An Abrupt Climate Change Scenario and Its Implications for United

States National Security

October 2003

By Peter Schwartz and Doug Randall

Imagining the Unthinkable

The purpose of this report is to imagine the unthinkable – to push the boundaries of current

research on climate change so we may better understand the potential implications on United

States national security.

We have interviewed leading climate change scientists, conducted additional research, and

reviewed several iterations of the scenario with these experts. The scientists support this

project, but caution that the scenario depicted is extreme in two fundamental ways. First,

they suggest the occurrences we outline would most likely happen in a few regions, rather

than on globally. Second, they say the magnitude of the event may be considerably smaller.

We have created a climate change scenario that although not the most likely, is plausible, and

would challenge United States national security in ways that should be considered

immediately.

Executive Summary

There is substantial evidence to indicate that significant global warming will occur

during the 21st century. Because changes have been gradual so far, and are projected

to be similarly gradual in the future, the effects of global warming have the potential

to be manageable for most nations. Recent research, however, suggests that there is a

possibility that this gradual global warming could lead to a relatively abrupt slowing

of the ocean’s thermohaline conveyor, which could lead to harsher winter weather

conditions, sharply reduced soil moisture, and more intense winds in certain regions

that currently provide a significant fraction of the world’s food production. With

inadequate preparation, the result could be a significant drop in the human carrying

capacity of the Earth’s environment.

The research suggests that once temperature rises above some threshold, adverse

weather conditions could develop relatively abruptly, with persistent changes in the

atmospheric circulation causing drops in some regions of 5-10 degrees Fahrenheit in

a single decade. Paleoclimatic evidence suggests that altered climatic patterns could

last for as much as a century, as they did when the ocean conveyor collapsed 8,200

years ago, or, at the extreme, could last as long as 1,000 years as they did during the

Younger Dryas, which began about 12,700 years ago.
Abrupt Climate Change 2

In this report, as an alternative to the scenarios of gradual climatic warming that are

so common, we outline an abrupt climate change scenario patterned after the 100-

year event that occurred about 8,200 years ago. This abrupt change scenario is

characterized by the following conditions:

• Annual average temperatures drop by up to 5 degrees Fahrenheit over Asia

and North America and 6 degrees Fahrenheit in northern Europe

• Annual average temperatures increase by up to 4 degrees Fahrenheit in key

areas throughout Australia, South America, and southern Africa.

• Drought persists for most of the decade in critical agricultural regions and in

the water resource regions for major population centers in Europe and eastern

North America.

• Winter storms and winds intensify, amplifying the impacts of the changes.

Western Europe and the North Pacific experience enhanced winds.

The report explores how such an abrupt climate change scenario could potentially

de-stabilize the geo-political environment, leading to skirmishes, battles, and even

war due to resource constraints such as:

1) Food shortages due to decreases in net global agricultural production

2) Decreased availability and quality of fresh water in key regions due to shifted

precipitation patters, causing more frequent floods and droughts

3) Disrupted access to energy supplies due to extensive sea ice and storminess

As global and local carrying capacities are reduced, tensions could mount around the

world, leading to two fundamental strategies: defensive and offensive. Nations with

the resources to do so may build virtual fortresses around their countries, preserving

resources for themselves. Less fortunate nations especially those with ancient

enmities with their neighbors, may initiate in struggles for access to food, clean

water, or energy. Unlikely alliances could be formed as defense priorities shift and

the goal is resources for survival rather than religion, ideology, or national honor.

This scenario poses new challenges for the United States, and suggests several steps

to be taken:

• Improve predictive climate models to allow investigation of a wider range of

scenarios and to anticipate how and where changes could occur

• Assemble comprehensive predictive models of the potential impacts of abrupt

climate change to improve projections of how climate could influence food,

water, and energy

• Create vulnerability metrics to anticipate which countries are most vulnerable

to climate change and therefore, could contribute materially to an increasingly

disorderly and potentially violent world.
Abrupt Climate Change 3

• Identify no-regrets strategies such as enhancing capabilities for water

management

• Rehearse adaptive responses

• Explore local implications

• Explore geo-engineering options that control the climate.

There are some indications today that global warming has reached the threshold

where the thermohaline circulation could start to be significantly impacted. These

indications include observations documenting that the North Atlantic is increasingly

being freshened by melting glaciers, increased precipitation, and fresh water runoff

making it substantially less salty over the past 40 years.

This report suggests that, because of the potentially dire consequences, the risk of

abrupt climate change, although uncertain and quite possibly small, should be

elevated beyond a scientific debate to a U.S. national security concern.

Climate Change

Cold

Dry

Storms

Reduction in Carrying

Capacity

Food

Water

Energy

National Security

Implications

Border management

Global conflict

Economic malaise
Abrupt Climate Change 4

An Abrupt Climate Change Scenario and Its Implications for United

States National Security

October 2003

Introduction

When most people think about climate change, they imagine gradual increases in

temperature and only marginal changes in other climatic conditions, continuing

indefinitely or even leveling off at some time in the future. The conventional wisdom

is that modern civilization will either adapt to whatever weather conditions we face

and that the pace of climate change will not overwhelm the adaptive capacity of

society, or that our efforts such as those embodied in the Kyoto protocol will be

sufficient to mitigate the impacts. The IPCC documents the threat of gradual climate

change and its impact to food supplies and other resources of importance to humans

will not be so severe as to create security threats. Optimists assert that the benefits

from technological innovation will be able to outpace the negative effects of climate

change.

