Where do you stand on the GW/AGW issue?

[Dr. Imago]

I'm interested in seeing the results of what people think, based on current state of the science.

Discussion encouraged (including the inevitable criticisms of the way the poll's questions were worded).

-Dr. Imago

 

[Dr. Imago]

Discussion point:

http://www.noaanews.noaa.gov/stories2005/s2412.htm

No doubt humans are adding CO2 to the atmosphere, but at the current rate it will take 214 years for it to reach the dreaded doubling to 700 PPM. Even then, the overall amount of CO2 in the atmosphere, by weight, will only increase from 0.0577% where it was in 2005 to 0.1064% in the year 2219.

-Dr. Imago

 

[mhaze]

What those types of articles never seem to point out is the relevant fact (they do actually loiter on irrelevance quite nicely) which is the approximate CO2 content of the atmosphere WHEN THE FOSSIL FUELS RUN OUT.

Hint: It ain't nothing to worry about.

 

[Dr. Imago]

Well, what I thought was most interesting about that particular article was the fact that in 2002 and 2003 there was a "bump" in the measurement of atmospheric CO2. That was then followed by a return to the normal increases seen in the ensuing year.

If we are increasing the rate of fossil fuel consumption and we're meaningfully impacting or increasing the amount of CO2 poured into the atmosphere, wouldn't that "bump" have continued and/or been increasing? Certainly no one will try to argue that we've curtailed our CO2 emissions since then, would they?

I read somewhere recently (can't find the source now) that atmospheric CO2 actually follows global warming, not causes it. As oceans warm, their ability to store gasseous CO2 decreases and the near-surface dissolved CO2 would be liberated from them. If CO2 truly had a forcing effect, wouldn't this be a positive or "feed-forward" mechanism? In other words, we'd expect as the atmosphere got warmer more CO2 would be freed from the oceans into the atmosphere.

I don't know how current climatology models can explain the NOAA report. I'd like to hear, though. That one report has huge ramifications, if it is to be believed, across the entire spectrum of this argument, in my humble opinion.

-Dr. Imago

 

[Pixel42]

No doubt humans are adding CO2 to the atmosphere, but at the current rate it will take 214 years for it to reach the dreaded doubling to 700 PPM. Even then, the overall amount of CO2 in the atmosphere, by weight, will only increase from 0.0577% where it was in 2005 to 0.1064% in the year 2219.

The GMST (Global Mean Surface Temperature) is approximately 30 degrees Celsius higher than it would be in the absence of greenhouse gases. That's how much difference the current trace amounts make. Doubling them does not sound like a good idea to me.

 

[Tippit]

Both Global Warming and Anthropogenic Global Warming are real. The question is, how does the former relate to the latter, and what is the scope. The average global temperature has increased by .5 to .75 degrees Celsius over the past century depending on who you ask, so global warming is indeed a real phenomenon. CO2 is a greenhouse gas with one of the highest GWPs (global warming potential), and human beings certainly contribute to CO2 in the atmosphere.

The largest constituent greenhouse gas in the atmosphere is water vapor, and it has by far the highest GWP as well. The aggregate GWP of CO2 is a fraction of water vapor's. The world's oceans transfer far more CO2 with the atmosphere than human activity emits, and there are other CO2 sinks like flora and various negative feedbacks that are not well understood and which all serve to regulate both atmospheric CO2, and global temperature.

In my opinion, CO2 is not a pollutant, and the AGW doom and gloom scenarios pushed by the IPCC are a way to justify global taxation by the UN, and to give credibility to UN regulating bodies. Global Warming is probably caused by changing trends in solar radiation, and/or geothermal activity that is part of a natural cycle. Something is heating the oceans, and the oceans are releasing the vast majority of the CO2 in the atmosphere. It is true that CO2 levels are among the highest they've ever been, and this is in part due to human activity, but this is also mostly irrelevant due to CO2's relatively low GWP next to H2O.

I would recommend watching both "An Inconvienient Truth" as well as "The Great Global Warming Swindle" to better understand the cases being made. I would also point out that some of the IPCC and US government websites that list greenhouse gases and their GWPs seem to omit water vapor from the list, ostensibly to heighten the perception that CO2 is a huge problem because it appears first on their lists. The only rationale I could find for why they do this is that since water vapor is not significantly influenced by human activity they choose to remove it from some lists, which seems deceptive to me.

 

[m_huber]

What those types of articles never seem to point out is the relevant fact (they do actually loiter on irrelevance quite nicely) which is the approximate CO2 content of the atmosphere WHEN THE FOSSIL FUELS RUN OUT.

Hint: It ain't nothing to worry about.

There are two relevant questions in this debate.
1. Is the world warming up?
2. Are we causing it?

I offer for your consideration (taken from http://math.ucr.edu/home/baez/temperature/)

Global temperatures since the dinosaurs:


Global temperatures in (roughly) primate times:



Trend in the last 1000 years:


There are a couple of things to notice here. One, the temperatures about 400 thousand years ago (Kya) were higher than temperatures now. Two, temperatures greater than 10 Mya were much higher than temperatures now. And three, temperatures have recently increased sharply.

