Climate Monday: Repeat Photography

April 15th, 2018

The semester is winding down, so we only have a few more of these climate visualization posts to go. Today, I want to highlight repeat photography. Taking a picture of the same place several or many years apart can be a striking demonstration of change and capture the imagination better than a sterile graph or abstract map.

The flashiest examples applying the idea to climate change come from productions like Chasing Ice by the Extreme Ice Survey or Chasing Coral by Exposure Labs. (Chasing Coral was recently featured here at the College of Wooster as part of the “Great Decisions” series.) The products can be truly fascinating, especially when many photographs are combined in a time lapse video.  For example, the video of the Extreme Ice Survey’s repeat photography of Mendenhall Glacier, embedded below, gives a better impression of glaciers as flowing masses of ice than any single photograph or model simulation.  It also shows the decline in mass at the toe of the glacier between May 2007 and August 2011.

Rules of Climate Change Repeat Photography

Showing climate change with repeat photography requires a few special considerations:

First, you need to have not only the same location, but the same angle for your shot, showing the same context around the feature of interest in each and every photograph being compared.  This is why the Extreme Ice Survey set automated stations with the cameras well-mounted rather than using hand-held cameras.  Much of the Chasing Ice documentary is about building and installing the equipment necessary to achieve this fundamental “rule” of repeat photography. The Chasing Coral team tried similar techniques, only with the added complication of being under water.  Needless to say, it was harder for the Chasing Coral team.

Second, any repeat photography of environmental phenomena had better avoid making natural seasonal cycles look like climate change.  The two pictures of Sub Lake in Rocky Mountain National Park above were taken in June 2015 and January 2013.  The difference between the two isn’t climate change; it’s winter. Another example: The Mendenhall Glacier video shown above is labeled as “May 2007 to August 2011”.  A red outline of the glacier in the first frame is compared to the outline of the glacier in the final frame, and that’s a little deceptive.  Just like snow cover and sea ice, the Menhendall Glacier has a greater extent and thickness at the end of winter than the end of summer — especially at the toe. So part of that difference you’re seeing is just the fact that a) over 80 inches of snow typically fall on the toe of the Mendenhall from October to March and b) the average high temperature is over 60°F in June, July and August in southeast Alaska.  It’s likely to look more robust in May than August, so the time lapse would be better starting and ending in the same month.

Image result

Cherry blossoms in Washington, D.C. (from the National Park Service)

Third, climate change is not the only factor that determines whether one year is cooler or warmer or wetter or drier than the last.  Climate change is not the only factor that determines whether coral bleaching will occur or whether a glacier will retreat.  For example, in Chasing Coral, a coral bleaching event in Australia is highlighted and attributed to climate change.  At the same time, though, an El Niño event was occurring. El Niño is a natural part of the climate system, but it can also lead to warming and coral bleaching. Was global warming a factor in this bleaching event? Absolutely, but the devastation depicted in Chasing Coral may have been less overwhelming in a La Niña or normal year. As another example, if you were trying to take pictures in Washington DC to show how the date of cherry trees blooming was coming earlier each year, you might be disappointed.   Although blooming is now occurring on average about a week earlier than in the 1970s, peak bloom was actually slightly later than average this year. The best way to get around this issue is to have several decades between the start and end of the repeat photography pair or sequence.

The Repeat Photography Project at Glacier National Park

With all these rules in mind, the United States Geological Survey (USGS) is currently undertaking a repeat photography project for the failing glaciers of Glacier National Park. They’re also soliciting help from visitors in a crowd-sourcing effort. The time spans exceed 50 or even 100 years for these photos, which is enough time to see some truly remarkable changes to Glacier National Park’s namesakes. It’s even long enough to avoid the seasonal issues discussed above. As an example of the output, below is repeat photography of Boulder Glacier (1932 to 2005) from the Northern Rocky Mountain Science Center (NOROCK).