Climatically, the gradual change view of the future assumes that agriculture will

continue to thrive and growing seasons will lengthen. Northern Europe, Russia, and

North America will prosper agriculturally while southern Europe, Africa, and

Central and South America will suffer from increased dryness, heat, water shortages,

and reduced production. Overall, global food production under many typical climate

scenarios increases. This view of climate change may be a dangerous act of selfdeception, as increasingly we are facing weather related disasters -- more hurricanes,

monsoons, floods, and dry-spells – in regions around the world.

Weather-related events have an enormous impact on society, as they influence food

supply, conditions in cities and communities, as well as access to clean water and

energy. For example, a recent report by the Climate Action Network of Australia

projects that climate change is likely to reduce rainfall in the rangelands, which could

lead to a 15 per cent drop in grass productivity. This, in turn, could lead to

reductions in the average weight of cattle by 12 per cent, significantly reducing beef

supply. Under such conditions, dairy cows are projected to produce 30% less milk,

and new pests are likely to spread in fruit-growing areas. Additionally, such

conditions are projected to lead to 10% less water for drinking. Based on model

projections of coming change conditions such as these could occur in several food

producing regions around the world at the same time within the next 15-30years,

challenging the notion that society’s ability to adapt will make climate change

manageable.
Abrupt Climate Change 5

With over 400 million people living in drier, subtropical, often over-populated and

economically poor regions today, climate change and its follow-on effects pose a

severe risk to political, economic, and social stability. In less prosperous regions,

where countries lack the resources and capabilities required to adapt quickly to more

severe conditions, the problem is very likely to be exacerbated. For some countries,

climate change could become such a challenge that mass emigration results as the

desperate peoples seek better lives in regions such as the United States that have the

resources to adaptation.

Because the prevailing scenarios of gradual global warming could cause effects like

the ones described above, an increasing number of business leaders, economists,

policy makers, and politicians are concerned about the projections for further change

and are working to limit human influences on the climate. But, these efforts may not

be sufficient or be implemented soon enough.

Rather than decades or even centuries of gradual warming, recent evidence suggests

the possibility that a more dire climate scenario may actually be unfolding. This is

why GBN is working with OSD to develop a plausible scenario for abrupt climate

change that can be used to explore implications for food supply, health and disease,

commerce and trade, and their consequences for national security.

While future weather patterns and the specific details of abrupt climate change

cannot be predicted accurately or with great assurance, the actual history of climate

change provides some useful guides. Our goal is merely to portray a plausible

scenario, similar to one which has already occurred in human experieince, for which

there is reasonable evidence so that we may further explore potential implications for

United States national security.

Creating the Scenario: Reviewing History
Abrupt Climate Change 6

The above graphic, derived from sampling of an ice core in Greenland, shows a

historical tendency for particular regions to experience periods of abrupt cooling

within periods of general warming.

1

The Cooling Event 8,200 Years Ago

The climate change scenario outlined in this report is modeled on a century-long

climate event that records from an ice core in Greenland indicate occurred 8,200

years ago. Immediately following an extended period of warming, much like the

phase we appear to be in today, there was a sudden cooling . Average annual

temperatures in Greenland dropped by roughly 5 degrees Fahrenheit, and

temperature decreases nearly this large are likely to have occurred throughout the

North Atlantic region. During the 8,200 event severe winters in Europe and some

other areas caused glaciers to advance, rivers to freeze, and agricultural lands to be

less productive. Scientific evidence suggests that this event was associated with, and

perhaps caused by, a collapse of the ocean’s conveyor following a period of gradual

warming.

Longer ice core and oceanic records suggest that there may have been as many as

eight rapid cooling episodes in the past 730,000 years, and sharp reductions in the

ocean conveyer--a phenomenon that may well be on the horizon – are a likely

suspect in causing such shifts in climate.

The Younger Dryas

About 12,700 years ago, also associated with an apparent collapse of the

thermohaline circulation, there was a cooling of at least 27 degrees Fahrenheit in

Greenland, and substantial change throughout the North Atlantic region as well, this

time lasting 1,300 years. The remarkable feature of the Younger Dryas event was that

it happened in a series of decadal drops of around 5 degrees, and then the cold, dry

weather persisted for over 1,000 years. While this event had an enormous effect on

the ocean and land surrounding Europe (causing icebergs to be found as far south as

the coast of Portugal), its impact would be more severe today – in our densely

populated society. It is the more recent periods of cooling that appear to be

intimately connected with changes to civilization, unrest, inhabitability of once

desirable land, and even the demise of certain populations.

The Little Ice Age

Beginning in the 14th century, the North Atlantic region experienced a cooling that

lasted until the mid-19th century. This cooling may have been caused by a significant

slowing of the ocean conveyor, although it is more generally thought that reduced

solar output and/or volcanic eruptions may have prompted the oceanic changes.

This period, often referred to as the Little Ice Age, which lasted from 1300 to 1850,

brought severe winters, sudden climatic shifts, and profound agricultural, economic,

and political impacts to Europe.

1 R.B. Alley, from The Two Mile Time Machine, 2000.
Abrupt Climate Change 7

The period was marked by persistent crop failures, famine, disease, and population

migration, perhaps most dramatically felt by the Norse, also known as the Vikings,

who inhabited Iceland and later Greenland. Ice formations along the coast of

Greenland prevented merchants from getting their boats to Greenland and fisherman

from getting fish for entire winters. As a result, farmers were forced to slaughter

their poorly fed livestock -- because of a lack of food both for the animals and

themselves -- but without fish, vegetables, and grains, there was not enough food to

feed the population.

