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The Pentagon and Abrupt Climate Change
Alex Steffen, 5 Feb 04

One of the problems with the phrase "global warming" is that warming is a pleasant and mild word. We all like to be warm. Much less pleasant, though, are some of the potential consequences of climate change, like super-storms, persistant drought, and abrupt climate change.

The last is particularly nasty, involving really drastic and relatively permanent shifts in weather patterns over entire continents. It's happened before. But will it happen again, and how seriously should we take the threat? That's a pretty critical piece of environmental knowledge being parsed out by our friends at... the Pentagon?

"But what would abrupt climate change really be like? Scientists generally refuse to say much about that, citing a data deficit. But recently, renowned Department of Defense planner Andrew Marshall sponsored a groundbreaking effort to come to grips with the question. A Pentagon legend, Marshall, 82, is known as the Defense Department's "Yoda"—a balding, bespectacled sage whose pronouncements on looming risks have long had an outsized influence on defense policy. Since 1973 he has headed a secretive think tank whose role is to envision future threats to national security. The Department of Defense's push on ballistic-missile defense is known as his brainchild. Three years ago Defense Secretary Donald Rumsfeld picked him to lead a sweeping review on military "transformation," the shift toward nimble forces and smart weapons."(more below)

(thanks, Henry!)

The result is an unclassified report, completed late last year, that the Pentagon has agreed to share with FORTUNE. It doesn't pretend to be a forecast. Rather, it sketches a dramatic but plausible scenario to help planners think about coping strategies. Here is an abridged version:

A total shutdown of the ocean conveyor might lead to a big chill like the Younger Dryas, when icebergs appeared as far south as the coast of Portugal. Or the conveyor might only temporarily slow down, potentially causing an era like the "Little Ice Age," a time of hard winters, violent storms, and droughts between 1300 and 1850. That period's weather extremes caused horrific famines, but it was mild compared with the Younger Dryas.

For planning purposes, it makes sense to focus on a midrange case of abrupt change. A century of cold, dry, windy weather across the Northern Hemisphere that suddenly came on 8,200 years ago fits the bill—its severity fell between that of the Younger Dryas and the Little Ice Age. The event is thought to have been triggered by a conveyor collapse after a time of rising temperatures not unlike today's global warming. Suppose it recurred, beginning in 2010. Here are some of the things that might happen by 2020:

At first the changes are easily mistaken for normal weather variation—allowing skeptics to dismiss them as a "blip" of little importance and leaving policymakers and the public paralyzed with uncertainty. But by 2020 there is little doubt that something drastic is happening. The average temperature has fallen by up to five degrees Fahrenheit in some regions of North America and Asia and up to six degrees in parts of Europe. (By comparison, the average temperature over the North Atlantic during the last ice age was ten to 15 degrees lower than it is today.) Massive droughts have begun in key agricultural regions. The average annual rainfall has dropped by nearly 30% in northern Europe, and its climate has become more like Siberia's.

Violent storms are increasingly common as the conveyor becomes wobbly on its way to collapse. A particularly severe storm causes the ocean to break through levees in the Netherlands, making coastal cities such as the Hague unlivable. In California the delta island levees in the Sacramento River area are breached, disrupting the aqueduct system transporting water from north to south.

Megadroughts afflict the U.S., especially in the southern states, along with winds that are 15% stronger on average than they are now, causing widespread dust storms and soil loss. The U.S. is better positioned to cope than most nations, however, thanks to its diverse growing climates, wealth, technology, and abundant resources. That has a downside, though: It magnifies the haves-vs.-have-nots gap and fosters bellicose finger-pointing at America.

Turning inward, the U.S. effectively seeks to build a fortress around itself to preserve resources. Borders are strengthened to hold back starving immigrants from Mexico, South America, and the Caribbean islands—waves of boat people pose especially grim problems. Tension between the U.S. and Mexico rises as the U.S. reneges on a 1944 treaty that guarantees water flow from the Colorado River into Mexico. America is forced to meet its rising energy demand with options that are costly both economically and politically, including nuclear power and onerous Middle Eastern contracts. Yet it survives without catastrophic losses.

Europe, hardest hit by its temperature drop, struggles to deal with immigrants from Scandinavia seeking warmer climes to the south. Southern Europe is beleaguered by refugees from hard-hit countries in Africa and elsewhere. But Western Europe's wealth helps buffer it from catastrophe.

