When a young Edwin Hubble started looking out into the universe at the beginning of the 20th century experts thought that this universe was only tens or maybe hundreds of millions years old (most people thought the world was less than 10,000 years old). Now, on a 4 1/2 billion year old Earth in a 13 billion year old universe, the odds against the end of the world today or tomorrow are astronomical. (Unless you belong to a willfully ignorant cult like the President.)

But don't make fun of the end of the world catastrophists . And don't be overly optimistic about the resilience and adaptability of our civilization, profoundly misunderstanding the challenge facing us today.

In man's long history - ten thousand years since the innovation of agriculture and civilization; seventy thousand years since the bottleneck where geneticists have determined that only around ten thousand humans out of a global population of tens of millions survived a 'volcanic winter'; and back at least hundreds of thousands of years to taming fire, learning language and the dawn of religion and culture - it has been only in the last century that we have had the ability to alter the surface of the Earth so that human life was in jeopardy.

Twice (at least) in the past century we have created a possibility of our own accidental extinction: nuclear winter and depletion of the ozone layer.

So far the existing thousands of powerful nuclear warheads haven't been unleashed in mutually assured destruction (potentially blocking the Sun for a decade like the presumed bottleneck- causing Toba explosion). But Bush Administration acceleration of US militarization of foreign affairs, advocacy of a pre-emptive unilateralism specifically aimed at any emerging threat to US supreme power, and pure, grab the oil, aggression for self-interest in Iraq, is taking us down a resource war path, putting us closer to that final nuclear world war than any time since '62. (It is remarkably underappreciated how Bush Admin aggression challenges still nuclear Russia and emerging power China and how much more dangerous life is for all of us through the choice of the resource war path instead of multilateral cooperation and innovation.)

The second possibility of extinction was one small family of the ninety thousand plus synthetic chemicals created in the past century which floated up after their useful life in aerosols and solvents and refrigeration to interact with and corrode a thin layer of ozone surrounding the Earth and absolutely necessary to the survival of most forms of life. Fifty years after their industrial application scientists clued in that CFCs were not harmless inert gases but, fortunately, the cumulative damage to the ozone was only thinning and holes and not the possible century of invading radiation scouring life from Earth's surface.

At the end of the 19th century scientists began considering the long term effects of burning fossil fuels and specifically the effects of the extra CO2 released into the atmosphere. By the end of the last century measurement of accumulating CO2 and other greenhouse gases and climate modeling based upon scientific determination of climate changes over the past hundred thousand years strongly suggested that there was a potentially very serious global warming problem.

Several decades ago some scientists predicted that raising global mean temperatures would lead to the release of huge amounts of presently safely sequestered greenhouse gases - methane, especially, stored safely away under the oceans and in peak bogs - and that there was a potential for runaway global warming pushed by this positive feedback of freed greenhouse gases. They warned that runaway global warming could raise temperatures to such a degree that most life forms on Earth including man would certainly become extinct. Somewhere around 400 ppm amounts of CO2 in the atmosphere and nature takes over.

Fortunately, as we have developed the power to re-engineer the world for human use and therefor the power to self-extinct we have developed a maturity to safeguard humanity's future. Not.

Matt Simmons re-thirty years on evaluation of Limits to Growth is relevant. William Catton Jr's OVERSHOOT has been reborn on the net because the relevant catastrophe graph isn't Hubbert's Curve but that graph we all know where human population bumps along the bottom of the graph for millennia before spiking exponentially beginning in the 16 century with the use of fossil fuel. Catton views us as a species needing, using, and dissipating energy, as a species that should be concerned by a tendency for animal populations to rise exponentially, overshoot and crash. What goes exponentially up promises to go exponentially down.

Exponential growth on a finite planet has consequences.

Edward O. Wilson has developed a Bottleneck metaphor graphing the consequences of ever expanding human populations with powerful technologies in the 21st century. Human populations with a biomass a hundred times any previous animal except bacteria are eliminating untold biodiversity in re-engineering formerly wilderness habitat for human use. Humanities cumulative footprint will cause severe resource depletion - now peak oil, but water and food in the future too. Greenhouse gas production is another example of the possible negative consequences of our overwhelming footprint. Wilson envisions human survivors of the Bottleneck maelstrom, but his fear is a world where biodiversity has been severely depleted, a Sixth Extinction that requires millions of years to recover.

A Darwin Award - how to explain this most terrible possible idea to someone eating a burger before the next text distracts. Those denying the very real probability of catastrophe help keep us in growth economy business as usual 'muddling through' instead of taking urgent corrective measures. Darwin Awards to all and every person who chooses to remain willfully ignorant of who we are on this planet, our precarious position, and our responsibilities.

Dad, Mom and the kids are out boating on the reservoir: little Johnny's helping Dad fish (and the fishing is hot); Mom's enjoying a relaxing nap and the twins are playing in the front of the boat. Everybody's having so much fun they aren't really aware that they are drifting towards the dam and the spillway. Even if the fishing is wonderful, reasonable people would make sure that they stayed far away from the point of no return past which they couldn't escape death for the whole family.