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Atmosphere, Biosphere, Climate, Cryosphere, Geosphere, Hydrosphere, Oceans



Evidence of global climate change is all around us, including melting ice caps and glaciers, changes in ocean and atmospheric chemistry, changes in timing and duration of growing seasons, and species extinction. Some like to point out that Earth has changed before; it has been both a hothouse and an ice house. So why worry? One reason may arise from one of the most singular events in Earth's history. It took place about 55 million years ago at the end of the Paleocene and beginning of the Eocene epochs. This episode is known as the Paleocene Eocene Thermal Maximum (PETM).

The Earth was free of snow and ice during the PETM period. The Arctic was subtropical with crocodiles swimming in the warm waters off of Greenland. Records suggest that the planet experienced a period of gradual warming, followed by an abrupt and massive carbon input into the atmosphere (Zachos, Dickens & Zeebe, 2008), Earth's land and oceans warmed. The Arctic's sea surface temperature, for example, was approximately 23C or 73 degrees Fahrenheit. The PETM was also marked by a massive input of carbon into the oceans and many deep sea organisms went extinct. Land animals experienced a turnover, with many mammals such as the horse existing in dwarf form.

Scientists have questioned whether the warming or the massive input of carbon dioxide occurred first. Although estimates of the amount of carbon injected into the atmosphere vary, Zeebe, Zachos and Dickens (2009) estimate that 3000 gigatons of carbon must have been added to the Earth's system.

The PETM was marked by an estimated increase in atmospheric carbon dioxide content of between 750 to 26,000 ppm (parts per million) (Pagani,, 2006). Today it is approximately 387 ppm. Scientists continue to speculate and investigate the huge increase in carbon dioxide. Many suggest a massive release of methane from deposits in the sea floor as the contributing cause for the increase in atmospheric carbon dioxide. As the planet warmed and the ocean currents changed, scientists theorize that the methane, which is locked up in an ice-like structure in deposits known as clathrates, was released to the atmosphere. This methane would then have broken down to carbon dioxide.

The events tied to the PETM may explain what is happening today and may help us predict events to come. For example, if trends continue, by 2400 we will add the same amount of atmospheric carbon dioxide as occurred during the PETM. Over half of the current carbon dioxide increases have been absorbed by the oceans. As a consequence, oceans are becoming more acidic. The acidification during the PETM coincided with the extinction of many deep dwelling marine life . Sediment cores recording the PETM episode show a rapid ocean acidification, indicating a huge release of carbon dioxide entering the atmosphere. In 80,00 to 180,000 years, Earth recovered by returning to its pre-PETM climate.


Assume that the current addition rate of carbon dioxide to the atmosphere continues. Some estimate this amount to be 10 gigatons per year with 500 gigatons already added. We will eventually reach or surpass the amount added during the PETM. A senate panel on climate change needs your Earth system analysis of the expected environmental impact and changes that may occur as carbon dioxide atmospheric content approximates that of the PETM.

An article about the PETM written by Dr. Jeff Masters of Weather Underground alludes to some geologists' skepticism concerning human induced climate change. Some geologists, for example, might point out that chemical weathering of silicate rocks has to be considered as a feedback process dealing with excess carbon dioxide. Included in the Weather Underground article are links to survey results of scientists concerning climate change beliefs. Along the same vein regarding human induced climate change and geologists' beliefs, science writer Paul MacRae states that geologists study the Earh on a geologic time scale, not just short term changes in climate and temperature. He argues that on a geologic time scale evidence will show that the current warming is to be expected. He further suggests the planet could even be headed toward a cooling phase.

These issues concern your boss, an elected official and member on the U.S. senate climate panel. She wants to know whether skeptics to human-induced climate change have valid points. She wants you to show her the evidence for or against whether human contributions to atmospheric carbon dioxide will lead to another PETM. She has tasked your team with weighing the evidence in order to support recommendations concerning climate related policy.


Kennett, J.P., and Stott, L.D., 1991. Abrupt deep-sea warming, paleoceanographic changes and benthic extinctions at the end of the Palaeocene. Nature (London, U. K.), 353:225–229.

Pagani, M., Caldeira, K., Archer, D., and Zachos, J.C., 2006: An ancient carbon mystery, Science. 314, 1556-1557

Schmitt, G. (2009). PETM Weirdness. Real Climate

Sluijs A., (2010). The Palaeocene-Eocene Thermal Maximum super greenhouse: biotic and geochemical signatures, age models and mechanisms of global change. Yale Climate and Energy Institute. Feb 21, 2011.

Zachos, J.C., Dickens, G.R., and Zeebe, R.E. (2008, January 17). An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics. Nature, 45.

Zeebe, R. E., Zaschos,J.C., and Dickens, G.R. (2009). Carbon dioxide forcing alone insufficient to explain Paleocene-Eocene thermal maximum warming. Nature Geoscience.


Date: 12/10/2010

Scenario Images:

NOAA Paleoclimatology
Image courtesy NOAA.
NOAA site with Data, PaleoPerspective and Outreach.

