A reasonable projection set forth in the recent Scientific American article, "The Great Climate Experiment," September, 2012, pages 78-83, points out that, whereas the average global temperature when humanity spread out of Africa to the Middle East, Europe, Asia, Australia, and the Americas was probably about 8°C (roughly 46°F), when I was a child it was about 14° Celsius (around 57° Fahrenheit), and it is now 15°C (59°F), it is likely to rise about 10 degrees Celsius (roughly 18 degrees Fahrenheit) from here as global warming takes hold, up to about 25°C (77°F), and then to remain at such lofty higher levels for hundreds of thousands of years, many times the extent of our species' existence so far.

Given that polar regions and areas adjacent to oceans are as a rule significantly cooler than ones closer to the Equator and more distant from the seas, for the global average temperature to reach 25°C will require that vast regions of the planet will be far warmer. In addition, the way that heat is transmitted away from the Equator by weather patterns suggests that substantial parts of the now developed world will suffer from a disproportionate increase in heat and drought.

For instance, the band of very hot, dry climate which now includes parts of Mexico plus the Sahara, the Arabian Peninsula, Iraq, Iran, and Pakistan will likely be heading farther north into the latitudes which currently embrace the southern U.S., Europe, and central China. Along with sea level rises, icecap melting, greater weather turbulence, and the much increased acidification of aquatic areas (eliminating coral reefs and the many species dependent on them), such shifts will probably remake the world into one less recognizable or hospitable to us. Our insurance companies will be hard pressed to cope with such alterations and the increased risks they represent without accelerating premiums.

Till now, Homo sapiens has only been on a planet which on the whole is relatively cool. The temperatures toward which Earth is heading will apparently, on a sustained global average basis, be about as hot as the warmest local environments our kind has had to endure.

For instance, paleontology suggests human origins probably were in sub-Saharan Africa, perhaps places like the flood plains and jungles of what is now the Democratic Republic of Congo. Here, as in projections for the entire planet's globally warmed future, the average temperature is 25°C (77°F).

Yet, due to great weather uncertainties and the prevalence in such conditions of rampant domesticated animal, crop, and human-borne diseases or parasites, significant agricultural production under these circumstances is problematic. Despite irrigation, fertilizer, insecticides, reasonably stable political systems, and a lack of general warfare, even in today's much more ideal climate circumstances, an estimated 14% of the human population is chronically malnourished. The costs and energies needed to provide for the food needs of billions once temperatures have climbed more markedly could be staggering.

In the book, On the Beach, which is also a pretty good 1959 movie starring Gregory Peck, Ava Gardner, Fred Astaire, and Anthony Perkins, conditions are already severe and still deteriorating after a nuclear war. People are OK, for now, in Australia, but massive radiation and the initial atomic blasts have killed off everyone else. Reliable forecasts indicate that deadly bands of radiation will soon be blown as well into this last outpost. Folks come to terms with it in various ways and as best they can. Yet the end is foregone, hopeless, and nobody is left alive as the last frames of the film stream by.

deadly influenza virus (Wikipedia)

The Cold War is over, of course, and much of the formerly huge stockpile of missiles has been destroyed or allowed to breakdown without adequate maintenance. However, other of our activities are pumping so much carbon dioxide or methane into the atmosphere that the biosphere as we know it cannot go on.

By some estimates, 95% of species will be lost if the heating proceeds to the point the global average temperature reaches Congo levels. In fact, with each degree of elevation in the mercury many thousands of species will be put at peril. Not every type of natural thing can freely move to where its environment will again be comfortable. The rate of change, 5000 times faster than the last time there was an equivalent rise in atmospheric carbon dioxide, is far too great for the majority of creatures to evolve and adjust.

Most of us are probably not too concerned about hundreds of thousands or millions of other species' continued existences. We assume, of course, that so adaptable a variety of life as ourselves will not be among those very badly affected. Yet what if it turns out that the "brave new world" we are creating is perfect for kinds of things that love hothouse conditions, require no extra efforts to survive in them, find us tasty and wonderful hosts, and are not too concerned whether or not our kind have continued existences? How flexible can we be if harboring aliens in our bodies that kill us off in great numbers, as smallpox did the American Indians when they were first exposed to that new virus?

The future may still contain factors we had not adequately considered which, when all is said and done, eradicate us as efficiently as the rest of the multi-cellular fauna and flora we regard as expendable. I believe that if we do not soon overcome our more natural impulses and respond proactively to the problem, runaway climate warming will occur, the changes will prove overwhelming for us as well, and so this On the Beach scenario indeed will be our fate.

So bleak an outcome does not at this point appear as probably, however, as that we, along with so many other creatures, shall find our existences challenged to a greater degree than has been the case in a very long time. In "The Skin of Our Teeth," a reasonably light-hearted, upbeat drama, all things considered, people face a series of horrendous disasters that all but wipe us out. Nonetheless, in each case enough manage to carry on that survival as a species remains possible, if only "by the skin of our teeth."

A thousand or ten thousand or so years from now, many current coastal regions will probably be underwater, including what is presently Texas as far north as Austin, much or all of Florida and parts of the eastern seaboard, far inland by today's map views, plus a majority of other currently developed coastal regions around the world. However, people will have stopped deliberately acting in ways that accelerate the challenge and, on a vast scale, much more and for far longer than we have for any other cause, will be taking measures to ameliorate the damage already done. It will be an effort that must be maintained almost as long as we may hope to exist.

In the final analysis, that may be the best hope for our kind. The far future will probably include at least a remnant of people far better adapted than we to desert and jungle conditions, frequent and violent storms, fires, droughts, disease, and limited food or fresh water supplies. We shall likely still have technology and at least our current genius for innovation and for passing along our knowledge and adaptive measures to others. They will all be required if we are to make it.

The entrepreneur of that time will likely be extremely nimble, catching quickly shifting opportunities for both profit and survival, as a sailor catches favorable winds to tack his or her craft ahead. A precious few of us then may well succeed and, many hundreds of millennia from now, their descendants could even see the end of the hell on Earth we are so swiftly fashioning, one compared to which today's pearly world will seem like a lost Garden of Eden.