Famine, caused in part by the more severe climatic conditions, is reported to have

caused tens of thousands of deaths between 1315 and 1319 alone. The general cooling

also apparently drove the Vikings out of Greenland -- and some say was a

contributing cause for that society’s demise.

While climate crises like the Little Ice Age aren’t solely responsible for the death of

civilizations, it’s undeniable that they have a large impact on society. It has been less

than 175 years since 1 million people died due to the Irish Potato famine, which also

was induced in part by climate change.

A Climate Change Scenario For the Future

The past examples of abrupt climate change suggest that it is prudent to consider an

abrupt climate change scenario for the future as plausible, especially because some

recent scientific findings suggest that we could be on the cusp of such an event. The

future scenario that we have constructed is based on the 8,200 years before present

event, which was much warmer and far briefer than the Younger Dryas, but more

severe than the Little Ice Age. This scenario makes plausible assumptions about

which parts of the globe are likely to be colder, drier, and windier. Although

intensified research could help to refine the assumptions, there is no way to confirm

the assumptions on the basis of present models.

Rather than predicting how climate change will happen, our intent is to dramatize

the impact climate change could have on society if we are unprepared for it. Where

we describe concrete weather conditions and implications, our aim is to further the

strategic conversation rather than to accurately forecast what is likely to happen with

a high degree of certainty. Even the most sophisticated models cannot predict the

details of how the climate change will unfold, which regions will be impacted in

which ways, and how governments and society might respond. However, there

appears to be general agreement in the scientific community that an extreme case like

the one depicted below is not implausible. Many scientists would regard this

scenario as extreme both in how soon it develops, how large, rapid and ubiquitous

the climate changes are. But history tells us that sometimes the extreme cases do
Abrupt Climate Change 8

occur, there is evidence that it might be and it is DOD’s job to consider such

scenarios.

Keep in mind that the duration of this event could be decades, centuries, or millennia

and it could begin this year or many years in the future. In the climate change

disruption scenario proposed here, we consider a period of gradual warming leading

to 2010 and then outline the following ten years, when like in the 8,200 event, an

abrupt change toward cooling in the pattern of weather conditions change is

assumed to occur.

Warming Up to 2010

Following the most rapid century of warming experienced by modern civilization,

the first ten years of the 21st century see an acceleration of atmospheric warming, as

average temperatures worldwide rise by .5 degrees Fahrenheit per decade and by as

much as 2 degrees Fahrenheit per decade in the harder hit regions. Such temperature

changes would vary both by region and by season over the globe, with these finer

scale variations being larger or smaller than the average change. What would be very

clear is that the planet is continuing the warming trend of the late 20th century.

Most of North America, Europe, and parts of South America experience 30% more

days with peak temperatures over 90 degrees Fahrenheit than they did a century ago,

with far fewer days below freezing. In addition to the warming, there are erratic

weather patterns: more floods, particularly in mountainous regions, and prolonged

droughts in grain-producing and coastal-agricultural areas. In general, the climate

shift is an economic nuisance, generally affecting local areas as storms, droughts, and

hot spells impact agriculture and other climate-dependent activities. (More French

doctors remain on duty in August, for example.) The weather pattern, though, is not

yet severe enough or widespread enough to threaten the interconnected global

society or United States national security.

Warming Feedback Loops

As temperatures rise throughout the 20th century and into the early 2000s potent

positive feedback loops kick-in, accelerating the warming from .2 degrees Fahrenheit,

to .4 and eventually .5 degrees Fahrenheit per year in some locations. As the surface

warms, the hydrologic cycle (evaporation, precipitation, and runoff) accelerates

causing temperatures to rise even higher. Water vapor, the most powerful natural

greenhouse gas, traps additional heat and brings average surface air temperatures

up. As evaporation increases, higher surface air temperatures cause drying in forests

and grasslands, where animals graze and farmers grow grain. As trees die and burn,

forests absorb less carbon dioxide, again leading to higher surface air temperatures

as well as fierce and uncontrollable forest fires Further, warmer temperatures melt

snow cover in mountains, open fields, high-latitude tundra areas, and permafrost

throughout forests in cold-weather areas. With the ground absorbing more and

reflecting less of the sun’s rays, temperatures increase even higher.
Abrupt Climate Change 9

By 2005 the climatic impact of the shift is felt more intensely in certain regions

around the world. More severe storms and typhoons bring about higher storm

surges and floods in low-lying islands such as Tarawa and Tuvalu (near New

Zealand). In 2007, a particularly severe storm causes the ocean to break through

levees in the Netherlands making a few key coastal cities such as The Hague

unlivable. Failures of the delta island levees in the Sacramento River region in the

Central Valley of California creates an inland sea and disrupts the aqueduct system

transporting water from northern to southern California because salt water can no

longer be kept out of the area during the dry season. Melting along the Himalayan

glaciers accelerates, causing some Tibetan people to relocate. Floating ice in the

northern polar seas, which had already lost 40% of its mass from 1970 to 2003, is

mostly gone during summer by 2010. As glacial ice melts, sea levels rise and as

wintertime sea extent decreases, ocean waves increase in intensity, damaging coastal

cities. Additionally millions of people are put at risk of flooding around the globe

(roughly 4 times 2003 levels), and fisheries are disrupted as water temperature

changes cause fish to migrate to new locations and habitats, increasing tensions over

fishing rights.

