Deep Future

by Curt Stager

  The points mentioned above are not necessarily as reassuring as they may sound at first, however. True, most of Greenland’s ice survived the Eemian, but the last interglacials were not as hot as the deep future may be, and partial but still substantial ice collapses did happen during those earlier warmings. Above all, the crucial factor that will determine the fate of polar ice is not so much the intensity of future warming as its longevity. Even a moderate 1,000-Gton emissions scenario means tens of thousands of years of higher than modern temperatures, and today’s summers are already removing more ice from Greenland than winter delivers to it. When we think in Anthropocene-scale terms it seems clear that most or all of that ancient ice is doomed.

  In 2005, glaciologist Richard Alley joined forces with European and American colleagues to publish an unusually detailed computer-generated outline of such a retreat. In their simulations, holding CO2 levels steady at 550 ppm warms the air over Greenland by another 6°F (3.5°C). That bites a deep notch into the southwestern sector of the ice sheet by 3000 AD, and the circumference of the sheet contracts slightly. In 5000 AD, about a third of the ice remains. More prolonged 550 ppm conditions eventually melt the whole thing.

  The most extreme situation modeled by Alley’s group involved CO2 concentrations of 1,000 ppm and about 13°F (7°C) of warming relative to today, a situation significantly less intense than what a 5,000-Gton emissions scenario might be like. In that case, about half of the ice melts down by 3000 AD, and by 5000 AD only a few glacial shreds linger in a rugged range of mountains along the eastern coast.

  That study, however, did not fully consider all the dynamic processes that could accelerate the languid pace of simple surface melting, so perhaps the actual de-icing time could shrink to a millennium or so. For now, at least, we should trust the proposed sequence of these events more than their timing.

  What might Greenland look like several centuries from today, say, in 2500 AD? Alley’s work suggests that a moderate-emissions scenario won’t bring much dramatically visible change by then other than some thinning along the coasts. In an extreme case, though, much of the southwestern third of the island could be exposed by surface melting alone.

  Now let’s imagine that Denmark still exists as a sovereign nation and continues to retain strong political and economic ties to Greenland well into the future. As Greenland emerges from beneath its icy mantle, low-lying Denmark could gain ground overseas while losing out to sea-level rise at home. Removing a third of the ice coverage by 2500 AD in a relatively extreme emissions scenario (or several centuries later in a moderate one) could expose 280,000 square miles of new land (725,000 km2). Denmark, in contrast, covers only a little over 16,600 square miles (43,000 km2).

  The newly unveiled landscape will surely support some kind of vegetation, and Greenland will begin to deserve its name. What could grow in such a place? We’re talking Arctic Circle here, so the mercury will still drop substantially in the darkness of winter. If it warms by several degrees, then we might expect some mix of tundra and forest to develop wherever suitable soil accumulates along the rocky coastlines. But we have better ways of making such guesses.

  Records that were kept by Norse settlers during the Medieval Warm Period describe birch woods with trees up to 20 feet (6 m) tall and hillsides thick with hay and willows. Scrubby birches and willows still grow in coastal Greenland today, and much of the rugged coastal landscape already turns green in summer, if only with soft mosses, tufted cotton grass, alpine flowers, and scruffy shrubs.

  Geohistorical evidence also provides glimpses of what grew there during longer warmings of the past. Marine sediment cores collected near Greenland’s southern coast contain pollen and spores that were blown out to sea during the last million years. During one warm interglacial 400,000 years ago, much of the land was cloaked in conifer forests. And DNA in gritty deposits that came up in the bottom of a mile-long ice core included genetic material from spruce, pine, yew, and alder trees as well as from butterflies, moths, and beetles.

  According to some experts, it’s not so much Greenland’s high latitude that keeps forests at bay today as it is the cold, fierce winds that roar down off the sides of the mountainous ice sheet. Whenever past warmings pushed the margins of the ice far enough away from the sea, trees moved right in. Coastal forests of birch, willow, spruce, pine, yew, and alder, then, are a good bet for 2500 AD, and local citizens of those times will have access to firewood and construction materials that must now be imported at great expense.