NOAA Paleoclimatology Borhole Data
Image Courtesy NOAA Paleoclimatology Program
Borehole data are direct measurements of temperature from boreholes drilled into the Earth crust. Most borehole data is available at the University of Michigan Global Database of Borehole Temperatures and Climate Reconstructions.



A Primer on the PETM (Cycle A)
This event happened at the end of a ten million year period of time known as the Paleocene. The gas release was initiated by an intense period of seafloor volcanic activity that...


NOAA Study: Reanalysis of Historical Climate Data for Key Atmospheric Features (Cycle A)
U.S. Climate Change Science Program; Synthesis and Assessment Product 1.3; Reanalysis of Historical Climate Data for Key Atmospheric Features:
Implications for Attribution of Causes of Observed Change..."anthropogenic greenhouse gas forcing alone is unlikely to be the main cause for regional and seasonal differences of surface temperature changes..." See also The role of scientific ocean drilling in understanding ocean acidification by NOAA scientients and others.


PETM greenhouse warming similar to today's? (Cycle A)
"If carbon dioxide emissions from the burning of fossil fuels continue on a "business-as-usual" trajectory, humans will have added about 5 trillion metric tons of carbon to the atmosphere by the year 2400." From the environmental news web site Mongabay.


Predicting Impact of Continued Carbon Emissions (comprehensive) (Cycle A)
An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics by Zachos, Dickens, and Zeebe. See also The Palaeocene-Eocene Thermal Maximum super greenhouse: biotic and geochemical signatures, age models and mechanisms of global change from the Yale Climate and Energy Institute.


Abrupt Climate Change (Cycle B)
Chapter 5, "Potential for Abrupt Climate Changes in Atmospheric Methane." From the U.S. Climate Change Science Program.


Could Human Carbon Dioxide Emissions Cause Another PETM? (Cycle B)
Suggested causes of the PETM include: "... massive continuous volcanic eruptions, world wide outbreak of forest fires, sudden reversals of circulating ocean currents and the release of deep sea deposits of methane held in methane-ice compounds known as clathrates."


Did volcanoes contribute to the PETM's massive warming? (Cycle B)
Volcanoes linked to massive global warming event.
Rhett A. Butler,


Is Carbon Dioxide Forcing Enough to Explain PETM Warming? (comprehensive) (Cycle B)
Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming by Zeebe, Zachos and Dickens.


Research article on massive methane release (comprehensive) (Cycle B)
Atmospheric composition, radiative forcing, and climate change as a consequence of a massive methane release from gas hydrates. See also the Science Brief by James Hansen: Trends of Measured Climate Forcing Agents


Grandchildren and the Future (Cycle C)
This isn't a peer reviewed research article, nor a government site with information about climate such as NOAA, NASA or other well known sources. It is a site put together by a grandfather in Australia. He is concerned about climate warming and wants to give us climate background to bring the public up to date. Good background for those new to climate science. Check out the links he provides. You may find this site useful for yourself or your students. This is a fine example of what a project to discuss global warming might look like.


NOAA's Paleoclimatology Program (Cycle C)
"NOAA Paleoclimatology is a branch of NOAA's National Climatic Data Center. Paleo data come from natural sources such as tree rings, ice cores, corals, and ocean and lake sediments--and extend the archive of weather and climate back hundreds to millions of years." See also the NOAA Paleoclimatology Site Map.


Why Paleoclimatology? (Cycle C)
The Microbial Life Educational Resources site is full of resources for teachers addressing how we can study past climates.


Sample Investigations:


NOAA's Climate TimeLine Information Tool (Cycle A)
A very dynamic site that will allow students to visualize climate conditions 100,000 years ago and beyond. Includes data access tools.
Difficulty: beginner


PETM Class Discussion from American Museum of Natural History (Cycle A)
Watch this video with your class before the discussion. From the American Museum of Natural History: This Classroom PETM Discussion Activity can be used to connect your students to the process of science, highlight overarching scientific themes, and enhance comprehension of the story. The AMNH site also includes a useful glossary covering climate change.
Difficulty: beginner


Climate Change Curricula for K-12 (Cycle B)
From the National Environmental Education Foundation, a series of climate related lessons and activities for K-12.
Difficulty: beginner


Physical Geography: Earth Processes (Cycle B)
A series of lessons including math, Earth science, physical geography. Lessons include: Inside Planet Earth, Earth structure, minerals, plate tectonics, volcanoes. Lesson 2.4 addresses paleoclimatolgy.
Difficulty: beginner


Climate Curriculum Resources from California (Cycle C)
The California EPA Air Resources Board provides activities and lessons for K-12.
Difficulty: beginner


Global Climate Change Education (Cycle C)
A series of projects on climate change for students in all grades.
Difficulty: beginner