Each of these local disasters caused by severe weather impacts surrounding areas

whose natural, human, and economic resources are tapped to aid in recovery. The

positive feedback loops and acceleration of the warming pattern begin to trigger

responses that weren’t previously imagined, as natural disasters and stormy weather

occur in both developed and lesser-developed nations. Their impacts are greatest in

less-resilient developing nations, which do not have the capacity built into their

social, economic, and agricultural systems to absorb change.

As melting of the Greenland ice sheet exceeds the annual snowfall, and there is

increasing freshwater runoff from high latitude precipitation, the freshening of

waters in the North Atlantic Ocean and the seas between Greenland and Europe

increases. The lower densities of these freshened waters in turn pave the way for a

sharp slowing of the thermohaline circulation system.

The Period from 2010 to 2020

Thermohaline Circulation Collapse

After roughly 60 years of slow freshening, the thermohaline collapse begins in 2010,

disrupting the temperate climate of Europe, which is made possible by the warm

flows of the Gulf Stream (the North Atlantic arm of the global thermohaline

conveyor). Ocean circulation patterns change, bringing less warm water north and

causing an immediate shift in the weather in Northern Europe and eastern North

America. The North Atlantic Ocean continues to be affected by fresh water coming

from melting glaciers, Greenland’s ice sheet, and perhaps most importantly increased

rainfall and runoff. Decades of high-latitude warming cause increased precipitation
Abrupt Climate Change 10

and bring additional fresh water to the salty, dense water in the North, which is

normally affected mainly by warmer and saltier water from the Gulf Stream. That

massive current of warm water no longer reaches far into the North Atlantic. The

immediate climatic effect is cooler temperatures in Europe and throughout much of

the Northern Hemisphere and a dramatic drop in rainfall in many key agricultural

and populated areas. However, the effects of the collapse will be felt in fits and starts,

as the traditional weather patterns re-emerge only to be disrupted again—for a full

decade.

The dramatic slowing of the thermohaline circulation is anticipated by some ocean

researchers, but the United States is not sufficiently prepared for its effects, timing, or

intensity. Computer models of the climate and ocean systems, though improved,

were unable to produce sufficiently consistent and accurate information for

policymakers. As weather patterns shift in the years following the collapse, it is not

clear what type of weather future years will bring. While some forecasters believe the

cooling and dryness is about to end, others predict a new ice age or a global drought,

leaving policy makers and the public highly uncertain about the future climate and

what to do, if anything. Is this merely a “blip” of little importance or a fundamental

change in the Earth’s climate, requiring an urgent massive human response?

Cooler, Drier, Windier Conditions for Continental Areas of the Northern Hemisphere

The Weather Report: 2010-2020

• Drought persists for the entire decade in critical agricultural regions

and in the areas around major population centers in Europe and

eastern North America.

• Average annual temperatures drop by up to 5 degrees Fahrenheit over

Asia and North America and up to 6 degrees Fahrenheit in Europe.

• Temperatures increase by up to 4 degrees Fahrenheit in key areas

throughout Australia, South America, and southern Africa.

• Winter storms and winds intensify, amplifying the impact of the

changes. Western Europe and the North Pacific face enhanced

westerly winds.

Each of the years from 2010-2020 sees average temperature drops throughout

Northern Europe, leading to as much as a 6 degree Fahrenheit drop in ten years.

Average annual rainfall in this region decreases by nearly 30%; and winds are up to

15% stronger on average. The climatic conditions are more severe in the continental

interior regions of northern Asia and North America.
Abrupt Climate Change 11

The effects of the drought are more devastating than the unpleasantness of

temperature decreases in the agricultural and populated areas. With the persistent

reduction of precipitation in these areas, lakes dry-up, river flow decreases, and fresh

water supply is squeezed, overwhelming available conservation options and

depleting fresh water reserves. The Mega-droughts begin in key regions in Southern

China and Northern Europe around 2010 and last throughout the full decade. At the

same time, areas that were relatively dry over the past few decades receive persistent

years of torrential rainfall, flooding rivers, and regions that traditionally relied on

dryland agriculture.

In the North Atlantic region and across northern Asia, cooling is most pronounced in

the heart of winter -- December, January, and February -- although its effects linger

through the seasons, the cooling becomes increasingly intense and less predictable.

As snow accumulates in mountain regions, the cooling spreads to summertime. In

addition to cooling and summertime dryness, wind pattern velocity strengthens as

the atmospheric circulation becomes more zonal.

While weather patterns are disrupted during the onset of the climatic change around

the globe, the effects are far more pronounced in Northern Europe for the first five

years after the thermohaline circulation collapse. By the second half of this decade,

the chill and harsher conditions spread deeper into Southern Europe, North America,

and beyond. Northern Europe cools as a pattern of colder weather lengthens the

time that sea ice is present over the northern North Atlantic Ocean, creating a further

cooling influence and extending the period of wintertime surface air temperatures.

Winds pick up as the atmosphere tries to deal with the stronger pole-to-equator

temperature gradient. Cold air blowing across the European continent causes

especially harsh conditions for agriculture. The combination of wind and dryness

causes widespread dust storms and soil loss.

Signs of incremental warming appear in the southern most areas along the Atlantic

Ocean, but the dryness doesn’t let up. By the end of the decade, Europe’s climate is

more like Siberia’s.

