Investigating Paleoclimate: Understanding Global Climate Change by Investigating the End Triassic Mass Extinction?
Summary
As climate continues to change due to anthropogenic releases of greenhouse gases, it is important to understand how future greenhouse gas emissions will impact ecosystems and global climate. Quantification of the impacts of rapid climate change due to greenhouse gas emissions during the Mesozoic Era can be directly applied to emission levels being predicted in the future. Herein we describe a paleoclimate lab developed by the Suarez Research Group at the University of Arkansas, which is an in-person lab, virtual field trip and virtual lab session. Embedded within the virtual field trip and lab are a series of videos that introduces students to the field of paleoclimatology and the study of Earth's climate in deep time (greater than 2.5 million years ago) and guides them to use many of the same tools and strategies used by paleoclimatologists. Students are introduced to foundational concepts and methods of paleoclimatology with a strong emphasis on isotope geochemistry (Video 1: General Introduction to Paleoclimatology), are guided to collect and generate authentic isotope data (Virtual Field Trip) and learn how these data can be used to quantitatively infer paleoclimate (Video 2: Applications of Paleoclimate Proxy Data). Using generated data (isotope data from the rock and fossil record of the Newark Basin, USA), students use carbon isotopes to calculate atmospheric carbon dioxide concentration (pCO2) levels before, during and after the end-Triassic mass extinction (ETE) (Lab).
Learning Goals
Our primary motivation in designing this lab was to introduce students to the field of paleoclimatology, how paleoclimate scientists collect data, and how they interpret that data. The lab will address all three dimensions of the Next Generation Science Standards adopted by many states and developed by the National Research Council, National Science Teachers and Association, and the American Association for the Advancement of Science. These dimensions include 1) cross-cutting concepts, 2) science and engineering practices, and 3) disciplinary core ideas.
Cross-Cutting Concepts: Cause and Effect, System and System Models, Stability and Change, Influence of Engineering, Technology, and Science on Society and the Natural World
Science and Engineering Practices: Planning and Carrying out Investigations, Analyzing and Interpreting Data, Using Mathematics and Computational Thinking,
Developing and Using Models, Obtaining, Evaluating, and Communicating Information
Disciplinary Core Ideas:
PS1A: Structure and Properties of Matter
PS1B: Chemical reactions
ESS1C: The History of Planet Earth
ESS2B: Plate tectonics and Large-scale systems
ESS2E: Biogeology
ESS3D: Global Climate Change
Context for Use
The focus of this curriculum on paleoclimate change was intended to make content relevant to students, attracting students to the geosciences and improving their perception of the geosciences as a field of study. Engaging students with relevant content is a high-impact educational practice with several documented effects, including increased appeal to underrepresented groups within the geosciences and increases in self-motivation, self-efficacy, and learning, which is also a good predictor of student success. The teaching unit developed here is designed to introduce students to how scientists reconstruct climate in deep-time using basic concepts of stable isotope geochemistry and its utility to paleoclimate interpretations in advanced high school science classes, undergraduate and graduate geoscience/earth science/environmental science courses using a virtual field and lab experience in a classroom exercise. Paleoclimatology focuses on the causes of climate change in deeper time to better understand our present and future climate using proxy records. Stable isotope geochemistry is a powerful proxy for paleoclimate reconstruction and is often taught at the undergraduate level either as a distinct course or within courses in hydrology, paleoclimatology, and geochemistry using traditional light stable isotopes. Students at a range of levels can complete the exercise. The manipulation of the output data can be modified for advanced middle-school to high-school level students by providing an Excel or Google Sheet that has equations pre-programmed into the sheet. Alternatively, advanced high school to college level students can be expected or taught to create these sheets themselves by providing instruction within the lecture associated with the lesson.
Our target group is advanced 9 – 12 graders as well as undergraduate and graduate students. This teaching unit was tested on a group of advanced high schoolers as well as undergraduate students.