Boulder Glacier - 1932 Boulder Glacier - 2005 color

 

Climate Monday: Climate Change Hot Spots

April 2nd, 2018

It’s no secret that global warming does not simply mean more warm days and fewer cold ones. Warming is uneven, with some regions (like the Arctic) warming faster than others. Additionally, warming of the atmosphere and oceans has a cascading effect on other parts of the Earth system, from the amount of ice stored in Greenland to the variability of global wind patterns, to the extent of various habitats. The world is complex, and it the impacts of climate change myriad. With so many changes happening, what places or changes should humans focus adaptation and mitigation efforts? Enter the concept of “climate change hot spots”. Let’s examine three frameworks and how they’re visualized.

Example #1: One of the simplest frameworks for talking about climate change hot spots is to consider places where various physical aspects of the climate are projected to change the most (Kerr 2008). This was the tactic used by a group of climate modelers from the National Center for Atmospheric Research back in 2008.  They ran detailed, regional-scale climate models into the future and looked for a) places with the most change in average temperature and precipitation, and b) places with the most change in the variability of temperature and precipitation (in other words, heat waves, cold snaps, floods, and droughts).  The result was a relative index from low change to high change:

Figure 1: Map of the “relative responsiveness” of the USA and northern Mexico to climate change based on projected changes in temperature and precipitation under a suite of climate models. (Kerr 2008)

The nice thing about this measure is that it’s objective and gives a value of overall impact for everywhere in the lower 48.  It’s limited in it’s utility, though.  For one thing, it only measures temperature and precipitation, omitting related concepts like sea level rise and wildfire frequency/intensity.  It also is a projection of the future, which is problematic both because there’s less certainty about the future and because there are changes already happening that might be more pressing to address.

Example #2: That in mind, another way to define “climate hot spot” is a location that has already changed substantially. The Union of Concerned Scientists (2011) has compiled a map of locations that have “well-documented” changes already occurring. Here’s a snapshot, but the visualization is meant to be an interactive map, not a static image, which is certainly inviting.  The “well-documented” claim is supported by reference lists and descriptions for each event. In other words, these have been researched substantially.  Another interesting point is that the map shows a much broader view of “climate change” than the earlier climate model studies.  Sure, there’s “extreme wet” and “air temperature”, but there’s also “ecosystem” sections and “health” and “food” for people. This is definitely better suited for a broader audience and broader concerns.

Figure 2: Snapshot example of climate hot spots by the Union of Concerned Scientists (2011).

Still, the above example may seem lacking with regard to two elements (and maybe others): First, it is clearly focused on the USA.  There is a data bias, of course — the Union of Concerned Scientists has many American scientists, and many of them study the USA. But it may give the false impression that the USA has more dire situations than the rest of the world.  Second, there is still little sense of risk versus vulnerability.

If we think of climate change as a natural hazard, just like a volcanic eruption or an earthquake or a hurricane, we can talk about both risk and vulnerability of populations.  For example, both the Netherlands and Florida are at great risk of sea level rise, but the Dutch are bettered prepared to adapt to rising seas because of past experience and current cultural, political, and physical infrastructure. The same risk can lead to more or less hardship depending on how vulnerable a place is — and assuming sea level rises about the same in both locations, Florida is likely to have more hardship from sea level rise than the Netherlands.

Example #3: This added concept of vulnerability is used to define “climate hot spots” in yet another way: as locations where “strong physical and ecological effects of climate change come together with large numbers of vulnerable and poor people and communities” (Neumann and Szabo 2016). Their map is still really a measure of risk, not vulnerability, but they use it to help highlight areas with high risk that also have special vulnerability (originally identified by De Souza et al. 2015):

  1. Deltas in Africa and South Asia that have large populations of poorer people. Groundwater extraction and other human activities that make deltas sink can exacerbate the effects of sea level rise.
  2. Semi-arid regions in parts of Africa, South Asia, and Central Asia that may become drier. Again, the lower economic resources in these regions make them more vulnerable.
  3. River basins dependent on glaciers and snowpacks as a water source, especially in the Himalaya, where there are large populations of poorer people.

Figure 3: Climate risks based on three factors: snow-dependence, semi-arid climate, and river deltas. (Neumann and Szabo 2016).