An Alternative Scenario for the Southern Hemisphere

There is considerable uncertainty about the climate dynamics of the Southern

Hemisphere, mainly due to less paleoclimatic data being available than for the

Northern Hemisphere. Weather patterns in key regions in the Southern Hemisphere

could mimic those of the Northern Hemisphere, becoming colder, drier, and more

severe as heat flows from the tropics to the Northern Hemisphere, trying to

thermodynamically balance the climatic system. Alternatively, the cooling of the

Northern Hemisphere may lead to increased warmth, precipitation, and storms in

the south, as the heat normally transported away from equatorial regions by the

ocean currents becomes trapped and as greenhouse gas warming continues to
Abrupt Climate Change 12

accelerate. Either way, it is not implausible that abrupt climate change will bring

extreme weather conditions to many of the world’s key population and growing

regions at the same time – stressing global food, water, and energy supply.

The Regions: 2010 to 2020

COLD,

DRY,

WINDY

COLD,

DRY,

WINDY

DRY

WET,

STORMY

DRY,

INTERMITTENT

MONSOONS

The above graphic shows a simplified view of the weather patterns portrayed in this scenario.

Europe. Hit hardest by the climatic change, average annual temperatures drop by 6

degrees Fahrenheit in under a decade, with more dramatic shifts along the

Northwest coast. The climate in northwestern Europe is colder, drier, and windier,

making it more like Siberia. Southern Europe experiences less of a change but still

suffers from sharp intermittent cooling and rapid temperature shifts. Reduced

precipitation causes soil loss to become a problem throughout Europe, contributing

to food supply shortages. Europe struggles to stem emigration out of Scandinavian

and northern European nations in search of warmth as well as immigration from

hard-hit countries in Africa and elsewhere.

United States. Colder, windier, and drier weather makes growing seasons shorter

and less productive throughout the northeastern United States, and longer and drier

in the southwest. Desert areas face increasing windstorms, while agricultural areas

suffer from soil loss due to higher wind speeds and reduced soil moisture. The

change toward a drier climate is especially pronounced in the southern states.
Abrupt Climate Change 13

Coastal areas that were at risk during the warming period remain at risk, as rising

ocean levels continues along the shores. The United States turns inward, committing

its resources to feeding its own population, shoring-up its borders, and managing the

increasing global tension.

China. China, with its high need for food supply given its vast population, is hit hard

by a decreased reliability of the monsoon rains. Occasional monsoons during the

summer season are welcomed for their precipitation, but have devastating effects as

they flood generally denuded land. Longer, colder winters and hotter summers

caused by decreased evaporative cooling because of reduced precipitation stress

already tight energy and water supplies. Widespread famine causes chaos and

internal struggles as a cold and hungry China peers jealously across the Russian and

western borders at energy resources.

Bangladesh. Persistent typhoons and a higher sea level create storm surges that

cause significant coastal erosion, making much of Bangladesh nearly uninhabitable.

Further, the rising sea level contaminates fresh water supplies inland, creating a

drinking water and humanitarian crisis. Massive emigration occurs, causing tension

in China and India, which are struggling to manage the crisis inside their own

boundaries.

East Africa. Kenya, Tanzania, and Mozambique face slightly warmer weather, but

are challenged by persistent drought. Accustomed to dry conditions, these countries

were the least influenced by the changing weather conditions, but their food supply

is challenged as major grain producing regions suffer.

Australia. A major food exporter, Australia struggles to supply food around the

globe, as its agriculture is not severely impacted by more subtle changes in its

climate. But the large uncertainties about Southern Hemisphere climate change make

this benign conclusion suspect.

Impact on Natural Resources

The changing weather patterns and ocean temperatures affect agriculture, fish and

wildlife, water and energy. Crop yields, affected by temperature and water stress as

well as length of growing season fall by 10-25% and are less predictable as key

regions shift from a warming to a cooling trend. As some agricultural pests die due

to temperature changes, other species spread more readily due to the dryness and

windiness – requiring alternative pesticides or treatment regiments. Commercial

fishermen that typically have rights to fish in specific areas will be ill equipped for

the massive migration of their prey.
Abrupt Climate Change 14

With only five or six key grain-growing regions in the world (US, Australia,

Argentina, Russia, China, and India), there is insufficient surplus in global food

supplies to offset severe weather conditions in a few regions at the same time – let

alone four or five. The world’s economic interdependence make the United States

increasingly vulnerable to the economic disruption created by local weather shifts in

key agricultural and high population areas around the world. Catastrophic shortages

of water and energy supply – both which are stressed around the globe today –

cannot be quickly overcome.

Impact on National Security

Human civilization began with the stabilization and warming of the Earth’s climate.

A colder unstable climate meant that humans could neither develop agriculture or

permanent settlements. With the end of the Younger Dryas and the warming and

stabilization that followed, humans could learn the rhythms of agriculture and settle

in places whose climate was reliably productive. Modern civilization has never

experienced weather conditions as persistently disruptive as the ones outlined in this

scenario. As a result, the implications for national security outlined in this report are

only hypothetical. The actual impacts would vary greatly depending on the nuances

of the weather conditions, the adaptability of humanity, and decisions by

policymakers.

Violence and disruption stemming from the stresses created by abrupt changes in the

climate pose a different type of threat to national security than we are accustomed to

today. Military confrontation may be triggered by a desperate need for natural

resources such as energy, food and water rather than by conflicts over ideology,

religion, or national honor. The shifting motivation for confrontation would alter

which countries are most vulnerable and the existing warning signs for security

threats.

