The World in 2050_ Four Forces Shaping Civilization's Northern Future - Laurence C. Smith [68]
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