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Works Cited

De Souza, K., Kituyi, E., Harvey, B. et al.  (2015). Vulnerability to climate change in three hot spots in Africa and Asia: key issues for policy-relevant adaptation and resilience-building research. Reg Environ Change, 15: 747. https://doi.org/10.1007/s10113-015-0755-8

Kerr, R. (2008). Climate Change Hot Spots Mapped Across the United States. Science, 31: 909. http://science.sciencemag.org/content/sci/321/5891/909.full.pdf

Neumann, B. and Szabo, S. (2016). Climate change ‘hotspots’: why they matter and why we should invest in them. The Conversation. Accessed 2 Apr 2018. http://theconversation.com/climate-change-hotspots-why-they-matter-and-why-we-should-invest-in-them-68770

Union of Concerned Scientists (2011). Climate Hot Map. Accessed 2 Apr 2018. http://www.climatehotmap.org

Wooster Geology at AGU 2017

December 18th, 2017

The Mississippi River in New Orleans, Louisiana. Photo: Dr. Karen Alley

Three Wooster Geologists (Dr. Karen Alley, Dr. Alex Crawford, and senior Geology major Cole Jimerson) descended on New Orleans last week to attend the Fall Meeting of the American Geophysical Union. With 20 to 25 thousand attendees each year, this is the largest Earth and space science meeting in the world.

On Wednesday, Dr. Crawford gave a talk about his research in seasonal sea ice prediction. As the Arctic continues to warm, seasonal sea ice melt is occurring progressively earlier each year. Although almost unheard of 20 years ago, commercial shipping along the Russian coastline (the “Northern Sea Route”) is now a routine summer operation. However, the seasonal timing of when the sea ice melts enough for normal shipping is highly variable from year to year. Dr. Crawford and his collaborators are investigating various ways of improving our ability to predict that variability. Better predictions can aid shipping companies in planning their summer routes.

The Northern Sea Route through the Arctic Ocean and the “last retreat day” (LRD), which means the last day of the year on which sea ice concentration is above 50% (left) or 15% (right). Adapted from Stroeve, Crawford, & Stammerjohn (2016); 10.1002/(ISSN)1944-8007.

On Thursday, Dr. Alley gave an invited talk about a new data product she and her collaborators have developed for researchers studying the Antarctic ice sheet. Using ice velocity derived from satellites and sophisticated mathematics and computer coding, they calculated strain rates for Antarctica’s ice sheet and ice shelves. These strain rates are a measure of how fast the ice deforms by stretching and compressing as it moves. They are a fundamental parameter to know for anybody trying to understand how Antarctica’s ice is responding to climate change.

Strain rates on the Filchner Ice Shelf, Antarctica. From Dr. Karen Alley.

Finally, Cole Jimerson presented a poster on Friday overviewing some of the research he and other students performed through a Keck Geology project concerning erosion rates on the Caribbean Island of Dominica. Dominica is a volcanic island prone to explosive ash eruptions. Many of the rocks and sediments on the island are quickly eroded by rivers and chemical weathering in the hot, wet tropical climate. These and other factors lead to landslide risks, and better understanding erosion rates can improve hazard mitigation strategies.

Cole Jimerson presents his poster at the Fall Meeting of the American Geophysical Union.

Wooster’s Fossils of the Week: Sponge and clam borings that revealed an ancient climate event (Upper Pleistocene of The Bahamas)

April 28th, 2017

This week’s fossils celebrate the publication today of a paper in Nature Geoscience that has been 20 years in the making. The title is: “Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas coral”, and the senior author is the geochronological wizard Bill Thompson (Woods Hole Oceanographic Institution). The junior authors are my Smith College geologist friends Al Curran and Brian White and me.

The paper’s thesis is best told with an explanation of this 2006 image:
This photograph was taken on the island of Great Inagua along the coast. The flat dark surface in the foreground is the top of a fossil coral reef (“Reef I”) formed during the Last Interglacial (LIG) about 123,000 years ago. It was eroded down to this flat surface when sea-level dropped, exposing the reef to waves and eventually terrestrial weathering. The student sitting on this surface is Emily Ann Griffin (’07), one of three I.S. students who helped with parts of this project. (The others were Allison Cornett (’00) and Ann Steward (’07).) Behind Emily Ann is a coral accumulation of a reef (“Reef II”) that grew on the eroded surface after sea-level rose again about 119,000 years ago. These two reefs show, then, that sea-level dropped for about 4000 years, eroding the first reef, and then rose again to its previous level, allowing the second reef to grow. (You can see an unlabeled version of the photograph here.) The photograph at the top of this post is a small version of the same surface.

