Throughout Earthís history, the melting and regrowth of major ice sheets has followed the patterns of orbital variations and natural changes in greenhouse gas levels, but human activity may be changing this. Changes in land use and industrialization are becoming a dominant driver of global temperature and atmospheric greenhouse gas levels. Quite possibly, anthropogenic climate change could delay the onset of the next glacial cycle or perhaps even cause the ice-age cycle to altogether cease. Continued aggressive emissions with little mitigation could lead to future increases in carbon dioxide that cause the loss of major ice sheets. Even if we do not lose all of our ice cover right away, we could inhibit the natural replenishment of polar ice due to changes in Earthís orbit and axis over long periods of time. Thus, anthropogenic climate change could shift Earth toward a greenhouse regime with little hope of recovering major ice cover.
What the loss of the ice-age cycle would mean for our civilization is open to debate. Reduced ice cover might benefit frigid regions like northern Canada and Siberia by providing temperate conditions for industry, more arable farmland and additional space for a growing population. Future generations would also not have to worry about recurring changes in ice coverage, which could potentially allow for more stable and long-lived infrastructure for such civilization.
On the other hand, these potential benefits would come at the expense of people living elsewhere. Some effects of climate change would be especially pronounced in the tropics, where shifting patterns of rainfall and desertification are already contributing to increases in emigration. The continuation of such warming could also render farmland at midlatitudes less productive, thereby placing even more demands upon newly arable polar resources. If Earth were to lose all or most of its polar ice, we would be consigned to a greenhouse future where the melted poles provide some of the planetís best real estate. And this doesnít even factor in all the loss of land due to sea-level rise.
The planet has been there before. All ice has melted, sea levels have been much higher, and temperatures and carbon dioxide levels have been higher. But humans werenít alive then. Human civilization is now an integral part of Earthís climate system. And our current trajectory, left unabated, could plummet Earth into a virtually inescapable greenhouse future the likes of which humans havenít seen and for which we are not prepared.
But it is also within our power to steer the planet toward a more viable and resilient future through reductions in our energy consumption and investments in sustainable sources of energy. Although concern over the distant future of the ice caps is certainly not the most prominent driver of policy, our actions today may exert unprecedented influence on our climatic future.