SlideShare a Scribd company logo
Robert B. Gagosian
President and Director, Woods Hole Oceanographic Institution
Prepared for a panel on abrupt climate change at the
World Economic Forum
Davos, Switzerland, January 27, 2003
ABRUPT CLIMATE CHANGE
Should We Be Worried?
For more information, contact Shelley Dawicki
Woods Hole Oceanographic Institution
Woods Hole, MA 02543
(508) 289-2270 • sdawicki@whoi.edu
www.whoi.edu/institutes/occi/hottopics_climatechange.html
www.whoi.edu
2 3
JayneDoucette,WHOIGraphicServices
Are we overlooking potential abrupt climate shifts?
Most of the studies and debates on potential climate
change, along with its ecological and economic impacts, have
focused on the ongoing buildup of industrial greenhouse gases
in the atmosphere and a gradual increase in global tempera-
tures. This line of thinking, however, fails to consider another
potentially disruptive climate scenario. It ignores recent and
rapidly advancing evidence that Earth’s climate repeatedly has
shifted abruptly and dramatically in the past, and is capable of
doing so in the future.
Fossil evidence clearly demonstrates that Earth’s climate
can shift gears within a decade, establishing new and different
patterns that can persist for decades to centuries. In addition,
these climate shifts do not necessarily have universal, global
effects. They can generate a counterintuitive scenario: Even
as the earth as a whole continues to warm gradually, large
regions may experience a precipitous and disruptive shift into
colder climates.
This new paradigm of abrupt climate change has been well
established over the last decade by research of ocean, earth
and atmosphere scientists at many institutions worldwide. But
the concept remains little known and scarcely appreciated in
the wider community of scientists, economists, policy mak-
ers, and world political and business leaders. Thus, world lead-
ers may be planning for climate scenarios of global warming
that are opposite to what might actually occur.1
It is important to clarify that we are not contemplating a
situation of either abrupt cooling or global warming. Rather,
abrupt regional cooling and gradual global warming can un-
fold simultaneously. Indeed, greenhouse warming is a desta-
bilizing factor that makes abrupt climate change more prob-
able. A 2002 report by the US National Academy of Sciences
(NAS) said, “available evidence suggests that abrupt climate
changes are not only possible but likely in the future, poten-
tially with large impacts on ecosystems and societies.”2
The timing of any abrupt regional cooling in the future also
has critical policy implications. An abrupt cooling that hap-
pens within the next two decades would produce different
climate effects than one that occurs after another century of
continuing greenhouse warming.
The global ocean circulation system, often called the Ocean Conveyor,
transports heat worldwide. White sections represent warm surface cur-
rents. Purple sections represent cold deep currents.
The Global Ocean Conveyor
4 5
edge of ocean dynamics does not match our knowledge of atmo-
spheric processes. The oceans’ essential role is too often neglected
in our calculations.
Does Earth’s climate system have an ‘Achilles’ heel’?
Here is a simplified description of some basic ocean-atmo-
sphere dynamics that regulate Earth’s climate:
The equatorial sun warms the ocean surface and enhances
evaporation in the tropics. This leaves the tropical ocean saltier.
The Gulf Stream, a limb of the Ocean Conveyor, carries an enor-
mous volume of heat-laden, salty water up the East Coast of the
United States, and then northeast toward Europe.
This oceanic heat pump is an important mechanism for re-
ducing equator-to-pole temperature differences. It moderates
Earth’s climate, particularly in the North Atlantic region. Con-
veyor circulation increases the northward transport of warmer
waters in the Gulf Stream by about 50 percent. At colder north-
ern latitudes, the ocean releases this heat to the atmosphere—
especially in winter when the atmosphere is colder than the ocean
and ocean-atmosphere temperature gradients increase. The Con-
veyor warms North Atlantic regions by as much as 5° Celsius
and significantly tempers average winter temperatures.
But records of past climates—from a variety of sources such as
deep-sea sediments and ice-sheet cores—show that the Conveyor
has slowed and shut down several times in the past. This shutdown
curtailed heat delivery to the North Atlantic and caused substan-
tial cooling throughout the region. One earth scientist has called
the Conveyor “the Achilles’ heel of our climate system.”3
Are we ignoring the oceans’ role in climate change?
Fossil evidence and computer models demonstrate that Earth’s
complex and dynamic climate system has more than one mode
of operation. Each mode produces different climate patterns.
The evidence also shows that Earth’s climate system has sen-
sitive thresholds. Pushed past a threshold, the system can jump
quickly from one stable operating mode to a completely differ-
ent one—“just as the slowly increasing pressure of a finger even-
tually flips a switch and turns on a light,” the NAS report said.
Scientists have so far identified only one viable mechanism
to induce large, global, abrupt climate changes: a swift reorgani-
zation of the ocean currents circulating around the earth. These
currents, collectively known as the Ocean Conveyor, distribute
vast quantities of heat around our planet, and thus play a funda-
mental role in governing Earth’s climate.
The oceans also play a pivotal role in the distribution and
availability of life-sustaining water throughout our planet. The
oceans are, by far, the planet’s largest reservoir of water. Evapo-
ration from the ocean transfers huge amounts of water vapor to
the atmosphere, where it travels aloft until it cools, condenses,
and eventually precipitates in the form of rain or snow. Changes
in ocean circulation or water properties can disrupt this hydro-
logical cycle on a global scale, causing flooding and long-term
droughts in various regions. The El Niño phenomenon is but a
hint of how oceanic changes can dramatically affect where and
how much precipitation falls throughout the planet.
Thus, the oceans and the atmosphere constitute intertwined
components of Earth’s climate system. But our present knowl-
If too much fresh water enters the North Atlantic, its waters could
stop sinking. The Conveyor would cease. Heat-bearing Gulf Stream
waters (red lines) would no longer flow into the North Atlantic, and
European and North American winters would become more severe.
(See computer animation at www.whoi.edu/institutes/occi/
climatechange_wef.html)
The Ocean Conveyor is propelled by the sinking of cold, salty (and
therefore denser) waters in the North Atlantic Ocean (blue lines).
This creates a void that helps draw warm, salty surface waters
northward (red lines). The ocean gives up heat to the atmosphere
above the North Atlantic Ocean, and prevailing winds (large red ar-
rows) carry the heat eastward to warm Europe.
JackCook,WHOIGraphicServices
Today With additional fresh water
The Conveyor’s Achilles’ Heel?
A F R I C A
S P A I N
N O R T H A M E R I C A
ADDITIONAL FRESH WATER
A F R I C A
S P A I N
N O R T H A M E R I C A
ADDITIONAL FRESH WATER
A F R I C A
S P A I N
N O R T H A M E R I C A
A F R I C A
S P A I N
N O R T H A M E R I C A
6 7
Computer models simulating ocean-atmosphere climate dy-
namics indicate that the North Atlantic region would cool 3° to
5° Celsius if Conveyor circulation were totally disrupted. It would
produce winters twice as cold as the worst winters on record in
the eastern United States in the past century. In addition, previ-
ous Conveyor shutdowns have been linked with widespread
droughts throughout the globe.
It is crucial to remember two points: 1) If thermohaline circu-
lation shuts down and induces a climate transition, severe win-
ters in the North Atlantic region would likely persist for decades
to centuries—until conditions reached another threshold at which
thermohaline circulation might resume. 2) Abrupt regional cool-
ing may occur even as the earth, on average, continues to warm.
Are worrisome signals developing in the ocean?
If the climate system’s Achilles’ heel is the Conveyor, the
Conveyor’s Achilles’ heel is the North Atlantic. An influx of fresh
water into the North Atlantic’s surface could create a lid of more
buoyant fresh water, lying atop denser, saltier water. This fresh
water would effectively cap and insulate the surface of the North
Atlantic, curtailing the ocean’s transfer of heat to the atmosphere.
An influx of fresh water would also dilute the North Atlantic’s
salinity. At a critical but unknown threshold, when North Atlan-
tic waters are no longer sufficiently salty and dense, they may
stop sinking. An important force driving the Conveyor could
quickly diminish, with climate impacts resulting within a decade.
In an important paper published in 2002 in Nature, oceanog-
What can disrupt the Ocean Conveyor?
Solving this puzzle requires an understanding of what launches
and drives the Conveyor in the first place. The answer, to a large
degree, is salt.
For a variety of reasons, North Atlantic waters are relatively
salty compared with other parts of the world ocean. Salty water
is denser than fresh water. Cold water is denser than warm wa-
ter. When the warm, salty waters of the North Atlantic release
heat to the atmosphere, they become colder and begin to sink.
In the seas that ring the northern fringe of the Atlantic—the
Labrador, Irminger, and Greenland Seas—the ocean releases large
amounts of heat to the atmosphere and then a great volume of
cold, salty water sinks to the abyss. This water flows slowly at
great depths into the South Atlantic and eventually throughout
the world’s oceans.
Thus, the North Atlantic is the source of the deep limb of the
Ocean Conveyor. The plunge of this great mass of cold, salty
water propels the global ocean’s conveyor-like circulation sys-
tem. It also helps draw warm, salty tropical surface waters north-
ward to replace the sinking waters. This process is called “ther-
mohaline circulation,” from the Greek words “thermos” (heat)
and “halos” (salt).
If cold, salty North Atlantic waters did not sink, a primary
force driving global ocean circulation could slacken and cease.
Existing currents could weaken or be redirected. The resulting
reorganization of the ocean’s circulation would reconfigure Earth’s
climate patterns.
Dramatic Changes in the North Atlantic
Subpolar seas bordering the North Atlantic have become noticeably
less salty since the mid-1960s, especially in the last decade. This is
the largest and most dramatic oceanic change ever measured in the
era of modern instruments. This has resulted in a freshening of the
deep ocean in the North Atlantic, which in the past disrupted the
Ocean Conveyor and caused abrupt climate changes.
B.Dickson,etal.,inNature,April2002
1965 1970 1975 1980 1985
Year
1990 1995 20001965 1970 1975 1980 1985
Year
1990 1995 2000
34.96
34.95
34.94
34.93
34.92
Salinity(partsperthousand)
East Irminger Sea 34.93
34.92
34.91
34.90
34.89
34.88
Denmark Strait
34.93
34.92
34.91
34.90
34.89
34.88
Faroe-Shetland Channel34.95
34.94
34.93
34.92
34.91
34.90
34.89
34.88
34.87
Labrador Sea
500
25003500
3500
3500
2500
1500
500
500
500
500
1500
2500
500
500
500
1500
1500
2500
2500
4500
Denmark
Strait
Labrador
Sea
Irminger
Sea
Faroe-
Shetland
Channel
Greenland
Iceland
Scotland
Ireland
Labrador
Atlantic Ocean
Denmark
Strait
Labrador
Sea
Irminger
Sea
Faroe-
Shetland
Channel
8 9
1015
Age (thousand years before present)
Little Ice Age
Medieval Warm Period
Younger Dryas
5 0
8,200-Year Event
-60
-50
-40
-30
-20
TemperatureoverGreenland(˚F)
rivers that discharge into the Arctic Ocean.6 Global warming
may be an exacerbating factor.
Though we have invested in, and now rely on, a global net-
work of meteorological stations to monitor fast-changing atmo-
spheric conditions, at present we do not have a system in place for
monitoring slower-developing, but critical, ocean circulation changes.
The great majority of oceanographic measurements was taken
throughout the years by research ships and ships of opportunity—
especially during the Cold War era for anti-submarine warfare
purposes. Many were taken incidentally by Ocean Weather Sta-
tions—a network of ships stationed in the ocean after World War
II, whose primary duty was to guide transoceanic airplane flights.
Starting in the 1970s, satellite technology superseded these
weather ships. The demise of the OWS network and the end of
the Cold War have left oceanographers with access to far less data
in recent years.
Initial efforts to remedy this deficit are under way,7 but these
efforts are nascent and time is of the essence. Satellites can mea-
sure wind stress and ocean circulation globally, but only at the ocean
surface. Also recently launched (but not nearly fully funded) is the
Argo program—an international program to seed the global ocean
with an armada of some 3,000 free-floating buoys that measure
upper ocean temperature and salinity. Measuring deep ocean cur-
raphers monitoring and analyzing conditions in the North At-
lantic concluded that the North Atlantic has been freshening
dramatically—continuously for the past 40 years but especially
in the past decade.4 The new data show that since the mid-1960s,
the subpolar seas feeding the North Atlantic have steadily and
noticeably become less salty to depths of 1,000 to 4,000 meters.
This is the largest and most dramatic oceanic change ever measured in the era
of modern instruments.
At present the influx of fresher water has been distributed
throughout the water column. But at some point, fresh water
may begin to pile up at the surface of the North Atlantic. When
that occurs, the Conveyor could slow down or cease operating.
Signs of a possible slowdown already exist. A 2001 report in
Nature indicates that the flow of cold, dense water from the Nor-
wegian and Greenland Seas into the North Atlantic has dimin-
ished by at least 20 percent since 1950.5
At what threshold will the Conveyor cease?
The short answer is: We do not know. Nor have scientists
determined the relative contributions of a variety of sources that
may be adding fresh water to the North Atlantic. Among the
suspects are melting glaciers or Arctic sea ice, or increased pre-