The significance of this set of reefs is that the erosion surface separating them can be seen throughout the world as evidence of a rapid global sea-level event during the Last Interglacial. Because the LIG had warm climatic conditions similar to what we will likely experience in the near future, it is crucial to know how something as important as sea-level may respond. The only way sea-level can fluctuate like this is if glacial ice volume changes, meaning there must have been an interval of global cooling (producing greater glacial ice volume) that lowered sea-level about 123,000 years ago, and then global warming (melting the ice) that raised it again within 4000 years. As we write in the paper, “This is of great scientific and societal interest because the LIG has often been cited as an analogue for future sea-level change. Estimates of LIG sea-level change, which took place in a world warmer than that of today, are crucial for estimates of future rates of rise under IPCC warming scenarios.” With our evidence we can show a magnitude and timing of an ancient sea-level fluctuation due to climate change.

Much of the paper concerns the dating techniques and issues (which is why Bill Thompson, the essential geochronologist, is the primary author). It is the dating of the corals that makes the story globally useful and significant. Here, though, I want to tell how the surface was discovered in the first place. It is a paleontological tale.

In the summer of 1991 I worked with Al Curran and Brian White on San Salvador Island in The Bahamas. They were concentrating on watery tasks that involved scuba diving, boats and the like, while I stayed on dry land (my preferred environment by far). I explored a famous fossil coral exposure called the Cockburntown Reef (Upper Pleistocene, Eemian) that Brian and Al had carefully mapped out over the past decade. The Bahamian government had recently authorized a new harbor on that part of the coastline and a large section of the fossil reef was dynamited away. The Cockburntown Reef now had a very fresh exposure in the new excavation quite different from the blackened part of the old reef we were used to. Immediately visible was a horizontal surface running through the reef marked by large clam borings called Gastrochaenolites (see below) and small borings (Entobia) made by clionaid sponges (see the image at the top of this post).
Inside the borings were long narrow bivalve shells belonging to the species Coralliophaga coralliophaga (which means “coral eater”; see below) and remnants of an ancient terrestrial soil (a paleosol). This surface was clearly a wave-cut platform later buried under a tropical soil.


My colleagues and I could trace this surface into the old, undynamited part of the Cockburntown Reef, then to other Eemian reefs on San Salvador, and then to other Bahamian islands like Great Inagua in the far south. Eventually this proved to be a global erosion surface described or at least mentioned in many papers, but its significance as an indicator of rapid eustatic sea-level fall and rise was heretofore unrecognized. Finally getting uranium-thorium radioactive dates on the corals above and below the erosion surface placed this surface in a time framework and ultimately as part of the history of global climate change.

This project began 25 years ago with the discovery of small holes left in an eroded surface by humble sponges and clams. Another example of the practical value of paleontology.

References:

Thompson, W.G., Curran, H.A., Wilson, M.A. and White, B. 2011. Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas coral. Nature Geoscience (DOI: 10.1038/NGEO1253).

White, B.H., Curran, H.A. and Wilson, M.A. 1998. Bahamian coral reefs yield evidence of a brief sea-level lowstand during the last interglacial. Carbonates and Evaporites 13: 10-22.

Wilson, M.A., Curran, H.A. and White, B. 1998. Paleontological evidence of a brief global sea-level event during the last interglacial. Lethaia 31: 241-250.

[Originally posted September 11, 2011. Some updates and editing.]

Wooster Geologists participate in the historic March For Science on Earth Day, 2017

April 22nd, 2017

Wooster, Ohio — It was a chilly day downtown, but several hundred people gathered for the national March For Science. We were one of over 500 local events across the country advocating for science awareness, education and funding. Thank you very much for retired Wooster Professor of Biology Lyn Loveless for organizing such a complex meeting with speakers and break-out discussions in local businesses. It was a great success. Above are some of the signs held by children in attendance. Several Wooster Geologists were in the diverse crowd, and some participated directly.

One view of the attendees. We all see the distinctive profile of Dr. Wiles in the foreground. Kelli Baxstrom may recognize someone on the far right!

