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Earth's climate history includes not only long periods of cooling (glacial) and warming (interglacial), but shorter periods characterized by abrupt climate change. One such period of abrupt change occurred about 8200 YBP (years before present), less than 3500 years into the Earth's current interglacial phase of the glacial-interglacial cycle. During this period of abrupt cooling, known as the 8.2ka event, temperatures in Greenland dropped by about 5ºC before it began to warm again and climate patterns in Europe, North America, the North Atlantic and even North Africa were altered for more than a century.

To understand the dynamics of climate change, scientists look at changes in the Earth's climate over long time scales to identify patterns and determine the causes of the changes. Since instrumental data for climate indicators is only available for the past few hundred years, scientists use information from geologic evidence to analyze and interpret climate change history. Evidence of climate change, sometimes called paleoclimates, can be found in diverse contexts called proxies: sediments from lake bottoms and the ocean floor, flowstone and speleothems in caves and rockshelters, glacial ice, and fossil remains of living things such as tree rings, coral and pollen.

Oscillations of the climate between long warm and cool periods, such as the glacial advances throughout the Pleistocene ice ages appear to be planetary climate responses to periodic changes in insolation related to the position of the Earth with respect to the its orbit, slight changes in the tilt of the Earth on its axis, and the precession of seasons. Explaining the rapid cooling that occurred during the 8.2ka event is more challenging.

Hundreds of paleoclimate records gathered from all over the world demonstrate that Earth's climate system is not always predictable or "well-behaved". Computerized climate simulation experiments conducted using general circulation models (GCMs) reveal chaotic behavior that can only be described statistically. For this reason scientists cannot describe with 100% certainty what will happen to Earth's climate in the future.

Recent changes in the Earth's climate, although reason for great concern, have been gradual compared to changes reflected in its climate record during the periods of rapid change like the 8.2ka event. There is a possibility, however, that if global warming reaches an as yet-to-be-determined level, a new period of abrupt change could be triggered. Positive feedbacks can amplify small disturbances in the Earth's system and result in abrupt changes in climate. A future abrupt change in the ocean's thermohaline circulation system, for example, could set off a cascade of changes that affect climate.

Task: The U.S. Congress has commissioned your team of Earth system scientists to develop a top-secret report for the Pentagon to help them better understand and prepare for the potential implications of an abrupt climate change on National Security. They are interested in worst-case scenarios. Use the 8.2ka event as an analogue (model) to construct your own abrupt climate change worst-case scenario, to conduct an Earth system science analysis of the potential national and global impacts resulting from that abrupt change and to prepare your report.


Date: 12/24/2009

Scenario Images:

Abrupt Change at 8200 BP
Graphs of snow accumulations and atmospheric temperatures reconstructed using proxy climate data in Greenland GISP2 ice core and Lake Ammersee fossil shells in sedment cores showing the 8200 YBP event. Image: NOAA

A 100,000 year record of sudden warmings and coolings of the Earth
The 8.2ka event is clearly evident in this average yearly temperatures in Greenland over the past 100,000 years graph, reconstructed from Oxygen isotope analysis of the GISP2 Greenland ice core. More... (Source: Cuffey and Clow 1997, Journal of Geophysical Research 102: 383-396.)

Great Ocean Conveyor Belt
Diagram showing how heat is transferred from the equator to the poles by thermohaline ocean circulation. Watch this animation and see how the oceanic conveyor belt moves. Image: IPCC 2007

Lake Agassiz
Freshwater pooled to the south of the Hudson's Bay prior to its release and initiation of the 8200 YBP abrupt climate event. More... Image: University of British Columbia Department of Earth and Ocean Sciences

Pattern of Climatic Anomalies During the 8200 BP event
Map of climate anomalies during the 8200 YBP event from published paleoclimate records. (Source: Morrill and Jacobsen 2005, Geophysical Research Letters 32: L1970). More... Image: NOAA



Abrupt Climate Change (Cycle A)
From Lamont-Doherty Earth Observatory the Earth Institute at Columbia University. This resource explores abrupt climate change through a series of questions and answers. The Younger Dryas is discussed in depth as an example of scientific evidence of abrupt climate change.


Abrupt Climate Change 8200 BP (Cycle A)
Did the influx of freshwater from large lakes in North America into the ocean trigger the abrupt cold event recorded in paleoclimate proxy data archives 8200 years ago?


Abrupt Climate Change: Inevitable Surprises (Cycle A)
This online book resource from the National Academies Press covers a wide variety of abrupt climate change topics. You can access the chapters from the Table of Contents (scroll down the page) or you can use the Search This Book tool to access information about ice cores, Younger Dryas, foraminifera data, and other specific climate change topics of interest


The Climatologist's Toolbox (Cycle A)
Learn the basics about the tools and tricks scientists use to study Earth's climate history.


Clues to the Big Chill (Cycle B)
What caused the 8.2ka event? This article from National Geographic explores the some of the clues to the answer.