  • Science
    National Science Education Standards - Science Content Standards The science content standards outline what students should know, understand, and be able to do in the natural sciences over the course of K-12 education.
      The understandings and abilities associated with the following concepts and processes need to be developed throughout a student's educational experiences:
      • Systems, order, and organization
      • Constancy, change, and measurement
      • Science as Inquiry (Std A)
        • Abilities necessary to do scientific inquiry
        • Understanding about scientific inquiry
      • Life Science (Std C)
        • The characteristics of organisms
        • Life cycles of organisms
        • Organisms and environments
      • Earth and Space Science (Std D)
        • Properties of earth materials
        • Changes in earth and sky
      • Science and Technology (Std E)
        • Understanding about science and technology
      • History and Nature of Science (Std G)
        • Science as a human endeavor
      • Science as Inquiry (Std A)
        • Abilities necessary to do scientific inquiry
        • Understanding about scientific inquiry
      • Physical Science (Std B)
        • Properties and changes of properties in matter
        • Motions and forces
        • Transfer of energy
      • Life Science (Std C)
        • Structure and function in living systems
        • Reproduction and heredity
        • Regulation and behavior
        • Populations and ecosystems
        • Diversity and adaptations of organisms
      • Earth and Space Science (Std D)
        • Structure of the earth system
        • Earth's history
      • History and Nature of Science (Std G)
        • Science as a human endeavor
        • Nature of science
      • Science as Inquiry (Std A)
        • Abilities necessary to do scientific inquiry
        • Understanding about scientific inquiry
      • Physical Science (Std B)
        • Structure and properties of matter
        • Chemical reactions
        • Motions and forces
        • Interactions of energy and matter
      • Life Science (Std C)
        • Interdependence of organisms
        • Matter, energy, and organization in living systems
      • Earth and Space Science (Std D)
        • Energy in the earth system
        • Geochemical cycles
        • Origin and evolution of the earth system
      • History and Nature of Science (Std G)
        • Science as a human endeavor
  • Mathematics
    Principles and Standards for School Mathematics, National Council of Teachers of Mathematics (NCTM), 2000 This set of Standards proposes the mathematics concepts that all students should have the opportunity to learn. Each of these ten Standards applies across all grades, prekindergarten through grade 12. Even though each of these ten Standards applies to all grades, emphases and expectations will vary both within and between the grade bands (K-2, 3-5, 6-8, 9-12). For instance, the emphasis on number is greatest in prekindergarten through grade 2, and by grades 9-12, number receives less instructional attention. Also the total time for mathematical instruction will be divided differently according to particular needs in each grade band - for example, in the middle grades, the majority of instructional time would address algebra and geometry.
      Mathematics instructional programs should foster the development of number and operation sense so that all students—
      • understand numbers, ways of representing numbers, relationships among numbers, and number systems;
      Mathematics instructional programs should include attention to patterns, functions, symbols, and models so that all students—
      • understand various types of patterns and functional relationships;
      • use symbolic forms to represent and analyze mathematical situations and structures;
      Mathematics instructional programs should include attention to geometry and spatial sense so that all students—
      • use visualization and spatial reasoning to solve problems both within and outside of mathematics.
      Mathematics instructional programs should include attention to data analysis, statistics, and probability so that all students—
      • pose questions and collect, organize, and represent data to answer those questions;
      • interpret data using methods of exploratory data analysis;
      • develop and evaluate inferences, predictions, and arguments that are based on data;
      Mathematics instructional programs should focus on solving problems as part of understanding mathematics so that all students—
      • apply a wide variety of strategies to solve problems and adapt the strategies to new situations;
      • monitor and reflect on their mathematical thinking in solving problems.
      Mathematics instructional programs should focus on learning to reason and construct proofs as part of understanding mathematics so that all students—
      • select and use various types of reasoning and methods of proof as appropriate.
      Mathematics instructional programs should use communication to foster understanding of mathematics so that all students—
      • organize and consolidate their mathematical thinking to communicate with others;
      • express mathematical ideas coherently and clearly to peers, teachers, and others;
      Mathematics instructional programs should emphasize mathematical representations to foster understanding of mathematics so that all students—
      • create and use representations to organize, record, and communicate mathematical ideas;
      • develop a repertoire of mathematical representations that can be used purposefully, flexibly, and appropriately;
  • Geography
    Geography for Life: National Geography Standards, 1994
      Geography studies the relationships between people, places, and environments by mapping information about them into a spatial context. The geographically informed person knows and understands:
      • How to use maps and other geographic representations, tools and technologies to acquire, process, and report information from a spatial perspective
      Physical processes shape Earth’s surface and interact with plant and animal life to create, sustain, and modify ecosystems. The geographically informed person knows and understands:
      • The physical processes that shape the patterns of Earth’s surface
      • The characteristics and spatial distribution of ecosystems on Earth’s surface
      Knowledge of geography enables people to develop an understanding of the relationships between people, places, and environments over time — that is, of Earth as it was, is, and might be. The geographically informed person knows and understands:
      • How to apply geography to interpret the past
  • Technology
    The International Society for Technology Education From and
      • Students demonstrate a sound understanding of the nature and operation of technology systems.
      • Students practice responsible use of technology systems, information, and software.
      • Students develop positive attitudes toward technology uses that support lifelong learning, collaboration, personal pursuits, and productivity.
      • Students use technology to locate, evaluate, and collect information from a variety of sources.
      • Students use technology tools to process data and report results.
      • Students evaluate and select new information resources and technological innovations based on the appropriateness for specific tasks.
      • Students use technology resources for solving problems and making informed decisions.
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