One of the speakers was ace Wooster physicist and former dean Dr. Shila Garg. Note her coat on this mid-April day.

I include this photo (taken by Wooster political scientist Matt Krain) of Dr. Wiles and me to show my Paleontological Society colleagues that I wore The Shirt, even if no one noticed under the jacket.

One of the break-out sessions was on climate change. Greg Wiles and Clara Deck (’17) did great outreach work explaining their research to the large gathering. Wooster’s paleoclimate and climate change research and education is making a difference. Visit the Tree-Ring Lab website to see more details about the operation.

It was an inspiring afternoon, especially seeing the many young scientists and scientists-to-be who participated. Of course, for someone my age it is astonishing that we have to advocate for something so self-evidently beneficial as science, but such are our times.

Wooster Geologist at Argonne National Laboratory

July 16th, 2016

ANL_PMS_P_HEditor’s note: The following post is from guest blogger Clara Deck (’17) about her research experience this summer with an internship at one of the world’s most prominent laboratories. She is working on an important climate change project involving the carbon budget of permafrost. Last summer Clara completed a dendrochronology climate project in Wooster with Dr. Greg Wiles.

This summer I am working as a research intern at Argonne National Laboratory in Illinois as part of the ten week Student Undergraduate Laboratory Internship (SULI) program. The laboratory occupies 1500 acres located just north of Chicago and is a Department of Energy (DOE) facility. I have the privilege of joining Dr. Julie Jastrow and her terrestrial ecology research team on a project focused on organic carbon stocks in permafrost across Alaska. Soils serve as the largest terrestrial carbon reservoir, containing more than two times the amount of carbon found in the atmosphere.
Image 2About 25% of land mass in the northern hemisphere is dominated by permafrost soils. The long term goal of this project is to improve estimates of the total quantity of C contained in permafrost, as findings to-date are immensely variable. This is important because soil carbon will be affected by environmental change, especially in high latitude regions.

(Canadian Soil Information Service)

(Canadian Soil Information Service)

Field sampling targets features known as ice wedge polygons, which form similarly to mud cracks, but then fill with ice. The soil within these polygons is characterized by substantial cryoturbation, or mixing, due to freeze-thaw processes.

(Julie Jastrow, Argonne National Laboratory)

(Julie Jastrow, Argonne National Laboratory)

A trench like this is dug across a polygon, in order to sample from each distinguishable layer across an entire transect. This summer, I am performing fractionation procedures on these samples, which means separating the soil into different size components. The fractions will then be analyzed for carbon content.  I will then use GIMP Image Manipulation Software to convey C density data in a cross sectional image of the polygon.

(J.D. Jastrow (Argonne National Laboratory) and C.L. Ping (University of Alaska Fairbanks), unpublished data)

(J.D. Jastrow (Argonne National Laboratory) and C.L. Ping (University of Alaska Fairbanks), unpublished data)

(IJ.D. Jastrow (Argonne National Laboratory) and C.L. Ping (University of Alaska Fairbanks), unpublished data)

(IJ.D. Jastrow (Argonne National Laboratory) and C.L. Ping (University of Alaska Fairbanks), unpublished data)

These diagrams illustrate the progression from a field sketch to a digital image showing C density in a polygon cross section. Ice wedge polygons adhere to large scale patterns across the landscape, so data from each polygon has upscaling potential for larger models. Further studies will include analysis of the carbon decomposability and the depth to which permafrost will thaw with predicted temperature rise.

I am excited to be at Argonne conducting research so closely related to modern climate change, and will be continuing these studies throughout the year for my Senior Independent Study. Thanks for reading!

What we learned in Climate Change (Geology 210, Spring 2016)

May 31st, 2016

boulder

A dedicated group of geologists, physicists, archaeologists, political scientists, biologists, english and history majors joined forces to learn a bit about Climate Change in the natural laboratory of Northeast Ohio. Here they surround a glacial erratic in Secrest Arboretum of the OARDC – where The Ohio State University and the National Weather Service has meteorological records extending back to the late 1800s CE. The Arboretum also has an extensive collection of stands of trees from around the world that are used in our climate studies below (special thanks to Joe Cochran (OSU) for permission to work at Secrest).

