For those few who still doubt that human-generated greenhouse gases are causing runaway global warming (and also for those of us who have understood the danger for several decades), the PBS NOVA special Extreme Ice is jaw-dropping. The program demonstrates with compelling video and scientific data the extent to which glaciers around the globe are disappearing ~ rivers of ice disintegrating faster than they can be replenished by snowfall. The same holds true for the vast ice sheets of Greenland and Antarctica. As ice on a glacier or ice sheet melts, gravity channels it to low-lying hollows which become temporary lakes ~ temporary because the combination of water pressure and the water's warmer temperature cleave fissures into the underlying ice, fracturing it to depths up to a mile. The water flow reaches bedrock and proceeds to carve its way downhill toward the sea, lubricating the flow of the overlying ice. It is a self-perpetuating cycle on a monumental scale, beautiful and terrifying.
Okay, you ask, it's all very impressive, but so what? After all, Earth has always gone through periods of warming and cooling, influenced mostly by shifts in the planet's orbit. But this is different. Due to man-induced global warming, the ice melt has accelerated more quickly, over a much shorter period of time (since the start of the Industrial Revolution, when we began pouring greenhouse gases into the atmosphere), surpassing ANY recorded changes in the geologic record. The likelihood is real for a rise in sea level of three feet (one meter) or more by the end of this century, flooding coastal cities worldwide (see image above, click to enlarge), and altering the circulation within the world ocean and within the atmosphere, with climate consequences we cannot yet imagine.
Please click on the link and watch for just a few minutes. You'll be hooked.
By coincidence, earlier this month a NYTimes article examined another, somewhat overlooked aspect of global warming and ice melt ~ the thawing of permafrost in the world's arctic regions. Permafrost "underlies nearly a quarter of the Northern Hemisphere, and contains twice as much carbon as the entire atmosphere." Melting permafrost will release not only carbon dioxide, but also methane, a gas which traps even more of the sun's heat.
Even if we had begun to rigorously rein in our greenhouse gas emissions in 1980, it would have been a toss-up whether we had already passed the point of no return. Now .... this observer is certain that we have already passed the threshold. We have set in motion processes which we understand but poorly, and which are irreversible. Fasten your seat belts, it's going to be a bumpy ride.