Australia's size and resources help it cope, as does its location—the conveyor shutdown mainly affects the Northern Hemisphere. Japan has fewer resources but is able to draw on its social cohesion to cope—its government is able to induce population-wide behavior changes to conserve resources.

China's huge population and food demand make it particularly vulnerable. It is hit by increasingly unpredictable monsoon rains, which cause devastating floods in drought-denuded areas. Other parts of Asia and East Africa are similarly stressed. Much of Bangladesh becomes nearly uninhabitable because of a rising sea level, which contaminates inland water supplies. Countries whose diversity already produces conflict, such as India and Indonesia, are hard-pressed to maintain internal order while coping with the unfolding changes.

As the decade progresses, pressures to act become irresistible—history shows that whenever humans have faced a choice between starving or raiding, they raid. Imagine Eastern European countries, struggling to feed their populations, invading Russia—which is weakened by a population that is already in decline—for access to its minerals and energy supplies. Or picture Japan eyeing nearby Russian oil and gas reserves to power desalination plants and energy-intensive farming. Envision nuclear-armed Pakistan, India, and China skirmishing at their borders over refugees, access to shared rivers, and arable land. Or Spain and Portugal fighting over fishing rights—fisheries are disrupted around the world as water temperatures change, causing fish to migrate to new habitats.

Growing tensions engender novel alliances. Canada joins fortress America in a North American bloc. (Alternatively, Canada may seek to keep its abundant hydropower for itself, straining its ties with the energy-hungry U.S.) North and South Korea align to create a technically savvy, nuclear-armed entity. Europe forms a truly unified bloc to curb its immigration problems and protect against aggressors. Russia, threatened by impoverished neighbors in dire straits, may join the European bloc.

Nuclear arms proliferation is inevitable. Oil supplies are stretched thin as climate cooling drives up demand. Many countries seek to shore up their energy supplies with nuclear energy, accelerating nuclear proliferation. Japan, South Korea, and Germany develop nuclear-weapons capabilities, as do Iran, Egypt, and North Korea. Israel, China, India, and Pakistan also are poised to use the bomb.

The changes relentlessly hammer the world's "carrying capacity"—the natural resources, social organizations, and economic networks that support the population. Technological progress and market forces, which have long helped boost Earth's carrying capacity, can do little to offset the crisis—it is too widespread and unfolds too fast.

As the planet's carrying capacity shrinks, an ancient pattern reemerges: the eruption of desperate, all-out wars over food, water, and energy supplies. As Harvard archeologist Steven LeBlanc has noted, wars over resources were the norm until about three centuries ago. When such conflicts broke out, 25% of a population's adult males usually died. As abrupt climate change hits home, warfare may again come to define human life.

Over the past decade, data have accumulated suggesting that the plausibility of abrupt climate change is higher than most of the scientific community, and perhaps all of the political community, are prepared to accept.

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The quote from the Fortune article:

"But what would abrupt climate change really be like? Scientists generally refuse to say much about that, citing a data deficit."

Isn't really true. Scientists have been saying a lot about abrupt climate change. The USA's National Research Council published a book summarizing the state of the science in 2002. The book, Abrupt Climate Change: Inevitable Surprises, can be read online at:

Posted by: Garry Peterson on 5 Feb 04

Thanks, Garry!

Posted by: Alex Steffen on 5 Feb 04

I think we need to translate the word "Scientists" in this context to read:

"those scientists that our adminsitration and its supporters consider the experts on this sort of thing, because they're paid by oil companies and business lobbying groups to be noncomittal wusses who know their place."

Posted by: Stefan Jones on 5 Feb 04

The Woods Hole Oceanographic Institute (WHOI) website has an excellent section on abrupt climate change. It includes the presentation its President and Director Robert Gagosian made to the World Economic Forum in Davos, Switzerland, January 27, 2003, called "Abrupt Climate Change: Should We Be Worried?" Short answer: yes. Their FAQs on this issue are also very good.

