Climate Reconstruction from the Sedimentary Record

Allison Jacobel, Middlebury College

Initial Publication Date: April 24, 2024

Summary

This module guides students through an examination of how Earth scientists use marine sediments to reconstruct changes in Earth's past climate. They then compare records of changes in Earth's climate from different archives (sediments & ice) to understand the interconnected nature of the climate system and explore climate feedbacks.

History and evolution of Earth's climate, Paleoclimate records, ...(more) | High School (9-12) | Online Adaptable

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Context

Audience

This module was designed for use as part of a 12th grade IB course on 'Environmental Systems and Societies'.

Skills and concepts that students must have mastered

The activity requires that students have experience determining the slope of a line.

How the activity is situated in the course

The module should take approximately 100 minutes total (2-3 class periods) to complete, including the presentation of the module PowerPoint. Module Activities A and B are designed to be completed individually; Activity C should be completed in collaborative teams.

Goals

Content/concepts goals for this activity

By the end of the module students should be able to:
1. Describe how scientists determine age-depth relationships in marine sediment cores.
2. Describe how sediment cores and ice cores can be analyzed to obtain information about Earth's climate history.
3. Quantify sedimentation rates (slope analysis) and calculate rates of change.
4. Evaluate rates of change to determine that the rate of anthropogenic CO2 release is unprecedented in (at least) the last 800kyr and that current climate change cannot be attributed to natural processes.
5. Evaluate relative magnitudes of change to understand climate system non-linearities and feedbacks.

Higher order thinking skills goals for this activity

The overarching questions the module helps students answer are:

How do scientists reconstruct past climate change?

What external forcing is responsible for natural variations in Earth's climate?

Why are feedbacks important for climate system responses to change?

How does the current direction and rate of climate change compare to natural variability?

These questions correspond with Next-Generation Science Standard (NGSS) HS-ESS2-2:b

Analyze geoscience data to make the claim that one change to Earth's surface can create feedbacks that cause changes to other Earth systems.

Other skills goals for this activity

Description and Teaching Materials

Instructors should begin by sharing the module powerpoint to introduce key concepts. In Part A of the module, students use synthetic sediment cores to learn about the sedimentary record and how scientists relate depth to age in the geologic record. In Part B, students examine an 'undated' sediment core and use the global benthic oxygen isotope 'stack' to determine the ages and sedimentation rates of different core sections. In Part C, students choose between several reconstructions of climate system change to investigate the relationship between solar forcing (orbital changes in insolation) and the response of either the cryosphere or the oceans. Part C asks students to build on their understanding of sedimentation rates to describe rates of change and relative rates of change introducing the concept of feedbacks.