While I essentially agree with the notion that there are compensating factors that keep earth within a 'normal' range and that 'global climate change' doesn't seem to have exerted a fraction of the destruction that it was supposed to have, let me play devil's advocate for a minute here;

Ryan: I think you're on relatively credible grounds when one makes the minimal claim that perhaps the climate will move into areas it has occupied previously, but which we might not enjoy or benefit from as much.

That's plausible, but problematic, for various "Devil's advocates" -- because it still falls into the "stable" scenario.

Example: If earth weathered an ice age, then perhaps we wouldn't like it much -- but earth seems to have weathered one before, leaving us with all the species we have today. And of course, you're making the argument that cold, not warmth, is the bigger danger. (I agree, incidentally.)

Of course the global warming movement isn't based on the idea we merely won't like things much: its more about mass extinctions, etc. If those have happened before, then it's not clear why they would be such a big deal now. (Survival of the fittest, and all that, right?) On the other hand, if they haven't happened before, then either we must exert a never-before seen influence*, or history has been miraculous.

* This point could be attacked, of course. But the problem is that the events of the earth's history are so much more huger-er (grin) than our own influence.

The sun emits heat by burning -- what -- four million tons of hydrogen a second, and spits that out at everything near it -- and we think these tiny internal combustion engines are a comparatively big influence? Solar heat influences water vapor -- which is a much stronger greenhouse gas than CO2. We've survived the age (and intestinal tracts) of the Megafauna and Diplodicus -- not to mention vast herds of buffalo covering the US plains -- but now somehow think that our comparatively few herds of dairy and beef cows are going to do the planet in? Weren't there animals there before too? And are people not aware that the biomass of insect life alone outweighs everything else ten to one? (An an insect alone doesn't digest much, but per pound it's probably no different than any other form of life.)

It seems to me there's a serious failure of perspective happening here.

And of course, you're making the argument that cold, not warmth, is the bigger danger. (I agree, incidentally.)

If you have less heat being moved from the equator to the poles it's possible to get both more heat (at the equator) and more cold (at the poles.) If you have less 'evening out' of temperature disparities via ocean currents it seems possible there might be more evening out via the atmosphere. But again, this assumes that CO2 alone really does exhibit some kind of 'forcing effect' putting more water vapor into the air and that increased albedo from more cloud cover does not compensate for increased retention of heat. I have no clue if this is true or not, or how much heat the oceans actually move around.

Of course the global warming movement isn't based on the idea we merely won't like things much: its more about mass extinctions, etc. If those have happened before, then it's not clear why they would be such a big deal now.

Life seems to have survived even the KT extinction. But God forbid we have to live through that much destruction. I doubt global warming would effect anything close to the chaos of a rock as tall as the atmosphere hitting the earth. I'm just responding to the general logic; that horrible things can't happen within the "normal" range of events.

I think a lot of global warming arguments boil down to "this is going to do a lot of harm (unproven)" without calculating the actual cost of measures to prevent global climate change and weighing them against the supposed harm. Some seem to view climate change as inherently immoral.

But then you're back to my last point: our impact, especially the fraction we can ethically influence, isn't anywhere near as significant as various factors over which we have no influence.

Agreed. If Antarctica is part of the reason for our stable temperatures (which seems reasonable) or if dating of past temperatures is horribly flawed then the whole thing is out of our hands.

Stability followed by chaos can be more destructive than constant chaos... Stability works against that ability to adapt.

Not sure what the larger point here is, though.

It's like saying "well, the dodo's ancestors survived predators by flying away, so the dodo should be able to fly away as well..." Not necessarily.

I bring it up in response to the assertion that systems should be able to survive in the present anything they have survived in the past. That argument isn't prima facie true. Though I'm not expecting global climate change to have a massive effect.

This is being sent from my phone so bear with me please if there's typos or bad punctuation.

I'm not a geologist but I do work in medicine so I'm going to create an analogy here, which is apt. The biosphere is really no different than biology. The human body is inherently "stable". If it wasn't we wouldn't be alive. If our body's core temperature increased even 2 degrees it could lead to serious sickness. A couple more degrees and you could die. Conversely, a temperature drop of a few degrees could lead to mild to severe hypothermia, hypothermic shock and death. The idea od an environment being stable doesn't negate the fact that's what is apparently minor changed can have a major impact.

Also, the argument that "life" survived bad environments is a false comparison. The forms of life that made it through past ice ages and mass extinctions had evolved to be able to survive extremes. Scientists aren't arguing that nothing will live on. The argument is that life will change and depending on the level of change in our environment (which isn't agreed on yet), there may be extinctions of some species. Evolution works 2 ways. It gives us ways to better survive in our current environment and it also takes away attributes that seem "useless" currently. Its a gradual process that, in the face of sudden and drastic change, fails to help.

(BTW, the Atlantic conveyor warming Europe appears to be a myth.)

Just curious, how reliable to you consider computer modeling of atmospheric conditions (long or short term) to be? I really haven't kept up with my reading in this regard, so I don't know if modern models are far more accurate than they used to be.