Help me verify if this old claim re: greenhouse gasses is true.

February 27, 2010 12:22 PM

I recall reading in an older (70's or 80's) conservationist-type book this claim: If all CO2 emissions were set to zero today (i.e. all cars/factories/cows/etc. were permanently turned off), the amount of man-made CO2 would keep increasing for another 100-120 years.

I think the basis of this claim was something about greenhouse gasses taking a great deal of time to actually go from the tailpipe of your car to the part of the atmosphere where they start trapping heat or affecting climate.

Is this true, or even supported by modern science? I've never heard anybody, from either side of the AGW debate, make this claim.

Thanks

posted by r_nebblesworthII to Science & Nature (6 answers total)

Human garbage dumps will be outgassing methane and CO2 for centuries.
posted by Chocolate Pickle at 12:29 PM on February 27, 2010

Perhaps you are confusing the idea that the effects of the current amount of CO2 will increase for the next 100 years with the idea that the amount of CO2 will increase for the next100 years.
posted by JackFlash at 12:55 PM on February 27, 2010

CO2 is a stock pollutant, meaning it continues to accumulate over time, and doesn't quickly break down and dissipate once released into the atmosphere. So while man-made CO2 emissions would not increase further if we stopped emitting CO2 today, it is commonly held that the effects of emissions already in the atmosphere will continue to be felt for around 1000 years.
posted by just_ducky at 1:10 PM on February 27, 2010 [2 favorites]

I think the scenario was that increased CO2 emissions makes it hotter, which makes more stuff belch and fart CO2 (animals, oceans, etc), which makes it hotter. After a while, plant life increases and tries to balance it out.

just_ducky, CO2 doesn't just accumulate. It is a stock part of the cycle that sustains life on the planet. Plants make O2 which makes animals which makes CO2 which makes plants. Repeat. The reason CO2 excess emissions are bad is that there aren't enough plants to keep that cycle in equilibrium.
posted by gjc at 5:57 PM on February 27, 2010

Chocolate Pickle's comment isn't relevant. What's in human trash is mostly organic origin CO2 anyway: paper, food, wood, etc. There's a lot of plastic but that isn't going to turn into CO2 unless it burns or some bacteria finally figures out how to eat it.
posted by chairface at 11:02 PM on February 27, 2010

It's not fatalistic environmentalists, it's that you're mis-remembering the details. You're pretty close though...

The claim today is that even if humans stop producing CO2 today, it would take decades for the world's forests and oceans to absorb what is already in our atmosphere. That would mean decades more of the warming effect continuing until equilibrium between natural production and absorption is achieved.

The delay isn't in the CO2 (and other greenhouse gas equivalents) reaching the atmosphere, it's in the rate of absorption. Deforestation and ocean warming are slowing this already slow rate.

James Hansen's report is the best place to get the details, but I found the claim on several environment websites (notably 350.org), so it's not just an old claim, it's still relevant.
posted by harriet vane at 1:11 AM on March 1, 2010