So, the Earth naturally goes through warming cycles. We are currently in a warming cycle. So to (1), the answer is "yes."

The second question is a little more tricky, and the truth is that no peer reviewed articles on the subject are being written that say that humans are not causing an increase in the effect. There are some written that are undecided, but most say we are having a profound effect.

But the Earth has been warmer in the past, and even if we accelerate the rate of temperature increase, we won't be pushing the Earth past what it's seen before.

Does this mean that we shouldn't worry? No. Warmer temperatures mean less ice, which in turn means higher sea level. If all of the glaciers on the globe were to melt, vast areas along coastal regions (such as Louisiana, where I live currently) would be flooded. Even a rise in global sea level of a foot or two would cause flooding in areas like New York City, which has portions that are at sea level.

What we shouldn't worry about is destroying our planet. The Earth, and in fact, life, is going to be fine. We aren't going to mess with those, no matter how much CO2 we pump into the air. The Earth will sort it all out eventually, and life will evolve in new interesting and different ways.

What we could potentially do, and what scientific concern is really about, is accelerate the destruction of our own habitat. Mass migrations away from coastal areas would wreck our economy and likely lead to war in some form or another (not a guarantee, but a very plausible scenario).

It isn't "nothing to worry about." It is possibly that it will not play out in the doomsday scenario that it has been painted by some, but it is also possible that it will. Unfortunately, only time will tell.

 

[Pixel42]

The only rationale I could find for why they do this is that since water vapor is not significantly influenced by human activity they choose to remove it from some lists, which seems deceptive to me.

Water vapour tends to be ignored because there is a limit to the amount the atmosphere can absorb. Then it rains, and the level goes back down. There is no limit to the amount of CO2, methane etc that the atmosphere can hold.

Lots of useful info here: http://openlearn.open.ac.uk/course/view.php?id=2805

 

[Dr. Imago]

It seems to me that the most reasonable way of testing this would be to replicate, in the lab, atmospheric conditions where only the content of CO2 - in the fractions concerned - is used as the variable. The temperature changes could then be recorded and the actual contribution to warming or stored heat could be observed and recorded.

I've tried to find data published on such experiments, but can't seem to locate one. I've found at least one example of an experiment that is designed for high school students where 100% CO2 is used in comparison to current atmospheric air, and the variance doesn't seem to be more than four degrees Celsius when other factors are controlled.

Does anyone know of such data? Have such experiments been run?

-Dr. Imago

 

[Tippit]

I read somewhere recently (can't find the source now) that atmospheric CO2 actually follows global warming, not causes it. As oceans warm, their ability to store gasseous CO2 decreases and the near-surface dissolved CO2 would be liberated from them. If CO2 truly had a forcing effect, wouldn't this be a positive or "feed-forward" mechanism? In other words, we'd expect as the atmosphere got warmer more CO2 would be freed from the oceans into the atmosphere.

This is true. In fact there is a 600 year lag between global temperature change, and atmospheric CO2. The level of CO2 in our atmosphere is mostly regulated by the oceans, and yes, more CO2 in the atmosphere does provide positive feedback. But there are other dynamic CO2 sinks which regulate this in turn.

I don't know how current climatology models can explain the NOAA report. I'd like to hear, though. That one report has huge ramifications, if it is to be believed, across the entire spectrum of this argument, in my humble opinion.

The problem with climate models, is that you can tweak a few parameters and get them to indicate just about anything, and they probably don't fully reflect anywhere near the complexity that is involved in climate change. The science also exists in a highly politicized and polarized environment.

 

[Tippit]

Water vapour tends to be ignored because there is a limit to the amount the atmosphere can absorb. Then it rains, and the level goes back down. There is no limit to the amount of CO2, methane etc that the atmosphere can hold.

Lots of useful info here: http://openlearn.open.ac.uk/course/view.php?id=2805

CO2 is also absorbed. It's food for the plants and trees that cover the earth's surface, and it is absorbed from the atmosphere by the oceans as the earth cools. In fact there will be more flora as more CO2 food is produced, which serves as a natural sink for human CO2 emissions. Deforestation will of course offset this, but probably not in a meaningful way. And lets not forget that CO2 has a miniscule GWP next to water vapor. The crucial point is that CO2 is not the driving factor in greenhouse warming, not even close. CO2 would have to increase anywhere from 38 to 678%, depending on which GWP numbers you believe, in order to have the same warming potential.

 

[AK-Dave]

I really don't care too much about the warming aspects of increased CO2 in the atmosphere. Most animals (remember that most animals live in the ocean) will adapt by adjusting where they live. I'm more worried about the dissolved CO2 in the ocean lowering the pH of the ocean, which will prevent many organisms (corals, clams, etc) from being able to extract calcium from the water. A major disruption of the ocean ecology will have a more immediate impact than a global warming trend, as many people rely on fish and other ocean products for their protein.

I can dig up some relevant articles if anyone is interested in the effects of increased CO2 in the ocean.