cipitation falling directly into the ocean or entering via the great
R.B.Alley,fromTheTwo-MileTimeMachine,2000
A Long Record of Abrupt Climate Changes
Ice cores extracted from the two-mile-thick Greenland ice sheet pre-
serve records of ancient air temperatures. The records show several
times when climate shifted in time spans as short as a decade.
• The Younger Dryas—About 12,700 years ago, average tempera-
tures in the North Atlantic region abruptly plummeted nearly 5°C
and remained that way for 1,300 years before rapidly warming again.
• The 8,200-Year Event—A similar abrupt cooling occurred 8,200
years ago. It was not so severe and lasted only about a century. But if
a similar cooling event occurred today, it would be catastrophic.
•The Medieval Warm Period—An abrupt warming took place about
1,000 years ago. It was not nearly so dramatic as past events, but it
nevertheless allowed the Norse to establish settlements in Greenland.
• The Little Ice Age—The Norse abandoned their Greenland settle-
ments when the climate turned abruptly colder 700 years ago. Be-
tween 1300 and 1850, severe winters had profound agricultural,
economic, and political impacts in Europe.
10 11
rents is critical for observing Conveyor behavior, but it is more
difficult. Efforts have just begun to measure deep ocean water
properties and currents at strategic locations with long-term
moored buoy arrays, but vast ocean voids remain unmonitored.
New ocean-based instruments also offer the potential to re-
veal the ocean’s essential, but poorly understood, role in the hy-
drological cycle—which establishes global rainfall and snowfall
patterns. Global warming affects the hydrological cycle because
a warmer atmosphere carries more water. This, in turn, has im-
plications for greenhouse warming, since water vapor itself is
the most abundant, and often overlooked, greenhouse gas.
What can the past teach us about the future?
Revealing the past behavior of Earth’s climate system pro-
vides powerful insight into what it may do in the future. Geo-
logical records confirm the potential for abrupt thermohaline-
induced climate transitions that would generate severe winters
in the North Atlantic region. A bad winter or two brings incon-
venience that societies can adapt to with small, temporary ad-
justments. But a persistent string of severe winters, lasting de-
cades to a century, can cause glaciers to advance, rivers to freeze,
and sea ice to grow and spread. It can render prime agricultural
lands unfarmable.
About 12,700 years ago, as Earth emerged from the most re-
cent ice age and began to warm, the Conveyor was disrupted.
Within a decade, average temperatures in the North Atlantic
region plummeted nearly 5° Celsius.
This cold period, known as the Younger Dryas, lasted 1,300
years. It is named after an Arctic wildflower. Scientists have found
substantial evidence that cold-loving dryas plants thrived during
this era in European and US regions that today are too warm.
Deep-sea sediment cores show that icebergs extended as far south
as the coast of Portugal. The Younger Dryas ended as abruptly
as it began. Within a decade, North Atlantic waters and the re-
gional climate warmed again to pre-Younger Dryas levels.
A similar cooling occurred 8,200 years ago. It lasted only about
a century—a blip in geological time, but a catastrophe if such a
cooling occurred today.
Are ‘little ice ages’ and ‘megadroughts’ possible?
Scientists are investigating whether changes in ocean circu-
lation may have played a role in causing or amplifying the “Little
Ice Age” between 1300 and 1850. This period of abruptly shift-
ing climate regimes and more severe winters had profound agri-
cultural, economic, and political impacts in Europe and North
America and changed the course of history.
During this era, the Norse abruptly abandoned their settle-
ments in Greenland. The era is captured in the frozen landscapes
Rapid changes in ocean circulation are
linked to an abrupt climate change 8,200
years ago that had global effects. Some
regions turned significantly colder while
others experienced widespread drought.
R.B.Alley,etal.,inGeology,1997
8,200 Years Ago—An Abruptly Colder, Drier Earth
12 13
of Pieter Bruegel’s 16th-century paintings and in the famous paint-
ing of George Washington’s 1776 crossing of an icebound Dela-
ware River, which rarely freezes today. But the era is also marked
by persistent crop failures, famine, disease, and mass migrations.
“The Little Ice Age,” wrote one historian, “is a chronicle of hu-
man vulnerability in the face of sudden climate change.”8
Societies are similarly vulnerable to abrupt climate changes
that can turn a year or two of diminished rainfall into prolonged,
severe, widespread droughts. A growing body of evidence from
joint archaeological and paleoclimatological studies is demon-
strating linkages among ocean-related climate shifts, “mega-
droughts,” and precipitous collapses of civilizations, including
the Akkadian empire in Mesopotamia 4,200 years ago, the Mayan
empire in central America 1,500 years ago, and the Anasazi in
the American Southwest in the late 13th century.9
Rapid changes in ocean circulation associated with the abrupt
North Atlantic cooling event 8,200 years ago have been linked
with simultaneous, widespread drying in the American West,
Africa, and Asia.10 Regional cooling events also have been linked
with changes in the Southwest Asian monsoon, whose rains are
probably the most critical factor supporting civilizations from
Africa to India to China.11
What future climate scenarios should we consider?
The debate on global change has largely failed to factor in
the inherently chaotic, sensitively balanced, and threshold-laden
nature of Earth’s climate system and the increased likelihood of
abrupt climate change. Our current speculations about future cli-
mate and its impacts have focused on the Intergovernmental Panel
on Climate Change, which has forecast gradual global warming
of 1.4° to 5.8° Celsius over the next century.
It is prudent to superimpose on this forecast the potential for
abrupt climate change induced by thermohaline shutdown. Such
a change could cool down selective areas of the globe by 3° to
5° Celsius, while simultaneously causing drought in many parts
of the world. These climate changes would occur quickly, even
as other regions continue to warm slowly. It is critical to con-
sider the economic and political ramifications of this geographi-
cally selective climate change. Specifically, the region most af-
fected by a shutdown—the countries bordering the North At-
lantic—is also one of the world’s most developed.
The key component of this analysis is when a shutdown of the
Conveyor occurs. Two scenarios are useful to contemplate:
Scenario 1: Conveyor slows down within next two decades.
Such a scenario could quickly and markedly cool the North At-
lanticregion,causingdisruptionsinglobaleconomicactivity.These
disruptions may be exacerbated because the climate changes oc-
cur in a direction opposite to what is commonly expected, and
they occur at a pace that makes adaptation difficult.
Scenario 2: Conveyor slows down a century from now.
In such a scenario, cooling of the North Atlantic region may
partially or totally offset the major effects of global warming in
this region. Thus, the climate of the North Atlantic region may
rapidly return to one that more resembles today’s—even as other
parts of the world, particularly less-developed regions, experi-
ence the unmitigated brunt of global warming. If the Conveyor
subsequently turns on again, the “deferred” warming may be de-
livered in a decade.
What can we do to improve our future security?
Ignoring or downplaying the probability of abrupt climate
change could prove costly. Ecosystems, economies, and societies
can adapt more easily to gradual, anticipated changes. Some cur-
rent policies and practices may be ill-advised and may prove in-
adequate in a world of rapid and unforeseen climate change. The
challenge to world leaders is to reduce vulnerabilities by enhanc-
ing society’s ability to monitor, plan for, and adapt to rapid change.
All human endeavor hinges on the vicissitudes of climate.
Thus, the potential for abrupt climate change should prompt us
to re-examine possible impacts on many climate-affected sec-
tors. They include: agriculture; water resources; energy resources;
forest and timber management; fisheries; coastal land manage-
ment; transportation; insurance; recreation and tourism; disaster
relief; and public health (associated with climate-related, vec-
tor-borne diseases such as malaria and cholera).
Developing countries lacking scientific resources and eco-
nomic infrastructures are especially vulnerable to the social and
economic impacts of abrupt climate change. However, with grow-
ing globalization of economies, adverse impacts (although likely
to vary from region to region) are likely to spill across national
boundaries, through human and biotic migration, economic
shocks, and political aftershocks, the National Academy of Sci-
ences (NAS) report stated.
The key is to reduce our uncertainty about future climate
change, and to improve our ability to predict what could hap-
pen and when. A first step is to establish the oceanic equivalent
of our land-based meteorological instrument network. Such a
network would begin to reveal climate-influencing oceanic pro-
cesses that have been beyond our ability to grasp. These instru-
ments, monitoring critical present-day conditions, can be coupled
with enhanced computer modeling, which can project how Earth’s
climate system may react in the future. Considerably more re-
search is also required to learn more about the complex ocean-
air processes that induced rapid climate changes in the past, and
thus how our climate system may behave in the future.
The NAS report is titled Abrupt Climate Change: Inevitable Sur-
prises. Climate change may be inevitable. But it is not inevitable
for society to be surprised or ill-prepared.
14 15
ROBERT B. GAGOSIAN is Presi-
dent and Director of Woods
Hole Oceanographic Institution
in Woods Hole, Massachusetts.
He was appointed Director in
1994 and President in 2001, fol-
lowing a distinguished career as
a marine geochemist. He has
served as Chairman of the Board
of Governors for the 52-institu-
tion Consortium for Oceanographic Research and Education and
as a member of the Ocean Research Advisory Panel of the US
National Oceanographic Partnership Program. In 2002, he was
appointed to the Science Advisory Panel of the US Commission
on Ocean Policy and the US National Oceanic and Atmospheric
Administration’s Science Advisory Board, and was elected a Fel-
low of the American Academy of Arts & Sciences.
References:
1 ”Are We on the Brink of a New Little Ice Age?”—testimony to the
US Commission on Ocean Policy, September 25, 2002, by T. Joyce
and L. Keigwin (Woods Hole Oceanographic Institution).
2 Abrupt Climate Change: Inevitable Surprises, US National Academy of
Sciences, National Research Council Committee on Abrupt Cli-
mate Change, National Academy Press, 2002.
3 “Thermohaline Circulation, the Achilles’ Heel of Our Climate Sys-
tem: Will Man-Made CO2 Upset the Current Balance?” in Science,
Vol. 278, November 28, 1997, by W. S. Broecker (Lamont-Doherty
Earth Observatory, Columbia University).
4 “Rapid Freshening of the Deep North Atlantic Ocean Over the
Past Four Decades,” in Nature, Vol. 416, April 25, 2002, by B.
Dickson (Centre for Environment, Fisheries, and Aquaculture Sci-
ence, Lowestoft, UK), I. Yashayaev, J. Meincke, B. Turrell, S. Dye,
and J. Hoffort.
5 “Decreasing Overflow from the Nordic Seas into the Atlantic Ocean
Through the Faroe Bank Channel Since 1950,” in Nature, Vol. 411,
June 21, 2001, by B. Hansen (Faroe Fisheries Laboratory, Faroe Is-
lands), W. Turrell, and S. Østerhus.
6 “Increasing River Discharge to the Arctic Ocean,” in Science, Vol.
298, December 13, 2002, by B. J. Peterson (Marine Biological Labo-
ratory), R. M. Holmes, J. W. McClelland, C. J. Vörösmarty, R. B.
Lammers, A. I. Shiklomanov, I. A. Shiklomanov, and S. Rahmstorf.
7 “Ocean Observatories,” in Oceanus, Vol. 42, No. 1, 2000, published
by the Woods Hole Oceanographic Institution.
8 The Little Ice Age: How Climate Made History 1300-1850, by Brian Fagan
(University of California, Santa Barbara), Basic Books, 2000.
9 “Cultural Responses to Climate Change During the Late Holocene,”
in Science, Vol. 292, April 27, 2001, by P. B. deMenocal (Lamont-
Doherty Earth Observatory, Columbia University).
10 “Holocene Climate Instability: A Prominent, Widespread Event
8,200 Years Ago,” in Geology, Vol. 26, No. 6, 1997, by R. B. Alley
and T. Sowers (Pennsylvania State University), P. A. Mayewski, M.
Stuiver, K. C. Taylor, and P. U. Clark.
11 “A High-Resolution Absolute-Dated Late Pleistocene Monsoon
Record From Hulu Cave, China,” in Science, Vol. 294, December 14,
2001, by Y. J. Wang (Nanjing Normal University, China), H. Cheng,
R. L. Edwards, Z. S. An, J. Y. Wu, C. C. Shen, and J. A. Dorale.
WOODS HOLE OCEANOGRAPHIC INSTITUTION (WHOI) is a pri-
vate, nonprofit research and higher education facility dedicated
to the study of all aspects of marine science and to the education
of marine scientists. It is the largest independent oceanographic
research institution in the US, with staff and students number-
ing about 1,000.
In an atmosphere that nurtures discovery, WHOI scientists,
engineers, and students collaborate to explore the frontiers of
knowledge about planet Earth. They develop theories, test ideas,
build seagoing instruments, and collect data in hostile marine
environments. Their diverse research agenda includes geologi-
cal activity deep within the earth; plant, animal, and microbial
populations and their interactions in the oceans; coastal erosion;
ocean circulation; pollution control; and global climate change.
The WHOI fleet includes three large research vessels (R/V
Atlantis, R/V Knorr, and R/V Oceanus), coastal craft, remote and
autonomous vehicles, and the deep-diving human-occupied sub-
mersible Alvin. The WHOI annual operating budget of more than
$120 million is supported by grants from federal agencies, in-
cluding the National Science Foundation, the Office of Naval
Research, and the National Oceanic and Atmospheric Adminis-
tration, and by private contributions and endowment income.
TomKleindinst,WHOIGraphicServices

