NoaIzumi“Water vapor accounts for 95% of the greenhouse effect”: Deconstructing the Claim.
June 23rd 2009 21:18
The claim of water vapor being 95% of the greenhouse effect is still seen every so often, and can be traced to one source:
West Virginia Fossils
If you see this claim anywhere, chances are very good that it ultimately came from this site.
One of the first things that you may notice is in Table 3, around the middle of the page, where they don’t just claim that water is 95% of the greenhouse effect, they claim that it’s 95.000% of the greenhouse effect. Nothing in nature is that even, unless it’s being defined as such. This raises red flags right away.
But let’s take a look at what they have to back it up. (under References, #4)
a. Being the only peer-reviewed reference, this seems to be the strongest, but just take a look at the title. The paper looks at the absorption of solar radiation. The greenhouse effect is about the absorption of longer-wavelength terrestrial radiation. The reference is irrelevant to the topic.
b. Patrick Michaels is a respected scientist, but he gives no reference or experimental findings to back this claim up. It’s just his say-so.
c. Table D2 of the ref disagrees with the 95% claim, and the ref that the site wants us to see is actually the first paper on this list.
d. Personal communication. Again, Richard Lindzen is a respected scientist, but it’s just his say-so.
e. Dr. Patterson says that water vapor is 98% of all greenhouse gases by volume, but that’s not the same thing as saying it’s 95% of the greenhouse effect.
f. It’s a parody site, and only claims 90%.
g. Like Dr. Patterson, Lomborg says water vapor is 97% by volume, which is not the same thing as saying it’s 95% of the greenhouse effect.
h. This one actually has a paper to back it up, but the paper discusses radiative transfer in solids, not gases. It also looks only at the 5.6-7.2 micrometer range, while CO2 absorbs over a much greater portion of the infrared spectrum.
i.This one has three refs for the claim, two of which are a scientist’s say-so, while the third is a paper that concerns models. The third reference doesn’t measure contributions directly, although it might ref something else.
So, out of nine references, one doesn’t address the greenhouse effect at all, one disagrees with the claim and refs the first paper (and this was the site’s only ref for a long time), two are not scientific studies but opinions by scientists, one is a parody site, two address only the relative volume of water molecules and not their contribution to the greenhouse effect, and two reference other papers which do not measure the GH contribution directly but might (or might not) reference something else. None of the refs aside from the first are peer-reviewed scientific papers.
So, what’s on the other side of the argument? Just two references that say CO2 alone is responsible for at least 12% of the greenhouse effect, and come to that number by direct experimentation and observation.
Earth’s Annual Global Mean Energy Budget (PDF file)
Role of CO2 in Trapping Radiation
RealClimate’s two cents on the matter
WVFossil’s references may seem impressive, but quantity does not trump quality in this case.
West Virginia Fossils
If you see this claim anywhere, chances are very good that it ultimately came from this site.
One of the first things that you may notice is in Table 3, around the middle of the page, where they don’t just claim that water is 95% of the greenhouse effect, they claim that it’s 95.000% of the greenhouse effect. Nothing in nature is that even, unless it’s being defined as such. This raises red flags right away.
But let’s take a look at what they have to back it up. (under References, #4)
a. Being the only peer-reviewed reference, this seems to be the strongest, but just take a look at the title. The paper looks at the absorption of solar radiation. The greenhouse effect is about the absorption of longer-wavelength terrestrial radiation. The reference is irrelevant to the topic.
b. Patrick Michaels is a respected scientist, but he gives no reference or experimental findings to back this claim up. It’s just his say-so.
c. Table D2 of the ref disagrees with the 95% claim, and the ref that the site wants us to see is actually the first paper on this list.
d. Personal communication. Again, Richard Lindzen is a respected scientist, but it’s just his say-so.
e. Dr. Patterson says that water vapor is 98% of all greenhouse gases by volume, but that’s not the same thing as saying it’s 95% of the greenhouse effect.
f. It’s a parody site, and only claims 90%.
g. Like Dr. Patterson, Lomborg says water vapor is 97% by volume, which is not the same thing as saying it’s 95% of the greenhouse effect.
h. This one actually has a paper to back it up, but the paper discusses radiative transfer in solids, not gases. It also looks only at the 5.6-7.2 micrometer range, while CO2 absorbs over a much greater portion of the infrared spectrum.
i.This one has three refs for the claim, two of which are a scientist’s say-so, while the third is a paper that concerns models. The third reference doesn’t measure contributions directly, although it might ref something else.
So, out of nine references, one doesn’t address the greenhouse effect at all, one disagrees with the claim and refs the first paper (and this was the site’s only ref for a long time), two are not scientific studies but opinions by scientists, one is a parody site, two address only the relative volume of water molecules and not their contribution to the greenhouse effect, and two reference other papers which do not measure the GH contribution directly but might (or might not) reference something else. None of the refs aside from the first are peer-reviewed scientific papers.
So, what’s on the other side of the argument? Just two references that say CO2 alone is responsible for at least 12% of the greenhouse effect, and come to that number by direct experimentation and observation.
Earth’s Annual Global Mean Energy Budget (PDF file)
Role of CO2 in Trapping Radiation
RealClimate’s two cents on the matter
WVFossil’s references may seem impressive, but quantity does not trump quality in this case.
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