The World in 2050: Four Forces Shaping Civilization's Northern Future

by Laurence C. Smith

  The long-term trend for the Earth’s climate, for at least several centuries, is rising air temperatures in the troposphere (lower atmosphere). Its underlying driver is radiative forcing commanded by the steady rise of carbon dioxide and other greenhouse gases produced as by-products of human activity. Because carbon dioxide, in particular, can linger in the atmosphere for many centuries this buildup is, for all intents and purposes, permanent.273 Over the long haul, the world’s global average temperature must go up. As shown in Chapter 1, the physics of this has been known since Svante Arrhenius’ work in the 1890s.

  Beyond this broad, average trend, however, the warming process gets more complicated. Our planet is not simply a dry rock with a sunlamp shining on it. The additional heat trapped by greenhouse gases is absorbed, released, and moved around the planet by sloshing ocean currents and turbulent air circulation patterns. Living things breathe air in and out, and store or release carbon—a fundamental ingredient of CO2 and CH4 greenhouse gases—in their tissues. When the ground is bare, it absorbs sunlight, causing local heating. When snow-covered it reflects, causing local cooling. Volcanic eruptions punch aerosols into the stratosphere, shading and cooling the planet for a few years until they dissipate.274 The energy output of the Sun waxes and wanes slightly. All of these little and not-so-little natural mechanisms and feedbacks are to climate change what profit-taking, insider trading, and short sellers are to the stock market. They muck up the underlying greenhouse forcing trend, overprinting it with shorter fluctuations that rise and fall, then rise again.275 If not for this natural variability, we’d have caught on to the deeper greenhouse signal even sooner than we did.

  Any competent financial planner will tell you that the road to secure retirement is paved with market drops. Any competent climate scientist will tell you that our road to a hotter planet will be paved with cold snaps, even record-breakers. But unfortunately, when it comes to communicating this to the general public, we scientists have done a poorer job of it than financial planners. Perhaps it’s not surprising, therefore, that so many people will glance outside at the bitter cold and scoff at global warming—even as they log on to E-Trade to buy up the latest stock market dip.

  The second important fact about climate change is that its geography is neither always global nor always warming. To be sure, it is mostly global and mostly warming. But because of the many complex natural mechanisms and feedbacks that inject themselves into the process, the final climatic manifestations of greenhouse forcing vary greatly in spatial pattern. Climate change is not only erratic in time, like the stock market, but also in geography. A globally averaged temperature increase of one degree Celsius does not mean temperatures rise everywhere around the globe by one degree Celsius. That’s just the average. Some places will heat up a great deal, others won’t or might even cool. Summing them all together gets you to the +1°C global average. But that seemingly small number masks some stunning differences around the world.

  Consider the map below. It is a projection of our future temperature changes by the middle of this century. Some places are warming hugely but other places hardly at all.276 Why is this? Has some climate model gone haywire?

  This map is not an oddball, but just one of a family of nine related maps released by the latest IPCC Assessment.277 They all show irregular geographic patterns and appear together on the following page in a three-by-three grid. From left to right they plot out a three-stage timeline for our century, with average, smoothed-out temperature changes apparent by 2011-2030, by 2046-2065, and by 2080-2099. Like the single map on page 126, each one is actually produced from not one but many climate models—much like a stock index—thus capturing where the models robustly agree rather than the quirks of any particular climate model over another.

  Each of the three rows corresponds to a different concentration of greenhouse gas in the atmosphere. That, in turn, rests on all sorts of things, from political leadership to energy technology to gross domestic product. Rather than try to predict which outcome will actually transpire, the IPCC instead calculates outcomes for numerous possible social paths (called SRES scenarios 278), of which three are shown here. The first outcome (top row) may be described as a highly globalized world, with population stabilizing by midcentury and an aggressive transition to a modern information and service economy. This scenario (known to climate scientists as “B1”) is labeled “optimistic” on the figure.279 The second outcome also assumes a stabilizing population and fast adoption of new energy technologies, but with a balance of fossil and nonfossil fuels. That future (called “A1B” by climate scientists) is labeled “moderate.” The third outcome assumes a very divided world with high population growth, slower economic development, and slow adoption of new energy technology. This future (called “A2”) is labeled “pessimistic.”

  The third important fact about global climate change is revealed by comparing these three rows of maps. They show that, regardless of technology path, we are already locked in to some degree of warming; but by century’s end, the actions or inactions taken now to curb greenhouse gas emissions really will matter enormously. By 2080-2099 the “pessimistic” world is indeed a cauldron compared to the “optimistic” one, with temperatures rising 3.5°-5.0°C (9°F) across the conterminous United States, Europe, and China, rather than 2.0°-2.5°C (4.5°F). While these numbers may seem small, in fact there is a huge difference between the two outcomes. A 2.5°C rise in average annual temperature is actually huge, equivalent to the difference between a record cool and record warm year in New York City. So even in the “optimistic” world, what is today considered an extreme warm year in New York will become the norm; and the new extremes will be unlike anything New Yorkers have ever seen.