More Related Content

What's hot

Climate Change and Human Health
Climate Change and Human HealthClimate Change and Human Health
Climate Change and Human Health
Cary Institute of Ecosystem Studies
 
Global warming
Global warmingGlobal warming
Global warming
runilwazihab
 
Climate change mengistu
Climate change  mengistuClimate change  mengistu
Climate change mengistu
mengeppt123
 
Recent Advanced on Climate change and Human Health
Recent Advanced on Climate change and Human Health Recent Advanced on Climate change and Human Health
Recent Advanced on Climate change and Human Health
RAVIKANTAMISHRA
 
Climate Change - The Physical Science Basis
Climate Change - The Physical Science BasisClimate Change - The Physical Science Basis
Climate Change - The Physical Science Basis
Leonardo ENERGY
 
Climate Change and Health Presentation 1 Oct 2013
Climate Change and Health Presentation 1 Oct 2013Climate Change and Health Presentation 1 Oct 2013
A Brief History of Earth’s Climate Change
A Brief History of Earth’s Climate ChangeA Brief History of Earth’s Climate Change
A Brief History of Earth’s Climate Change
Larry Smarr
 
Global warming
Global warmingGlobal warming
Global warming
reshmafmtc
 
Climate changes past and future
Climate changes  past and futureClimate changes  past and future
Climate changes past and futureDocumentStory
 
Climate change
Climate changeClimate change
Climate change
Haje Cabalog
 
Climate Change
Climate ChangeClimate Change
Climate Change
AnamFatimaKazmi
 
IB Extended Essay Sample APA 2018-2019 by WritingMetier.com
IB Extended Essay Sample APA 2018-2019 by WritingMetier.comIB Extended Essay Sample APA 2018-2019 by WritingMetier.com
IB Extended Essay Sample APA 2018-2019 by WritingMetier.com
Writing Metier
 
L 16 effects of gw & ozone derpletion
L   16 effects of gw & ozone derpletionL   16 effects of gw & ozone derpletion
L 16 effects of gw & ozone derpletion
MD SIAM
 
Climate change
Climate changeClimate change
Climate change
AMIT GAUTAM
 
Regional climate and ice sheet response: Antarctica
Regional climate and ice sheet response: AntarcticaRegional climate and ice sheet response: Antarctica
Regional climate and ice sheet response: Antarctica
ipcc-media
 
Indicators of climate change
Indicators of climate changeIndicators of climate change
Indicators of climate change
Prof. A.Balasubramanian
 
Home
HomeHome

What's hot (19)

Climate Change and Human Health
Climate Change and Human HealthClimate Change and Human Health
Climate Change and Human Health
 
Global warming
Global warmingGlobal warming
Global warming
 
Climate change mengistu
Climate change  mengistuClimate change  mengistu
Climate change mengistu
 
Recent Advanced on Climate change and Human Health
Recent Advanced on Climate change and Human Health Recent Advanced on Climate change and Human Health
Recent Advanced on Climate change and Human Health
 
