Previous  1  2  3  4  5  6  Next

I'm just interested to know from those that deny AGW what their model is for the radiative properties of a CO2 molecule. That's what I don't get. Do they think that CO2 is transparent to heat? I haven't heard a decent answer on that count from any of them. Probably because most of the deniers don't understand basic thermodynamics--if they did they likely wouldn't be deniers.

   

I think the understanding is that the way a handful of CO2 molecules react to heat in a controlled environment is pretty far removed from the additional effect of a few million tons of CO2 added to the existing billion (?) ton conglomerate of gases and chaotic turbulence that is the global atmosphere.

Similarly, a pinch of table salt might make your steamed carrots taste better, but that principle doesn't necessarily extend if you dump a few tankers of it into the ocean. It might not be enough to matter, or it might kill off some creatures that have more effect than itself, or it might accelerate the ocean's desalinization processes resulting in a return to homeostasis, or any number of other outcomes.

On the other hand, you're an actual environmental scientist and I'm not sure if a billion tons is the proper scale for Earth's atmosphere; maybe my reasoning is not the important factor here.

   

The math for the CO2 is actually quite simple. We know the concentration of CO2 in the atmosphere, and we know the weight of the atmosphere (about 15 lbs/square inch), so we can easily estimate the number of CO2 molecules, and and the quanta of infrared radiation absorbed by CO2, and the infrared radiation which is re-radiated back to the surface of the earth.

I think an atmosperic increase of 1 ppm CO2 equates to about two billion tons (2 Gt) of carbon (note: carbon, not CO2). According to wiki the average emission globally is about 4 tons carbon/person. Multiply by 7 billion, and you have humans adding about 28 Gt/year at current rates. Since CO2 is only increasing at about 2 ppm/year, obviously the CO2 we emit isn't all accumulating in the atmosphere.

That's fairly basic stuff. And since there's an exponential relationship between the radiative focing and the concentraiton of CO2, we can caluclate that each doubling of CO2 should add about 1.1 degree of heat to the atmosphere.

The measurement of CO2 in the atmosphere seems to be one of the few areas of global warming that isn't very controversial. Most folks are willing to admit that the concentration of CO2 was about 280 ppm about 150 years ago and now we're at about 390 ppm. Regardless of where you think that increase came from, that's a pretty significant jump.

Of course, CO2 in the atmosphere acts within a complex and interdependent ecosystem. So, in practice, the heat affect of more CO2 is either amplified or attenuated based on a myriad of other things (most importantly, most think, its effect on water vapour). So cimate scientists came up with a fudge factor, called climate sensitivity, to account for feedback effects. A climate sensitivity greater than one means that affects of CO2 heating are amplified by other systems; less than one and the feedback systems attenuate or lessen the effects of CO2.

IPCC scientists think that a doubling of CO2 will actually result in a temperature increase of 3 deg C (three times the number based solely on the radiative physics) due to amplifying feedback effects which I won't go into here. I'm skeptical of that number myself.

AGW skeptics, on the other hand, say that doubling CO2 will result in a temperature increase of 0 deg C. Yet I've never seen a decent explanation as to what negative feedback effects would be causing that. If the energy isn't heating the atmosphere, it must be doing something else. Energy is indestructible.

   

You will be interested in this, zipperfish, with its references that put long term climate sensitivity at greater than 3C.

http://www.skepticalscience.com/estimat ... s-ago.html

This is one who puts the sensitivity lower and with a narrower range of uncertainty.

http://newscience.planet3.org/2011/11/2 ... l-maximum/

This shows the shortcomings in Urban's calculation of sensitivity with a very thorough examination of sensitivity.

http://www.realclimate.org/index.php/ar ... nsitivity/

   

A few tankers of salt in the ocean doesn't equal the atmospheric rise in CO2. Atmospheric CO2 has increased by 70% (from 280ppm to 390ppm). There are 16 quadrillion tonnes of salt in the ocean so you would have to add another 11 quadrillion tonnes to equal the percentage increase in CO2 in the atmosphere. That's a lot of tankers, and maybe you've put your finger on why people don't seem to believe in warming caused by anthropogenic CO2.

