Evidence for Trends inClimate Change

By Danelle Schuh-Philippe and Suse Riddle

Introduction:

The purpose of this unit is to allow Eighth Grade Earth Science students to experience the process by which evidence is gathered about climate changes. The students will be supported in their science research and data collection processes by activities and lessons in their mathematics class. With information gathered, students will then use various techniques to define trends in climate changes.

Objectives:

  • To make students aware of the processes scientists use to determine the climate of an area before recorded history.
  • To guide students in the discovery of trends in climate changes

Target class: This project is targeted at 8th grade students. The projected time allotment is 4-6 weeks.

Course Structure:

This unit is broken into 4 sub-units, each which may stand alone, or be combined together. The sub-units include 3 processes for gathering evidence of climate change and a final unit addressing temperature trends over time.

I. Core sampling

Background information about ice core sampling is available. (Click Here)

Students will be introduced to the core sampling procedure initially with soil/ rock sampling. Using the activity "Cupcake Core Sampling".

Mathematics Skill Requirements:

  • Measuring using metric units /WMAS D.8.3
  • Determine measurements indirectly using ratio and proportion/WMAS D.8.4
Students will plot the age and parts per million of both CO2 and Methane gas bubbles trapped in the Vostok Ice Core. Using data from the following web site.
http://www.ngdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html (Visited on 6/21/2002)

Students will then observe and record trends seen in their graphs. Using background knowledge, the students will interpret the importance of the trends.

Mathematics Skill Requirements:

  • Work with data in real-world situations/WMAS E.8.1
  • Organize and display data from statistical investigations/WMAS E.8.3
  • Use the results of data analysis to draw conclusions/WMAS E.8.4
  • Compare several sets of data to generate and confirm or deny hypothesis/WMAS E.8.5

II. Fossil formation environments

Students will be introduced to the procedures for dating rock samples in both their math class and science class using the activity "Determining Age of Fossils" at http://www.ucmp.berkeley.edu/fosrec/McKinney.html (Visited on 6/21/2002) Radiometric dating and half life calculations will be covered during math while relative dating will be introduced during science.

Mathematics Skill Requirements:

  • Apply proportional thinking/WMAS B.8.5
  • Organize and display data from investigations using graphs/WMAS E.8.2
  • Extract and use information from displayed data/WMAS E.8.3
  • Use the results of data analysis to draw conclusions/ WMAS E.8.4

The students will continue to determine the age of fossils using relative dating in activity "Who's on First" at http://www.ucmp.berkeley.edu/fosrec/BarBar.html  (Visited on 6/21/2002)

Mathematics Skill Requirements:

  • Extract, interpret, and analyze information from organized and displayed data/WMAS E.8.3

Once students have an understanding of fossil ages, they will explore the environments fossils are formed in using the activity "Where can I see the Sea" at http://www.ucmp.berkeley.edu/fosrec/MunGun2.html (Visited on 6/21/2002).

III. Tree Ring Analysis/Dendrocronology

Students will be introduced to the process of tree ring analysis by measuring (in millimeters) the actual size of tree rings in tree cross-section samples. They will record their data and hypothesize the causes of the varying sizes.

Students will take a virtual field trip via the Internet to observe the oldest trees in the Pacific Northwest to discover clues to the past climates using the activity "History and Tree Rings" .

Students will find tree ring data from a local station and use climate data to determine relationships between tree width and precipitation using the activity "Lord of the (Tree) Rings" . This activity will be conducted in the math classroom and the students will utilize conclusions from this activity in the science classroom.