  The “pessimistic” numbers are even more alarming. They approach the magnitude of average temperature contrast between the world of today and the world of twenty thousand years ago during the last ice age, when global temperatures averaged about 5°C (9°F) cooler. Many areas of North America and Europe were under ice, sea levels were more than 100 meters (330 feet) lower, and Japan was actually connected to the Asia mainland.280

  All of these maps are conservative in that they awaken no hidden “climate genies” that give climate scientists nightmares.281 Instead, they chart out the plain vanilla, predictable intensification of the greenhouse effect, covering a realistic range of options lying well within control of human choices.

  The fourth important fact to take from these nine maps is that the irregular geography of climate change presented in the first single map is not at all random. Important spatial patterns remain broadly preserved in all model simulations, for all carbon emissions scenarios, and across all time frames. Temperature increases are higher over land than over the oceans. A bull’s-eye over the northern Atlantic Ocean stubbornly refuses to warm up. And without fail, regardless of which emissions path is followed, or what time slice is examined, or what climate models are run, all of the model projections—and measured observations too—consistently tell us something big. Again and again, they tell us that global climate change is hugely amplified in the northern high latitudes.282

  Even our “optimistic” scenario projects that the northern high latitudes will warm 1.5-2.5°C by midcentury and 3.5-6°C by century’s end, more than double the global average. Our “pessimistic” scenario suggests rises of +8°C (14.4°F) or more. Global climate change will not raise temperatures uniformly around the world. Instead, the fastest and most furious increases are under way in the North.

  There is another robust trend expected for the northern high latitudes. For much of the world it is very difficult to project future precipitation patterns with confidence. Cloud physics and rainfall are more complicated and tougher to model than greenhouse physics, especially at the coarse spatial resolution of today’s climate models. To the frustration of policy makers, model projections of future rainfall often lack statistical confidence, and even disagree as to whether it will increase or decrease. But not in
the North. If there is one thing that the climate models all agree on,283 it’s that precipitation (snow and rain) will increase there, especially in winter. It must increase, in obedience to physics284 and rising evaporation from open lakes and seas as they become unfrozen for longer times during the year.

  The plainest manifestation of this will be snowier winters and higher river flows. Across southern Europe, western North America, the Middle East, and southern Africa, river flows are projected to fall 10%-30% by 2050. However, they will increase by a similar amount across northern Canada, Alaska, Scandinavia, and Russia.285 This has already happened in Russia. Through statistical analysis of old Soviet hydrologic records, one of my own projects helped to confirm rising river flows there, including sharp increases in south-central Russia beginning around 1985.286

  Recall the bleak future of stressed human water supply all around the planet’s dry latitudes from Chapter 4? That future is not shared by the North. It is water-rich now and, except for Canada’s south-central prairies and the Russian steppes, will become even more water-rich in the future.

  Uncapping an Ocean

  To most people, there is nothing visceral about computer model projections of average climate statistics decades from now. But in September 2007 we got a taste of what the real world inside those maps might look like. For the first time in human memory, nearly 40% of the floating lid of sea ice that papers over the Arctic Ocean disappeared in a matter of months. The famed “Northwest Passage”—an ice-encased explorers’ graveyard—opened up. From the northern Pacific, where the United States and Russia brush lips across the Bering Strait, open blue water stretched almost all the way to the North Pole.

  There was an error-riddled media frenzy about a melting “ice cap” at the North Pole,287 then the story faded. But climate scientists were shocked to the bone. The problem wasn’t that it had happened, but that it had happened too soon. Our climate models had been preparing us for a gradual contraction in Arctic sea ice—and perhaps even ice-free summers by 2050—but none had predicted a downward lurch of this magnitude until at least 2035. The models were too slow to match reality. Apparently, the Arctic Ocean’s sea-ice cover could retreat even faster than we thought.

  Two months later several thousand of us were milling around the cavernous halls of San Francisco’s Moscone Center at our biggest yearly conference,288 nervously abuzz about the Arctic sea-ice retreat. In a keynote lecture, the University of Colorado’s brilliant, ponytailed Mark Serreze drove home the scale of the situation. When NASA first began mapping Arctic sea ice with microwave satellites in the 1970s, he intoned, flashing a political map of the lower forty-eight United States on the screen, its minimum summer sea-ice extent289 hovered near 8 million square kilometers, equivalent to all of the lower forty-eight U.S. states minus Ohio. POOF! Ohio vanished from the big projection screen. Since then its minimum area had been declining gradually, up until this year when it suddenly contracted abruptly, like a giant poked sea anemone, to just 4.3 million square kilometers. POOF! POOF! POOF! Gone was the entire United States east of the Mississippi River, together with North Dakota, Minnesota, Missouri, Arkansas, Louisiana, and Iowa. A murmur rolled through the hall—even scientists enjoy a good animated graphic over tables of numbers any day.

  After Serreze’s talk we milled around some more, wrangling over things like “model downscaling,” “cloud forcing,” and “nonlinear dynamics.” Some were revising the old projections for an ice-free Arctic Ocean from 2050 to 2035, or even 2013. Others—including me—argued for natural variability. We thought the 2007 retreat could just be a freak and the sea ice would recover, filling up its old territory by the following year.