  We might also expect to find more farmers raising the usual Scandinavian crops, such as potatoes, turnips, sugar beets, cabbage, carrots, and rye. This would generate fresh local produce for folks who may not be able to afford costly imported vegetables. With abundant homegrown silage on hand, it should likewise become easier to raise livestock. Sheep and reindeer are already farmed successfully in southern Greenland, and a recent article in Spiegel International reports that the government hopes to launch a dairy industry there as the warming continues.

  This new world will awaken while an open-water fishery is booming on the ice-free Arctic Ocean. Greenlandic harbors will be well positioned for fishing and trade with other nations both around and over the pole, and local shipyards and fish-processing plants could thrive. Depending upon what species are available then in the acidified northern ocean, the Greenlanders might harvest cod, halibut, shrimp, and salmon as they do now, but yields will probably rise and southerly species such as mackerel should also lengthen that list. By one estimate, simply establishing a new, self-sustaining cod fishery in western coastal waters could generate as much money as Denmark now donates to the Greenlandic economy annually. In any case, the accessible range of fishing grounds will be hugely expanded during the ice-free summers of the new north.

  Fishing might also expand in the interior. A survey of under-ice topography, published in 2001 by British glaciologist Jonathan Bamber and colleagues, shows that central Greenland has been deeply deformed by the weight of its overlying ice. If the southern third of the ice disappears, then the tip of that central depression will be exposed and will trap meltwater. We might therefore expect large, deep lakes to form there. Perhaps they’ll be stocked with salmon and trout for recreation and commerce.

  As for the underlying rock itself, the Danish geological survey has mapped existing coastal exposures in order to preview what lies farther inland. Geologically speaking, Greenland is an eastern outlier of the Canadian mainland, which is generally known more for its vast granite and gneiss formations than for eye-popping gems and metals. However, some noteworthy impurities sparkle in that otherwise unremarkable matrix.

  Today, at least ten gold-bearing localities have been mapped in the ice-free regions, and several molybdenum and lead-zinc mines are currently active. Rubies occasionally turn up here and there, and diamond-laden kimberlites are common along the southwestern coast. A green mineral found near Nuuk bears the unofficial name of “greenlandite” with an eye toward future gem markets. As the ice pulls back, prospectors will find new deposits of such stuff, as well as the copper, platinum, uranium, titanium, nickel, and iron formations that are already known but not yet heavily exploited. And petroleum companies are planning to exploit rich carbon-fuel reserves offshore; according to one assessment by the U.S. Geological Survey, the East Greenland rift basins alone may contain 9 billion barrels of oil and 86 trillion cubic feet of natural gas.

  Put all of this together, the open land, the crops, the livestock, the seafood, the minerals, and the fossil fuels, and you have the makings of a prosperous economy—at least, barring major oil spills. But in any environmental reorganization of this magnitude, of course, some must lose while others gain. Traditional Inuit hunting culture, which depends on solid ice for travel and for the environmental needs of seals and other prey, may be lost as the planet continues to warm, and petroleum extraction comes with a risk of major spills. But by most measures, Greenland as a whole will be among the world’s overall winners as the
Anthropocene proceeds.

  What are the greatest uncertainties in this picture? I see two of them: how fast the ice actually melts, and who controls Greenland when the ice goes. It is surely the latter, cultural aspect that will play the more important role in determining how the story of this new world plays out. Will some superpower manufacture an excuse to invade the place? The United States has a military base at the northwestern settlement of Thule (Qaanaaq), after all. Will World War X have left us in a quasi-Neolithic state by then? Or will the native Greenlanders cut their last political ties to Scandinavia and tell the Danes to stay home? Only time will tell.

  Now, while we’re still on the topic of long-term ice retreat, let’s look even farther ahead in time. What might Greenland look like … naked?

  Leaving unresolved the questions about mechanisms and dates aside, let’s imagine how the basic steps of such an unveiling might progress. A study headed by British Meteorological Office scientist Jeff Ridley has modeled a Greenlandic meltdown in detail, and I’ll use it here to help sketch a likely sequence of events.