The first project: the glacial transition in a sediment core from  Browns Lake Bog

rundown

Dr. Thomas Lowell gives the rundown at Browns Lake Bog – Tom is a professor at the University of Cincinnati and long-time collaborator and the core boss.

lab

Initial description of the 5 meter core – we obtained two radiocarbon ages, measured magnetic susceptibility, loss on ignition, in addition to core description and sediment analyses.

The Upshot of the Lake Work – The two ages were chosen at transitions in the character of the peat and mineral matter – we identified a major shift at the time of the Bolling – Allerod warming and at the cooling of the Younger Dryas.  The abrupt climate changes (ACCs) and discussion of how the world moves from the Pleistocene to the Holocene is brought home to Ohio in this core (Figure below). It is exciting to explore how these ACCs affected NE-Ohio’s ecosystems and physical landscapes.

master_bog

Project 2: Tree Ring Dating of the Biggio Barn

rundown

The barn owner gives the rundown on the history and possible ages of the hand hewn timber frame. The dating of the barn project introduced the class to the science of tree-rings.

vincent

Hong Kong dendrochronologist, Vincent shows the class how by standing on two milk crates he cores a beam – the instructor adds a stabilizing foot to Vincent’s precarious sampling strategy.

The upshot of Barn Dating: Ten of the beams from the Biggio Barn were cut in the spring of 1840 CE. The building then was likely constructed shortly after that cut date.  A copy of the report to the owner from the class can be found here. The ring-width data obtained in this study are used in drought studies below. The Wooster Tree Ring lab has dated over 60 barns and houses in Ohio and PA (this video describes the process and some of the science).

Project 3a: Extracting a Temperature Proxy Record from Larch in Kamchatka
Vincent Hui, Abbey Martin, Sarah McGrath, Matthew Shearer, Ann Wilkinson

The purpose of this study was to analyze Kamchatka larch (Larix cajandery Mayr.) tree ring widths from Fareast, Russia. The team standardized the chronology using two methods, (1)  negative exponential, and (2) regional curve standardization (RCS), and they then compared how the standardization technique influenced correlations. Both standardized series were correlated with meteorological records showing high positive correlations for summer temperatures. The RCS showed stronger correlations and was used for NTREND comparison, temperature reconstruction, and spectral analysis. Together these correlations and comparisons showed the larch primarily responds to summer temperature and can be used to reconstruct summer temperatures.

kamchatka

The Kamchatka team of researchers (without Vincent) who did the study. They are posing at Wooster Memorial Park where a recent planting of 700 trees and prairie will sequester more carbon in the future than the previous agricultural land use at the site.

Figure2

ntrendConclusions: 
1 – The Kamchatka larch tree-ring widths are most sensitive to summer (May through September) temperatures.

2 – The team recommends the region curve standardization method) RCS method for standardization with a sample size of 190 series.

3 – The RCS series showed similar trends as the NTREND series, suggesting the Kamchatka site follows the same trends as much of the northern hemisphere.

4 – Ring-widths show a general increase in temperature over the last 350 years for the interior of Kamchatka. This is unprecedented over the past 300 years and is consistent with other proxies such as glaciers.

Project 3b: Past climate inferences using data from Johnson Woods
 Sharron Osterman, Annette Hilton, Cameron Steckbeck, Gina Malfatti, Amineh AlBashair

  • tst
  • The Johnson Woods team assembled a newly compiled data set originally sampled in 1985 by Dr. Ed Cook (LDEO), by the Wooster Tree Ring Lab in 2003 and most recently updated by Dr. Justin Maxwell (Indiana State University). They found there was a marked release in the tree ring record across northern Ohio about the time of European Settlement in the region. This may be in part due to the disturbance in the record, however it could also persist due to the positive response that tree growth has to summer precipitation.
  • Slide2
  • Slide1Above is a histogram showing the correlations of the Johnson Woods ring-width series and monthly precipitation and temperature records from the OARDC spanning 1880 to 2014 CE. The trees are a record of summer precipitation (positive correlation) and favor wet summers. These trees are negatively correlated with high summer temperatures.

One Question on the final exam:
What is the Climate response of European Larch to climate of Ohio – Secrest Arboretum (and why might this exploration be relevant?).

