Consider this argument often made by climate skeptics:
Water vapor is the most important gas, contributing 97 percent of the greenhouse effect. Carbon dioxide is only small percentage. Therefore, regulating carbon dioxide will have no impact on our climate.
WhileEven if these numbers are generally correct, there are lots of problems with this argument. For example, it disregards the fact that climate forcing by water is really a feedback, and that changes in carbon dioxide are amplified by the water vapor feedback.
Then there's this problem: the argument includes an implicit assumption that a small fractional change of any quantity is intrinsically unimportant. It might make intuitive sense: carbon dioxide is only 3 percent of total forcing, and how can 3 percent of anything be important?
This is, of course, nonsense. Consider the following example. You make $2,000 per month and your expenses are also $2,000 per month. Now let's assume that a new expense of $10 per month suddenly arises. You might argue that the $10 expense is insignificant compared to the existing expense of $2,000 per month. But on long time scales, regardless of how much money you have saved up, this small imbalance will eventually bankrupt you.
This analogy is quite apt when considering carbon dioxide and climate. Our relatively small additions of carbon dioxide each year trap a correspondingly small amount of energy. Over the course of a century, however, these small increments of energy combine to greatly warm the planet -- just like the $10 per month increment in expenses adds up over many years to completely drain your account.
Here's a more concrete example. The average depth of the ocean is 4,000 m (about 12,000 feet). Consider a 0.1 percent increase in ocean depth. That's a small amount. How could a 0.1 percent increase in anything be important?
Here's how: a 0.1 percent increase is 4 meters (about 12 feet). Such a sea level rise would be a catastrophe of unimaginable scale. Over 300 million people live within 12 feet of sea level (that's today; many more will do so in a future world). Not only will such a sea level rise result in the relocation of people and loss of land, it will also destroy trillions of dollars of infrastructure.
While changes in carbon dioxide only change the total forcing by a few percentage points, the total forcing is so large that this change is really significant. It's enough to increase our surface temperature by a few degrees in a century, a rate of change that has few, if any, precedents in the history of the world. And certainly no precedents since the rise of modern human society a few hundred years ago. Let's hope we act to head off this very bad future.
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Comments
View as Flat
MarkUK Posted 6:42 am
04 Apr 2007
A % of A %...
Of course they also like to point out that of the CO2 only a tiny part is of human origin. So the effect of human CO2 emissions must be close to zero...
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fermiparadox Posted 6:53 am
04 Apr 2007
Even the 97% are wrong
The number 97% is just plain wrong. Surprising that you say it's correct, since there is an answer to that in the guide here.
Apart from that, good points.
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GreyFlcn Posted 6:55 am
04 Apr 2007
Well
Then you point out that the balance of natural carbon sinks, versus natural carbon emmisions were pretty well in balance.
And that never in 650,000 years of previously recorded history did the CO2 levels go above 281ppm
We're currently at +480ppm of CO2 in the atmosphere.
_
To me that was the major take away point from that Gore movie.
_
But also people act like water vapor is ignored.
NO.
http://www.greyfalcon.net/forcing3.png
Water vapor in the stratosphere lasts for about 1 year. (The upper atmosphere)
Water vapor in clouds is rather important.
_
But water vapor in the troposphere can't be forcing global warming. (The lower atmosphere)
The amount of water vapor in the lower atmosphere changes near instantaneously to the temperature.
Colder it gets, the more water condenses and rains out.
Warmer it gets, the less water condenses and rains out.
But any EXCESS water vapor instantly condenses and rains out.
And there's a lot of excess.
Assuming we took out all the water vapor.
Given the rapid rate of evaporation.
Within 2 days, almost all of it would be put back.
Within 10 days, all of it would be put back.
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mspelto Posted 7:00 am
04 Apr 2007
Good analogy
Using budget examples is the best way to bring a message home. Having observed 47 North Cascades glaciers every year since 1984, well actually only 43 are left, we have noted that a small percent change in snowmelt compounds quite dramatically. We measure glacier mass balance, and if glacier snowmelt increases by 3%, than the mass of the glacier declines by a like amount each year, rather quickly leading to its disappearance. Glacier mass balance is an annual budget, they have income snowfall and expenditures snowmelt. If there is a deficit they have to pay it out of pocket, depleting the glacier. North Cascade Glacier Research
mspelto
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Andrew Dessler Posted 7:29 am
04 Apr 2007
You're right
Fermiparadox-
I should have said "Even if these numbers are correct ...". You're correct that those numbers are wrong.