Mathematics Skill Requirements

  • Organize and display data from statistical investigations using graphs/WMAS E.8.2
  • Extract, interpret, analyze information from organized and displayed data/WMAS E.8.3
  • Use the results of data analysis to draw conclusions/WMAS E.8.4
  •  Compare several sets of data to generate hypothesis/WMAS E.8.5
  • Use reasoning abilities to evaluate information and identify relationships/WMAS A.8.1
  • Communicate logical arguments clearly to show why a result makes sense/WMAS A.8.2
  • Develop effective oral and written presentations that include appropriate use of technology, clear organization of ideas and procedures/WMAS A.8.4

IV. Temperature Trends Over Time

Students will use internet resources to determine the strength of the global warming "signal" at four sites in the United States using activity "She Warms Me, She Warms Me Not" 

Mathematics Skills Requirements:

  • Work with data in real-world situations/WMAS E.8.1
  • Organize and display data from statistical investigations/WMAS E.8.2
  • Extract and analyze information from data/WMAS E.8.3
  • Use the results of data analysis to draw conclusions/WMAS E.8.4
  • Compare several sets of data to generate hypotheses/WMAS E.8.5
  • Work with linear patterns and relationships describing and interpreting their graphical representations (slope)/WMAS F.8.2

Capstone Activities

DEBATE:

Students will conclude their unit with an organized debate about whether global warming is occurring. They will utilize the data they have gathered though out the unit and any additional data they may access. They must prepare both sides of the argument, and be able to defend pro and con positions.

CONSENSUS-BUILDING ACTIVITY:

2-4-8 Activity

Students will write four supported implications concerning global environmental change and man's response to it. Students will then share their statements with a partner, and decide which four of their combined statements are the most important. The group of 2 will then join another group of 2, the 4 combining their findings, producing their four most important statements. The group of 4 will join another group of 4, and the group of 8 will repeat the summary process.

The eight groups will then report out their results using sticky notes, and the class as a whole will synthesize 4 summary statements from the responses which will be written on chart paper and displayed in the classroom.

Summary of Standards Addressed:
Wisconsin Model Academic Science Performance Standards

E.8.2   E.8.4    E.8.4   A.8.6   C.8.2

Wisconsin Model Academic Mathematics Performance Standards 

A.8.1   A.8.2   A.8.4   B.8.2   B.8.5   D.8.3   D.8.4

E.8.1   E.8.2   E.8.3   E.8.4   E.8.5   F.8.2
 

Core Sampling Background Knowledge

During the past few decades, researchers have established the existence of a climate system on Earth that is characterized by complex integration and feedback. The sun and all the parts of the Earth - the oceans, the atmosphere, the land masses, the snow and ice masses, all life, and the inner earth - are parts of this system. Changes in any one part of the system affect all the others and ultimately result in climate change. Climate change is actually a continuous process, but in the past the changes have ranged from the slow and gradual to the surprisingly fast and dramatic. This much we have learned about the climate system; but beyond this we are less knowledgeable. How do the parts of the system interact? How will specific changes in one part affect the others and, ultimately, the climate? What patterns of processes occur to produce the changes we have observed such as the cycle of glacial advances and retreats? What climate changes will occur as a result of our activities?

Humanity's production of CO2, nitrous oxide, sulfuric and nitric acids, CFC's and other "greenhouse" gases, as well as our direct impact on large ecosystems, makes understanding the climate system an imperative. From what we do know now, our activities could raise the average temperature a few to several degrees centigrade over he next few decades in addition to altering weather patterns. If so, the potential exists for severe, or catastrophic, disruption of the Earth's living and climate systems.

How can a history of climate be reconstructed from an ice core? When snow falls it carries with it the compounds that are in the air at the time, compounds ranging from sulfate, nitrate and other ions, to dust, radioactive fallout, and trace metals. When snow falls in a place where temperatures above freezing are rare (there is only a hint of any melting at the GISP2 site in the 750 year record recovered to date), such as in polar regions or at high altitude, the snow from one year falls on top of the previous year without melting.

As each year's snowfall is buried by successive years' snowfall, the constituents contained in the snow are buried along with it. By drilling down from the surface of an ice sheet and analyzing snow from greater and greater depths, a history of the compounds in the air can be obtained. Further, snow that is deeper than 80 meters turns into ice from the weight of the snow above it, and trapped in the ice are small bubbles of air. Thus, in addition to trapping compounds from the air, an ice sheet traps a small sample of the air itself. This trapped air is also analyzed and provides information about the composition of the atmosphere at the time the ice formed.