There is a long-standing academic debate over the extent to which resource

constraints and environmental challenges lead to inter-state conflict. While some

believe they alone can lead nations to attack one another, others argue that their

primary effect is to act as a trigger of conflict among countries that face pre-existing

social, economic, and political tension. Regardless, it seems undeniable that severe

environmental problems are likely to escalate the degree of global conflict.

Co-founder and President of the Pacific Institute for Studies in Development,

Environment, and Security, Peter Gleick outlines the three most fundamental

challenges abrupt climate change poses for national security:

1. Food shortages due to decreases in agricultural production

2. Decreased availability and quality of fresh water due to flooding and droughts

3. Disrupted access to strategic minerals due to ice and storms
Abrupt Climate Change 15

In the event of abrupt climate change, it’s likely that food, water, and energy resource

constraints will first be managed through economic, political, and diplomatic means

such as treaties and trade embargoes. Over time though, conflicts over land and

water use are likely to become more severe – and more violent. As states become

increasingly desperate, the pressure for action will grow.

Decreasing Carrying Capacity

The graphic shows how abrupt

climate change may cause

human carrying capacity to fall

below usage of the eco-system,

suggesting insufficient

resources leading to a

contraction of the population

through war, disease, and

famine.

Today, carrying capacity, which is the ability for the Earth and its natural ecosystems

including social, economic, and cultural systems to support the finite number of

people on the planet, is being challenged around the world. According to the

International Energy Agency, global demand for oil will grow by 66% in the next 30

years, but it’s unclear where the supply will come from. Clean water is similarly

constrained in many areas around the world. With 815 million people receiving

insufficient sustenance worldwide, some would say that as a globe, we’re living well

above our carrying capacity, meaning there are not sufficient natural resources to

sustain our behavior.

Many point to technological innovation and adaptive behavior as a means for

managing the global ecosystem. Indeed it has been technological progress that has

increased carrying capacity over time. Over centuries we have learned how to

produce more food, energy and access more water. But will the potential of new

technologies be sufficient when a crisis like the one outlined in this scenario hits?

Abrupt climate change is likely to stretch carrying capacity well beyond its already

precarious limits. And there’s a natural tendency or need for carrying capacity to

become realigned. As abrupt climate change lowers the world’s carrying capacity

aggressive wars are likely to be fought over food, water, and energy. Deaths from

war as well as starvation and disease will decrease population size, which overtime,

will re-balance with carrying capacity.
Abrupt Climate Change 16

When you look at carrying capacity on a regional or state level it is apparent that

those nations with a high carrying capacity, such as the United States and Western

Europe, are likely to adapt most effectively to abrupt changes in climate, because,

relative to their population size, they have more resources to call on. This may give

rise to a more severe have, have-not mentality, causing resentment toward those

nations with a higher carrying capacity. It may lead to finger-pointing and blame, as

the wealthier nations tend to use more energy and emit more greenhouse gasses such

as CO2 into the atmosphere. Less important than the scientifically proven

relationship between CO2 emissions and climate change is the perception that

impacted nations have – and the actions they take.

The Link Between Carrying Capacity and Warfare

Steven LeBlanc, Harvard archaeologist and author of a new book called Carrying

Capacity, describes the relationship between carrying capacity and warfare. Drawing

on abundant archaeological and ethnological data, LeBlanc argues that historically

humans conducted organized warfare for a variety of reasons, including warfare

over resources and the environment. Humans fight when they outstrip the carrying

capacity of their natural environment. Every time there is a choice between starving

and raiding, humans raid. From hunter/gatherers through agricultural tribes,

chiefdoms, and early complex societies, 25% of a population’s adult males die when

war breaks out.

Peace occurs when carrying capacity goes up, as with the invention of agriculture,

newly effective bureaucracy, remote trade and technological breakthroughs. Also a

large scale die-back such as from plague can make for peaceful times---Europe after

its major plagues, North American natives after European diseases decimated their

populations (that's the difference between the Jamestown colony failure and

Plymouth Rock success). But such peaceful periods are short-lived because

population quickly rises to once again push against carrying capacity, and warfare

resumes. Indeed, over the millennia most societies define themselves according to

their ability to conduct war, and warrior culture becomes deeply ingrained. The

most combative societies are the ones that survive.

However in the last three centuries, LeBlanc points out, advanced states have

steadily lowered the body count even though individual wars and genocides have

grown larger in scale. Instead of slaughtering all their enemies in the traditional

way, for example, states merely kill enough to get a victory and then put the

survivors to work in their newly expanded economy. States also use their own

bureaucracies, advanced technology, and international rules of behavior to raise

carrying capacity and bear a more careful relationship to it.

All of that progressive behavior could collapse if carrying capacities everywhere

were suddenly lowered drastically by abrupt climate change. Humanity would

revert to its norm of constant battles for diminishing resources, which the battles
Abrupt Climate Change 17

themselves would further reduce even beyond the climatic effects. Once again

warfare would define human life.