Climate Change - The Physical Science Basis
Climate Change - The Physical Science BasisClimate Change - The Physical Science Basis
Climate Change - The Physical Science Basis
 
Climate Change and Health Presentation 1 Oct 2013
Climate Change and Health Presentation 1 Oct 2013Climate Change and Health Presentation 1 Oct 2013
Climate Change and Health Presentation 1 Oct 2013
 
A Brief History of Earth’s Climate Change
A Brief History of Earth’s Climate ChangeA Brief History of Earth’s Climate Change
A Brief History of Earth’s Climate Change
 
Global Warming
Global WarmingGlobal Warming
Global Warming
 
Global warming
Global warmingGlobal warming
Global warming
 
Climate changes past and future
Climate changes  past and futureClimate changes  past and future
Climate changes past and future
 
Climate change
Climate changeClimate change
Climate change
 
Climate Change
Climate ChangeClimate Change
Climate Change
 
What climate changes are likely
What climate changes are likelyWhat climate changes are likely
What climate changes are likely
 
IB Extended Essay Sample APA 2018-2019 by WritingMetier.com
IB Extended Essay Sample APA 2018-2019 by WritingMetier.comIB Extended Essay Sample APA 2018-2019 by WritingMetier.com
IB Extended Essay Sample APA 2018-2019 by WritingMetier.com
 
L 16 effects of gw & ozone derpletion
L   16 effects of gw & ozone derpletionL   16 effects of gw & ozone derpletion
L 16 effects of gw & ozone derpletion
 
Climate change
Climate changeClimate change
Climate change
 
Regional climate and ice sheet response: Antarctica
Regional climate and ice sheet response: AntarcticaRegional climate and ice sheet response: Antarctica
Regional climate and ice sheet response: Antarctica
 
Indicators of climate change
Indicators of climate changeIndicators of climate change
Indicators of climate change
 
Home
HomeHome
Home
 

Similar to Abruptclimatechange 7229

Ten clear indicators our climate is changing
Ten clear indicators our climate is changingTen clear indicators our climate is changing
Ten clear indicators our climate is changing
Liwayway Memije-Cruz
 
Global climate watch
Global climate watchGlobal climate watch
Global climate watchEdwin Clerval
 
Global_warming_presentation.pptx
Global_warming_presentation.pptxGlobal_warming_presentation.pptx
Global_warming_presentation.pptx
viveksingh20861
 
THERMOHALINE CIRCULATION
THERMOHALINE CIRCULATIONTHERMOHALINE CIRCULATION
THERMOHALINE CIRCULATION
Himadri Samal
 
Gem ppt-12-climate change
Gem ppt-12-climate changeGem ppt-12-climate change
Gem ppt-12-climate change
ijcparish
 
Lesson1 climate and change GCSE Edexcel B Geography
Lesson1 climate and change GCSE Edexcel B GeographyLesson1 climate and change GCSE Edexcel B Geography
Lesson1 climate and change GCSE Edexcel B Geographysarah marks
 
Presentation on climate change
Presentation on climate changePresentation on climate change
Presentation on climate change
Ankita Khobragade
 
Science climate project
Science climate projectScience climate project
Science climate projectnashmiya
 
Effects of Global Warming
Effects of Global WarmingEffects of Global Warming
Effects of Global Warming
Vaibhav Agrawal
 
Ocean atmosphere interactions
Ocean atmosphere interactionsOcean atmosphere interactions
Ocean atmosphere interactions
Janine Samelo
 
Earth_Science_&_Climate_Change_Somenath_Ganguly
Earth_Science_&_Climate_Change_Somenath_GangulyEarth_Science_&_Climate_Change_Somenath_Ganguly
Earth_Science_&_Climate_Change_Somenath_GangulySomenath Ganguly
 
Gloomy Climate Calculation Collapse of Atlantic Ocean Current Predicted
Gloomy Climate Calculation Collapse of Atlantic Ocean Current PredictedGloomy Climate Calculation Collapse of Atlantic Ocean Current Predicted
Gloomy Climate Calculation Collapse of Atlantic Ocean Current Predicted
ZaighamKamal
 
New Climate Change Statement from the American Meteorological Society
New Climate Change Statement from the American Meteorological Society New Climate Change Statement from the American Meteorological Society
New Climate Change Statement from the American Meteorological Society
Earth Institute of Columbia University
 
Weather
WeatherWeather
Weather
m_garrido
 
Melting polar ice caps
Melting polar ice capsMelting polar ice caps
Melting polar ice caps
jpallaresm
 
ICE CAPS
ICE CAPSICE CAPS
ICE CAPS
jpallaresm
 
Global Warming
Global WarmingGlobal Warming
Global Warming
djhammond
 
Climate change and aspects of earth system
Climate change and aspects of earth system Climate change and aspects of earth system
Climate change and aspects of earth system
TanvirHridoy1
 

Similar to Abruptclimatechange 7229 (20)

Ten clear indicators our climate is changing
Ten clear indicators our climate is changingTen clear indicators our climate is changing
Ten clear indicators our climate is changing
 
Global climate watch
Global climate watchGlobal climate watch
Global climate watch
 
The physical environment
The physical environmentThe physical environment
The physical environment
 
Global_warming_presentation.pptx
Global_warming_presentation.pptxGlobal_warming_presentation.pptx
Global_warming_presentation.pptx
 
THERMOHALINE CIRCULATION
THERMOHALINE CIRCULATIONTHERMOHALINE CIRCULATION
THERMOHALINE CIRCULATION
 
Gem ppt-12-climate change
Gem ppt-12-climate changeGem ppt-12-climate change
Gem ppt-12-climate change
 
Lesson1 climate and change GCSE Edexcel B Geography
Lesson1 climate and change GCSE Edexcel B GeographyLesson1 climate and change GCSE Edexcel B Geography
Lesson1 climate and change GCSE Edexcel B Geography
 
Presentation on climate change
Presentation on climate changePresentation on climate change
Presentation on climate change
 
Science climate project
Science climate projectScience climate project
Science climate project
 
Effects of Global Warming
Effects of Global WarmingEffects of Global Warming
Effects of Global Warming
 
Ocean atmosphere interactions
Ocean atmosphere interactionsOcean atmosphere interactions
Ocean atmosphere interactions
 
Earth_Science_&_Climate_Change_Somenath_Ganguly
Earth_Science_&_Climate_Change_Somenath_GangulyEarth_Science_&_Climate_Change_Somenath_Ganguly
Earth_Science_&_Climate_Change_Somenath_Ganguly
 
Gloomy Climate Calculation Collapse of Atlantic Ocean Current Predicted
Gloomy Climate Calculation Collapse of Atlantic Ocean Current PredictedGloomy Climate Calculation Collapse of Atlantic Ocean Current Predicted
Gloomy Climate Calculation Collapse of Atlantic Ocean Current Predicted
 
New Climate Change Statement from the American Meteorological Society
New Climate Change Statement from the American Meteorological Society New Climate Change Statement from the American Meteorological Society
New Climate Change Statement from the American Meteorological Society
 
Weather
WeatherWeather
Weather
 
Melting polar ice caps
Melting polar ice capsMelting polar ice caps
Melting polar ice caps
 
ICE CAPS
ICE CAPSICE CAPS
ICE CAPS
 
Global Warming
Global WarmingGlobal Warming
Global Warming
 
Globalwarming
GlobalwarmingGlobalwarming
Globalwarming
 
Climate change and aspects of earth system
Climate change and aspects of earth system Climate change and aspects of earth system
Climate change and aspects of earth system
 

More from www.thiiink.com

Flies like a plane Safe as a plane with the Power of a plane TS820 Brief intro
Flies like a plane Safe as a plane  with the Power of a plane TS820 Brief introFlies like a plane Safe as a plane  with the Power of a plane TS820 Brief intro
Flies like a plane Safe as a plane with the Power of a plane TS820 Brief intro
www.thiiink.com
 
THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?
THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?
THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?
www.thiiink.com
 
10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...
10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...
10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...
www.thiiink.com
 
100913 enercon presentation september 2013 paper (4)
100913 enercon presentation september 2013  paper (4)100913 enercon presentation september 2013  paper (4)
100913 enercon presentation september 2013 paper (4)
www.thiiink.com
 
070317 THiiiNK-technical performance verification
070317 THiiiNK-technical performance verification 070317 THiiiNK-technical performance verification
070317 THiiiNK-technical performance verification
www.thiiink.com
 
R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...
R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...
R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...
www.thiiink.com
 
130617 airbus A380 vs TS820_THiiiNK
130617 airbus A380 vs TS820_THiiiNK130617 airbus A380 vs TS820_THiiiNK
130617 airbus A380 vs TS820_THiiiNK
www.thiiink.com
 
LIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSAT
LIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSATLIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSAT
LIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSAT
www.thiiink.com
 
Burden of proof: A comprehensive review of the feasibility of 100% renewable-...
Burden of proof: A comprehensive review of the feasibility of 100% renewable-...Burden of proof: A comprehensive review of the feasibility of 100% renewable-...
Burden of proof: A comprehensive review of the feasibility of 100% renewable-...
www.thiiink.com
 
Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...
Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...
Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...
www.thiiink.com
 
Eu coal stress_test_report_2017 WindSolar = More and More Coal (1)
Eu coal stress_test_report_2017  WindSolar = More and More Coal (1)Eu coal stress_test_report_2017  WindSolar = More and More Coal (1)
Eu coal stress_test_report_2017 WindSolar = More and More Coal (1)
www.thiiink.com
 
Tuesday climate stabalization and reducing carbon and ghg emissions
Tuesday  climate stabalization and reducing carbon and ghg emissionsTuesday  climate stabalization and reducing carbon and ghg emissions
Tuesday climate stabalization and reducing carbon and ghg emissions
www.thiiink.com
 
Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...
Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...
Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...
www.thiiink.com
 
Righi et-al-acp-15-633-2015
Righi et-al-acp-15-633-2015Righi et-al-acp-15-633-2015
Righi et-al-acp-15-633-2015
www.thiiink.com
 
Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...
Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...
Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...
www.thiiink.com
 
Full accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWER
Full accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWERFull accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWER
Full accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWER
www.thiiink.com
 
Accidents (1) Windpower the most dangerous power source in the world
Accidents (1) Windpower the most dangerous power source in the world  Accidents (1) Windpower the most dangerous power source in the world
Accidents (1) Windpower the most dangerous power source in the world
www.thiiink.com
 
Niels Bohr må vende sig i sin grav
Niels Bohr må vende sig i sin gravNiels Bohr må vende sig i sin grav
Niels Bohr må vende sig i sin grav
www.thiiink.com
 
Abruptclimatechange 7229
Abruptclimatechange 7229Abruptclimatechange 7229
Abruptclimatechange 7229
www.thiiink.com
 
Team Ice
Team IceTeam Ice
Team Ice
www.thiiink.com
 

More from www.thiiink.com (20)

Flies like a plane Safe as a plane with the Power of a plane TS820 Brief intro
Flies like a plane Safe as a plane  with the Power of a plane TS820 Brief introFlies like a plane Safe as a plane  with the Power of a plane TS820 Brief intro
Flies like a plane Safe as a plane with the Power of a plane TS820 Brief intro
 
THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?
THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?
THiiiNKSail© Hybrid Evolution why 4 or 2 Rotors if you can do it with 2 or 1?
 
10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...
10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...
10 days Retrofit to fix most problems, in a normal docking Cycle cost Only $1...
 
100913 enercon presentation september 2013 paper (4)
100913 enercon presentation september 2013  paper (4)100913 enercon presentation september 2013  paper (4)
100913 enercon presentation september 2013 paper (4)
 
070317 THiiiNK-technical performance verification
070317 THiiiNK-technical performance verification 070317 THiiiNK-technical performance verification
070317 THiiiNK-technical performance verification
 
R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...
R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...
R&D Tanker gas certified base index technical doc TS rotor system THiiiNK 220...
 
130617 airbus A380 vs TS820_THiiiNK
130617 airbus A380 vs TS820_THiiiNK130617 airbus A380 vs TS820_THiiiNK
130617 airbus A380 vs TS820_THiiiNK
 
LIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSAT
LIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSATLIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSAT
LIFE-CYCLE IMPACTS OF TESLA MODEL S ͦͣ AND VOLKSWAGEN PASSAT
 
Burden of proof: A comprehensive review of the feasibility of 100% renewable-...
Burden of proof: A comprehensive review of the feasibility of 100% renewable-...Burden of proof: A comprehensive review of the feasibility of 100% renewable-...
Burden of proof: A comprehensive review of the feasibility of 100% renewable-...
 
Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...
Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...
Expect the-unexpected cti-imperial " Yes Carbon Tracker forgot 10,000 billion...
 
Eu coal stress_test_report_2017 WindSolar = More and More Coal (1)
Eu coal stress_test_report_2017  WindSolar = More and More Coal (1)Eu coal stress_test_report_2017  WindSolar = More and More Coal (1)
Eu coal stress_test_report_2017 WindSolar = More and More Coal (1)
 
Tuesday climate stabalization and reducing carbon and ghg emissions
Tuesday  climate stabalization and reducing carbon and ghg emissionsTuesday  climate stabalization and reducing carbon and ghg emissions
Tuesday climate stabalization and reducing carbon and ghg emissions
 
Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...
Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...
Peters et al_a_search_for_large-scale_effects_of_ship_emissions_on_clouds_and...
 
Righi et-al-acp-15-633-2015
Righi et-al-acp-15-633-2015Righi et-al-acp-15-633-2015
Righi et-al-acp-15-633-2015
 
Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...
Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...
Righi et al_climate_impact_of_biofuels_in_shipping-global_model_studies_og_th...
 
Full accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWER
Full accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWERFull accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWER
Full accidents GLOBAL WINDPOWER more dangerous that NUCLEAR POWER
 
Accidents (1) Windpower the most dangerous power source in the world
Accidents (1) Windpower the most dangerous power source in the world  Accidents (1) Windpower the most dangerous power source in the world
Accidents (1) Windpower the most dangerous power source in the world
 
Niels Bohr må vende sig i sin grav
Niels Bohr må vende sig i sin gravNiels Bohr må vende sig i sin grav
Niels Bohr må vende sig i sin grav
 
Abruptclimatechange 7229
Abruptclimatechange 7229Abruptclimatechange 7229
Abruptclimatechange 7229
 
Team Ice
Team IceTeam Ice
Team Ice
 

Recently uploaded

NRW Board Paper - DRAFT NRW Recreation Strategy
NRW Board Paper - DRAFT NRW Recreation StrategyNRW Board Paper - DRAFT NRW Recreation Strategy
NRW Board Paper - DRAFT NRW Recreation Strategy
Robin Grant
 
How about Huawei mobile phone-www.cfye-commerce.shop
How about Huawei mobile phone-www.cfye-commerce.shopHow about Huawei mobile phone-www.cfye-commerce.shop
How about Huawei mobile phone-www.cfye-commerce.shop
laozhuseo02
 
Characterization and the Kinetics of drying at the drying oven and with micro...
Characterization and the Kinetics of drying at the drying oven and with micro...Characterization and the Kinetics of drying at the drying oven and with micro...
Characterization and the Kinetics of drying at the drying oven and with micro...
Open Access Research Paper
 
Presentación Giulio Quaggiotto-Diálogo improbable .pptx.pdf
Presentación Giulio Quaggiotto-Diálogo improbable .pptx.pdfPresentación Giulio Quaggiotto-Diálogo improbable .pptx.pdf
Presentación Giulio Quaggiotto-Diálogo improbable .pptx.pdf
Innovation and Technology for Development Centre
 
UNDERSTANDING WHAT GREEN WASHING IS!.pdf
UNDERSTANDING WHAT GREEN WASHING IS!.pdfUNDERSTANDING WHAT GREEN WASHING IS!.pdf
UNDERSTANDING WHAT GREEN WASHING IS!.pdf
JulietMogola
 
Daan Park Hydrangea flower season I like it
Daan Park Hydrangea flower season I like itDaan Park Hydrangea flower season I like it
Daan Park Hydrangea flower season I like it
a0966109726
 
alhambra case study Islamic gardens part-2.pptx
alhambra case study Islamic gardens part-2.pptxalhambra case study Islamic gardens part-2.pptx
alhambra case study Islamic gardens part-2.pptx
CECOS University Peshawar, Pakistan
 
Alert-driven Community-based Forest monitoring: A case of the Peruvian Amazon
Alert-driven Community-based Forest monitoring: A case of the Peruvian AmazonAlert-driven Community-based Forest monitoring: A case of the Peruvian Amazon
Alert-driven Community-based Forest monitoring: A case of the Peruvian Amazon
CIFOR-ICRAF
 
International+e-Commerce+Platform-www.cfye-commerce.shop
International+e-Commerce+Platform-www.cfye-commerce.shopInternational+e-Commerce+Platform-www.cfye-commerce.shop
International+e-Commerce+Platform-www.cfye-commerce.shop
laozhuseo02
 
AGRICULTURE Hydrophonic FERTILISER PPT.pptx
AGRICULTURE Hydrophonic FERTILISER PPT.pptxAGRICULTURE Hydrophonic FERTILISER PPT.pptx
AGRICULTURE Hydrophonic FERTILISER PPT.pptx
BanitaDsouza
 
Artificial Reefs by Kuddle Life Foundation - May 2024
Artificial Reefs by Kuddle Life Foundation - May 2024Artificial Reefs by Kuddle Life Foundation - May 2024
Artificial Reefs by Kuddle Life Foundation - May 2024
punit537210
 
Sustainable farming practices in India .pptx
Sustainable farming  practices in India .pptxSustainable farming  practices in India .pptx
Sustainable farming practices in India .pptx
chaitaliambole
 
Environmental Science Book By Dr. Y.K. Singh
Environmental Science Book By Dr. Y.K. SinghEnvironmental Science Book By Dr. Y.K. Singh
Environmental Science Book By Dr. Y.K. Singh
AhmadKhan917612
 
ppt on beauty of the nature by Palak.pptx
ppt on  beauty of the nature by Palak.pptxppt on  beauty of the nature by Palak.pptx
ppt on beauty of the nature by Palak.pptx
RaniJaiswal16
 
Sustainable Rain water harvesting in india.ppt
Sustainable Rain water harvesting in india.pptSustainable Rain water harvesting in india.ppt
Sustainable Rain water harvesting in india.ppt
chaitaliambole
 
Summary of the Climate and Energy Policy of Australia
Summary of the Climate and Energy Policy of AustraliaSummary of the Climate and Energy Policy of Australia
Summary of the Climate and Energy Policy of Australia
yasmindemoraes1
 
一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理
一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理
一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理
zm9ajxup
 
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Ventures
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business VenturesWillie Nelson Net Worth: A Journey Through Music, Movies, and Business Ventures
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Ventures
greendigital
 
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for..."Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...
MMariSelvam4
 
growbilliontrees.com-Trees for Granddaughter (1).pdf
growbilliontrees.com-Trees for Granddaughter (1).pdfgrowbilliontrees.com-Trees for Granddaughter (1).pdf
growbilliontrees.com-Trees for Granddaughter (1).pdf
yadavakashagra
 

Recently uploaded (20)

NRW Board Paper - DRAFT NRW Recreation Strategy
NRW Board Paper - DRAFT NRW Recreation StrategyNRW Board Paper - DRAFT NRW Recreation Strategy
NRW Board Paper - DRAFT NRW Recreation Strategy
 
How about Huawei mobile phone-www.cfye-commerce.shop
How about Huawei mobile phone-www.cfye-commerce.shopHow about Huawei mobile phone-www.cfye-commerce.shop
How about Huawei mobile phone-www.cfye-commerce.shop
 
Characterization and the Kinetics of drying at the drying oven and with micro...
Characterization and the Kinetics of drying at the drying oven and with micro...Characterization and the Kinetics of drying at the drying oven and with micro...
Characterization and the Kinetics of drying at the drying oven and with micro...
 