Like ice cores, deep sea cores have also provided information about climate, but from accumulated sediments on the ocean floor. Unlike ice cores, which provide direct climate information, sediment cores provide indirect information. An example of this indirect evidence is the method for determining temperature. When sediment cores are analyzed researchers painstakingly sort out plankton shells, which twist in different directions depending on the temperature of the water they grew in. By counting the number of shells that twist each way the temperature of the surface water at the time that they grew can be determined. Understanding the behavior of these plankton in the modern world is necessary to produce a historical record of temperature for the ocean.

Sediments also accumulate very slowly relative to snow on an ice sheet. This results in much longer records from sediment cores, but a much reduced ability to resolve short term changes. While periods of hundreds to thousands of years might be resolved in a sediment core, annual and even seasonal resolutions are possible with ice cores. On the other hand, sediment cores can provide records which are as long as several million years compared with the several hundred thousand years of ice cores. Because of these differences, sediment cores and ice cores provide complimentary climate information; ices cores provide high resolution, direct information and sediment cores lower resolution, less direct records, but from much longer time periods.

Cupcake Core Sampling

Objectives:

  • Students will experience core sampling first hand.
  • Students will use their core samples to develop a geologic profile for a simulation area.
  • Students will analyze their geologic profile to determine the climates of the area during the time the rock layers were formed.

Materials:

  • 3 white cake mixes
  • Red and blue food coloring
  • Clear straws (larger than 1/4 in diameter)
  • Green tinted frosting
  • Foil cupcake papers
  • Scissors
  • Plastic knife
  • Metric rulers
  • Colored pencils
  • 1 copy of the columned paper for each student

Teacher Preparation:

1 or 2 days prior prepare cake mixes according to package directions. Divide batter into 3 bowls. Add red food coloring to 1 bowl, Blue food coloring to a second bowl and leave
the third bowl white. Spoon alternating layers of colored batter into foil cupcake papers until about 2/3 full. Bake according to package directions.

Procedure:

  1. Each student needs a cupcake, 2 straws, colored pencils, scissors, a metric ruler and a
    copy of the columned paper.
  2. Have students cut the straws in half so that they are working with 4 pieces.
  3. Model taking a core sample using the straws as the probes in the pattern shown.
  4. Direct students to take samples and to transfer the colored layers onto the columns
    with a scale of 1mm=1 cm.
  5. Using the columns the students have sketched as point cores, connect the correlating layers, creating a geologic profile.
  6. Students may then cut open their cupcake along the sample axis to compare their profiles with the actual layers.
  7. Students may dispose of the cupcake appropriately.

History and Tree Rings

Lesson 1: Tree Ring Overview

Title: Dendrochronology - tree rings of the past...key to the future?
http://www.ltrr.arizona.edu/dendrochronology.html
(Visited on 6/21/2002)

Students -- Lesson 1:

Directions :

Access The Gallery WWW site. Move your arrow to the title of the history or the tree, ring . Discuss the comment and your group answer to the question, write it down. Next move the arrow cursor to (answer below) click there to read the correct comment and answer. Compare your written answer and correct if needed on the next line before you move on to the next question.

HISTORY, TREES and RINGS

History 1:

This map shows where tree-ring dating is possible and where tree-ring collections have been made (graphic © H.D. Grissino-Mayer). Note the concentration of tree-ring sites in the United States, Europe, and Canada. Why are there no tree-ring sites in the tropics between 30 degrees north and south latitude? (Answer below.)

History 2:

Dendrochronology had its beginnings early in this century when A.E. Douglass dated the construction periods for Puebloan ruins throughout the American Southwest. Here, a large ruin at Tonto National Monument in southern Arizona overlooks the desert grasslands below, next to Lake Roosevelt (photo © H.D. Grissino-Mayer). Just how accurate are the construction dates for these ruins based on tree rings? (Answer below.)