After completing the resources provided, students should be able to:
- Describe the science of paleoclimatology and why it is important
- Describe what isotope geochemists do in terms of fieldwork and analysis
- Collect and generate data, observe trends, produce graphs, interpret them, and compare datasets
- Explain how the analysis of scientific data leads to a deeper understanding of the challenges we face as a society and can be used to help guide policy and decision-making
Description and Teaching Materials
This learning module utilizes published pedogenic carbonate data from the paleosol-bearing, latest Triassic – earliest Jurassic, Newark Basin, eastern United States. Carbon isotope analysis of these nodules is used to generate quantitative estimates for atmospheric carbon dioxide concentration (pCO2), which provide additional evidence of carbon-cycle perturbations due to Central Atlantic Magmatic Province (CAMP) volcanism. The CAMP is one of the most voluminous and aerially extensive Phanerozoic large igneous provinces. The emplacement of CAMP was the result of rifting of the supercontinent Pangea and caused major perturbations within the global carbon cycle, which led to major changes in global climate such as increased global temperatures, ocean anoxia, and increased greenhouse-gas emissions and ultimately caused the end-Triassic Mass Extinction.
The central focus of the exercise is the reproduction of a key graph published by Schaller et al. (2013) that demonstrates the onset of CAMP volcanism in the carbon record and how pCO2 changed through time pre- and post-CAMP volcanism. This exercise was created to provide important context to students about how materials for paleoclimate research are collected, processed, and analyzed. In the form of a virtual field trip hosted through Gather Town, students take part in an expedition to the badlands of Arizona and Utah from the comfort of their classroom. The virtual fieldtrip is accessed using a URL to Gather Town. The virtual fieldtrip gives students the opportunity to explore a field site virtually by controlling an avatar that can engage with other users and their environment, fostering a collaborative working space. While in the field, students will interact with a series of embedded webpages, videos, and photographs to aid in explaining how field sites are selected, what geologists/paleoclimatologists are looking for in the field, and what field methods are used for different aspects of sample collection as the method of collection and amount of sample harvested are determined by the analysis being conducted. For this exercise, we are collecting rock samples to analyze for organic carbon, thus the field procedures reflect the processes for bulk organic and carbonate carbon collection.
Along with a virtual field experience, a virtual laboratory space shows students how lab analyses are performed and what these procedures look like. The virtual lab is accessed using a URL to Gather Town. The virtual lab is set up with stations depicting different steps and types of lab equipment used to perform analyses. The students follow the guided arrows to each station and are shown videos as well as infographics that explain each step of sample preparation within the lab, what lab method is being used at each station, and why they are doing this step. The stations take students through the Suarez et al. (2017) decarbonation method which removes carbonate carbon, leaving behind the remnant organic carbon in a powdered rock sample. The final station is the stable isotope lab where prepared rock samples return isotope values. These values are given to the students in the form of a google sheet which can be downloaded. The isotope values are used for future calculations.
Using the data set generated in Gather Town, students will perform the calculations demonstrated above to calculate pCO2. Depending on the level of the student, calculations are conducted via pre-inputted functions within Excel or Google Sheets, or the student (if at a higher level, e.g. advanced high school, upper-level undergraduate or graduate students) can input the equations themselves into Excel, Google Sheets, or programs such as Python, R, or Matlab.
The final part of the exercise is completing a series of questions that prompt the students to interpret the data and calculated values. Students will answer questions about the graphs they created as well as questions about additional graphs showing atmospheric CO2 concentration change through time as well as future projections. They should be expected to make interpretations about climate change and the carbon cycle based on what they learned during the exercise.
Included materials:
- Background information presentation (Paleoclimate lab presentation.pptx (PowerPoint 2007 (.pptx) 29.4MB Oct15 25))
- Assignment worksheet (Worksheet.docx (Microsoft Word 2007 (.docx) 2.5MB Oct15 25)) and
- Excel spreadsheet with published dataset (Isotope data.xlsx (Excel 2007 (.xlsx) 13kB Oct15 25)) and
- How to do the assignment presentation (How to do the assignment.pptx (PowerPoint 2007 (.pptx) 55.1MB Oct15 25))
- Background informational videos (General Climate Change.mp4 (MP4 Video 454.1MB Oct15 25) and Paleoclimate lab.mp4 (MP4 Video 211.8MB Oct15 25))
Worksheet key -- educator-only file
HideThese materials are published online and can be accessed here as well.
Assessment
We administered a survey at the end of the teaching module to both instructors and students. The survey is a series of Likert-scale questions asking students about their experience with the material and making connections to larger scientific ideas.
If you use these materials, please provide feedback! (https://forms.gle/4Rc6bbicbCtzTaYV8)