How long do we have to go before were forced to abandon Earth?, page 2

Originally posted by Moley
I have to disagree with those who say humans can not destroy Earth.... a few dozen high-yield atomic blasts could create a nuclear winter which would block any sunlight for many years, producing devastating loss of animal, insect and plantlife.... probably only a few insects and basic plantlife such as lichen would be left after that. If that doesn't count as 'destroyed' then I don't know what does!

Stop dreaming about human's power over nature.
Even combined yield of world's nuclear stockpiles wouldn't come near power of small cosmic impact. And even Chixculub destroyed only under 90% of life.

Use this to calculate impact energies for different sized objects and for reality check.
www.lpl.arizona.edu...

And before someone says that leveling surface would be enough, there's lot of life underground in cracks of bedrock... to the depths of kilometers.

whyfiles.org...

The SLiME system discovered by Stevens and McKinley is not the only case of life either underground or far from sunlight. Deep sea hydrothermal (hot water) vents are teeming with life, as are buried sediments. In an article in the July, 1992 issue of the Proceedings of the National Academy of Sciences, Thomas Gold (Cornell University) has tried to calculate the amount of subsurface life in comparison with the above ground life all around us. His estimate necessarily contains some guesses, but all are reasonable. Assuming that the upper 5 kilometers of Earth has a porosity of 3% (porosity is the amount of space available for water in a rock or sediment), and that 1% of the mass of the water filling the pore spaces was bacteria, then the total mass of bacteria would be 200 trillion metric tons.

Putting it another way, Gold points out that this is equivalent to a layer on the order of 1.5 meters high covering the entire Earth! This is more than the existing plant and animal life on the surface, which is estimated to be about a trillion metric tons. Even if Gold's estimate is off by a factor of 100, the amount of subsurface life is at least equal to that on the surface.