GGR377H5F Global Climate Change Fall 2025 Mid-term Test

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GGR377H5F

Global Climate Change

Fall 2025

Mid-term (take-home) Test

Due: 24^th October (9 pm)

Instructions

1. Answer both Questions below using a 12 point font, single or double spaced. Use this file as the template and include the completed cover sheet – please use the following filename format: SURNAME_GGR377H5F_mid-term.pdf (or .doc)

2. For each answer use in-text citation (e.g. xxx, 2020) and provide a reference list of cited sources using APA or similar – these lists do not count against the word limits.

3. You may include diagrams and figures where appropriate (include a caption and source).

4. Submission is online as a .pdf or Word file (no other formats will be accepted) via Assignments on Quercus (includes Turnitin).

5. Please note the following extract from the syllabus regarding use of ChatGPT / Generative AI:

Students may choose to use generative artificial intelligence tools as they work through the assignments in this course; this use must be documented in an appendix for each assignment. The documentation should include what tool(s) were used, how they were used, and how the results from the AI were incorporated into the submitted work.
See below for AI statement – please complete as appropriate.

Question 1 (50 marks)

To what extent is the Palaeocene-Eocene Thermal Maximum ‘hyperthermal’ a good analogy for modern global warming?  (1200 words max).

Resources

Start with the Carbonbrief piece:

https://www.carbonbrief.org/hyperthermals-what-can-they-tell-us-about-modern-global-warming

Other papers:

· Gutjahr et al (2017) Very large release of mostly volcanic carbon during the Palaeocene-Eocene Thermal Maximum. Nature 548, 573-577.

· Haynes & Hönisch (2020) The seawater carbon inventory at the Paleocene–Eocene Thermal Maximum. Proceedings of the National Academy of Sciences, 117:39, p. 24088–24095.

· Kender et al (2021) Paleocene/Eocene carbon feedbacks triggered by volcanic activity. Nature Communications, Vol.12 (1), p.5186-5186.

· Gernon et al (2021) Global chemical weathering dominated by continental arcs since the mid-Palaeozoic. Nature geoscience, 2021, Vol.14 (9), p.690-696.

· Kaya et al (2022) The Eurasian epicontinental sea was an important carbon sink during the Palaeocene-Eocene thermal maximum. Communications earth & environment, 2022, Vol.3 (1), p.124-10.

· Hanson, J. et al (2022) Global warming in the pipeline. Oxford Open Climate Change, 2023, 3(1), kgad008.

· Berndt et al (2023) Shallow-water hydrothermal venting linked to the Palaeocene–Eocene

· Thermal Maximum. Nature Geoscience, 16: 803–809.

· Baumann, N. B., Smith, C. D., & Lee, E. (2024). Linking the PETM and North Atlantic volcanism using tellurium as a proxy. Palaeogeography, Palaeoclimatology, Palaeoecology 656 (2024) 112575.

· Jiang, S. et al (2025). Millennial‑timescale thermogenic CO₂ release preceding and during the Paleocene–Eocene Thermal Maximum. Nature Communications, 16:5375

· Piedrahita, V. A., Nguyen, H., & Roberts, L. (2025). Assessing the duration of the Paleocene‐Eocene Thermal Maximum. Geophysical Research Letters, 52, e2024GL113117.

Question 2 (50 marks)

To what extent should we be worried by climate tipping points? Discuss with specific reference to the West Antarctic Ice Sheet (1200 words max).

Resources:

Lecture 3 (and associated readings) for ‘tipping point’ context (including CarbonBrief pieces)

· Hulbe, C. (2017) Is ice sheet collapse in West Antarctica unstoppable? https://doi:10.1126/science.aam9728

o See also: https://www.carbonbrief.org/guest-post-collapse-west-antarctic-ice-sheet-inevitable/

o And: https://www.carbonbrief.org/guest-post-how-close-is-the-west-antarctic-ice-sheet-to-a-tipping-point/

· Garbe et al (2020) The hysteresis of the Antarctic Ice Sheet. https://www.nature.com/articles/s41586-020-2727-5

· De Conto et al (2021) The Paris Climate Agreement and future sea-level rise from Antarctica. https://www.nature.com/articles/s41586-021-03427-0

o See also: https://www.carbonbrief.org/guest-post-overshooting-2c-risks-rapid-and-unstoppable-sea-level-rise-from-antarctica

· Rosier et al (2021) The tipping points and early warning indicators for Pine Island Glacier, West Antarctica. https://doi.org/10.5194/tc-15-1501-2021

o See also: https://www.carbonbrief.org/guest-post-identifying-three-tipping-points-in-antarcticas-pine-island-glacier

· Sohail, T (2024) Committed future ice-shelf melt. https://doi.org/10.1038/s41558-023-01817-y

· Rosser, J.P. et al (2024) Polar ice sheets are decisive contributors to uncertainty in climate tipping projections. https://doi.org/10.1038/s43247-024-01799-5

· Bradley, A.T. and Hewitt, I.J. (2024) Tipping point in ice-sheet grounding-zone melting due to ocean water intrusion. https://doi.org/10.1038/s41561-024-01465-7

o See also: https://www.carbonbrief.org/guest-post-the-critical-role-of-grounding-zones-in-the-retreat-of-earths-ice-sheets/

· Abram, N.J. et al (2025) Emerging evidence of abrupt changes in the Antarctic environment. https://doi.org/10.1038/s41586-025-09349-5

· Chandler, D.M. et al (2025) Antarctic Ice Sheet tipping in the last 800,000 years warns of future ice loss. https://doi.org/10.1038/s43247-025-02366-2