@abarker said:
@CoyneTheDup said:If this has been in balance for the last 150,000 years
It wasn't in balance prior to the industrial age either. Atmospheric CO2 was actually decreasing, and has been for millions of years.
In fact, there are indications that, prior to the industrial revolution, atmospheric CO2 may have been nearing the critical 180 ppm point. Below 180 ppm, plants can no longer sustain effective photosynthesis and will die. If all the plants die off, then will the food chain last long enough for everyone to asphyxiate? Or will we all choke on the air with full stomachs?
Over a very long time scale, you're right, there has been surplus sequestration. That's a good thing; otherwise Earth would be more like Venus. But assuming there isn't a tip into an ice age (preconditions of which we still don't really know) then 180 ppm should be a limit in a positive feedback system. (Too low, plants die off, absorption is reduced.)
In fact, as conditions were pre-industry, there were surpluses both in ocean absorption and plant absorption, generally speaking. Human emission has easily exceeded the existing sequestration capability.
@abarker said:
Based on geological time-scale data, I'm pretty sure that the amount of CO2 we're putting in the air is not a problem. Current climate trends may make things a bit uncomfortable, but we'll likely survive. And even if we don't, life on Earth will.
As far as temperature goes, that graph is very poor. This is a better representation:
Note that this scale is logarithmic by age, so the rightmost 200 is 200,000 years ago. Man came of age roughly during the blue line area of the graph, and our recorded history is all within the steady-state trailing out from 11-12 thousand years ago.
Note that it also projects temperatures on the right-hand vertical, for 2050 and 2100, and that 2100 most likely projection is warmer than the planet has been since, oh, 10 million years ago. Everything alive now is adapted to that lower range of temperatures. (The original graph is here.)
There's some people who say, this is no big deal; after all the world has been warmer in the past. But our history in not-managing-our-problems has worked out so wellabsolutely abysmally in so many cases that I am distrustful of those who say nothing needs done; especially when those people are paid to say that.
If you want a comparative history, consider that of pollution. There's a lot of snide commentary these days about Beijing, but people have forgotten that Los Angeles was that bad back in the 50s to 70s. As much as it's improved, the smog is still estimated to kill 24,000 people/year in that area. (Overcoming the worst of the smog is a fundamental reason California is a leader in pollution regulation.)
Compare LA Smog: the battle against air pollution with the current global warming arguments and see if you can identify any similarities; there again you'll see the "deniers" and the scientists who were proved right.
(As Randall Monroe wrote, "Science. It works bitches." Those who want to dismiss global warming or science as "mere religion" are not on the side of history.)
There have been catastrophes in the past of the world; I (at least) really would prefer that humanity not become another. (As in, "Then came the next catastrophe, humans.")