Conflict Scenario Due to Climate Change

Europe Asia United States

2010-2020 2012: Severe drought

and cold push

Scandinavian

populations

southward, push back

from EU

2015: Conflict within

the EU over food and

water supply leads to

skirmishes and

strained diplomatic

relations

2018: Russia joins EU,

providing energy

resources

2020: Migration from

northern countries

such as Holland and

Germany toward

Spain and Italy

2010: Border

skirmishes and

conflict in Bangladesh,

India, and China, as

mass migration occurs

toward Burma

2012: Regional

instability leads Japan

to develop force

projection capability

2015: Strategic

agreement between

Japan and Russia for

Siberia and Sakhalin

energy resources

2018: China intervenes

in Kazakhstan to

protect pipelines

regularly disrupted by

rebels and criminals.

2010: Disagreements

with Canada and

Mexico over water

increase tension

2012: Flood of refugees

to southeast U.S. and

Mexico from

Caribbean islands

2015: European

migration to United

States (mostly

wealthy)

2016: Conflict with

European countries

over fishing rights

2018: Securing North

America, U.S. forms

integrated security

alliance with Canada

and Mexico

2020: Department of

Defense manages

borders and refugees

from Caribbean and

Europe.

2020-2030 2020: Increasing:

skirmishes over water

and immigration

2022: Skirmish

between France and

Germany over

commercial access to

Rhine

2025: EU nears

collapse

2027: Increasing

migration to

Mediterranean

countries such as

Algeria, Morocco,

Egypt, and Israel

2030: Nearly 10% of

European population

2020: Persistent

conflict in South East

Asia; Burma, Laos,

Vietnam, India, China

2025: Internal

conditions in China

deteriorate

dramatically leading

to civil war and border

wars.

2030: Tension growing

between China and

Japan over Russian

energy

*

2020: Oil prices

increase as security of

supply is threatened

by conflicts in Persian

Gulf and Caspian

2025: Internal struggle

in Saudi Arabia brings

Chinese and U.S.

naval forces to Gulf ,in

direct confrontation
Abrupt Climate Change 18

moves to a different

country

The chart above outlines some potential military implications of climate change

The two most likely reactions to a sudden drop in carrying capacity due to climate

change are defensive and offensive.

The United States and Australia are likely to build defensive fortresses around their

countries because they have the resources and reserves to achieve self-sufficiency.

With diverse growing climates, wealth, technology, and abundant resources, the

United States could likely survive shortened growing cycles and harsh weather

conditions without catastrophic losses. Borders will be strengthened around the

country to hold back unwanted starving immigrants from the Caribbean islands (an

especially severe problem), Mexico, and South America. Energy supply will be

shored up through expensive (economically, politically, and morally) alternatives

such as nuclear, renewables, hydrogen, and Middle Eastern contracts. Pesky

skirmishes over fishing rights, agricultural support, and disaster relief will be

commonplace. Tension between the U.S. and Mexico rise as the U.S. reneges on the

1944 treaty that guarantees water flow from the Colorado River. Relief workers will

be commissioned to respond to flooding along the southern part of the east coast and

much drier conditions inland. Yet, even in this continuous state of emergency the

U.S. will be positioned well compared to others. The intractable problem facing the

nation will be calming the mounting military tension around the world.

As famine, disease, and weather-related disasters strike due to the abrupt climate

change, many countries’ needs will exceed their carrying capacity. This will create a

sense of desperation, which is likely to lead to offensive aggression in order to

reclaim balance. Imagine eastern European countries, struggling to feed their

populations with a falling supply of food, water, and energy, eyeing Russia, whose

population is already in decline, for access to its grain, minerals, and energy supply.

Or, picture Japan, suffering from flooding along its coastal cities and contamination

of its fresh water supply, eying Russia’s Sakhalin Island oil and gas reserves as an

energy source to power desalination plants and energy-intensive agricultural

processes. Envision Pakistan, India, and China – all armed with nuclear weapons –

skirmishing at their borders over refugees, access to shared rivers, and arable land.

Spanish and Portuguese fishermen might fight over fishing rights – leading to

conflicts at sea. And, countries including the United States would be likely to better

secure their borders. With over 200 river basins touching multiple nations, we can

expect conflict over access to water for drinking, irrigation, and transportation. The

Danube touches twelve nations, the Nile runs though nine, and the Amazon runs

through seven.
Abrupt Climate Change 19

In this scenario, we can expect alliances of convenience. The United States and

Canada may become one, simplifying border controls. Or, Canada might keep its

hydropower—causing energy problems in the US. North and South Korea may align

to create one technically savvy and nuclear-armed entity. Europe may act as a

unified block – curbing immigration problems between European nations – and

allowing for protection against aggressors. Russia, with its abundant minerals, oil,

and natural gas may join Europe.

In this world of warring states, nuclear arms proliferation is inevitable. As cooling

drives up demand, existing hydrocarbon supplies are stretched thin. With a scarcity

of energy supply – and a growing need for access -- nuclear energy will become a

critical source of power, and this will accelerate nuclear proliferation as countries

develop enrichment and reprocessing capabilities to ensure their national security.

China, India, Pakistan, Japan, South Korea, Great Britain, France, and Germany will

all have nuclear weapons capability, as will Israel, Iran, Egypt, and North Korea.

Managing the military and political tension, occasional skirmishes, and threat of war

will be a challenge. Countries such as Japan, that have a great deal of social cohesion

(meaning the government is able to effectively engage its population in changing

behavior) are most likely to fair well. Countries whose diversity already produces

conflict, such as India, South Africa and Indonesia, will have trouble maintaining

order. Adaptability and access to resources will be key. Perhaps the most frustrating

challenge abrupt climate change will pose is that we’ll never know how far we are

into the climate change scenario and how many more years – 10, 100, 1000 --- remain

before some kind of return to warmer conditions as the thermohaline circulation

starts up again. When carrying capacity drops suddenly, civilization is faced with

new challenges that today seem unimaginable.

