Could you answer my objection to a ‘tipping point’ ?
IMO, that is the problem. We will never notice or precisely know the tipping point. And I believe you are correct in saying that the sun is the major source of heat on earth, but then no one is saying that CO2 creates heat, it just traps it.
All other things being equal, adding carbon dioxide (CO2) to the atmosphere—by, for example, burning millions of tons of oil, coal and natural gas—will make it warm up. That, as the Nobel Prize–winning chemist Svante Arrhenius first explained in 1896, is because CO2 is relatively transparent to visible light from the sun, which heats the planet during the day. But it is relatively opaque to infrared, which the earth tries to reradiate back into space at night
http://www.scientificamerican.com/article.cfm?id=global-warming-beyond-the-co2 (red emphasis mine)
As I understand it this creates an exponential warming effect. But even then, global warming itself would not be disasterous. Most species can tolerate a temperature difference of a few degrees. But the greatest threat is that the warming drastically alters weather patterns which become more violent and frequent. In addition, a rising ocean level will alter the entire geography of the earth, causing displacement of all living organisms. Life on earth can tolerate losing a few million individuals every so often, due to damage to the earth’s ecosystem, but not once or twice every year, everywhere. Somewhere in all these factors lies the tipping point between eventual global disaster and survivability.
The earth itself doesn’t care one way or another. But the mathematical precision of atmospheric thermodynamics tells us that we are dangerously close, if not already past the tipping point. The question is if we can stop it from happening at all. At least let’s not compound the problem.
There is one bright spot, we are running out of carbon fuels anyway. Conservative estimates give us 75 years (1 generation) recoverable oil reserves. Does common sense not tell us to seriously begin to explore alternate non-polluting fuels, just for our children and grandchildren ?
Do check the environment and energy statistics (at current levels).