-David

 

[Pixel42]

The crucial point is that CO2 is not the driving factor in greenhouse warming, not even close. CO2 would have to increase anywhere from 38 to 678%, depending on which GWP numbers you believe, in order to have the same warming potential.

So? I say again there is a limit to how much water vapour the atmsophere can hold. There is no such limit to how much carbon dioxide the atmosphere can hold. That's the crucial difference between them.

 

[Dr. Imago]

I really don't care too much about the warming aspects of increased CO2 in the atmosphere. Most animals (remember that most animals live in the ocean) will adapt by adjusting where they live. I'm more worried about the dissolved CO2 in the ocean lowering the pH of the ocean, which will prevent many organisms (corals, clams, etc) from being able to extract calcium from the water. A major disruption of the ocean ecology will have a more immediate impact than a global warming trend, as many people rely on fish and other ocean products for their protein.

I can dig up some relevant articles if anyone is interested in the effects of increased CO2 in the ocean.

-David

Yeah, let's look at them. I'd guess they are referring to increasing levels of carbonic acid and would be interested in seeing things such as what the actual effect is, as well as what the effect on photosynthetic microorganisms would be, especially in light of the fact that we are talking about parts per million changes.

-Dr. Imago

 

[Giggywig]

I'm on the "need more info" side. I'm also on the "I haven't felt like doing the research myself yet, and threads on GW around here degenerate by the 2nd page and become a chore to read" side.

 

[greymatters]

Stop climate change?!?

Nope, it's not photoshopped. This is a picture from Norway, where the former vice president was accepting his Nobel Peace Prize.

 

[Corsair 115]

In my opinion, CO2 is not a pollutant, and the AGW doom and gloom scenarios pushed by the IPCC are a way to justify global taxation by the UN, and to give credibility to UN regulating bodies.

Uh, just when did the UN become a global government? Last I checked, it was hard to get it to agree to take action on anything.

Besides, any collective action is a result of negotiation and mutual agreement among the participating nations. In other words, there's a lot of talking until such time all the parties agree to the plan the talking produced.

Global Warming is probably caused by changing trends in solar radiation...

If so then shouldn't we see warming on all the planets of the solar system? Especially the ones closer in? So shouldn't Mercury be a lot hotter now than before this solar radiation increase?

 

[Dr. Imago]

Thanks for your comments, Corsair and greymatters. But, I'm not really interested in the political side of the debate or speculation. I'm more interested in the "proof of concept" part.

I'd like to see an experiment, as described above, where the exact amounts of CO2 described are placed side-by-side in ideal conditions that control for other potentially confounding factors and a real measurement of the temperature change effects are observed and recorded.

I haven't been able to find such experiments published. It may be that I'm just not looking in the right places. If anyone can help and point us in the right direction, I'd be much obliged.

-copro

 

[EHLO]

Any waste product that humans produce and pump in to the land/ocean/atmosphere is going to have some effect, and if we don't fully understand what that effect is then it would seem prudent to minimise all emissions. I'm worried that the whole AGW/CO2 argument has obfuscated the issue of pollution/waste in general.

 

[m_huber]

Thanks for your comments, Corsair and greymatters. But, I'm not really interested in the political side of the debate or speculation. I'm more interested in the "proof of concept" part.

I'd like to see an experiment, as described above, where the exact amounts of CO2 described are placed side-by-side in ideal conditions that control for other potentially confounding factors and a real measurement of the temperature change effects are observed and recorded.

I haven't been able to find such experiments published. It may be that I'm just not looking in the right places. If anyone can help and point us in the right direction, I'd be much obliged.

-copro

Such an experiment would really be irrelevant. If we try to simulate the global effect of CO2 in a lab-scale system, we won't see the same results. Think about the column of atmosphere that sunlight radiates through, then tries to radiate back through. We cannot adequately replicate that on a smaller scale.

What we can do is look at indirect evidence of CO2 levels in the past. Check out what Yale has online about CO2 in the Cenozoic, which doesn't correlate temperature directly, but does show that ecological changes were driven by processes other than pCO2 in the atmosphere.

Looking at temperature in an environment is really complex, because there is the expected trend that would show a close correlation between greenhouse gas concentrations and temperature, and then there are extreme variations from that, often caused by meteor impacts or large volcanic events (or other large-scale phenomena). When we find periods of time that don't have these exacerbating factors, we see a close correlation between CO2 and temperature. The question, really, is whether the CO2 follows the temperature or visa-versa. We don't know the answer. We also don't know if it causes a feedback loop with global temperature.

You might look at this blog to see a straightforward analysis of why we think humans are playing a major role.

Greenhouse gases provide a reasonable explanation for the warming, while no other factor can explain the entire warming (though other factors, such as solar, might be playing a minor role).

And this entry on CO2/temperature correlation.

In summary, in the parlance of climate scientists, we would say that CO2 was acting as a "feedback" over the time period in the figure above. In the past century, however, humans have taken over the carbon cycle and now dominate the year-to-year atmospheric changes. Thus CO2 has now become a "forcing."