Thanks!
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GreenEngineer Posted 7:40 am
04 Apr 2007
small differences
Of course they also like to point out that of the CO2 only a tiny part is of human origin. So the effect of human CO2 emissions must be close to zero...
This comment, as well as the root issue (the relatively small fraction of atmosphere that is CO2) reveals a basic misunderstanding about how to think about this stuff. It's not a matter of absolute quantities or static values. It's a matter of balance. If the heat leaving equals the heat entering, you have a stable state. If the heat leaving is even slightly less than the heat entering, you get a net heating effect. Ditto with CO2 in the air: Natural processes make lots of CO2, and absorb lots of CO2. Human activity releases smaller volumes of CO2, but does not uptake CO2 in similar proportion. The degree of out-of-balance may be small, but if it's consistent over time, it will add up.
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GreyFlcn Posted 8:21 am
04 Apr 2007
Actually
Yeah,
Thats really what the issue is.
So the complaints about "OMG Volcanoes put up lots of CO2" It's really easy to shut that argument down for the strawman that it is.
In 650,000 years of records
Countless volcanic eruptions
We've never gone above 281ppm of atmospheric CO2.
This year, we're somewhere around 480ppm of CO2.
So it doesn't matter if our contribution is small.
The total net effect on atmospheric CO2 balance is large.
_
It's kind of like a counterweight pulley crane.
A little force in, and you can move amazingly heavy objects.
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Icelander Posted 8:25 am
04 Apr 2007
My Response
My response to that canard is usually "That may be true, but I haven't seen carbon dioxide condensing out of our atmosphere and falling to the ground."
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blogassault Posted 9:00 am
04 Apr 2007
Trying Too Hard
I have an easier way to explain it. When the U.N. needs to increase funds by 3%, it releases a report to show how the report they released last week was not quite accurate and that.... (whatever the problem is)it is significantly worse than first thought because our computor model had the wrong perameters inputed.
Once this is released to the media, a forward push is on, and funds increase.
Long story short, POLLUTION needs to be regulated, but not by an orginazation that swaps oil for food with a former thug, and has human rights commissions that set around for the entire year of 2006 to write up over 80 resolutions about how Isreal is mean to the Palestinians. If it looks bad, it probably is bad, including the IPCC.
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GreenEngineer Posted 9:09 am
04 Apr 2007
Wow!
Apparently discussions of global warming lead to incoherent blog posting. Amazing! I wonder if it's a causal relationship, or merely correlative.
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Coby Beck Posted 12:39 pm
04 Apr 2007
380 not 480
minor correction from the comments: CO2 is currently around 380ppm not 480ppm. This is still very much higher than ever seen in the 800+KY ice core records and perhaps unprecedented in many millions of years.
"The problem with people who have no vices is that they tend to have some pretty annoying virtues." -- [paraphrased] Elizabeth Taylor
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GreyFlcn Posted 12:48 pm
04 Apr 2007
Well yeah
re: Icelander
--My response to that canard is usually "That may be true, but I haven't seen carbon dioxide condensing out of our atmosphere and falling to the ground.--
Thats because carbon dioxide doesn't do that.
It floats back down, and is absorbed by plants as a gas.
Particularly Phytoplankton, (Which accounts for more than half the earth's biomass production capacity)
Where it then sinks to the bottom of the ocean until the bottom of the ocean warms up.
Which usually takes about 800 years give or take.
Catch is, carbon dioxide normally stays up there for about 100 years before it comes back down.
(Methane, only about 14 years, but it's 23x more potent as a greenhouse gas)
In a natural cycle, this hasn't been a problem since the ammount coming down and the ammount going up where mostly in balance with each other.
(Except of course when the bottoms of the ocean heats up)
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GreyFlcn Posted 12:49 pm
04 Apr 2007
Thanks
Cool beans.
I'll need to find a source for that info.