   

Some interesting stuff in here I'd never seen exposited. And, CO2 concentration has risen by 70% in the last 150 years. At 1 degree rise in temp per 100% increase in CO2, you would expect a rise in .7 degrees global temp. over the last 150 years What's the rise in global temp been over the last 150 years again?

   

The rise now, andy, is about .9C. However, that is not the whole story. The rest of the increase is built in to the CO2 and will come even if the rise in CO2 is stopped.

It is an eventual increase of between 2 and 4.5 (with the most support for around 3C) that comes from a doubling of CO2.

   

We're doomed.

That said, if we're doomed then why should I give a flying f*ck about AGW when Russia, China, India, Brazil, and all of Africa could care less?

   

Good stuff, thanks. I liked Urban's interview--he did a good job of explaining things so the reader can understand.

   

Andy, greenhouse gas forcings over the industrial period are estimated at 2.3 W/m2. (source: http://www.ipcc.ch/publications_and_dat ... ns2-2.html) That's for CO2, CH4 and N2O.

The temperature increase has been 0.6 or 0.7 deg C, leading to a climate sensitivity (usually shown as the small greek letter, lambda) of about .28 K.m2/W. This is a lot smaller than than the IPCC projection. The IPCC projection is 0.8 K.m2/W (which works out to a temperature increase of about 3 deg C for a doubling of CO2).

The explanation given by the IPCC for the discrepancy is, I think, the effects of aerosols.

The fact that the measured climate ensitivity sicne 1850 is small is one of th reasons I'm skeptical of the IPCC climate sensitivity.

   

Then why did you think I meant that? Yes, the amount of salt in the ocean is a closer metaphor for the amount of CO2 in the atmosphere, but my intent was to metaphorically compare the taste of salt in the ocean to the global temperature effects of CO2 in the atmosphere -- not the quantities directly. The imperfect correlation was kind of the point.

They do? I don't. The skeptic stuff I recall argues that the increase is 0 < x < 3 deg, and suggests that the consequences of an x increase are probably negligible. Anyway, that's the paradigm within which I consider myself a skeptic.

Of course not. It wasn't intended to be to scale.

   

Then it was a meaningless analogy. Or, worse than meaningless, deceptive.

   

I didn't think you meant that. My point was just to commuinicate that, unlike global average temperatures, the CO2 concentrsiton in the atmosphere isn' subject to much dispute.

My objective in that post was just to do g some math to demonstrate that the amount of CO2 we emit should be measurable in the atmosphere, both in terms of concentraion and radiative forcing (i.e. heat).



I'd be a skeptic by that yardstick to, since I believe that climate sensitivity is going to be less than 3 deg C/doubling of CO2 (except, perhaps, in the Arctic).

But most skeptics here at this site and elsewhere think the whole thing is being fabricated by a cabal of scientists and liberal elites. (Actually, I think it's being exaggerated (as opposed to fabricated) by advocacy scientists who are more concerned with communicating their perceived urgency of the situation than about scientific rigor.)

I just wonder if they believe there is more CO2 in the atmosphere, and, if they do believe that, where they think the heat is going, if not to heat the atmosphere.

I suspect, as I've said before, that the opposition to global wamring isn't so much the science as it is the various policy remedies proposed (particularly global wealth redistribution schemes).

   

What is the rate of increase of current CO2 emission? Presumably it's more than the 70% we added in the last 150 years. So at the rate of 1 deg/doubling of CO2, it may not take long to get to a 2 deg increase in global temp - which we are assured will have serious consequences. If that's true, then just business as usual doesn't seem like a good option.

   

In all due respect, as long as there is a debate from both sides, then that's ok.

The problem is that usually have only one side being presented in the media or in the schools for that matter. Ecologists are often the only ones being invited to discuss their opinion. Propaganda of sort. Anothing interesting thing would be to find out which interest groups fund these research.

But the thing is, that you have lobbyists inciting Governments to spend millions upon millions of dollars to go eco-friendly, often without even being challenged. Especially in QC, where our politicians in the PQ/PLQ give in to these Greenpeace types every time, you know those ones protesting in the middle of the day, every other day, as they don't have anything else to do. The important thing is to have both sides presented then have the population draw up their own interpretation.

   

Previous  1  2  3  4  5  6  Next