Thursday, February 15, 2007

CO2 (carbon dioxide) is a pollutant

I recently got into a online discussion with someone who made the ridiculous argument that CO2 (carbon dioxide) can not be classified as a pollutant. Below are the reasons he gave that it is not a pollutant and my responses:

".. benign gas..."

Many pollutants are "benign" at low levels. The are several ways in which CO2 is not benign at higher concentrations.

"..occurs naturally..."

Many pollutants (maybe even most) occur naturally - asbestos, mercury, sulphur, radiation,

"helps to maintain the earth at a temperature suitable for life"

Ozone as it exists in the atmosphere also helps to maintain life on the earth. But it is also considered a pollutant.

"...essential to the growth of all plants..."

Nitrates are essential to plant growth. Sulphur is an essential element for cell growth. But both are considered pollutants.


sylvia said...

labelling something a "pollutant" is much like calling something a weed. "pollutants" like CO2 and "weeds" like dandelions are benign, naturally existing / arising entities. but if there's too much CO2 gas being generated, or too many dandelions on that suburban lawn, then they get called "pollutants", or "weeds".

otherwise, one is simply the gas that plants require to photosynthesise, and the other is a plant that is both a lovely flower and cuppa tea.

Rob said...

Not sure I quite agree with the analogy. Too much C02 can do harm.

Too many dandelions - while some people might not like them,they won't do any harm.

"Weed" is a pretty arbitrary term. I heard once that in an Indian language what we call "weed" translates as "bonus crop."

Pollutants are not so arbitrary. If the levels are too high they cause very real and specific damage.

sylvia said...

"weed" = "bonus crop" is actually precisely my point. it's a matter of perception. i'm NOT saying here that too much CO2 is a matter of perception (you know whose side i'm on here), but if you talk to a moncrop farmer, "weeds" cause damage, for example. given my preferred method of farming, i don't agree, but your average big farm will show you the books.

anyway, for your convenience, let's erase the dandelion analogy and just say CO2 is a NECESSARY and naturally existing gas, when present at whatever benign level within whatever closed system you choose - and a pollutant at some, other, defined higher level. ie, "too much of anything is not a good thing".

sylvia said...

ps. the internet explains this better than i do. here's some bedtime reading :) looks like it's become quite the political issue. but an analytical biological chemist like myself WILL tell you that it's all about concentration.