Trees 3:

A bristlecone pine at treeline in the White Mountains of eastern California, the oldest known trees in the world (photo © L. Miller). More bristlecone pictures can be found at the Bristlecone Pine Home Page listed above. How old are the oldest bristlecone pine trees anyway? (Answer below.)

Trees 4:

A monstrous giant sequoia tree in Sequoia National Park, California (photo © A.C. Caprio). A normal-sized person would perhaps be as high as the knot on the lower right side of the tree. How wide can these trees become when they are mature? (Answer below.)

Trees 5:

A fire-scar wound ("catface") on a giant sequoia tree in Sequoia National Park, California (photo © A.C. Caprio). Many giant sequoia trees have been damaged by fire like this - do you think fire is harmful or beneficial to these trees? (Answer below.)

Trees 6:

A ponderosa pine tree in the Chiricahua Mountains of southeastern Arizona, showing a well-defined fire-scarred area (photo © H.D. Grissino-Mayer). That's Mariette Seklecki of the LTRR to the left for scale. To get the record of fires from the tree rings, did we have to cut this tree down? (Answer below.)

Trees 9:

Here, Chris Baisan of the LTRR is extracting a small plug out of a Douglas-fir snag near Mt. Graham in southeastern Arizona (photo © W. Edward Wright). Note that the tree did not have to be cut down to get its tree-ring record! This tree has an inside ring date of A.D. 1101, making it one of the oldest trees ever discovered in southern Arizona. What outward characteristics of this tree make it appealing to dendrochronologists? (Answer below.)

Trees 10:

Notice the large scar on this tree (photo © H.D. Grissino-Mayer). This is not a fire scar, as we've seen on some other photos already. Instead, the bark on this ponderosa pine tree in Montana was peeled off by Native Americans to retrieve the soft, inner bark for food or medicinal purposes. Why are these trees important to tree-ring scientists and archeologists? (Answer below.)

Trees 11:

Here, a researcher is coring a tree using an increment borer (photo © Government Printing Office, Washington, D.C.).The borer itself is hollow so that a core, the width of a pencil, can be extracted from the tree. After a core has been extracted from a conifer tree, what is the best way to plug the hole? (Answer below.)

Trees 13:

An immense, very old western juniper (Juniperus occidentalis) growing in the Sierra Nevada of California (photo © G.Burgess). Even though this tree has never been aged using tree rings, we can still see that it is likely to be vey old. What properties of this tree do we notice that indicates great longevity? (Answer below.)

Tree Rings 2:

A cross section of a Rocky Mountain juniper snag found in El Malpais National Monument near Grants, New Mexico (it's about 3 feet across) (photo © H.D. Grissino-Mayer and R.K. Adams). This tree had a pith date of 256 BC and a n outer ring of about AD 1320, making this a nearly 1,600 year old tree when it died! Why are such trees important to archeologists studying the Southwestern United States? (Answer below.)

Tree Rings 3:

A cross section of a giant sequoia showing a remarkable release in growth (notice the wider rings that start in the middle of the photo) following a widespread and intense fire in A.D. 1297 (photo © T.W. Swetnam and A.C. Caprio). Why would growth rates of trees increase like this after a fire? (Answer below.)

Tree Rings 5:

A close-up of a cross-section of a giant sequoia showing numerous fire scars and the growth patterns that resulted (photo © A.C. Caprio). Notice the two fire scars in the left center portion of the photo - how many years separated these two fires? (Answer below.)

Tree Rings 6:

Increment cores taken from Douglas-fir trees growing on Mt. Graham in southeastern Arizona (photo © H.D.Grissino-Mayer). Note the suppression in tree growth around 1685 due to a forest fire that caused damage to the trees. In the sequoia photo in Tree Rings 2, we saw a growth increase after a fire - what could cause a reduction in growth rates after a fire?(Answer below.)