Could This Really Happen?

Ocean, land, and atmosphere scientists at some of the world’s most prestigious

organizations have uncovered new evidence over the past decade suggesting that the

plausibility of severe and rapid climate change is higher than most of the scientific

community and perhaps all of the political community is prepared for. If it occurs,

this phenomenon will disrupt current gradual global warming trends, adding to

climate complexity and lack of predictability. And paleoclimatic evidence suggests

that such an abrupt climate change could begin in the near future.

The Woods Hole Oceanographic Institute reports that seas surrounding the North

Atlantic have become less salty in the past 40 years, which in turn freshens the deep

ocean in the North Atlantic. This trend could pave the way for ocean conveyor

collapse or slowing and abrupt climate change.
Abrupt Climate Change 20

34.96

34.94

34.92

34.90

34.88

34.86

34.84

34.82

34.80

1970 1975 1980 1985 1990 1995 2000

Representational Graph

S

A

LINIT

Y

M

E

DIA

N

YEAR

Northeast Atlantic

Denmark Strait

Labrador Sea

The above graphic shows early evidence that a thermohaline circulation collapse may be imminent,

as the North Atlantic is increasingly being freshened by surrounding seas that have become less

salty over the past 40 years.2

2 Adapted from I Yashayaev, Bedford Institute of Oceanography as seen in Abrupt Climate Change, Inevitable

Surprises, National Research Council.
Abrupt Climate Change 21

The above two headlines appeared in Nature Magazine in 2001 and 2002, respectively. They

suggest that the North Atlantic salinity level may lower, increasing the likelihood of a

thermohaline circulation collapse.

With at least eight abrupt climate change events documented in the geological

record, it seems that the questions to ask are: When will this happen? What will the

impacts be? And, how can we best prepare for it? Rather than: Will this really happen?

Are we prepared for history to repeat itself again?

There is a debate in newspapers around the globe today on the impact of human

activity on climate change. Because economic prosperity is correlated with energy

use and greenhouse gas emissions, it is often argued that economic progress leads to

climate change. Competing evidence suggests that climate change can occur,

regardless of human activity as seen in climate events that happened prior to modern

society.

It’s important to understand human impacts on the environment – both what’s done

to accelerate and decelerate (or perhaps even reverse) the tendency toward climate

change. Alternative fuels, greenhouse gas emission controls, and conservation efforts

are worthwhile endeavors. In addition, we should prepare for the inevitable effects

of abrupt climate change – which will likely come regardless of human activity.

Here are some preliminary recommendations to prepare the United States for abrupt

climate change:

1) Improve predictive climate models. Further research should be conducted so

more confidence can be placed in predictions about climate change. There

needs to be a deeper understanding of the relationship between ocean

patterns and climate change. This research should focus on historical, current,

and predictive forces, and aim to further our understanding of abrupt climate

change, how it may happen, and how we’ll know it’s occurring.

2) Assemble comprehensive predictive models of climate change impacts.

Substantial research should be done on the potential ecological, economic,

social, and political impact of abrupt climate change. Sophisticated models

and scenarios should be developed to anticipate possible local conditions. A

system should be created to identify how climate change may impact the

global distribution of social, economic, and political power. These analyses

can be used to mitigate potential sources of conflict before they happen.

3) Create vulnerability metrics. Metrics should be created to understand a

country’s vulnerability to the impacts of climate change. Metrics may include

climatic impact on existing agricultural, water, and mineral resources;

technical capability; social cohesion and adaptability.
Abrupt Climate Change 22

4) Identify no-regrets strategies. No-regrets strategies should be identified and

implemented to ensure reliable access to food supply and water, and to ensure

national security.

5) Rehearse adaptive responses. Adaptive response teams should be established

to address and prepare for inevitable climate driven events such as massive

migration, disease and epidemics, and food and water supply shortages.

6) Explore local implications. The first-order effects of climate change are local.

While we can anticipate changes in pest prevalence and severity and changes

in agricultural productivity, one has to look at very specific locations and

conditions to know which pests are of concern, which crops and regions are

vulnerable, and how severe impacts will be. Such studies should be

undertaken, particularly in strategically important food producing regions.

7) Explore geo-engineering options that control the climate. Today, it is easier

to warm than to cool the climate, so it might be possible to add various gases,

such as hydrofluorocarbons, to the atmosphere to offset the affects of cooling.

Such actions, of course, would be studied carefully, as they have the potential

to exacerbate conflicts among nations.

Conclusion

It is quite plausible that within a decade the evidence of an imminent abrupt climate

shift may become clear and reliable. It is also possible that our models will better

enable us to predict the consequences. In that event the United States will need to

take urgent action to prevent and mitigate some of the most significant impacts.

Diplomatic action will be needed to minimize the likelihood of conflict in the most

impacted areas, especially in the Caribbean and Asia. However, large population

movements in this scenario are inevitable. Learning how to manage those

populations, border tensions that arise and the resulting refugees will be critical.

New forms of security agreements dealing specifically with energy, food and water

will also be needed. In short, while the US itself will be relatively better off and with

more adaptive capacity, it will find itself in a world where Europe will be struggling

internally, large number so refugees washing up on its shores and Asia in serious

crisis over food and water. Disruption and conflict will be endemic features of life.