Presentación Giulio Quaggiotto-Diálogo improbable .pptx.pdf
Presentación Giulio Quaggiotto-Diálogo improbable .pptx.pdfPresentación Giulio Quaggiotto-Diálogo improbable .pptx.pdf
Presentación Giulio Quaggiotto-Diálogo improbable .pptx.pdf
 
UNDERSTANDING WHAT GREEN WASHING IS!.pdf
UNDERSTANDING WHAT GREEN WASHING IS!.pdfUNDERSTANDING WHAT GREEN WASHING IS!.pdf
UNDERSTANDING WHAT GREEN WASHING IS!.pdf
 
Daan Park Hydrangea flower season I like it
Daan Park Hydrangea flower season I like itDaan Park Hydrangea flower season I like it
Daan Park Hydrangea flower season I like it
 
alhambra case study Islamic gardens part-2.pptx
alhambra case study Islamic gardens part-2.pptxalhambra case study Islamic gardens part-2.pptx
alhambra case study Islamic gardens part-2.pptx
 
Alert-driven Community-based Forest monitoring: A case of the Peruvian Amazon
Alert-driven Community-based Forest monitoring: A case of the Peruvian AmazonAlert-driven Community-based Forest monitoring: A case of the Peruvian Amazon
Alert-driven Community-based Forest monitoring: A case of the Peruvian Amazon
 
International+e-Commerce+Platform-www.cfye-commerce.shop
International+e-Commerce+Platform-www.cfye-commerce.shopInternational+e-Commerce+Platform-www.cfye-commerce.shop
International+e-Commerce+Platform-www.cfye-commerce.shop
 
AGRICULTURE Hydrophonic FERTILISER PPT.pptx
AGRICULTURE Hydrophonic FERTILISER PPT.pptxAGRICULTURE Hydrophonic FERTILISER PPT.pptx
AGRICULTURE Hydrophonic FERTILISER PPT.pptx
 
Artificial Reefs by Kuddle Life Foundation - May 2024
Artificial Reefs by Kuddle Life Foundation - May 2024Artificial Reefs by Kuddle Life Foundation - May 2024
Artificial Reefs by Kuddle Life Foundation - May 2024
 
Sustainable farming practices in India .pptx
Sustainable farming  practices in India .pptxSustainable farming  practices in India .pptx
Sustainable farming practices in India .pptx
 
Environmental Science Book By Dr. Y.K. Singh
Environmental Science Book By Dr. Y.K. SinghEnvironmental Science Book By Dr. Y.K. Singh
Environmental Science Book By Dr. Y.K. Singh
 
ppt on beauty of the nature by Palak.pptx
ppt on  beauty of the nature by Palak.pptxppt on  beauty of the nature by Palak.pptx
ppt on beauty of the nature by Palak.pptx
 
Sustainable Rain water harvesting in india.ppt
Sustainable Rain water harvesting in india.pptSustainable Rain water harvesting in india.ppt
Sustainable Rain water harvesting in india.ppt
 
Summary of the Climate and Energy Policy of Australia
Summary of the Climate and Energy Policy of AustraliaSummary of the Climate and Energy Policy of Australia
Summary of the Climate and Energy Policy of Australia
 
一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理
一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理
一比一原版(UMTC毕业证书)明尼苏达大学双城分校毕业证如何办理
 
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Ventures
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business VenturesWillie Nelson Net Worth: A Journey Through Music, Movies, and Business Ventures
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Ventures
 
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for..."Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...
 
growbilliontrees.com-Trees for Granddaughter (1).pdf
growbilliontrees.com-Trees for Granddaughter (1).pdfgrowbilliontrees.com-Trees for Granddaughter (1).pdf
growbilliontrees.com-Trees for Granddaughter (1).pdf
 

