writing a book about the past, our own crisis of climate runs through my head. Every day. I find myself grasping for comparisons that aren’t quite clear. I have a friend, old-fashioned in his communication technology, who sends me news clips from newspapers and magazines by mail. He knows I’m working on a book about the Pleistocene and he wants to keep my mind straight. To keep my nose to the grindstone, I post his worst scenario for today’s global warming disaster to the back of a map of Yellowstone Park, where I can’t avoid looking at it.
“By 2100, the Earth’s population will be culled from today’s 6.6 billion to as few as 500 million;” says James Lovelock, independent scientist and father of the Gaia theory, “billions of us will die and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable.” Lovelock also thinks: “By 2040, the Sahara will be moving into Europe, and Berlin will be as hot as Baghdad. Atlanta will end up a kudzu jungle. Phoenix will become uninhabitable, as will parts of Beijing (desert), Miami (rising seas) and London (floods). Food shortages will drive millions of people north, raising political tensions. “The Chinese have nowhere to go but up into Siberia.” He hopes that “it doesn’t degenerate into Dark Ages, with warlords running things, which is a real danger.”
Yet Lovelock holds out a glimmer of light: “We are about to take an evolutionary step and my hope is that the species will emerge stronger. It would be hubris to think humans as they now are God’s chosen race.” Lovelock adds: “The human species has been on the planet for a million years now. We’ve gone through seven major climatic changes that are equivalent to this. The ice-ages were shifts in climate comparable with this one that’s coming. And we’ve survived. That series of glaciations and interglacials put the pressures on us to select the kind of human that could adapt. And we’re the progeny of them. And we’re just up against a new and different stress. Maybe we’ll come out better.”
My friend Scotch-taped to the bottom another scrap of newspaper:
“The Republicans are back in control of the House, and they’re bringing something with them: styrofoam cups. The cups, along with plastic forks and a number of other things seen as not eco-friendly, were done away with four years ago by Nancy Pelosi to reduce Congress’s carbon footprint.”
Green activists called the switch an insult to the environment, “Neanderthal” and a slap in the face to efforts to combat global warming.
My friend wonders if Lovelock is suggesting that the Pleistocene glacial fluctuations honed a more adaptable human, better able to cope with, say, the threat of modern global warming? These congressional folk not only don’t believe in global warming, they think it’s an environmental conspiracy. How does evolutionary pressure from the first (the Ice Age) select for the kind of person who seems indifferent to the second (climate change)? According to Lovelock, it should be the other way round. My friend finds grim humor here. Modern humans’ social tendencies paint the battles black and white in a world of friends and enemies; we focus on the fights that matter the least while ignoring what matters most.
A couple more clips, intrusive but closer to the heart of the matter:
The Los Angeles Times reports “Greenland’s Ice Sheet is Slip-Sliding Away.” By 2005, Greenland was losing more ice than anyone expected; the amount of freshwater ice dumped into the Atlantic had almost tripled in a decade. Summer meltwater, responding to recent warmer temperatures, also accelerated. The warm water on the top of the ice sheet made its way through a maze of tunnels, natural pipes and cracks in the ice to the bedrock below, lubricating the slip of ice over Greenland’s rock basement. The meltwater descended thousand of feet in weeks not decades. This was a surprise to scientists. If all glaciers draining the ice sheet slide too quickly, they could collapse suddenly and release the entire ice sheet into the ocean.
“Should all of the ice sheet ever thaw, the meltwater could raise sea level 21 feet and swamp the world’s coastal cities, home to a billion people. It would cause higher tides, generate more powerful storm surges and, by altering ocean current, drastically disrupt the global climate.”
Reuters: Arctic ice sheet may swamp U.S. coasts. The loss of the huge West Arctic Ice Sheet (WAIS) would cause sea levels to rise by 21 feet in North America and 16.5 feet worldwide.
Some scientists warn that the WAIS is fundamentally far less stable than the Greenland because most of it is grounded far below sea level. One expert considers the WAIS collapse is all but inevitable given the current business-as-usual projected warming of 5-7 degrees C.
Arctica’s Ross Ice Sheet is considered even more unstable than the WAIS because it had previously collapsed and could again at any moment. The Ross Ice Sheet collapse would result in an additional 15 feet of sea rise.
Fifty feet of sea rise would demolish the world’s coastal populations, flooding highly populated areas such as Washington, D.C., New York City and the California coastline, and deal disaster to the low-lying Third World, displacing countless millions. And some of these rises could be extremely rapid; the collapse of the Ross Ice Sheet could cause the world’s oceans to rise 15 feet in a week. If all the Arctic and Greenland ice sheets melt, the oceans would rise about 180 feet.
What about the Late Pleistocene? The most dramatic comparison to today’s situation might have been the rising ocean. At the onset of the previous global warming period, known as the Bølling-Allerød, 14,700 years ago and before, when the glaciers were still at their maximum extent, the sea level off British Columbia was 300 to 450 feet lower than today. By 9,000 years ago, the ocean had risen to current levels and, after some local sloshing up and down, settled to where it is now is by 5,500 years ago.
A few scientists are now suggesting that the onset of the warming period following the last glacial maximum might have begun a couple thousand years earlier. The research, some of it from lakes in Alaska, is recent and ongoing. Future research may push that 14,700-date deeper into the Late Pleistocene, say maybe 17,000 years ago, along with earlier dates for the feasibility of navigating the Pacific Coast or the opening of the ice-free corridor. But for the purposes of this book, 14,700 years ago marks the beginning of the warming period.
That amount of ocean rise seems enormous, though moving a shellfish camp might have been easier than relocating skyscrapers. The Pleistocene people would have seen the effects of sea rise as waters slowly drowned the forest of the Pacific continental shelf and glacial flour colored the milky deltas. They would not notice the actual rise of inches per century unless a great chunk of ice, like the Ross, broke off a sheet and fell into the ocean. But they would likely have a collective notion that the climate was changing, much as we have today.
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The end of the Late Pleistocene came suddenly. The global warming that began 14,700 years ago ceased abruptly with a sudden and relatively short-lived cold reversal known as the Younger Dryas (named for an ivory-colored alpine flower with a yellow center that thrived in the cooler air). This was a prolonged cold snap not a re-advance of the glaciers. Isotopes in the Greenland ice indicate the Younger Dryas (YD) began 12,880 years ago and lasted for around 1,300 years, when the warmer modern epoch called the Holocene began.
Causes of the Younger Dryas are hotly debated. One argument posits that the giant freshwater lake perched upon the surface of the North American ice sheet (Lake Agassiz) burst its ice-dam and dumped vast amounts of cold water through the St. Lawrence Valley into the North Atlantic Ocean interrupting the conveyor belt of warm surface water from the south—causing the sudden cooling. Others contend the amount of melt water from Lake Agassiz was insufficient to disrupt the heat conveyor, to the extent that it would alter climate, and that evidence of the eastward flood—flood debris, terraces or an outlet channel—is lacking. Besides, ice cores from the southern hemisphere show that the cooling was worldwide. Likewise, an asteroid theory—an extraterrestrial body smashing into the glacial ice north of the Great Lakes (but leaving no impact crater)—has played to a limited audience, and has been largely, but not entirely, debunked as the precise trigger that brought on the Younger Dryas and drove into extinction the last sabertooths, mammoths, mastodons, dire wolves, horses and short-faced bears (to name a few) in a heartbeat of geologic time.
Whatever the cause, the Younger