Tree Rings 7:

Close-up of a cross section of a ponderosa pine from Oregon, showing periods of growth reduction caused by pandora moths (photo © J.H. Speer). Note the narrow rings that begin around 1631, 1661, and 1677. Reconstructing past insect outbreaks is an important application of dendroecology - why? (Answer below.)

Tree Rings 8:

A diagram showing the tree rings of a "ring porous" tree species, such as oak and elm (growth is to the right) (photo © LTRR). Can trees with this type of wood be used for tree-ring research? (Answer below.)

Tree Rings 10:

Close-up photographs of conifer tree rings showing different types and rates of tree growth (photo © LTRR). If you wanted to find out how much rainfall fell in the past, how could you use tree rings to find out? (Answer below.)

Tree Rings 11:

Close-up photographs of two sets of pine tree rings (growth is to the right) (photo © LTRR). Besides information about past climate and fire occurrences, what other information about the environment can we learn from tree rings? (Answer below.)

SCENES FROM MY FIELD WORK

Scenes 1: A prescribed fire sweeping through the understory of a mixed conifer forest on Mt. Lemmon in the Santa Catalina Mountains, north of Tucson, Arizona, in May, 1993 (photo © H.D. Grissino-Mayer). What exactly is a prescribed burn anyway? (Answer below.)

Scenes 5: Another victim of the forest fire on Mt. Graham - the "Mother of the Forest," an immense Douglas-fir tree that was about six feet in diameter and over 600 years old when it was burned (photo © H.D. Grissino-Mayer). Once again, this emphasizes the unusual nature of this fire - this tree had lived through about 40 previous, low- intensity surface fires, but could not survive this one. What should the Forest Service do to prevent these types of fires from occurring? (Answer below.)

Scenes 9: So how do we get a cross section from stumps left over from logging? We use a chain saw as I'm demonstrating here.Notice all the protective gear - helmet, face shield, ear muffs, and leg chaps. We'll take this piece back to the lab and sand a beautiful surface on it (photo © H.D. Grissino-Mayer). Sometimes logging companies come in and cut down all the trees with fire scars - why? (Answer below.)

Scenes 10: Here, Rex Adams of the LTRR uses a drill to extract core samples from a beam used to build the pueblo at Tonto National Monument in southern Arizona (photo © H.D. are not able to date such ruins - why not? (Answer below.) Grissino-Mayer).

Scenes 11: Gosh, sometimes I really hate my job, especially when it takes me to places like this (photo © H.D.Grissino-Mayer). I've collected all over the Pinaleno Mountains in southeastern Arizona, here looking northwest towards the Santa Teresa Mountains. Yes, our mountain ranges do have trees! Such steep mountain ranges are often ideal locations for finding old trees - why? (Answer below.)

Scenes 12: Here's another scene from El Malpais National Monument in northwestern New Mexico (photo © H.D.Grissino-Mayer). I'm kneeling next to sample CRE46, which was troublesome to date. The reason? The inner ring date on this remnant ponderosa pine stump was A.D. 111, at the time older than any previous piece of wood in New Mexico. What are the oldest tree-ring samples yet discovered in the American Southwest? (Answer below.)

Teacher Copy

ANSWERS

History 1: For annual rings to form, trees must "shut down" growth at some point to form a distinct ring boundary. This occurs in the dormant season, usually in the fall and winter. In the tropics, the seasons are not as distinct, so that trees can grow year-round. Therefore, most tropical trees do not form annual rings.

History 2: If the wood used in the construction of these ruins has bark still intact, the exact year the ruin was built can be determined from tree rings, assuming the tree was cut for the explicit purpose of building the ruin. Tree rings dates from many beams in the ruin add further confidence if the cutting dates cluster within a short period.

Trees 3: Oh, about a gazillion years. Hah! Not really. The oldest bristlecone pine tree was almost 4,900 years old when it was cut down! (For more on that story, connect to the bristlecone pine home page above.) Many have been discovered that are well over 4,000 years old. Which means these trees were very old, about 2,500 years old, when Christ was born. That really puts the age of these trees in perspective, doesn't it?