Abruptclimatechange 7229

  • 1. Robert B. Gagosian President and Director, Woods Hole Oceanographic Institution Prepared for a panel on abrupt climate change at the World Economic Forum Davos, Switzerland, January 27, 2003 ABRUPT CLIMATE CHANGE Should We Be Worried? For more information, contact Shelley Dawicki Woods Hole Oceanographic Institution Woods Hole, MA 02543 (508) 289-2270 • sdawicki@whoi.edu www.whoi.edu/institutes/occi/hottopics_climatechange.html www.whoi.edu
  • 2. 2 3 JayneDoucette,WHOIGraphicServices Are we overlooking potential abrupt climate shifts? Most of the studies and debates on potential climate change, along with its ecological and economic impacts, have focused on the ongoing buildup of industrial greenhouse gases in the atmosphere and a gradual increase in global tempera- tures. This line of thinking, however, fails to consider another potentially disruptive climate scenario. It ignores recent and rapidly advancing evidence that Earth’s climate repeatedly has shifted abruptly and dramatically in the past, and is capable of doing so in the future. Fossil evidence clearly demonstrates that Earth’s climate can shift gears within a decade, establishing new and different patterns that can persist for decades to centuries. In addition, these climate shifts do not necessarily have universal, global effects. They can generate a counterintuitive scenario: Even as the earth as a whole continues to warm gradually, large regions may experience a precipitous and disruptive shift into colder climates. This new paradigm of abrupt climate change has been well established over the last decade by research of ocean, earth and atmosphere scientists at many institutions worldwide. But the concept remains little known and scarcely appreciated in the wider community of scientists, economists, policy mak- ers, and world political and business leaders. Thus, world lead- ers may be planning for climate scenarios of global warming that are opposite to what might actually occur.1 It is important to clarify that we are not contemplating a situation of either abrupt cooling or global warming. Rather, abrupt regional cooling and gradual global warming can un- fold simultaneously. Indeed, greenhouse warming is a desta- bilizing factor that makes abrupt climate change more prob- able. A 2002 report by the US National Academy of Sciences (NAS) said, “available evidence suggests that abrupt climate changes are not only possible but likely in the future, poten- tially with large impacts on ecosystems and societies.”2 The timing of any abrupt regional cooling in the future also has critical policy implications. An abrupt cooling that hap- pens within the next two decades would produce different climate effects than one that occurs after another century of continuing greenhouse warming. The global ocean circulation system, often called the Ocean Conveyor, transports heat worldwide. White sections represent warm surface cur- rents. Purple sections represent cold deep currents. The Global Ocean Conveyor
  • 3. 4 5 edge of ocean dynamics does not match our knowledge of atmo- spheric processes. The oceans’ essential role is too often neglected in our calculations. Does Earth’s climate system have an ‘Achilles’ heel’? Here is a simplified description of some basic ocean-atmo- sphere dynamics that regulate Earth’s climate: The equatorial sun warms the ocean surface and enhances evaporation in the tropics. This leaves the tropical ocean saltier. The Gulf Stream, a limb of the Ocean Conveyor, carries an enor- mous volume of heat-laden, salty water up the East Coast of the United States, and then northeast toward Europe. This oceanic heat pump is an important mechanism for re- ducing equator-to-pole temperature differences. It moderates Earth’s climate, particularly in the North Atlantic region. Con- veyor circulation increases the northward transport of warmer waters in the Gulf Stream by about 50 percent. At colder north- ern latitudes, the ocean releases this heat to the atmosphere— especially in winter when the atmosphere is colder than the ocean and ocean-atmosphere temperature gradients increase. The Con- veyor warms North Atlantic regions by as much as 5° Celsius and significantly tempers average winter temperatures. But records of past climates—from a variety of sources such as deep-sea sediments and ice-sheet cores—show that the Conveyor has slowed and shut down several times in the past. This shutdown curtailed heat delivery to the North Atlantic and caused substan- tial cooling throughout the region. One earth scientist has called the Conveyor “the Achilles’ heel of our climate system.”3 Are we ignoring the oceans’ role in climate change? Fossil evidence and computer models demonstrate that Earth’s complex and dynamic climate system has more than one mode of operation. Each mode produces different climate patterns. The evidence also shows that Earth’s climate system has sen- sitive thresholds. Pushed past a threshold, the system can jump quickly from one stable operating mode to a completely differ- ent one—“just as the slowly increasing pressure of a finger even- tually flips a switch and turns on a light,” the NAS report said. Scientists have so far identified only one viable mechanism to induce large, global, abrupt climate changes: a swift reorgani- zation of the ocean currents circulating around the earth. These currents, collectively known as the Ocean Conveyor, distribute vast quantities of heat around our planet, and thus play a funda- mental role in governing Earth’s climate. The oceans also play a pivotal role in the distribution and availability of life-sustaining water throughout our planet. The oceans are, by far, the planet’s largest reservoir of water. Evapo- ration from the ocean transfers huge amounts of water vapor to the atmosphere, where it travels aloft until it cools, condenses, and eventually precipitates in the form of rain or snow. Changes in ocean circulation or water properties can disrupt this hydro- logical cycle on a global scale, causing flooding and long-term droughts in various regions. The El Niño phenomenon is but a hint of how oceanic changes can dramatically affect where and how much precipitation falls throughout the planet. Thus, the oceans and the atmosphere constitute intertwined components of Earth’s climate system. But our present knowl- If too much fresh water enters the North Atlantic, its waters could stop sinking. The Conveyor would cease. Heat-bearing Gulf Stream waters (red lines) would no longer flow into the North Atlantic, and European and North American winters would become more severe. (See computer animation at www.whoi.edu/institutes/occi/ climatechange_wef.html) The Ocean Conveyor is propelled by the sinking of cold, salty (and therefore denser) waters in the North Atlantic Ocean (blue lines). This creates a void that helps draw warm, salty surface waters northward (red lines). The ocean gives up heat to the atmosphere above the North Atlantic Ocean, and prevailing winds (large red ar- rows) carry the heat eastward to warm Europe. JackCook,WHOIGraphicServices Today With additional fresh water The Conveyor’s Achilles’ Heel? A F R I C A S P A I N N O R T H A M E R I C A ADDITIONAL FRESH WATER A F R I C A S P A I N N O R T H A M E R I C A ADDITIONAL FRESH WATER A F R I C A S P A I N N O R T H A M E R I C A A F R I C A S P A I N N O R T H A M E R I C A
  • 4. 6 7 Computer models simulating ocean-atmosphere climate dy- namics indicate that the North Atlantic region would cool 3° to 5° Celsius if Conveyor circulation were totally disrupted. It would produce winters twice as cold as the worst winters on record in the eastern United States in the past century. In addition, previ- ous Conveyor shutdowns have been linked with widespread droughts throughout the globe. It is crucial to remember two points: 1) If thermohaline circu- lation shuts down and induces a climate transition, severe win- ters in the North Atlantic region would likely persist for decades to centuries—until conditions reached another threshold at which thermohaline circulation might resume. 2) Abrupt regional cool- ing may occur even as the earth, on average, continues to warm. Are worrisome signals developing in the ocean? If the climate system’s Achilles’ heel is the Conveyor, the Conveyor’s Achilles’ heel is the North Atlantic. An influx of fresh water into the North Atlantic’s surface could create a lid of more buoyant fresh water, lying atop denser, saltier water. This fresh water would effectively cap and insulate the surface of the North Atlantic, curtailing the ocean’s transfer of heat to the atmosphere. An influx of fresh water would also dilute the North Atlantic’s salinity. At a critical but unknown threshold, when North Atlan- tic waters are no longer sufficiently salty and dense, they may stop sinking. An important force driving the Conveyor could quickly diminish, with climate impacts resulting within a decade. In an important paper published in 2002 in Nature, oceanog- What can disrupt the Ocean Conveyor? Solving this puzzle requires an understanding of what launches and drives the Conveyor in the first place. The answer, to a large degree, is salt. For a variety of reasons, North Atlantic waters are relatively salty compared with other parts of the world ocean. Salty water is denser than fresh water. Cold water is denser than warm wa- ter. When the warm, salty waters of the North Atlantic release heat to the atmosphere, they become colder and begin to sink. In the seas that ring the northern fringe of the Atlantic—the Labrador, Irminger, and Greenland Seas—the ocean releases large amounts of heat to the atmosphere and then a great volume of cold, salty water sinks to the abyss. This water flows slowly at great depths into the South Atlantic and eventually throughout the world’s oceans. Thus, the North Atlantic is the source of the deep limb of the Ocean Conveyor. The plunge of this great mass of cold, salty water propels the global ocean’s conveyor-like circulation sys- tem. It also helps draw warm, salty tropical surface waters north- ward to replace the sinking waters. This process is called “ther- mohaline circulation,” from the Greek words “thermos” (heat) and “halos” (salt). If cold, salty North Atlantic waters did not sink, a primary force driving global ocean circulation could slacken and cease. Existing currents could weaken or be redirected. The resulting reorganization of the ocean’s circulation would reconfigure Earth’s climate patterns. Dramatic Changes in the North Atlantic Subpolar seas bordering the North Atlantic have become noticeably less salty since the mid-1960s, especially in the last decade. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments. This has resulted in a freshening of the deep ocean in the North Atlantic, which in the past disrupted the Ocean Conveyor and caused abrupt climate changes. B.Dickson,etal.,inNature,April2002 1965 1970 1975 1980 1985 Year 1990 1995 20001965 1970 1975 1980 1985 Year 1990 1995 2000 34.96 34.95 34.94 34.93 34.92 Salinity(partsperthousand) East Irminger Sea 34.93 34.92 34.91 34.90 34.89 34.88 Denmark Strait 34.93 34.92 34.91 34.90 34.89 34.88 Faroe-Shetland Channel34.95 34.94 34.93 34.92 34.91 34.90 34.89 34.88 34.87 Labrador Sea 500 25003500 3500 3500 2500 1500 500 500 500 500 1500 2500 500 500 500 1500 1500 2500 2500 4500 Denmark Strait Labrador Sea Irminger Sea Faroe- Shetland Channel Greenland Iceland Scotland Ireland Labrador Atlantic Ocean Denmark Strait Labrador Sea Irminger Sea Faroe- Shetland Channel
  • 5. 8 9 1015 Age (thousand years before present) Little Ice Age Medieval Warm Period Younger Dryas 5 0 8,200-Year Event -60 -50 -40 -30 -20 TemperatureoverGreenland(˚F) rivers that discharge into the Arctic Ocean.6 Global warming may be an exacerbating factor. Though we have invested in, and now rely on, a global net- work of meteorological stations to monitor fast-changing atmo- spheric conditions, at present we do not have a system in place for monitoring slower-developing, but critical, ocean circulation changes. The great majority of oceanographic measurements was taken throughout the years by research ships and ships of opportunity— especially during the Cold War era for anti-submarine warfare purposes. Many were taken incidentally by Ocean Weather Sta- tions—a network of ships stationed in the ocean after World War II, whose primary duty was to guide transoceanic airplane flights. Starting in the 1970s, satellite technology superseded these weather ships. The demise of the OWS network and the end of the Cold War have left oceanographers with access to far less data in recent years. Initial efforts to remedy this deficit are under way,7 but these efforts are nascent and time is of the essence. Satellites can mea- sure wind stress and ocean circulation globally, but only at the ocean surface. Also recently launched (but not nearly fully funded) is the Argo program—an international program to seed the global ocean with an armada of some 3,000 free-floating buoys that measure upper ocean temperature and salinity. Measuring deep ocean cur- raphers monitoring and analyzing conditions in the North At- lantic concluded that the North Atlantic has been freshening dramatically—continuously for the past 40 years but especially in the past decade.4 The new data show that since the mid-1960s, the subpolar seas feeding the North Atlantic have steadily and noticeably become less salty to depths of 1,000 to 4,000 meters. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments. At present the influx of fresher water has been distributed throughout the water column. But at some point, fresh water may begin to pile up at the surface of the North Atlantic. When that occurs, the Conveyor could slow down or cease operating. Signs of a possible slowdown already exist. A 2001 report in Nature indicates that the flow of cold, dense water from the Nor- wegian and Greenland Seas into the North Atlantic has dimin- ished by at least 20 percent since 1950.5 At what threshold will the Conveyor cease? The short answer is: We do not know. Nor have scientists determined the relative contributions of a variety of sources that may be adding fresh water to the North Atlantic. Among the suspects are melting glaciers or Arctic sea ice, or increased pre- cipitation falling directly into the ocean or entering via the great R.B.Alley,fromTheTwo-MileTimeMachine,2000 A Long Record of Abrupt Climate Changes Ice cores extracted from the two-mile-thick Greenland ice sheet pre- serve records of ancient air temperatures. The records show several times when climate shifted in time spans as short as a decade. • The Younger Dryas—About 12,700 years ago, average tempera- tures in the North Atlantic region abruptly plummeted nearly 5°C and remained that way for 1,300 years before rapidly warming again. • The 8,200-Year Event—A similar abrupt cooling occurred 8,200 years ago. It was not so severe and lasted only about a century. But if a similar cooling event occurred today, it would be catastrophic. •The Medieval Warm Period—An abrupt warming took place about 1,000 years ago. It was not nearly so dramatic as past events, but it nevertheless allowed the Norse to establish settlements in Greenland. • The Little Ice Age—The Norse abandoned their Greenland settle- ments when the climate turned abruptly colder 700 years ago. Be- tween 1300 and 1850, severe winters had profound agricultural, economic, and political impacts in Europe.
