Human Survival

[popeyespappy]

Depends on who you talk to. Estimates on how long the surface of Earth can support life vary greatly. Many think the oceans will only last another 500 million to 1 billion years. If that is true our planet won't be able to support much more than single cell organisms long before that. Some believe complex plant life could have as little as one or two hundred millions years left. When that is gone most of the rest of us will join it.

Recent geochemical and geophysical studies have suggested that compare to benus, the carbon inventory of the earth is sufficiently sequestered, and the evolution of earth's core is sufficiently more advanced, such that earth will never undergo Venus like super greenhouse. At the same time, the volume of water sequestered in earth's mantle far larger than was thought just 10 years ago, and may be 100 time more than the oceans, is sufficiently large so the it's leakage onto the surface via volcanic eruption will reach equilibrium with loss of sea water into space or through subduction, and earth surface will never go completely dry, and sizeable bodies of water, ranging in size from lakes and oasis to oceans, depending on assumptions about level of valcanism and atmosphere pressure, will remain on earth for several billion years at least, possibly until sun turns red giant.

These scenarios foresee multicellular life as being about to continue at higher latitudes on earth for 2-3 billion years more at least, possible all the way tithe red giant stage of the sun.

As I said it depends on who you talk to, but as far as greenhouse affects on Earth it is my understanding the sooner rather than later crowd believes the problem here in the distant future is expected to be water vapor as opposed to carbon dioxide. Initial heating due to more energy from the sun, possibly in combination with anthropogenic and other greenhouse gasses, raise the level of water vapor in the atmosphere and cause further heating. Eventually the water vapor vapor will be lost into space but not before it heats the place up more than the current ecosystem can bear.

Who knows though? Maybe by that time we will have the ability to move our planet to a bigger orbit. If we haven't gone the way of the dodo already.