Welcome to Week 7

One of the key aspects of why the planet is habitable is recycling. I’m not talking about you separating your waste (although that will help), but the fact that all the chemicals essential to life (called nutrients) are recycled throughout the Earth system (as we saw for water earlier on in the course). With the Earth being a closed system this is, of course, essential; if it wasn’t the case these nutrients would run out. In the first talk this week, Coral takes a look at the various ways in which elements are cycled through biological organisms and the Earth system.

The traditional view of the world contends that life is something that sits on the Earth, is contained by the environment and impacted on by the climate. In photosynthesis, we touched on the fact that if humans make the planet uninhabitable by releasing too much of a gas, they will not be the first organism to do so. This case study proves that organisms can impact climate. It turns out that far from being a passenger on the Earth System as we traditionally perceive it, life is often in the driving seat. As we find out from Sashan, biogeochemical feedbacks represent mechanisms by which life can change its environment and the climate. Some scientists think this collective ability of life to alter the conditions on the planet make the Earth System a living entity in its own right! Sounds crazy? Better watch the videos and find out….

1. This Week's Lectures

Core Science 13: Biogeochemical Cycles with Coral Mafole

Coral attended the ACCESS 25th Habitable Planet Workshop (HPW) for undergraduates in Cape Town in 2017 and later participated in the HPW Core Lecture leadership training in March 2023. She currently works as a research analyst in carbon management and is involved in phytoremediation research at the University of Cape Town (UCT). Coral completed postgraduate studies at both the University of KwaZulu-Natal (UKZN) and UCT, focusing on the nexus between plant ecology and climate change.

Core Science 14: Biogeochemical Feedbacks with Sashan

Sashan completed the inaugural HPW Online programme in September 2019 (he is one of you!) and attended HPW31 later that year after completing his B.Sc. Honours in Geology from UKZN. He went on to complete the Core Lecturer training programme and delivered multiple core lectures and a keynote lecture at HPW 33 and 34, receiving the Best Core Lecturer award during the former, and served as part of the leadership team for both workshops. He completed his M.Sc. in Geology at UKZN, investigating submerged landscapes along the east coast of South Africa, and has presented his research at national and international conferences. He is now studying for his PhD and works at the Council for Geoscience. Furthermore. he is passionate about understanding the dynamics of the Earth and the processes that shape it across various spatial and temporal scales. His other interests include exploring the dynamics at the interface of the natural environment and human society and the emerging field of geoethics. When not thinking about rocks, Sashan enjoys reading, hiking, writing, running and performing the "Sashan Shake".

The Carbon Cycle in detail

This is the most important cycle from Coral's talk, with the magnitude of all the fluxes (purple) and reservoirs (black) indicated. Have a good look.

2. This Week's Reading

James Lovelock’s Gaia theory remains controversial. It was, however, a departure point for the way scientists view biogeochemistry and life’s role in the Earth System. It’s worthwhile therefore running through this Harvard tutorial on the topic:

https://courses.seas.harvard.edu/climate/eli/Courses/EPS281r/Sources/Gaia/Gaia-hypothesis-wikipedia.pdf

Then look at how humans can manipulate biogeochemical feedbacks to their own ends via geoengineering:

“Give me half a tanker of iron and I’ll give you the next ice age”

3. Special South Africa

This week we have input from Dr Brett Kuyper (UWC) as to why South Africa is such a special place to study biogeochemistry.

Brett is a Scientific Officer in the Marine Biogeochemical Laboratory at the University of Cape Town. His work focuses on maintaining research infrastructure for isotope measurement. These measurements contribute to the understanding of biogeochemical processes in the Benguela and Southern Ocean. Brett has been involved in the HPW since the first ever workshop in Cape Town 2007.

4. Critical Eye from a Science Guy (or Girl)

This week Dr Sandy Thomala (CSIR) casts her eye over today’s core lecture topics.

Dr Sandy Thomalla is a Chief Researcher at the CSIR and the Research Group Leader of the Southern Ocean Carbon-Climate Observatory (SOCCO) in Cape Town, South Africa. Sandy obtained her PhD in 2007 from the University of Cape Town in association with the National Oceanography Centre, Southampton, UK. Her early research focused on understanding the biological carbon pump through measurements of primary production and carbon export. Sandy's postdoctoral research worked with satellite ocean colour data to characterise the seasonal cycle of chlorophyll in the Southern Ocean. This dynamic approach to understanding phytoplankton phenology based on underlying physical drivers rather than climatological means continues to influence SOCCO’s understanding of the Southern Ocean carbon – climate system. Her current and future research has expanded into the development and application of ecosystem-appropriate, well-characterised products that translate ocean colour and in situ bio-optical measurements into carbon biogeochemistry (phytoplankton biomass, community structure and physiology) allowing new insight into ecosystem function.

A key focus of her work is on assessing seasonal and intra-seasonal variability in ecosystem physical drivers and their biogeochemical response to better understand the potential for carbon sequestration at a regional scale. Quantifying the strength and efficiency of the Southern Ocean biological carbon pump and its sensitivity to predicted changes in the Earth’s climate is fundamental to our ability to predict long-term changes in the global carbon cycle and, by extension, the impact of continued anthropogenic perturbation of atmospheric CO2. Sandy’s unusual combination of experience at the interface of observations, autonomous technology, and ocean colour remote sensing, all centred on the biological response of phytoplankton primary production and associated carbon export, places her in a unique position to address the complex problem of understanding the climate sensitivity of the Southern Ocean biological carbon pump.

5. This Week's Test

Are you ready for this weeks test? Click here.

Due TUESDAY 21st at midnight - as always.

6. This Week's Cartoon

The name's Bond, Hydrogen Bond.

Hydrogen Bond was the hero in the amazing water talk. Look how he sits between two water molecules holding them together and is not involved within the water molecules at all. This is a common misconception many of you repeated on last week's test.

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