Frozen Planet, Frozen World

<p> The Discovery Channel series “Frozen Planet” (out April 17 on DVD and Blu-ray) demonstrates how the reach of documentary filmmaking is longer than had ever been possible. Years ago, divers in insulated suits couldn't have descended beneath the Antarctic ice with cameras; nor could a helicopter peer into the cone of the continent's active volcano, Mt. Erebus, in air too thin to hover. But while the human accomplishment behind “Frozen Planet” is remarkable, the natural world it uncovers is more startling still. </p> <p>The series affords a close look at the extreme ends of the Earth, the Arctic and Antarctic, whose cold landscapes are sculpted by howling winds and shaped by summer thaws. Inhospitable to humans, they are home to many animals. In the Arctic lives the world's largest land predator, the polar bear; two of the creatures are captured locked in fierce combat. From the Antarctic come comical scenes of a sea lion chasing a penguin, whose flightless wings prove superb as paddles in the water. More piteous yet fascinating, a pack of killer whales work as a team to dislodge a seal from its precarious perch on an ice flow. </p> <p>The reports from the cold regions are narrated in the resonant voice of Sir David Attenborough, who warns that what effects the poles, where much of the world's fresh water is frozen, will effect all of us. </p> <p>If current trends prevail, the Earth will grow warmer and the polar ice will shrink. But in earlier times, too much ice was the problem. The History Channel series “Frozen World” (out on DVD) presents the most recent Ice Age in a set of human and computer reenactments. Evidence shows that the eruption of the super volcano Toba in Sumatra (c. 73,000 BC) triggered a “volcanic winter” lasting tens of thousands of years. Spewing magma 30 miles into the air, Toba sent dust over a radius of thousands of miles and sulfur gas that sailed even further on the wind. Toba produced clouds that darkened the sky and reflected the sun away from the Earth. As a result, temperatures dropped 25 degrees and many areas plunged into perpetual winter. </p> <p>And what about the people? Two species of humans roamed parts of Europe at the time, the Neanderthals, who were native to the continent, and our Cro-Magnon ancestors who came from East Africa by way of the Middle East. “Frozen World” depicts the rival species clawing for control of a Europe half-covered in ice and with reindeer migrating as far south as Italy. The Neanderthals were stocky and strong but not too bright; they left behind no art or evidence of symbolic thinking save the burial of their dead. According to the program, the Cro-Magnons won because of superior technology in the form of aerodynamic spears, while the Neanderthals never progressed beyond hand-held weapons. </p> <p>Of course, even with such recent tools as DNA analysis, the evidence base for anything remains thin. One of the most persistent questions is whether Neanderthals and Cro-Magnons could interbreed. Most scientists say no, but others aren't so sure. </p>