  We were wrong. The excursion persisted for two more years, with 2008 and 2009 also breaking records for the Arctic summer sea-ice minimum. They were the second- and third-lowest years ever seen, and had followed right on the heels of what happened before.290

  Ice Reflects, Oceans Absorb

  The broader impacts of amplified warming—more rain and snow, and reduced summer sea ice at the top of our planet—extend far beyond the region itself. They will drive important climatic feedbacks that flow out to the rest of the world, influencing atmospheric circulation, precipitation patterns, and jet streams. Unlike land ice, melting sea ice does not directly affect sea level (in accordance with Archimedes’ Principle291), but its implications for northern shipping and logistical access are so profound they are the subject of the following chapter. Perhaps most importantly of all, an open ocean releases heat, causing milder temperatures to penetrate even the much larger frigid landmasses to the south. Indeed, the loss of sea ice is the single biggest reason why the geographic pattern of climate warming is so magnified in the northern high latitudes.

  Look again at the nine maps (p. 128) charting different temperature outcomes for the coming decades. In every one, the epicenter of climate warming is the Arctic Ocean, radiating (relative) warmth southward like a giant mushrooming umbrella. You are looking at the power of the ice-albedo effect, one of the stronger self-reinforcing climate feedbacks on Earth.

  Albedo is the light-reflectivity of a surface. Its values range from 0 to 1 (meaning 0% to 100% reflective). Snow and ice have high albedo, bouncing as much as 90% of incoming sunlight back out to space. Ocean water has very low albedo, reflecting less than 10% and absorbing the rest. Just as a white T-shirt feels cool in the Sun but a black T-shirt feels hot, so also does a white Arctic Ocean stay cool while a dark one heats up.

  Compared to land glaciers, sea ice is thin and flimsy, an ephemeral floating membrane just 1-2 meters thick. The greenhouse effect, by melting it back somewhat, thus unleashes a self-reinforcing effect even greater than the greenhouse warming itself. It’s rather as if when struck by blazing hot sun, one discards a white shirt and puts on a black one. By responding in this way to small global temperature changes, sea ice thus amplifies them even more.292

  While its global effect is small, the ice-albedo feedback is uniquely powerful in the Arctic because it is the only place on Earth where a major ocean gets coated with ephemeral floating sea ice during the summer. Antarctica, in contrast, is a continent of land, thickly buried beneath permanent, kilometers-thick glaciers. For this and several other reasons, climate warming is more amplified in the Arctic than the Antarctic. 293,294

  As an ice-free Arctic Ocean warms up, it acts like a giant hot-water bottle, warming the chilly Arctic air as the Sun crawls off the horizon each winter. The sea ice that does eventually form is thin and crackly, allowing more of the ocean’s heat to seep out even during the depths of winter. Winters become milder, the autumn freeze-up happens later, and the spring thaw arrives earlier. The warming effect is highest over the ocean and from there spills southward, warming vast landscapes across some of the coldest terrain on Earth.

  Dr. Smith Goes to Washington

  I first met National Center for Atmospheric Research (NCAR) climate modeler David Lawrence in Washington, D.C. We had been brought to the Russell Senate Office Building to brief U.S. Senate staffers on the ramifications of thawing Arctic permafrost. It was exciting. The Russell is the Senate’s oldest building and the site of many historic events, including the Watergate hearings. Its hallways are white marble and mahogany, with important-looking people clacking around in dark power-suits. Just a few yards from our briefing room were the offices of Senator John Kerry and former senator John F. Kennedy. Moments before we got started, the moderator pulled us aside to whisper that Senator John McCain might show up. He didn’t, but it was cool just wondering if he would.

  After the briefings and a pleasant lunch reception were over, Dave and I headed out to a local pub for a beer before catching our flights home. Over microbrews, he described his next big idea: figuring out how much northern landscapes might warm up, based purely on the ice-albedo feedback from reduced summer sea-ice. I told him he was on to something. It was critical to separate out the ice-dependent feedback from overall greenhouse gas forcing, I pointed
out. That way, if the ice shrank faster than expected, we’d know what the immediate climate response could be—even ahead of the longer-term cumulative effect of greenhouse gas loading. We drained our pints and left. I promptly forgot all about the conversation until eighteen months later when I ran into Dave at a conference. Whipping out his laptop, he showed me a preliminary model simulation of his big idea.295

  My eyes widened. I was gazing at a world with northern high latitudes plastered everywhere in vivid orange—a pool of spreading warmth as much as five, six, or seven degrees Celsius (8° to 12°F) higher—spreading southward from the Arctic Ocean. All of Alaska and Canada and Greenland were bathed in it. It grazed other northern U.S. states from Minnesota to Maine. Russia’s vast bulk was lit up from one end to the other. Only Scandinavia and Western Europe, already warmed by the Gulf Stream, were untouched. Then I looked closer and saw what time of year it was.

  November . . . December . . . January . . . February. The warming effect was greatest not in summer but during the coldest months of the year. I was staring at a map of the relaxing grip of winter’s iron clench. It was an easing, a partial lifting, of the Siberian Curse.