[mkempe]

Yes, climate and atmosphere do change. There is nothing sacred about current measurements and composition.

Here are estimated CO2 levels through geologic time -- "currently" rather low! -- at UCSD site:

http://earthguide.ucsd.edu/virtualmuseum/climatechange2/07_1...

CO2 is essentially airborne fertilizer. Our planet wouldn't be so green without lots of it. (I'd rather be alive during an interglacial, abundantly green geological period.)

[ceejayoz]

> CO2 is essentially airborne fertilizer.

Sure, but as with fertilizer on fields, there are consequences for using way too much.

> I'd rather be alive during an interglacial, abundantly green geological period.

As long as there aren't a billion or so refugees from the low-lying areas rampaging through.

[mkempe]

> using way too much

Hence my link to CO2 levels over Geologic Time. Do you think there was "way too much" CO2 in the past?

[ceejayoz]

For Earth? No. For human society as we currently know it? Seems that way. We'll survive climate change, but flooding places like Bangladesh is going to cause tremendous upheaval.

Humanity survived the ice age, but that didn't make it a fun period in our history.

[mkempe]

You seem to suggest a pessimistic and static view of human society. The planet is not static, climate isn't either; why would society and civilization be? is there a single, optimum equilibrium for humanity? what's the evidence?

[ceejayoz]

There's no single, optimum equilibrium, but a disaster that makes double-digit percentages of the planet refugees seems to fit squarely in the "sucky" end of the spectrum.

[seabee]

There is no single optimum, however there is value beyond merely surviving. Our quality of life is better than it was in the past, so why would anyone be happy at the prospect of that going down due to climate change?

[mkempe]

True, it shouldn't be survival for its own sake. But do we really believe that our quality of life will be going down because of (some, warmer or glacial) climate change? how soon does that happen, and is humanity powerless to adapt? I have a very optimistic view of human potential, I think in essence and the long term all problems can be solved.

Does the fact that CO2 levels have varied hugely in Geologic Time affirm that we are under imminent threat of terrible climate changes? is it irrelevant? or contradictory? or a puzzle? is it impolitick to ask such questions?

[mkempe]

How interesting that my honest questions are being down-voted.

Edit: I want to be scientific, include all relevant evidence, and some people here dislike it? (I'm not interested in the politics -- I've never even voted in a national election. And yes, I see these down-votes as a form of political activism. Disagree and argue if you have reason and facts.)