Above graphic taken from a 2006 report by Lowell and others coring lakes in northern Minnesota. Dr. Lowell is on the right without a coat. Henry Loope is in the middle (Henry sent us 20,000 year old LGM wood from Indiana a few weeks ago). Tim Fisher (U.Toledo) in on the left. Jenn Horton (’13) is currently working with Tim as a grad. student.

As it turns out the coring this weekend of the Cedar Creek Mastodon site is timely with our discussion of Abrupt Climate Change and the Younger Dryas (YD). Tom Lowell (aka the core boss) from the University of Cincinnati has been a major player in refuting the hypothesis that the draining of Glacial Lake Agassiz triggered the YD. Saturday AM we will be coring with Tom and Monday we will be visiting Browns Lake Bog – where Tom cored with us this past winter (while an episode of the polar vortex was raging).

Wooster’s Climate Change class is starting the semester by  coring a bog adjacent to a recent Mastodon find in Morrow County, Ohio. The Mastodon work and related excavation is being led by Nigel Brush, University of Ashland.  Above is a photo (courtesy of Nigel Brush) of the original mastodon tooth find.

After a fairly extensive theoretical conceptualization – theory was successfully brought to practice and in some cases the probe was sunk over 20 feet into the soft mud of the bog. The 20+ feet of mud is a record of environmental change over the last ~15,000 years.

The lead probe team – one taking notes, one operating the GPS, one on the blunt end of the probe, and two others reflecting on the experience.

                     The survey team shares a humorous moment while setting up the total station.

Sharing another humorous moment as an interdisciplinary (Archaeology/Spanish/ Geology) tile probe team – note the Mastodon Excavation Site in the background.

The Google earth map above shows the tile probe points taken for the construction of the isopach map. The area of the tight spacing of data points in the northwest is the excavation site. Now for the contouring of the map and the determination of where the team will extract sediment cores.

Washing up and wondering about how the Mastodon may have met its fate along the shore of a muddy lake during the Pleistocene.

2013 was tied for the fourth warmest year since we have been keeping track of global temperatures over the last 150 years. This course is an exploration of climate basics, paleoclimatology and contemporary climate change. The lab and lecture are integrated and we are about to explore past climate changes, how the present climate works, and critically assess the ongoing warming.

Global warming and climate change will be the environmental issue to receive the most attention over this century. Understanding how and why climate changes is important for interpreting the past geologic record and evaluating contemporary climate change. After an overview of Earth’s ocean-atmosphere system and energy balance, we will explore Quaternary (last 2 million years) dating methods and techniques of reconstructing past climates through field and lab projects. Students will work with paleoclimate data sets from ocean cores, ice cores, tree-rings, lake cores and corals. Labs will include computer modeling, analysis of time series and field and lab projects extracting lake sediment cores and collecting and processing dendrochronological data.

Preparation questions: At each class I will handout should be answered for the following class. They are designed to guide the discussion for the next class AND I will occasionally collect them and they will count as one of your quizzes.

Text books: We will be having readings from a variety of texts and one required book EARTH’S CLIMATE PAST AND FUTURE by William Ruddiman. Additional readings will be handed out in class. Some readings throughout the class will be from THE GLACIAL WORLD ACCORDING TO WALLY and THE ROLE OF THE OCEAN IN CLIMATE YESTERDAY, TODAY , AND TOMORROW (available online and at the password protected readings tab)- written by Wally Broecker, a renowned climate scientist from Lamont-Doherty Earth Observatory.

Goals: Climate Change is a Q (quantitative) course thus students will need to generate, manipulate and interpret quantitative data, use geologic concepts to solve problems and understand and apply scientific methodology. This course is also field and lab intensive and so students will demonstrate their ability to apply Field/Laboratory skills, Map Interpretation/Geographical Information skills, and Information Technology skills. As we will be performing original studies of lake and tree-ring proxies in the Wooster region students will be need to demonstrate independence of thought and expression. The work in this class will demonstrate integrative thinking by problem solving through multiple approaches. Finally through writing reports and giving class presentations the students will develop their communication skills.

Specific Learning Goals are to deepen your understanding in and to think critically about:

– the fundamentals of the Earth’s climate and how biogeochemical cycles and ocean-atmosphere systems operate and interact.

– how the observational and proxy records of climate change are generated and analyzed.

– the role and significance of natural and anthropogenic (human-caused) forcings on climate and strategies that can mitigate the impact of climate change.

Below are posts from Climate Change 21010 – Last Year Class.

Review will be Sunday 11 Dec. in Scovel 116 at 9pm. Here is the review topics. Kit here is the Final Exam.

The 2011 Climate change class set out on an epic adventure to reconstruct the climate of the College of Wooster Campus. To take a closer look at the local climate 12 of the majestic oak trees were cored. After intense debate, with no help from our resident biologist or his geology and political science counterparts, the trees were determined to be white oak.

One team of corers, from left to right Stephen Perrott ‘13, Andy Nash ’14, and Ned Weakland ’12.

Two or three cores were taken from each tree 180 degrees apart using a 5 mm increment borer. The samples were taken at breast height. All cores were sealed into straws and transported back to the lab. A measurement of both the diameter of the trees and the height to the place the core was taken.

The cores were taken with a 5 mm increment borer. The tree core is then sealed into a straw. A GPS coordinate was taken for each tree. The diameter and height the core was take at was measured. All measurements and GPS points were recorded in ourfield books.

A map generated by Google Earth of the white oak trees that were sampled on campus.