  • coring1

Obtaining high quality cores for ring-width chronologies from European Larch at Secrest Arboretum.

coring2

 The upshot here is the ring-width chronology below. The class worked on this as part of the final exam and found that similar to the oaks in the region, the European Larch is sensitive to summer precipitation and is stressed by high summer temperatures. The tailing off of the ring-widths during recent decades could be the result of warmer summer temperatures – a hypothesis that needs testing. The relevance of this study is that as climate changes in the high latitudes of Europe and Asia, where these larch dominate – it may be the case, that warming may stress the species leading to decreases in bioproductivity – these ideas need further work to test if this is a viable hypothesis.

Plot 1

jw

A day in Johnson Woods – the full class in the rain.

jw

danWe also learned that Dan Misinay (’16) is a pretty fair teaching assistant.

milling

The class wanders around the gas power plant on the Wooster campus – three years ago the college transitioned from coal burning to natural gas – the carbon dioxide emissions on campus have been cut in half. However, now the College buys its power for cooling (air conditioning) off campus from the grid, where much of the electricity is powered by coal, but with a growing portfolio of clean energy sources (special thanks to Lanny Whitaker who showed us the plant and explained where our energy comes from – thank you). We also thank Nick Wiesenberg (our able Geology Technician) for his knowledge of trees, barn dating and general troubleshooting,  Tom Lowell and his students for the high quality sediment cores, our TA Dan and a host of tree-ring scientists who contributed data to our efforts in this course. Special thanks too – to the Secrest Arboretum. A portion of the Kamchatka tree-ring record was supported by NSF- AGS – 1202218.

Last Fieldtrip for Climate Change

November 13th, 2014

GROUP

As the weather cools – the Wooster Geology Climate Change class ventured out in the field one more time. For the remainder of the semester we will try to get some work done. Two sites were visited – the Cedar Creek Mastodon Site and the OARDC.

excavationTwo weeks ago a pit was dug from our coring sites to the Mastodon excavation site. The mission was to link the cores to the archaeological site.

pit

The general stratigraphy of the mastodon site. The muds have a high calcium carbonate content that helped preserve the bones and tusk. Note the plow horizon about 25 cm down – the trip also focused on the agricultural history of Ohio and the role it plays in climate change.

anomalyJeff Dilyard, who hosted us at the site, explains to the class that a GPR (ground penetrating radar) survey identified an anomaly at this location. Isabel probed the area (see below) and “clunked” on a tile.

probingIsabel above used a tile probe to investigate the subsurface (note the chin method she is employing).

tileWhat is a “tile”? above is an old drainage tile from the site. This one is plugged with mud and the plugging was the reason the mastodon was discovered. New tiles were installed last year and the digging brought up the original tooth of the mastodon. Tile and draining of the Midwest allowed for our great agricultural history. In addition, the tile and draining allowed widespread plowing that released the carbon in naturally sequestered organic rich wetland soils to the atmosphere.

in_pitThe crucial end of the backhoe pit where probing and sampling links the bog cores to the mastodon site.

group_no_till

A quick stop ate the Triplett-Van Doren Experimental Plot. For over 50 years a variety of experiments have been underway here. We discussed the side-by-side no-till and mold board plowed sites and their ability to sequester carbon. Not plowing (no-till) sequesters carbon and mitigates erosion. Less carbon dioxide to the atmosphere and less sediment flux on the landscape.

no_till

A darker colored soil in the core barrel above shows more carbon in the soil relative to the one below.

DR

A quick stop at Secrest Arboretum to view the famous Dawn Redwoods. Under the proper conditions these trees can grow a meter each year. Our tree-ring data from this stand helps define the optimum conditions for their growth. Planting trees sequesters carbon and helps out in lots of other ways as well.

weather

In addition to the no-till fields and trees at Secrest – there is a meteorological record that spans more than 120 years (note how Tom – far left, seems to be the only student listening to the instructor). These instruments have been keeping track of climate and we will use it to compare with our tree ring study. Our tree ring project asks the question: during the time of European Settlement in Ohio what were the climate conditions like? (precipitation and temperature) and could the widespread deforestation and tile and draining of the region have perturbed the climate (see this video for more on this subject). This question is relevant to the ever-present striving of climate scientists to investigate the relative roles of natural climate variability and anthropogenic change.