Paleoclimatology (Cycle B)
NOAA Paleoclimatology site.


The Science of Abrupt Climate Change: Should we be worried? (Cycle B)
This resource provides an excellent primer on what we know about abrupt change in the past and how we know it.


U.S. Climate Change Science Program: Synthesis and Assessment Report 3.4 (2008) (Cycle B)
This report investigates the potential for abrupt climate change related to global warming this century, examining 4 major areas:
Will there be an abrupt change in sea level?
Will ther be an abrupt change in the hydrologic cycle?
Will there be an abrupt change in the Atlantic Meridional Overturning Circulation?
Will there be abrupt change in atmospheric methane?


Climate Change Classroom Activities (Cycle C)
Links to 157 activities. A variety of climate change topics are explored.


Climate Proxies Advanced Collection (Cycle C)
Links to a variety of proxy related sites and sources.


DLESE (Cycle C)
Digital Libray for Earth System Education, the ultimate resource for Earth Science lesson plans, investigations and publications.


Essential Principles of Climate Literacy (Cycle C)
US Climate Change Science Program 2009 edition. Presents information that is deemed important for individuals and communities to know and understand about Earth climate, impacts of climate change, and approaches to adaptation or mitigation.


Paleoclimate: Climate Change Through Time (Cycle C)
Access to a spectrum of visualizations and supporting material that can be used effectively to teach students about paleoclimate through geologic time. Visualizations include simple animations, GIS-based animated maps, paleogeographic maps, as well as numerous illustrations and photos.


Sample Investigations:


Natural Records of Change: Working with Indirect Evidence of Past Climates (Cycle A)
Do this investigagtion and explore the how relationship between natural systems and the indirect evidence they generate works.
Difficulty: beginner


Temperature Reconstruction Using Vostok Ice Core Data (Cycle A)
In this investigation learn how scientists reconstruct Earth's climate history from the particulates, isotopes and atmospheric gases trapped in the Vostok ice cores and other ice cores.
Before beginning this investigation, read the Lab Tips.
Difficulty: advanced


Using Published Ice Core Graphs to Explore Climate Change (Cycle A)
Use this investigation to explore graphs of ice core data and learn more about what the gases and materials in ice cores tell us about past and future climate changes. Use this investigation in place of the Vostok Lab (does not require Excel) or as a source of published graphs for comparison to those generated in the Vostok Lab Investigation. From the home page, use the Investigation navigation button to access the entire list of investigations. Scroll down the listing to Chapter 21: Climate and Climate Change and select the "How Do Ice Core Glaciers Tell Us About Climate Past?" investigation.
Difficulty: intermediate


Climate Reconstruction Using Formanifera Data in Deep Sea Sediments (Cycle B)
Use pasta and a cardboard tube to construct deep sea sediment core. Correlate the abundance of forams at different levels in your core to generate temperature profiles. Materials include foraminifera information, videos about analysis and handouts.
Difficulty: intermediate


Inferring Ancient Environments from Fossil Formanifera (Cycle B)
In this investigation, use a reference diagram of fossil foraminifera with paleo-water-depth assignments to interpret the water-depth of a particular area of California during the geologic past. The model of paleoenvironments and the species found in the samples are based on actual work by Ingle (1980) and Olson (1990). The reconstruction of Miocene environments is applied to the petroleum industry by looking for potential reservoir rock and source rock.
Difficulty: intermediate


Using the Very, Very Simple Climate Model in the Classroom (Cycle B)
Use a simple online, model to learn about the relationship between average global temperature and carbon dioxide emissions while predicting temperature change over the 21st century.
Difficulty: beginner


Foram Data Subantarctic Zone 2000-543,000 YBP (Cycle C)
Use this dataset and Excel to create your own foraminfera profiles. Dataset is available in tab-delimited text for import into Excel. You decide which species and parameters to investigate.
Difficulty: advanced


Graphing Sea Ice Extent in the Arctic and Antarctic (Cycle C)
Graph sea ice extent in the polar regions to learn about seasonal variation and about long-term trends that may represent response to climate change.
Difficulty: beginner


Tracking Global Climate: Microfossil Record of the Planetary Heat Pump (Cycle C)
This lesson plan integrates physics, biology, and geology to understand planetary processes that contribute to climate change through time. The plan includes a hands-on activity that demonstrates heat transfer as well as uses figures and charts to demonstrate how foraminifera (shelled microorganisms)can be used to interpret past climates.
Difficulty: beginner


Using Real Data from Ices Cores and Salt Cores to Interpret Paleoclimate (Cycle C)
Do this investigation to compare data from two ice cores (Vostok and GRIP) and two halite cores (Death Valley and Chile) to identify core trends, explore core correlations and distinguish local, regional and global warming and cooling trends.
Difficulty: advanced




  • Science
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        • Transfer of energy
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    Geography for Life: National Geography Standards, 1994
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