Trees 4: Some giant sequoia trees can grow to be 33 feet in diameter at the base! In the late 1800s when these trees were being heavily logged, some newspapers reported that dance cotillions with as many as 50 people were held on the remaining stumps.

Trees 5: Unknown to most people, fire is actually beneficial to the giant sequoia trees, and to many other tree species such as ponderosa pine. Without fire to prepare the soil (by removing the needles, twigs, and branches that clutter the forest floor), seedlings of giant sequoia trees may not survive their first few years. Fire also helps open the cones of these trees so that the seeds can be dispersed. Which makes one wonder: why do we spend so much time and money putting out forest fires if they're beneficial to some of our forests?

Trees 6: Heck no! This tree had a record of about ten forest fires in its rings (see the other photos), and we really needed a small section from this tree. Using a chain saw, we deftly cut a small wedge from one side of the tree that contains the fire scars. The tree is relatively unhamed and remains living.

Trees 9: The tree is relatively short, contorted and twisted, and has numerous large branches. The bark is already eroded. This all indicate this is a very old tree - indeed, this southwestern white pine tree dates back to 1101 and extends out to about A.D. 1650 before it died.

Trees 10: Because dendrochronologists can extract cores from the scar areas on these trees, and date when the peeling events occurred. This alerts archeologists when the area was occupied by Native Americans, and helps scientists learn more about the habits of ancient Indian cultures.

Trees 11: You should NOT plug the hole left in a conifer tree by an increment borer! Why? Because conifer trees are very capable of repairing the small wound by filling the hole with resin to prevent contamination. You should never insert a stick or anything else as this may actually introduce diseases!

Trees 13: First, notice the tree is not very tall, only about 25 feet (8 meters) - it is "short and squat." Second, the tree has veryheavy lower branches, always indicating old age. Third, the tree is growing on a ridge with little groundcover - growing conditions would be considered limiting here. Fourth, the tree has marked "spiral grain" in the tree trunk. Fifth, quite a bit of remnant wood lies around the tree, which indicates wood can persist on the surface for many years after death. All these indicate this is a very old tree!

Tree Rings 2: Because trees like this can be used to reconstruct past climate variables, such as precipitation. The ancient Indian cultures of the Southwest were perhaps at the mercy of the environment, and changes in climate may have triggered certain changes in their culture (for example, migration to other locations). However, climate was not the sole reason changes in these cultures occurred.

Tree Rings 3: Because plants (other trees, smaller shrubs in the understory, and grasses) are removed after a fire, reducing the competition for nutrients. Hence, surviving trees will increase their growth rates because plants that had been competing for nutrients and water were burned off. There is also a "green-up" after a forest fire, caused by the release of nitrogen into the soil, which acts like a fertilizer in some respects.

Tree Rings 5: I count about 19 annual rings (years) between those two fire scars. Note that by counting the rings between successive fire scars, we can get some indication about how often forest fires had occurred in these forests. The National Park Service is very interested in this type of information for developing their fire management policies.

Tree Rings 6: If a fire is intense enough, the foliage of a tree may be severely burned off. If some foliage remains, the tree may survive. However, for some years after, growth rates will be reduced because the tree has lost some of its ability to photosynthesize (which occurs in the foliage), or create nutrients from sunlight and water.

Tree Rings 7: Because insects are an integral component of forest ecosystems. For example, mass tree mortality caused by bark beetle outbreaks may lead to increased wildfire hazard due to all the dead stems. Pandora moths and spruce budworms munch on the trees' needles, causing reductions in growth (fewer leaves to photosynthsize), which mean reduced timber yield for logging companies!

Tree Rings 8: Of course! In fact, the longest continuous tree-ring chronology in the world is composed of many, many series of oak sequences that overlap back in time for almost 10,000 years! Developed in Europe by Bernd Becker and his colleagues in Germany, this tree-ring chronology offers us a peek to what climate was like just after the Ice Age ended about 11,500 years ago!