 

 

 

 

Wooster Geologists return to the Cedar Creek Bog and Excavation Site

October 25th, 2014

DigOverview102514WOOSTER, OHIO–Greg Wiles and I got to experience a bit of field archaeology today at the Cedar Creek Mastodon excavation site. Greg’s Climate change class has visited the site and its associated bog twice this semester: once to do some soil probing and exploration, and then again to extract a core from the bog. This time Greg and I went to consult with the chief archaeologist of the site, Nigel Brush of Ashland University. Nigel wanted our opinions on the stratigraphy of the dig, especially those parts associated with mastodon remains and flint artifacts. The hypothesis the archaeologists are testing is that the mastodon bones and flint blades are part of an ancient butchery site.  It was a joy to join our friends on this fantastic Fall day.

BonesFlagged102514Who doesn’t love an archaeology site? All that enthusiastic hard work with brushes, spades and trowels revealing hidden treasures. Those little orange flags above are tagging bits of mastodon bone that the volunteer excavators have uncovered for mapping and collection. Several schools are represented at this site, and at least a couple dozen citizen scientists.

HannahJim102514Wooster is represented at the dig by archaeology professor Nick Kardulias, along with two of his students shown above. Hannah Matulek is on the left; Jim Torpy on the right.

BoneFragment102514Here is some mastodon bone embedded in one of the excavation walls. The bones are scattered, with some large pieces and many small fragments.

Sieving102514This is the line of sieves for sorting through the excavated sediment. Pleasant enough work today, but I can imagine it’s not so fun in the rain and sleet.

GregSoilProbing102514And now for our bit of work. Greg went off into the bog with a soil probe to plan out a new trench to be dug by the landowner. This trench will help correlate the strata in the excavation with what Greg and his students have cored from the bog.

StratView102514I spent most of my time in the excavations examining the simple layering of the sediments. At the bottom we have a coarse conglomerate with cobble-sized rounded grains. The bones and artifacts lie on top of and among these clasts. Above that unit is a matrix-supported conglomeratic mud with broken rock fragments. At the top is a loam representing the disturbed (plowed) part of the section.

MudWithClasts102514This is a closer view of that middle unit with the “floating” angular rock fragments. My quick assessment (just a suggestion!) is that the coarse gravels beneath are part of a deltaic complex feeding into the bog, which was at the time a marl lake. The mud-with-clasts above it is a debris flow from the surrounding elevations that cascaded down the creek channel and its banks, entombing the bones and artifacts under a slurry of muddy debris. There is scattered charcoal throughout this unit and the top of the cobbles below. Maybe a forest fire denuded the upstream slopes and led to a rain-soaked mudslide? Then again, the charcoal could have come from an ancient barbecue of the mastodon meat.

In any case, Greg and I had a great time visiting our archaeological colleagues on such a fine day.

 

Dating Houses and Reconstructing Climate

September 22nd, 2014

porchThe Wooster Geology Climate Change class spent a beautiful fall day in Stony Creek, Ohio coring beams in three structures of historical significance. They will determine the cut dates (calendar dates when the timber for the houses were felled) for the homeowners and then examine the tree-ring data that results to help reconstruct drought for the region. The class will write a report for the homeowner as part of the project. The Wooster tree-ring lab has dated over 50 buildings. Many of the reports are archived here.

willy2

Willy coring a hand hewn beam with an increment borer in the basement of one of the structures.

dan

Dan cores into the white oak beam as Meredith keeps the utilities at bay.

 julia

Julia identifies the outer (bark year) rings of a large oak beam and sets the spoon to extract the core.

haloMeredith and Haley team up to extract another core from a structure.

mounting2Zach shows how the 5 mm core is mounted in a slotted core mount.

coreSarah glues the carefully oriented core into the mount.

mounting

Orienting the core properly is crucial for the next step of sanding the surface. This interdisciplinary group of historians, archaeologists, communication studies and geologists will learn bit about history of Ohio while learning some of the statistics of climate change and earning a Q (quantitative) course credit.

houseThe group should be able to determine when the timber was cut to build this restored structure. Sometime in early November the analyses should be completed.

extra_coringSome extracurricular coring of young white pines in the area.

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