I shouldn't be quoting it so idlly without ;D
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tico89 Posted 1:52 pm
04 Apr 2007
"I hadn't thought of it that way"
It's easy to throw percentages around without thinking about what they actually mean. In any terms, most people just dismiss something like 3% as unimportant. "3% of the people taking that vitally important country-wide exam failed." "Oh, that's no big deal, that means 97% passed. That's a good record." "But 1000 people took the test. That means 30 people have just had their futures ruined." "Oh. I hadn't thought of it that way."
It's like saying "well the IPCC report did leave a slight margin of error", or "well, if the sea levels only rise about 25cm, that's nothing." It's very difficult to look at numbers on a wider scale. Must be why so many hate maths.
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MarkUK Posted 5:39 pm
04 Apr 2007
Bit off topic...
Just in case anybody missed this blog:
http://initforthegold.blogspot.com/
It's a real gold nugget and well worth a read...
An excellent article on dealing with denial...
http://initforthegold.blogspot.com/2007/03/why-truth-is-l ...
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WWAGD?! Posted 2:55 am
05 Apr 2007
How Did We Last This Long?
Why is it that Grrrristers will go on and on about the wonder of nature and harmony of planet Earth and so on...but when they want to sell you some silly idea like CO2 "forcing" they then claim that Earth is like a frail old lady that can catch cold from a single dust spec?
I mean, seriously, if these minuscule amounts of carbon are (butterfly effect style) causing Armageddon, I can't really say much for the planetary designers of spaceship earth.
As is well known, my own feeling is that the CO2 increases are a result -- not a cause -- of the warming. Human activity has increased because of whatever it is that's raising the temperature and hence more CO2 (as well as other stuff).
The Texeme Construct offers international text memetics construction and textcasting services. http://www.you-read-it-here-first.com
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MarkUK Posted 3:05 am
05 Apr 2007
huh?
"Human activity has increased because of whatever it is that's raising the temperature and hence more CO2 (as well as other stuff)."
I don't get it. Can you explain?
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GreyFlcn Posted 3:22 am
05 Apr 2007
Well
We know:
- It's not the sun
- It's not cosmic rays
- It's not water vapor
- It's not volcanoes
- It's never been this hot in recorded human history.
Certainly whatever is causing it is something that we are causing.And all the models, and evidence agrees with the CO2 theory.
_
Could it be something besides CO2?
Sure.
But it's mostly likely something that humans are causing, since there are no known natural forces that can explain the rapid warming of the last 3 decades.
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Andrew Dessler Posted 4:21 am
05 Apr 2007
still haven't read the IPCC?
Jabailo-
I guess this means that you still haven't read the 2001 IPCC document that lays out why the scientific community thinks humans are to blame. In case you lost the link, you can find it here:
but then you don't take the time to actually read the literature.http://www.grida.no/climate/ipcc_tar/wg1/439.htm
If find it interesting when people like you say you want:
As far as your statement above, even George W. Bush would disagree with you. The most convincing evidence that the CO2 increase is manmade comes from isotopic analysis. Atmospheric measurements show that the increase in atmospheric CO2 is caused by a flux of "radiocarbon dead" CO2, meaning that it has no carbon 14 in it. The source of this CO2 must also be radiocarbon dead. Fossil fuels are indeed radiocarbon dead, while biomass is not. One can therefore conclude that the increase is due to fossil fuel combustion and not a biogenic source. I'm certain there are other reasons to conclude this, but to me the isotopic analysis is entirely conclusive.
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tico89 Posted 8:14 am
05 Apr 2007
How very scientific
"Feeling"? "Whatever it is"? "Other stuff"?
Hey, jabailo, you couldn't be a little bit more vague could you?
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GreenEngineer Posted 8:30 am
05 Apr 2007
watch out!
Hey, jabailo, you couldn't be a little bit more vague could you?
Don't tempt him. He might spontaneously generate a black hole of vagueness, which sucks in all sense and spits it out in some other universe.
The really tough thing, of course, would be figuring out where the damn thing is. :)
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tico89 Posted 1:02 pm
05 Apr 2007
Standard Form
(Too true, GreenEngineer)
Going back to my original comment, this is of course where standard form, plus all the micros and nanos (and the megas and teras), came from. Move the numbers closer to the decimal point to make them seem more important, as it's tough to realise that a small number can mean anything.
Seems like a lot of what is supposedly there to make things easier is actually there to get people to realise they're dealing with something real.
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