Tree Rings 10: The width of each individual ring is usually dependent on how much rainfall fell during the year the ring was formed. First, you would have to measure the widths of all rings using special instruments. Then, you calibrate the tree-ring widths with rainfall records from a nearby weather station: in other words, you develop a statistical relationship that says "a tree ring that is this wide means this much rainfall fell." You can then find out how much rainfall fell per year well before weather records were ever kept!

Tree Rings 11: Quite a bit actually. Tree rings have been used to reconstruct past outbreaks of insects that damage trees and large forests. Tree rings can be used to reconstruct past glacial activity, as well as past volcanic events. Tree-ring information is also vital to understanding the "age structure" of a forest to help land managers better manage their forests.

Scenes 1: A prescribed fire is one that was intentionally lit by forest managers. The effects of these fires are beneficial to the forest in many ways (recycles nutrients, creates open areas for wildlife), and they also help prevent larger, more catastrophic fires later!

Scenes 5: Several things. First, the fuels must be reduced in all western forests since they've been building up for about 80 to 100 years. Second, the Forest Service must educate the public about the beneficial nature of fire to our forests. Third, perhaps a change in management policy is in order - perhaps the millions of dollars spent on fighting fires should be used to help return the forests to more managable conditions!

Scenes 9: Because the wood from these trees is usually inferior due to the damage caused by the repeated fires. Logging companies sometimes will salvage what they can from these types of trees - in many ways this is fortunate for our research as it leaves us with plenty of stumps to analyze!

Scenes 10: Various reasons. Sometimes, the cores we extract do not have enough rings to provide confident dates. Sometimes the tree species used are not datable by dendrochronology (Arizona sycamore, for example). Sometimes the wood is so decayed,we can't see the rings.

Scenes 11: These areas often have steep, rocky cliffs, where trees often grow in cracks and crevices. These trees are usually slow growing (see the "Principle of Site Selection"), and have been protected from the elements (from fire, for example, because fire can not spread over the rocky areas) for centuries.

Scenes 12: Don Graybill discovered bristlecone pine samples in southern Utah at a location called Mammoth Creek which date back to ca. 600 BC. The oldest samples in Colorado also date back to ca. 600 BC from a Basketmaker (Anasazi) site near Durango. The oldest wood in New Mexico dates back to 200 BC - in fact, it was a piece of wood found about 200 feet near this particular sample!

The Lord of the (Tree) Rings:

(Detective Work on Past Climates Using Dendroclimatology)

  1. Find a tree ring data site located in close proximity to a long-term climate station that has data available for use in ClimProb software.
  2. Download standardized tree ring data at http://www.ngdc.noaa.gov/paleo/ftp-treering.html(Visited on 6/21/2002)
  3. Using ClimProb, open a time window of 9/1-8/31 and determine total precipitation for the entire period of record .
  4.  Graph standardized tree ring v\1dth (y-axis) as a function of time (x-axis) Graph precipitation (y-axis) as a function of time.
  5.  Describe the relationship between tree ring width and precipitation. Is there a correlation? How can this information be used in relation to increasing CQ2 concentrations and climate change?

She Warms Me, She Warms Me Not

(Regional Trends in U.S. Temperatures)

  1. Use the ClimProb software to determine the strength of the global warming "signal" (slope of the regression line) at each of the following sites:
    1. Central Park in New York, NY
    2. Ukiah, CA
    3. Lincoln, NE
    4. Mobile, AL
  2. Examine maximum and minimum temperature trends for the four different seasons and the entire year over the length of record.
  3. Record your findings in the Tables provided.
  4. Draw your own conclusions: Is global warming occurring? Are there any non-climatological circumstances that need to be taken into consideration when examining the temperature trends/patterns?
  5. Other observations?
Season Maximum Temperature slope Minimum Temperature slope Mean Temperature slope
Winter (DJF)      
Spring (MAM)      
Summer (JJA)      
Autumn (SON)      
Annual (J-D)