Do you realize that it's possible for what you say to be true (and I agree with the general point) AND for it to also be true that humans are capable of altering the environment? Given that, it's also possible that the natural changes wouldn't be so bad, but the human caused changes might end up being very bad for us. So shouldn't we do something to stop the changes we can stop?
The answer to your questions lies not in the direct answer, but the indirect one. To give the answer I have to give a little background.
The Earth's climate has always been changing and it always will. The treehugger notion we could or should stop the climate from changing is great irony - because that would be a bigger imposition on the Earth's ecology than doing nothing. It would introduce a static climate never before seen on Earth - if it were possible - with inevitable and unforeseen consequences. But there are temperature zones the Earth appears not to like, and it transitions through them swiftly - and then stays on one side or another of this zone for a longer time. There are other zones that global average temperature can vary in for a considerable period of time - until it enters this unsavory zone and then rapidly crosses over it again. I'll leave the "why" of this to some philosopher or trained scientist, but it's a useful observed fact without understanding why.
Giving the average global temperature of the 21st century as 0, we reached the peak of the current temperate zone about 5,000 years ago at a level called the Holocene Climatic Optimum at about +1C. This is about 4-8C below the maximum temperature for the last 450K years or so, and there appear to be feedback effects which prevent the temperature from going any higher than that maximum because it hasn't deviated from this pattern for 2.5 million years - longer than humans have been around. There is a climate danger zone at -0.6C and if we enter it the temperature drops quickly to a new range of -5 to -8C for a very long time. Glaciers march and scrape our cities into the sea, owning the land for a hundred thousand years.
Unfortunately for our teeming billions, up until about 300 years ago the temperature had declined from the Holocene Optimum of +1C to -0.6C and was trending down. -0.6C appears to be the upper bound of one of those unsavory zones, and the next stop is -5C [wikimedia.org] which is quite a drastic change. We were on the cusp of transition into the ice, and in fact that period is called the "little ice age". Each time in the last half-million years the average temperature passed below -0.7C it skipped directly over the intervening temperatures and went directly to the lower level - resulting in the die-off of terrestrial animals including humans, glaciation, and other unpleasant effects. The duration of this cold period averages 100,000 years which is likely longer than we could bear it. If it had not been for the warming currently attributed by some to the burning of fossil fuels and its concomitant CO2 discharge, we would likely already be suffering the cold dipping to -5C or more.
Perhaps 6 billion of us would be dead already, or never born - not from the cold, but from the inevitable famine and struggling for resources that it would bring. But that's not the end. 300 years from now there would be only a few million of our seven billions left, if the resulting wars didn't leave the planet uninhabitable entirely. Our entire industrial revolution, sciences and arts these last 200 years? Lost, perhaps forever.
No matter what we do the Earth will not stay habitable to this many humans forever. In the last half-million years we've had only four such periods lasting an average 12,000 years or so. This warm period we now enjoy is not the Earth's normal temperature. And when it's over, it really and truly does appear to be over for a very long time. It will be cold sooner or later. For me and mine, I
greg giraldo greg giraldo bob hope mariano rivera mariano rivera anderson cooper dadt repeal
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