I’ve been thinking a lot about how to tackle the problem of misinformation in the global warming debate. Shouting matches on the internet just feed the trolls and rarely achieve anything, and people don’t want to read accurate technical, science-y things, so what can we scientists really do? We can’t attack peoples’ character even when they attack ours, because that just makes us look bad, and fuels the global warming denier image of being an “underdog” or an “outsider”. These people are not on a crusade against science, they are just concerned (and a bit paranoid).
Global warming deniers are people too.
So I’ve decided there are two ways I can actually do something about this problem.
- Make simplified explanations of work in climate science more widely available.
- Write respectful critiques of contrarian ideas.
This is an information war, but unfortunately the right answers don’t win by virtue. Warming contrarians have made huge strides in convincing people of their wild ideas because they have drowned out the correct ideas within certain audiences. The best way to combat this problem is to be more vocal. In my case, I’m going to try and get more articles like this higher up in Google search results.
The second point above is something that is severely lacking. Even I will admit to being overly crude in my criticism. This is clearly illustrated by numerous responses to the work of biologist Nasif S. Nahle, which simply try to discredit him based on his background, and not his ideas.
This is the wrong way to approach the issue.
He claims to prove that an increase in the concentration of atmospheric CO2 will result in a cooling effect on the climate system. He does this with idealized calculations of radiative properties of a mixture of gases.
Before I talk about whether his ideas are valid, I feel compelled to point out that his paper is terribly written (technically speaking). For anyone thinking that people can’t get published when they do work that goes against the current understanding, this is a good example of work that could never be published either way! I don’t buy the idea that you won’t get published if you propose something “against the grain”. But you certainly won’t get published if you are a terrible writer.
In this case, the writing is so bad, that the equations are hard to follow. Many symbols are not defined, or the symbols are switched to different ones without explanation. Being familiar with this type of derivation makes it possible to figure out what was done, but it really shouldn’t be this hard.
Now on to the real problem with Dr. Nahle’s idea
He assumes a mixture of water vapor and CO2. With the equation above he calculates the emissivity of the mixture.
But then he compares this with the correction factor for a new mixture that includes oxygen:
And makes the following (slightly inaccurate) conclusion:
“The emissivity of the water vapor decreased by 0.0872 units.”
He really means to say that the emissivity of the mixture decreases, because he has assumed a fixed amount of mass and unintentionally decreased the amount of water vapor in the mixture. He partially acknowledges this issue:
“The general conclusion is that by adding any gas with total emissivity/absorptivity lower than the total emissivity/absorptivity of the main absorber/emitter in the mixture of gases makes that the total emissivity/absorptivity of the mixture of gases decreases.”
So he has essentially replaced some H2O molecules with molecules of a lower emissivity. In the case of more CO2 it make perfect sense that the emissivity of a mixture with fixed mass would decrease, since H2O is a stronger infrared absorber than CO2. But, then he makes the incorrect jump that adding CO2 must therefore cool the planet, which is a gross misrepresentation of his own results.
Increasing atmospheric CO2 will not lead to reduced H2O,
because the mass of the atmosphere is not fixed.
producing a more accurate version of his calculation is a bit difficult. The mass of CO2 in the atmosphere is small compared to other constituents, but its effect can still be quite large. The more complicated part of the problem comes with understanding the feedbacks. Water vapor is expected to increase with increasing CO2, but it’s not straightforward to build this effect into a simple calculation like the one presented by Dr. Nahle. doing this in a single equation would require many more dubious simplifications.
We have definitely not observed a decrease in H2O, but there has been an obvious increase in CO2. Below I’ve created a plot of globally averaged column water vapor from NCEP Reanalysis 2. As we can clearly see, the trend is positive (and statistically significant), consistent with the notion that water vapor increases with increasing CO2.
Here’s a poor man’s legend:
- Monthly mean
- Annual mean
- Linear Trend (significant at the 99% confidence level)
Hopefully this article can help show why Nasif Nahle’s ideas about global warming are erroneous and misinformed.
However, I want to stress that this is not meant to discredit or demoralize him.