You can find it all on line at:

Posted by: Peter+Trudy Johnson-Lenz on 7 Feb 04

I've always been interested in the global warming issue. After reading the Fortune mag article and other sites, I'm convinced that this threat is real and bound to happen within the next 10-20 years. What bothers me is that most people I talk to about abrupt climate change get defensive and try to prove how smart they are by touting their own knowlege about the issue instead of focusing on the threat.A case in point is the comments on this site that pick apart the article instead of presenting meaningful dialog. We should be telling the public about this threat, because I can just imagine what our current goverment is going to do with this information.

Posted by: Tom Mohler on 14 Feb 04

The case of greater energy efficiency can hardly get any stronger! It's quick to implement, uses existing technology, is relatively cheap, makes huge savings, reduces exposure to overseas energy supplies, the list goes on... It is simply a shame that we are so bad at challenging and changing lazy, greedy + harmful behaviour! We are the limiting factor.

Posted by: Matt Prescott on 15 Feb 04

The Fortune article refers to an unclassified report that was released late last year. I think this report was authored by Peter Schwartz and Doug Randall of the Global Business Network, and is called "An Abrupt Climate Change Scenario and Its Implications for United States National Security." I have not been able to find a copy anywhere. Is it public domain? Does anybody know where to get a copy?

Posted by: Mark on 18 Feb 04

This was on the Philadelphia Weekly website. I think it is refering to the report you mention.

"United States Marine Corps Capt. David Romley, a spokesperson for the Office of the Assistant Secretary of Defense, says via email that "the report is being cleared for public distribution and may be made available after that process is complete.""

The quote came from this article:

Posted by: David on 21 Feb 04

This post is some weeks old, but given the extensive linking to the Guardian article, I'd suggest a look at Bruce's most recent Viridian Note (401), which should be posted soon:

Also, as Bruce and others have pointed out, the full .pdf document is available via Greenpeace:

Posted by: Dawn Danby on 27 Feb 04

From Nature 427, 769 (26 February 2004); doi:10.1038/427769a

Gulf Stream probed for early warnings of system failure

Climate researchers set sail from the Canary Islands today to begin an ambitious, four-year programme that will assess the behaviour of currents, such as the Gulf Stream, in the north Atlantic Ocean.

The US$20-million programme is part of a wider investigation into rapid climate change, known as Rapid. It will take the most detailed look yet at the strength, structure and variability of the currents that carry warmth northwards in the Atlantic.

Climatologists worry that global warming could disrupt these currents, which make Western Europe's climate far warmer than other parts of the world at the same latitude. Without the Gulf Stream, for example, the south of England would be as cold as Iceland.

Researchers think the currents are caused by a combination of wind, differences in water density, and the special geometry of Atlantic Ocean basins and the surrounding continents. They think the system may have broken down before, driving large, abrupt changes in climate (see Nature 364, 203–207; 1993).

Given the extent of global climate change at the moment, some suspect this could happen again. Models suggest that currents are already affected by increased freshwater flow from precipitation, river runoff and ice-sheet melting (see Nature 378, 145–149; 1995).

The Rapid team on board the British research vessel RRS Discovery will try to establish if this is really happening. "Complete collapse of the north Atlantic circulation is a worst-case scenario," says Stefan Rahmstorf, a climate modeller at the Potsdam Institute of Climate Impact Research in Germany. "But no one really has any firm idea of what is going on out there, and that is why this project is so important."

The team will use 22 moorings across the subtropical Atlantic: near the Canary Islands, on the Mid-Atlantic Ridge and off the Bahamas. Sensors will travel up and down wires from buoys to the moorings on the sea floor. Differences in water density will be calculated from the temperature and salinity measured throughout these water columns. With US measurements from the Florida Strait and satellite observation of wind-driven surface currents, these will help researchers understand water flow in the north Atlantic.

"It is unlikely that we will detect dramatic changes within the next four years," says Jochem Marotzke, an oceanographer at the Max Planck Institute of Meteorology in Hamburg, and one of the principal investigators in Rapid. "But we will learn lots of exciting things about ocean circulation, and work out how to design a stable monitoring system for the next few decades." Rapid is being jointly sponsored by Britain's Natural Environment Research Council and the US National Science Foundation.

One long-term goal, says Marotzke, is an early-warning programme that would raise the alarm if the present system was close to failure. Even if nothing could be done, society could prepare for the results, he says. A German–Norwegian project called Integration is already assessing the impact of a failure on climate, fisheries and agriculture.

for more see:

Posted by: Garry Peterson on 28 Feb 04



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