Raised Beaches Podcast: Episode 6

Raised Beaches Podcast: Episode 6

The deep dive of episode 6 is on the topic of CO2 changes through time.

Listen here: https://raisedbeaches.buzzsprout.com/

Watch here: https://www.youtube.com/@evangowan

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Episode 6 – Intro

In the intro, I discuss about the hot start to the summer and my trip to Mt. Aso volcano. I discuss about my experience at the Japan Geoscience Union conference in May, highlighting some of the interesting talks I saw. I briefly discuss Canada’s first mission to Antarctica. Finally I give some commentary on the cuts being made to Earth science in the United States.

CBC documentary on Canada’s scientific mission to Antarctica: https://www.youtube.com/watch?v=vwe6ptJ2gkY

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Episode 6 Deep Dive – CO2 changes through time

I discuss why CO2 changes naturally. I give an overview of CO2 changes in the recent past, as well in the deep time period, covering the past 480 million years. I discuss why the current CO2 levels are unprecedented.

The Keeling Curve at the Scripps Institution of Oceanography, UC San Diego: https://keelingcurve.ucsd.edu/
The Carbon Cycle at NASA: https://earthobservatory.nasa.gov/features/CarbonCycle
CO2 measurements at NASA: https://climate.nasa.gov/vital-signs/carbon-dioxide/?intent=121
Ice cores at wikipedia: https://en.wikipedia.org/wiki/Ice_core
Rubino et al (2019) – 2000 year record of CO2 from the Law Dome in Antarctica: https://doi.org/10.25919/5bfe29ff807fb
Lüthi et al (2008) – 800,000 year record of CO2 from Antarctica: https://doi.org/10.1038/nature06949
Yamamoto et al (2022) – Leaf Wax record of CO2: https://doi.org/10.1038/s41561-022-00918-1
Bartoli et al (2011) – estimates of Pliocene CO2 from boron isotopes: https://doi.org/10.1029/2010PA002055
The Cenozoic CO2 Proxy Integration Project (CenCO2PIP) Consortium (2023): Cenozoic CO2 estimates: https://doi.org/10.1126/science.adi5177
Weekly CO2 estimates from NOAA: https://gml.noaa.gov/ccgg/trends/weekly.html
Judd et al (2024) – a record of global temperature and CO2 for the Phanerozoic: https://doi.org/10.1126/science.adk3705

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Episode 6 – More on the CO2 changes through time

I discuss the efforts to find ice older than 800,000 years old in Antarctica to measure past CO2 levels, and discuss about the difference between C3 and C4 plants and their importance in terms of CO2 levels.

Oldest Ice on Science: https://www.science.org/content/article/oldest-ever-ice-offers-glimpse-earth-ice-ages
Rice on Wikipedia: https://en.wikipedia.org/wiki/Rice
Corn/Maize on Wikipedia: https://en.wikipedia.org/wiki/Maize
Tipple and Pagani (2007) – The Early Origins of Terrestrial C4 Photosynthesis: https://doi.org/10.1146/annurev.earth.35.031306.140150
Hui et al (2021) – Intensified fire activity induced by aridification facilitated Late Miocene C4 plant expansion in the northeastern Tibetan Plateau, China: https://doi.org/10.1016/j.palaeo.2021.110437

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Episode 6 – Papers

I discuss a recent paper I published about changes to the rainfall in Eastern Asia due to sea level changes.

Gowan et al (2025) – https://doi.org/10.1186/s40645-024-00681-4