No. 70: Jul-Aug 1990
Geologists have generally assumed that the ponderous Antarctic ice sheets do not change their behavior rapidly. But, according to NASA's R. Bindschadler, an ongoing study of the Antarctic coast near the Ross Ice Shelf casts doubt upon this assumption of long-term stability. Measurements of one ice stream flowing down from the mountains to the sea in dicate a sudden unexplained, 20% reduction in speed over the past decade. Perhaps even more significant is that, even with this reduction in flow velocity, this particular ice stream carries ice into the sea 40% faster than ice accumulates up in the mountains.
The sudden, rather large velocity change is alarming because it may signify widespread instability in the continent's icy mantle. Researchers state that there is even a chance that much of the Antarctic ice cap could collapse into the sea in the next few centuries -- a catastrophic event that would raise global sealevels by 6 meters!
(Anonymous; "Antarctic Ice Potentially Unstable," Science News, 137:285, 1990.)
Comment. In addition to looking at future consequences of collapsing Antarctic ice sheets, we should mark that what might happen in the future might also have happened in the past. Obviously, we refer to the often-discussed speculation that the Antarctic was nearly ice-free within historical times. In this connection, we cannot escape mentioning that remarkable ancient map of Piri Re'is that, some say, shows an icefree Antarctica, mapped presumably by ancient mariners. This was the theme of C.H. Hapgood's book, Maps of the Ancient Sea Kings.