Linden points out that cold weather alone did not kill the Greenlanders; their own political limitations, including racism and a rigid class hierarchy, also contributed. Based on the historical and archaeological record, he suggests that “the Christian Norse likely regarded the shamanistic Inuit as unenlightened and beneath them.” The Inuit, who arrived 100 years after the Norse, were known by the Viking settlers as Skraeling or “wretched people.” Instead of turning to the Inuit for help, the Norse simply perished. The lesson of this history is clear enough: adapt or die.
Following this logic throughout his book, Linden goes on to discuss the political impact of nineteenth-century El Niño events. This climatic phenomenon involves a weakening or reversal of the trade winds, building up warm surface water off the coast of South America and in turn destroying much needed fisheries and causing massive storms. To some extent Linden relies on Mike Davis’s pioneering book Late Victorian Holocausts to remind us that upheavals in the climate system often reinforce economic inequality and create social instability. “El Niño did not create the Third World, but it provided a powerful instrument to smash the traditional economies and social structures that formerly promised self-sufficiency in many parts of the tropics.” Linden’s message: the use of calamity to reinforce wealth and privilege is exactly what we do not need if we are to overcome the crisis of climate change.
Most disturbingly, ice-reading scientists now believe that past climate change was not always a linear process. Instead, the last 110,000 years have seen numerous rapid shifts in the global environment. Full-scale ice ages have started and stopped in mere decades rather than centuries. Other data shows that at times the seas rose and fell by several feet per decade. To paraphrase Linden, when considering the global thermostat we ought to think in terms not of a dial, but of an on-off switch.
Meticulously documented by Kolbert, Linden, and former US vice-president Al Gore, the key lesson concerns the crucial role of polar ice. The polar ice sheets currently throw back as much as 30 percent of the solar radiation hitting the earth, and the loss of this capacity will lead to an increased absorption of heat and an acceleration in warming — a positive-feedback loop whose effects compound and amplify the original cause. And the polar ice caps are now melting very quickly. Kolbert reports that, “since 1979 the perennial sea ice has shrunk by 250 million acres, an area the size of New York, Georgia, and Texas combined.”
An ice-free planet would bring with it sea levels sixty metres higher than today and the inundation of our coastal cities. But before the last stop of an ice-free Götterdämmerung lie other dangers. Sea ice, though formed in large part from salt water, has the salt pressed out of it over time so that icebergs are in effect desalinated by years of cold. Melting polar ice unleashes huge amounts of fresh water into the ocean and threatens to disrupt the global system of currents known as the “thermohaline circulation,” a flow system that redistributes heat and precipitation in ways that civilization depends on.
The North Atlantic offers the best example of this dynamic. Here the Gulf Stream sweeps north from the equator toward Europe carrying with it massive amounts of warm surface water. As the warm water approaches Europe it evaporates, dumping precipitation and heat on northern Europe. If half of the Greenland Ice Sheet melts along with half of the Antarctic Ice Sheet, it would disrupt the thermohaline circulation, probably plunging Europe into a very cold period just as the globe in general grew hotter. Among the potential consequences would be the undermining of European agriculture, an ensuing famine, and the mass migration of people to warmer climes.
The oceans are a hard-to-predict and dangerously slow indicator of climate change. The seas absorb huge amounts of CO2 and heat — exactly how much and to what effect are not clear. “It takes the oceans around three decades to catch up with the heat accumulated in the atmosphere,” writes Flannery. Some scientists fear that the oceans are so slow to catch up with atmospheric warming that we may have already gone over the edge and tripped the switch that will create an ice-free planet.
But never mind the bad future — climate change is already having measurable effects. Species are migrating toward the poles and to higher, cooler altitudes if they can. Caterpillars and migratory birds in Europe are increasingly out of sync, leaving their freshly hatched chicks with inadequate food. Multiply this dynamic 10,000 times and you get the picture: half of all species are “committed to extinction,” according to Flannery. And no one really understands the long-term effects of the incremental disruption of ecosystems on, for instance, the quality of soil, which is under increasing pressure to feed escalating urban populations.
