In yet another attack on CNBC skeptic Joe Kernen, the Bad Astronomer (aka Phil Plait) writes at Slate:
That’s right, [Kernen] thinks CO2 isn’t a big deal because it’s a tiny fraction of the total content of our air. To people who understand reality, yes, 0.04% does sound like a lot, because we understand how the greenhouse effect works. If Kernen thinks 0.04% isn’t a lot, would he drink a glass of water that was 0.04% arsenic? I wouldn’t: That’s hundreds of times the minimum lethal dose. How about if that water contained 0.04% botulinum? A microgram of that protein is deadly. A level of 0.04% in a glass of water would be millions of times the lethal dose.
Dose makes the poison, as doctors say. It doesn’t matter what the amount sounds like. What matters is what it can do. In this case, CO2 makes it hotter, and it doesn’t take much in our air to do that. That is a fact.
Yes, it is the dose that makes the poison. Water with 0.04% arsenic may be lethal — but an atmosphere with 0.04% CO2 is… not an obvious problem despite tens of billions of dollars worth of investigation.