  In this scenario of intermediate-scale severity, which is driven by continuous CO2 concentrations of 1,160 ppm, a widening halo of open ground encircles the shrinking ice sheet by 3000 AD, and the lower third of the island lies fully exposed. But the process slows down after that. The sides of the ice mass have become steeper, so they undergo less direct heating from the sun, and bergs no longer drop into the ocean because the ice margins now lie too far inland; good news for northern shipping. Meltwater lakes, some of them more than 100 miles (160 km) across, ripple under brisk Arctic breezes as they collect runoff from the stubs of ancient ice beside them. Cold-weather farms and forests keep the land green in summer, and that darkening of the landscape launches a new kind of local weather pattern.

  Removing much of the high, cool, reflective ice sheet warms Greenland dramatically, and the combination of darkening and lowering of exposed surfaces in the ice-free halo raises local air temperatures by nearly 23°F (13°C) in summer. Now lying close to sea level instead of hundreds or thousands of feet in the air, even the winter landscapes are 13°F (7.5°C) warmer than they would be with the ice still in place. In combination with the greenhouse effect, these changes have boosted Greenland’s average annual temperature by 19°F (10.5°C) or more. At Thule/Qaanaaq, for example, this means average July temperatures of 60°F (15°C) at the height of the summer melt season and average midwinter temperatures of-13°F (-25°C).

  As summer ripens, warm chimney-plumes of air float above the defrosted regions and then bend sideways over the central ice sheet. From there they cool, sink, and slide back downslope, closing the loop on a new kind of weather system. The streams of dense cold air rushing down the ice sheet’s steep flanks cool the marginal areas where most summer melting occurs, thus delaying their final demise.

  A matching circulation cell points seaward and drives moisture-rich winds ashore from the North Atlantic. As a result, Greenland’s summer weather varies considerably from place to place. Cold glacial winds buffet the ice margins, afternoon sea breezes freshen the coasts, and more rain and snowstorms than usual form over the intermediate uplift zones.

  In 4000 AD, as much as a third of the central ice sheet still leans against the eastern mountains. As the sheet sinks lower it presents less and less of a barrier to westerly winds that tend to skirt Greenland’s southern tip until they blow straight across the mainland more and more easily. This reshapes the paths of storm tracks over Europe and cools the Barents Sea region that lies east and downwind of Greenland, increasing its floating winter ice cover. If polar bears and ringed seals still exist this far into the future, then the localized cooling here means that Svalbard and Nova Zemlya might be good places to look for them.

  Finally, in 5000 AD, Greenland lies nearly ice-free under the midnight suns of summer and the noontime stars of winter. Along the eastern coast, a range of mountains up to 12,000 feet high (3,700 m) cradles the last shrunken glaciers. If Santa Claus still exists in the farther reaches of the Anthropocene, that mountain refuge could be where he makes his last wintery stand; in fact, most Scandinavian children will already tell you that “Nisse” or “Tomte” has been living there all along, rather than at the North Pole where American kids now write to him.

  By this time, a prominent new feature has appeared on the national map. Under the thickest portions of ice, the rock was depressed far below sea level. With most of the ice sheet gone, rising seas pushed through narrow northern channels and flooded that central depression. Now a vase-shaped, island-studded fjord 500 miles long (800 km), up to 310 miles wide (500 km), and perhaps 1,500 feet deep (450 m) straddles Greenland’s down-warped spine. Spruce and birch forests crowd the shores except where settlements, roads, and farms carve up the greenery. Whether people of those future times ply the waves of this fjord under the power of petroleum, steam, sail, or paddles, ply it they do. It’s safely sheltered from the heavy swells of the open ocean, and with outlets to the sea it provides easy access to rich northern fishing grounds as well as inland water routes to much of the country.