Once back in the lab the cores were mounted and allowed to dry for 24 hours. The cores were then sanded to perfection and the width of each ring measured. The ring width measurements were then correlated together into a master chronology using the program COFECHA.

In the lab the cores were mounted, sanded and measured.

The master chronology was then standardized using the program ARSTAN and the Freidman Super Smoother with a flexibility of 5. The standardized chronology was then correlated with the local meteorological data, temperature and precipitation. The trees showed a strong negative correlation with temperature data and a strong positive correlation with precipitation data. The local precipitation for the months of May, June, and July were then reconstructed using 6 northeastern Ohio tree ring chronologies.

The Google Earth Map shows six tree ring chronologies across northeastern Ohio used to reconstruct climate data by correlating the chronologies against the closest meteorological data from the OARDC.

During precipitation reconstruction, we used six tree ring chronologies. The location, range, and the number of each of the six series from the master chronology are located in this figure.

A graph showing the explosive growth that the campus trees experienced upon the establishment of The College of Wooster in 1866. This was due to the thinning of the stand reducing the amount of competition between the trees for resources. The College of Wooster also maintains the trees improving their growth.

The standardization of the tree rings using the Friedman Super Smoother with a flexibility of 5 eliminates the signal of the establishment of The College of Wooster and allows for the reconstruction of the local climate using meteorological data from the OARDC.

Observed May, June, and July precipitation in comparison with the tree ring reconstruction. The relationship between these to systems correlate with an r value of 0.56.

The tree ring based reconstuction correlated with the meterological data for Northeastern Ohio.

r = 0.56

We would like to thank the contributors to this project, Beau Mastrine for granting us permission to sample the campus trees and Dr. Wiles for his input.

Late September of the year 2011, the leaves were only beginning don their autumnal coats.  The weather was crisp and clear, the last vestiges of summer still clinging to the liberal land of Higher Education.  Unbeknownst to the eleven students of Dr. Wiles climate change class they were about to embark on the journey of a semester.  The discoveries to come would change regional Ohio dendrochronology forEVER (maybe…), as well as the course of their very lives.  And it all began with Figure 1.Fig. 1 Tasteful pile of wood.

 

The Journey

Methods and Analyses:

Four series were measured from wood cross sections from Miller House. Four series were measured from each of four cross sections of wood — two Oak and two Ash. The cores were prepared and sanded; annual rings were counted, measured to the nearest 0.001 mm, and then cross-dated using standard dendrochronological techniques (Fig. 4). Multiple cores were measured from Miller House to determine annual ring correlation along differing cross sectional radii. All series from a site are then cross-dated against each other, developing a “floating” site chronology before cross-dating with the calendar dated Southwestern Ohio regional series. Cross-dating shows a strong correlation with a regional master chronology from Southwest Ohio.

Which series from which houses were successfully calendar dated? Which series provided true outer rings (which are important in determining the year of felling)?

The two cross sections of oak from the Miller House mantle were successfully cross-dated.  There was an overlap of 20 years between the oak sample containing the bark and the oak sample from the mantle.  Miller Farmhouse creates a 240 year chronology spanning the years 1573-1812 A.D. This data places the construction date for Miller Farmhouse around the year 1812.  The data from these structures is instrumental in expanding our knowledge of the chronology not only of Franklin, but also of the greater Southwestern Ohio region

The small core from the mantle of Miller Farmhouse has a full outer ring, however the small holes in the middle of the figure (Fig. 2) illustrate that the tree must have been on the verge of a non-growing season, since they’re new enough to not be filled in like the remainder of the porous areas on the wood.

Figure 2. Image of the outer rings of a large oak from the mantle of Miller House that was used for dating.

Figure 3.  Graph of Tree Ring widths versus years.  Ring widths vary based on environmental conditions like precipitation, soil nutrients, and sunlight.  The fluctuations within the graph reflect fluctuations in environmental conditions at the associated date.

Figure 4. Image that shows how tree wing widths from different trees and tree cores are correlated in order to build a tree ring chronology and date the wood.

This diagram illustrates the principles of cross-dating. Samples are taken from very old, living, and recently dead trees.  The ring-width patterns are then correlated and matched to long dead trees. Once enough cores are correlated, a chronology can be formed.

Our class trudged up the staircase with no railings, to a level with gaps in the floorboards here and there. A few of us ventured on a wobbly ladder all the way upstairs into the attic. Who knows how old this place is?

We now have a better idea. To date the house’s timber—we cored seven beams, using a drill and manual coring. Dr. Wiles sawed a block from one beam. We took these samples back to the lab and sanded away.

Here’s where Alex, Lauren, and I—the Sloane House group—come in. Peering under microscopes, we counted the number of rings each sample had. Our data on this ranged from about 50 to over 100. We measured the cores multiple times, under microscopes, with a program that recorded how far the sample moved. We counted from the year 1000. Sometimes, the lighter early wood and the darker late wood blurred together. Sometimes, the rings zigzagged and were not parallel. Sometimes, our measurements did not correlate.

We used the computer program COFECHA to crossdate the samples against each other and to develop a “floating” site chronology, which we calendar dated. This chronology was then crossdated with trees from The College of Wooster campus (thank you to that group) and the Northeastern Ohio database.

So when do we think the house was built?

Two of our samples have bark (SH02 and SH03), which means they show outer rings and the latest date the timber was cut. The calculated date for is 1851 for SH02 and 1852 for SH03. Our other dates are listed in the table below. What could this mean?