  • 6. 10 11 rents is critical for observing Conveyor behavior, but it is more difficult. Efforts have just begun to measure deep ocean water properties and currents at strategic locations with long-term moored buoy arrays, but vast ocean voids remain unmonitored. New ocean-based instruments also offer the potential to re- veal the ocean’s essential, but poorly understood, role in the hy- drological cycle—which establishes global rainfall and snowfall patterns. Global warming affects the hydrological cycle because a warmer atmosphere carries more water. This, in turn, has im- plications for greenhouse warming, since water vapor itself is the most abundant, and often overlooked, greenhouse gas. What can the past teach us about the future? Revealing the past behavior of Earth’s climate system pro- vides powerful insight into what it may do in the future. Geo- logical records confirm the potential for abrupt thermohaline- induced climate transitions that would generate severe winters in the North Atlantic region. A bad winter or two brings incon- venience that societies can adapt to with small, temporary ad- justments. But a persistent string of severe winters, lasting de- cades to a century, can cause glaciers to advance, rivers to freeze, and sea ice to grow and spread. It can render prime agricultural lands unfarmable. About 12,700 years ago, as Earth emerged from the most re- cent ice age and began to warm, the Conveyor was disrupted. Within a decade, average temperatures in the North Atlantic region plummeted nearly 5° Celsius. This cold period, known as the Younger Dryas, lasted 1,300 years. It is named after an Arctic wildflower. Scientists have found substantial evidence that cold-loving dryas plants thrived during this era in European and US regions that today are too warm. Deep-sea sediment cores show that icebergs extended as far south as the coast of Portugal. The Younger Dryas ended as abruptly as it began. Within a decade, North Atlantic waters and the re- gional climate warmed again to pre-Younger Dryas levels. A similar cooling occurred 8,200 years ago. It lasted only about a century—a blip in geological time, but a catastrophe if such a cooling occurred today. Are ‘little ice ages’ and ‘megadroughts’ possible? Scientists are investigating whether changes in ocean circu- lation may have played a role in causing or amplifying the “Little Ice Age” between 1300 and 1850. This period of abruptly shift- ing climate regimes and more severe winters had profound agri- cultural, economic, and political impacts in Europe and North America and changed the course of history. During this era, the Norse abruptly abandoned their settle- ments in Greenland. The era is captured in the frozen landscapes Rapid changes in ocean circulation are linked to an abrupt climate change 8,200 years ago that had global effects. Some regions turned significantly colder while others experienced widespread drought. R.B.Alley,etal.,inGeology,1997 8,200 Years Ago—An Abruptly Colder, Drier Earth
  • 7. 12 13 of Pieter Bruegel’s 16th-century paintings and in the famous paint- ing of George Washington’s 1776 crossing of an icebound Dela- ware River, which rarely freezes today. But the era is also marked by persistent crop failures, famine, disease, and mass migrations. “The Little Ice Age,” wrote one historian, “is a chronicle of hu- man vulnerability in the face of sudden climate change.”8 Societies are similarly vulnerable to abrupt climate changes that can turn a year or two of diminished rainfall into prolonged, severe, widespread droughts. A growing body of evidence from joint archaeological and paleoclimatological studies is demon- strating linkages among ocean-related climate shifts, “mega- droughts,” and precipitous collapses of civilizations, including the Akkadian empire in Mesopotamia 4,200 years ago, the Mayan empire in central America 1,500 years ago, and the Anasazi in the American Southwest in the late 13th century.9 Rapid changes in ocean circulation associated with the abrupt North Atlantic cooling event 8,200 years ago have been linked with simultaneous, widespread drying in the American West, Africa, and Asia.10 Regional cooling events also have been linked with changes in the Southwest Asian monsoon, whose rains are probably the most critical factor supporting civilizations from Africa to India to China.11 What future climate scenarios should we consider? The debate on global change has largely failed to factor in the inherently chaotic, sensitively balanced, and threshold-laden nature of Earth’s climate system and the increased likelihood of abrupt climate change. Our current speculations about future cli- mate and its impacts have focused on the Intergovernmental Panel on Climate Change, which has forecast gradual global warming of 1.4° to 5.8° Celsius over the next century. It is prudent to superimpose on this forecast the potential for abrupt climate change induced by thermohaline shutdown. Such a change could cool down selective areas of the globe by 3° to 5° Celsius, while simultaneously causing drought in many parts of the world. These climate changes would occur quickly, even as other regions continue to warm slowly. It is critical to con- sider the economic and political ramifications of this geographi- cally selective climate change. Specifically, the region most af- fected by a shutdown—the countries bordering the North At- lantic—is also one of the world’s most developed. The key component of this analysis is when a shutdown of the Conveyor occurs. Two scenarios are useful to contemplate: Scenario 1: Conveyor slows down within next two decades. Such a scenario could quickly and markedly cool the North At- lanticregion,causingdisruptionsinglobaleconomicactivity.These disruptions may be exacerbated because the climate changes oc- cur in a direction opposite to what is commonly expected, and they occur at a pace that makes adaptation difficult. Scenario 2: Conveyor slows down a century from now. In such a scenario, cooling of the North Atlantic region may partially or totally offset the major effects of global warming in this region. Thus, the climate of the North Atlantic region may rapidly return to one that more resembles today’s—even as other parts of the world, particularly less-developed regions, experi- ence the unmitigated brunt of global warming. If the Conveyor subsequently turns on again, the “deferred” warming may be de- livered in a decade. What can we do to improve our future security? Ignoring or downplaying the probability of abrupt climate change could prove costly. Ecosystems, economies, and societies can adapt more easily to gradual, anticipated changes. Some cur- rent policies and practices may be ill-advised and may prove in- adequate in a world of rapid and unforeseen climate change. The challenge to world leaders is to reduce vulnerabilities by enhanc- ing society’s ability to monitor, plan for, and adapt to rapid change. All human endeavor hinges on the vicissitudes of climate. Thus, the potential for abrupt climate change should prompt us to re-examine possible impacts on many climate-affected sec- tors. They include: agriculture; water resources; energy resources; forest and timber management; fisheries; coastal land manage- ment; transportation; insurance; recreation and tourism; disaster relief; and public health (associated with climate-related, vec- tor-borne diseases such as malaria and cholera). Developing countries lacking scientific resources and eco- nomic infrastructures are especially vulnerable to the social and economic impacts of abrupt climate change. However, with grow- ing globalization of economies, adverse impacts (although likely to vary from region to region) are likely to spill across national boundaries, through human and biotic migration, economic shocks, and political aftershocks, the National Academy of Sci- ences (NAS) report stated. The key is to reduce our uncertainty about future climate change, and to improve our ability to predict what could hap- pen and when. A first step is to establish the oceanic equivalent of our land-based meteorological instrument network. Such a network would begin to reveal climate-influencing oceanic pro- cesses that have been beyond our ability to grasp. These instru- ments, monitoring critical present-day conditions, can be coupled with enhanced computer modeling, which can project how Earth’s climate system may react in the future. Considerably more re- search is also required to learn more about the complex ocean- air processes that induced rapid climate changes in the past, and thus how our climate system may behave in the future. The NAS report is titled Abrupt Climate Change: Inevitable Sur- prises. Climate change may be inevitable. But it is not inevitable for society to be surprised or ill-prepared.
  • 8. 14 15 ROBERT B. GAGOSIAN is Presi- dent and Director of Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. He was appointed Director in 1994 and President in 2001, fol- lowing a distinguished career as a marine geochemist. He has served as Chairman of the Board of Governors for the 52-institu- tion Consortium for Oceanographic Research and Education and as a member of the Ocean Research Advisory Panel of the US National Oceanographic Partnership Program. In 2002, he was appointed to the Science Advisory Panel of the US Commission on Ocean Policy and the US National Oceanic and Atmospheric Administration’s Science Advisory Board, and was elected a Fel- low of the American Academy of Arts & Sciences. References: 1 ”Are We on the Brink of a New Little Ice Age?”—testimony to the US Commission on Ocean Policy, September 25, 2002, by T. Joyce and L. Keigwin (Woods Hole Oceanographic Institution). 2 Abrupt Climate Change: Inevitable Surprises, US National Academy of Sciences, National Research Council Committee on Abrupt Cli- mate Change, National Academy Press, 2002. 3 “Thermohaline Circulation, the Achilles’ Heel of Our Climate Sys- tem: Will Man-Made CO2 Upset the Current Balance?” in Science, Vol. 278, November 28, 1997, by W. S. Broecker (Lamont-Doherty Earth Observatory, Columbia University). 4 “Rapid Freshening of the Deep North Atlantic Ocean Over the Past Four Decades,” in Nature, Vol. 416, April 25, 2002, by B. Dickson (Centre for Environment, Fisheries, and Aquaculture Sci- ence, Lowestoft, UK), I. Yashayaev, J. Meincke, B. Turrell, S. Dye, and J. Hoffort. 5 “Decreasing Overflow from the Nordic Seas into the Atlantic Ocean Through the Faroe Bank Channel Since 1950,” in Nature, Vol. 411, June 21, 2001, by B. Hansen (Faroe Fisheries Laboratory, Faroe Is- lands), W. Turrell, and S. Østerhus. 6 “Increasing River Discharge to the Arctic Ocean,” in Science, Vol. 298, December 13, 2002, by B. J. Peterson (Marine Biological Labo- ratory), R. M. Holmes, J. W. McClelland, C. J. Vörösmarty, R. B. Lammers, A. I. Shiklomanov, I. A. Shiklomanov, and S. Rahmstorf. 7 “Ocean Observatories,” in Oceanus, Vol. 42, No. 1, 2000, published by the Woods Hole Oceanographic Institution. 8 The Little Ice Age: How Climate Made History 1300-1850, by Brian Fagan (University of California, Santa Barbara), Basic Books, 2000. 9 “Cultural Responses to Climate Change During the Late Holocene,” in Science, Vol. 292, April 27, 2001, by P. B. deMenocal (Lamont- Doherty Earth Observatory, Columbia University). 10 “Holocene Climate Instability: A Prominent, Widespread Event 8,200 Years Ago,” in Geology, Vol. 26, No. 6, 1997, by R. B. Alley and T. Sowers (Pennsylvania State University), P. A. Mayewski, M. Stuiver, K. C. Taylor, and P. U. Clark. 11 “A High-Resolution Absolute-Dated Late Pleistocene Monsoon Record From Hulu Cave, China,” in Science, Vol. 294, December 14, 2001, by Y. J. Wang (Nanjing Normal University, China), H. Cheng, R. L. Edwards, Z. S. An, J. Y. Wu, C. C. Shen, and J. A. Dorale. WOODS HOLE OCEANOGRAPHIC INSTITUTION (WHOI) is a pri- vate, nonprofit research and higher education facility dedicated to the study of all aspects of marine science and to the education of marine scientists. It is the largest independent oceanographic research institution in the US, with staff and students number- ing about 1,000. In an atmosphere that nurtures discovery, WHOI scientists, engineers, and students collaborate to explore the frontiers of knowledge about planet Earth. They develop theories, test ideas, build seagoing instruments, and collect data in hostile marine environments. Their diverse research agenda includes geologi- cal activity deep within the earth; plant, animal, and microbial populations and their interactions in the oceans; coastal erosion; ocean circulation; pollution control; and global climate change. The WHOI fleet includes three large research vessels (R/V Atlantis, R/V Knorr, and R/V Oceanus), coastal craft, remote and autonomous vehicles, and the deep-diving human-occupied sub- mersible Alvin. The WHOI annual operating budget of more than $120 million is supported by grants from federal agencies, in- cluding the National Science Foundation, the Office of Naval Research, and the National Oceanic and Atmospheric Adminis- tration, and by private contributions and endowment income. TomKleindinst,WHOIGraphicServices