It may be difficult for some to believe, but over the last three million years ice dominated earth’s climate. We remain in that long ice age; widespread glaciers still exist. For most of earth’s long, long existence no ice existed anywhere. Currently, we are in an interglacial period in which ice has retreated back to the poles and the highest mountain reaches. Earth as we know it has been shaped primarily by ice and to a lesser extent by volcanoes. Once ice lay hundreds of feet deep as far south as Chicago and London. What caused this see saw between Ice Ages and warm, wet periods where the ice retreated or disappeared entirely? The changing tilt of the earth’s axis. Currently, the earth’s tilt is 23.5 degrees or so. This tilt causes the seasons in non tropical areas. Earth’s tilt changes a degree or so over time, causing the alternating periods between extreme ice coverage and warm periods. At times the change has been so great that no ice remained even on the poles. Usually, these changes are very slow, over thousands of years. No longer.
Equatorial glaciers once common in the high equatorial mountains, e.g. Andes, Himalayas, a century ago no longer exist. Ernest Hemingway once described the glacier on Kilimanjaro as “wide as all the world”. Now nothing but a few patches of hard snow remain. The once giant ice fields in northern Patagonia in Chili and Argentina currently lose volume at an ever accelerating rate. While hiking and kayaking with a filming crew in this area, Childs saw just how rapidly this ice loss occurs. In one instance a huge ice lake run off from one glacier totally disappeared in two weeks. In Greenland an iceberg four times the size of Manhattan floated off in 2010 and finally melted in the Gulf Stream. It narrowly missed shipping lanes and offshore oil wells. The Larsen B ice shelf in Antarctica the size of Yosemite National Park and 700 feet deep had been stable for more than 12,000 years. It started coming apart over a decade ago. It eventually floated off and melted.
Why does any of this matter? Ice keeps the planet cooler. Solar radiation bounces off into space. Currently, ice reflects approximately 30 per cent of incoming sunlight. Few present animals and people are prepared for the hothouse that would exist if much more ice melts. This is in spite of the fact that radiation from the sun has actually gone down in the last fifty years. As the planet warms, more ice melts, more heat remains on earth, more ice melts and the cycle continues. The current acceleration of ice loss causes many scientists to question: where is the tipping point? How can we stop this rapidly accelerating ice loss?
Humans are increasing carbon dioxide levels ten thousand times faster than they changed over the last 65 million years. Our globe is warming; all climatologists agree. At what point will it be too late to turn this around? Indeed, can we turn this around? And if we do, will some of the ice return? No one knows. Nothing like this has occurred before in human history. All this melting ice causes sea rise. At the current rate a one meter sea rise by the end of this century is plausible. Many of the world’s largest cities already have a sea level problem e.g.Bangkok. Furthermore, the water supply for much of southern and southeast Asia depends on water from rivers and glaciers in the Himalayas. The world’s largest supply of fresh water depends on this system. Are we ready for a hotter, drier earth?