is rising from 1910 to 1950. The extra from 1940 to 1950 is a bit of a surprise to me, but that's OK, if we allow for other factors.

 

With the proviso that there are other factors, would you agree that sunspot activity is an important influence on global warming/cooling?

 

 

The TSI drop is almost entirely from 1870-1880, when the temperature was increasing (1879 was a local maximum). So there is an anti-correlation occurring here. From then until 1930 TSI is essentially flat — the fluctuations are of order 0.01% of TSI. If you accept the previous work of these authors (well, two of them anyway) then this causes temperature fluctuations of a few hundredths of a degree. So there is temperature change — in both directions, of a few tenths of a degree — with essentially no solar variation.

 

Then the TSI rises starting in 1930 — not 1910 — and it climbs steadily until 1960 — not 1950. There is no good correlation here. The graphs don't support your claim.

 

If you think there is a delay when the solar variation occurs to when the temperature changes, you have to explain why the temperature change lags the TSI change by ~10 years in 1870-1880, and why it precedes the TSI change when temperature begins increasing in 1910.

 

If TSI changes have a significant influence, then there must have been much larger changes in other factors to account for the non- or anti-corrleations from 1880-1930 and 1940-1950. Meaning TSI changes have to be a smaller contributor. This is what the scientists reporting this have been claiming and what several of us here have been arguing.

[SkepticLance]

Swansont

 

I had another look at the graphs, and I have to say that you should also.

 

The temperature graph I looked at showed a cooling from 1870, n0t 1880.

 

The TSI graph you posted showed that well before 1960, the TSI is falling. Take another look. I agree that the correlation is not point for point. However, it is still there, and quite strong. I do not have a correlation coefficient, but if I did, it would be well above 0.5. If we assume that other factors change the warming/cooling to a degree, the evidence is still there that sunspot activity is a major driver of temperature change.

 

In addition, lots of other studies show the relationship for other time periods.

 

eg. Nature : 431, 28 October 2004, page 1084. Shows a beautiful comparison between sunspot activity in the current warming with reconstructed sunspot activity (ice core studies) in the last inter-glacial.

 

You can get the abstract on :

http://www.nature.com/nature/journal/v431/n7012/abs/nature02995.html

[iNow]

If we assume that other factors change the warming/cooling to a degree, the evidence is still there that sunspot activity is a major driver of temperature change.

 

In addition, lots of other studies show the relationship for other time periods.

 

eg. Nature : 431, 28 October 2004, page 1084. Shows a beautiful comparison between sunspot activity in the current warming with reconstructed sunspot activity (ice core studies) in the last inter-glacial.

 

You can get the abstract on :

http://www.nature.com/nature/journal/v431/n7012/abs/nature02995.html

 

And as everyone has repeatedly been saying, it is a factor, but not the dominant one.

 

 

From your abstract:

 

http://www.nature.com/nature/journal/v431/n7012/abs/nature02995.html

Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades.

 

 

What is the overall point you are trying to make with all of these posts, lance? What goal are you seeking to achieve?

[swansont]

Swansont

 

I had another look at the graphs, and I have to say that you should also.

 

The temperature graph I looked at showed a cooling from 1870, n0t 1880.

 

<sigh> And which graph would this be? (the lack of citation is getting really frustrating)

 

The one you had previously deemed satisfactory, http://en.wikipedia.org/wiki/Image:Instrumental_Temperature_Record.png shows cooling starting in 1880.

 

 

The TSI graph you posted showed that well before 1960, the TSI is falling. Take another look. I agree that the correlation is not point for point. However, it is still there, and quite strong. I do not have a correlation coefficient, but if I did, it would be well above 0.5. If we assume that other factors change the warming/cooling to a degree, the evidence is still there that sunspot activity is a major driver of temperature change.

 

The resolution isn't all that great, so I may have misread it slightly, but the TSI is clearly increasing for several years after the temperature fell dramatically (0.2 ºC). And the increase doesn't occur until 1930. This gives you ~20 years out of ~100 where the graphs correlate well. The rest looks to me to be pretty much random. I simply don't see how a claim of "strong correlation" holds up to scrutiny.

 

In addition, lots of other studies show the relationship for other time periods.

 

eg. Nature : 431, 28 October 2004, page 1084. Shows a beautiful comparison between sunspot activity in the current warming with reconstructed sunspot activity (ice core studies) in the last inter-glacial.

 

You can get the abstract on :

http://www.nature.com/nature/journal/v431/n7012/abs/nature02995.html

 

That's another paper from Solanki, dating from 2004. The 2007 paper supercedes it — he/they admit the earlier analyses gave results that were too large. You have to go with the newer results.

 

http://www.nature.com/nature/journal/v431/n7012/abs/nature02995.html

 

Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades.

 

 

What is the overall point you are trying to make with all of these posts, lance? What goal are you seeking to achieve?

 

Actually, I think we're not focusing on the last three decades at all. The point of contention seems to be whether the solar variation prior to that has been properly tabulated; there was a paper from several years ago that SL has cited that claimed that basically all of the temperature variation from ~1910 - 1960 or was due to solar variation, but the same authors have corrected their analysis and find that the total solar irradiance was less than half of what they had previously calculated.

 

Which bring it in line with the other analyses that have been cited here.

[SkepticLance]

Thank you Swansont, for your comment about the last 30 years.

 

iNow

 

I really get a bit tired of this. Not just you, but others. I have said, I don't know how many times, that my case refers ONLY to the period before 30 years ago, and yet I get a whole lot of people who apparently cannot or do not read my posts, who think that any reference to the fact that sunspots have little effect over the past 30 years is some kind of major put down. Get real!

 

To Swansont

 

The temperature graph I was looking at came from the book : 'Meltdown'. However, whether the cooling starts 1870 or 1880 is not really the point. Sunspot activity and global warming/cooling does not correspond point for point for every year, and it is unreasonable to expect it to do so. As you pointed out many times, there are many factors driving warming/cooling. I am simply saying that sunspot activity is one of the more potent drivers. I am not quite sure why we keep arguing this point, since it is widely recognised as true.

[foodchain]

As you pointed out many times, there are many factors driving warming/cooling. I am simply saying that sunspot activity is one of the more potent drivers. I am not quite sure why we keep arguing this point, since it is widely recognised as true.

 

What is the CO2 driver. The argument is skipping this aspect and going straight to the sun. CO2 is also widely recognized as true as a greenhouse gas in which since the industrial revolution has been steadily increasing. I do not know of any other variable to drive this currently save for human behavior in which its linked. So if human behavior continues to increase concentration of a greenhouse gas in the atmosphere the result will be what?

[SkepticLance]

To foodchain

 

This point is not disputed. CO2 has been increasing in the air since the industrial revolution, and the cause is deforestation and burning of fossil fuels.

 

The CO2 increase has been pretty much trivial until WWII, and then has slowly increased, with the increase being close to a smooth exponential curve. From about 1880 to about 1940, CO2 increased at a bit less than 0.2 ppm per year. Today, it increases at a bit less than 2 ppm per year - a ten fold increase.

 

This is a big part of the reason I have claimed that the main causes of global warming were different in the past. Over the previous 30 years, with CO2 increase at more than 1 ppm per year, and an average warming of 0.17 C per decade, human generated CO2 is the prime driver of warming.