  When I first learned about this new waterway I realized that it might some day require a name. Why not propose one now? Perhaps some future geographer will find an old copy of this book and put the name on an official map. At first, my mischievous side was tempted to make it unpronounceable by Danes. I once lived in Denmark and found, to my amusement, that many of them struggle to pronounce “refrigerator,” just as most Anglophones can’t say “røged ørred” without gagging. Fridge-fjord briefly came to mind. But a better choice might be Ny Fjord (NEE fee-YORD, translating to “new fjord”) until, more appropriately, some native Greenlander names it.

  Progressive melting of Greenland’s ice cover under an emissions scenario of intermediate intensity. After Alley et al., 2005

  In any case, this scene won’t last forever, and it might not even last through much of the Anthropocene. Ny Fjord will eventually be destroyed by a delayed reaction to the very de-icing process that produced it.

  When the last ice age crushed the northern circumpolar lands, it pushed bedrock hundreds of feet down into the viscous mantle below. As the ice retreated, the crust bounced slowly back, and much of it is still rebounding. A map of uplift rates in Scandinavia, for example, reveals a ghostly silhouette of the ice that once squashed it, centering a bull’s-eye of concentric rings on the northwestern tip of the Baltic Sea. In that corner of Sweden near Luleå, the land rises a third of an inch (8 mm) every year. Move southward along the Baltic coast and the rates decrease; Stockholm is rebounding half as rapidly, Malmö is a quarter as fast, and so on. Something like this will happen in Greenland, too, once the Anthropocene defrosts it.

  In 5000 AD, the unburdened land lifts gently skyward, even though the weight of the water in Ny Fjord resists it. The bottoms of the deepest central basins will already have bounced about a third of the way back as quickly as the ice left them, but the rest of the recovery is sluggish. In 5000 AD, the floor of Ny Fjord rises by 2 or 3 inches (6 to 7 cm) per year, and chronic earthquakes rattle the towns and farmsteads of central Greenland.

  By 8000 AD the fjord is about half as deep as it was when it first formed. The coastal channels are still open because the coasts haven’t risen as much as the central depression has, and global sea level is much higher now that a great deal of polar ice has melted. But eventually, tens of millennia farther down the long tail of the CO2 curve, rebound leaves the outlets high and dry, cutting Ny Fjord off from the Atlantic. Freshwater runoff dilutes the marine brine, and the fjord becomes a lake.

  This sort of thing happened in eastern North America shortly after the last ice age. The newly deglaciated Saint Lawrence River corridor still lay so far below sea level that saltwater rolled in from the east and flooded the Champlain Valley when the ice left. For several centuries, seals and whales swam within sight of what is now the waterfront district of Burlington, Vermont, and fresh-looking shells of blue mussels an
d white Macoma clams still turn up in gravel pits near Plattsburgh, New York. As the land rebounded, the short-lived Champlain Sea lost its lifeline to the ocean, stranding any seals, whales, mussels, and clams unlucky enough to be born into those transitional times. Gradually, the water body was diluted by river and rainfall inputs and became what we now call Lake Champlain.

  In 10,000 AD, Ny Fjord Lake might still be larger than the state of Florida, but its rebounding floor is much higher now, and the water is only about 300 feet deep (100 m). As more millennia pass, bathtub rings of raised beach deposits encircle the contracting shorelines, some of them dotted with the remnants of former harbors and the crumbling foundations of former port towns.

  Climate whiplash is long past and a slow cooling trend is lowering temperatures ever closer to those of today. The change is too subtle for the average Greenlander to notice in the midst of natural year-to-year climate variations, just a small fraction of a degree per century, but the gradual ocean retreat that accompanies it is more readily noticeable in a nation that makes much of its living from the sea. Most who live and work on the ocean’s edge then consider the retreat to be a simple fact of life and easily adapt when necessary, as water-folk did during the more rapid changes of the twentieth and twenty-first centuries. Even so, long-term cooling makes each successive generation of Greenlanders expend a little bit more energy in order to maintain the same levels of indoor comfort that their parents enjoyed. Growing seasons cool and shorten over the course of centuries, and winter ice grips coastal waterways more and more tenaciously in spring.