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

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