By Sarah Andrew

*yes that is a Modest Mouse reference.

Earlier this month, I was lucky enough to attend the 4th International Symposium on the Ocean in a High CO2 World (AKA Ocean Acidification Conference) in Hobart, where over 300 scientists from around the world came together to discuss the implications of changing ocean chemistry and where our research needs to go next. A recurring theme in this conference was the realisation that scientists need to make a huge leap with experimental design (a bit more about this later) in order to start truly understanding the complicated aspects of such a dynamic environment.

As we zoom past the symbolic milestone of rising atmospheric carbon-dioxide exceeding a background level of 400ppm in the Southern Hemisphere, it is becoming all too clear that CHANGE. IS. HAPPENING. One could even joke that “Winter, most definitely is not, coming.” In light of the recent Paris agreement, it has been shown that with the current CO2 levels and rate of emissions, there is currently no way to limit warming below 1.5-1.7°C (as it would take a 90% slash in CO2 emissions to reach this goal)1.

However, warming can be limited below 2°C if carbon dioxide is PHYSICALLY removed from our atmosphere1 (Whew. That’s the good news part of this post done with). However, huge advances in geoengineering and carbon sequestration technologies need to be made before this is actually a realistic solution.

Figure 1: CO2 readings from Cape Grim station and some light relief in the form of a cartoon.

To further add to the doom and gloom, the current rate of CO2 emissions and resultant warming and ocean acidification; is unprecedented in the last 66 million years2. The Palaeocene – Eocene Thermal Maximum (PETM) is the only event that comes close to the rate of the present anthropogenic carbon release rate. Currently carbon emissions sit above ~10 Pg Cyr-1 (2014), whereas the maximum sustained PETM carbon release rate has been constrained to less than 1.1 Pg Cyr-1, with the onset occurring over a massive 4000 years.

This current accelerated rate of change in our atmosphere means that organisms are not given a huge window of time to adapt to new conditions, which will very likely see extinctions exceed those observed at the PETM. However, as there is no historical analogue, science has to resort to groping around in the dark.

Where I fit in and how this shapes my life (aka, the PhD).

Globally, ocean acidification will occur concomitantly with other changes, such as warming and stratification (which in turn affects the availability of nutrients and light, Figure 2). Additionally regional impacts such as eutrophication, fishery pressures, tourism and storms are also important to consider in order to understand how ecosystems will respond to future physical and chemical oceanic changes.

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Figure 2: Adapted from Doney, 20064

These concurrent changes make things slightly more difficult for scientists to understand and make accurate predictions regarding the future. Taking into consideration the dynamic natural environmental factors that my organisms (phytoplankton) are exposed to, I now have a lot of variables to control for. Light. Temperature. CO2. The list goes on. And this is just in the lab, never mind my real life. (JK. This is my only life). All of a sudden my experimental design has gone from a simple two factorial experiment with 3 replicates (Eg, an organism exposed to high vs low CO2) to a multifactorial experiment consisting of 4 variables (so 16 different treatments) while still maintaining those 3 biological replications. Now all of a sudden I have 48 experiments running and lab space, time + equipment is running out!

Yet these experiments will tell the scientific community very little about the response of phytoplankton to changing chemical and physical ocean conditions, because even though I’ve factored in multiple variables – currently I’m only working with a single species….in a laboratory (Figure 3. The holy grail of figures). In order to even begin to estimate ecosystem responses, I have to look at the responses of multiple species that span taxonomic groups. But then that doesn’t tell us about how these species will interact and compete against each other for resources or their resilience to predation or even a viral attack. So as well as taking into consideration multiple drivers in a system, I also have to look at multiple species in the lab, as well as studies in the field to understand how the whole ecosystem will respond to changing climate.

 

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FIGURE 3: THE FIGURE TO END ALL FIGURES. AND I FINALLY GET TO JOIN THE MASSES AND SHARE IT WITH YOU ALL. Riebesell and Gattuso, 20155. (Shared at least 100x at the conference)

So how does ocean acidification affect you?

Every second breath you take is from the ocean. You eat food from the ocean. The pretty corals that you love to admire and the fishies that live in and around them will no longer exist.

Recent research also suggests that in addition to the deleterious effects on ecosystems and organisms, ocean acidification with also alter the taste of seafood. Shrimp grown under differing CO2 and temperature treatments were taste tested and shrimp grown at lower pH treatments are consistently ranked as the least desirable shrimp3, as well as being least aesthetically pleasing.

How can you contribute to the issue?

We all know to buy locally and ethically sourced items. To replace a few meals each week with a vegetarian option. To re-use recyclable containers. To use the car less. These things were instilled in me while I was still at primary school around 20 years ago.

I personally know that as an adult (-in training) that sometimes I forget. Or take the easy route. But I know from experience that as a student, eating vegetarian meals sometimes just happens. Hello pasta and tomatoes for dinner. But back to the real talk. Every little reduction in your carbon footprint helps.

Important lessons learned.

Scientists are people too and sometimes we don’t get things exactly right (we mostly do though). International meetings like this bring together a diverse range of backgrounds, from policy makers (who scientists need to communicate effectively with in order to influence government actions) to evolutionary biologist, biogeochemists, oceanographers, climate modellers and lastly geologists (yay I fit in somewhere!). These gatherings enable us to collectively have a say in where this relatively new field is going and how we can better communicate with the public about what scientists get up to and how our findings will affect them.

So here’s a photo of the conference dinner. Post Conga Line. I got to have a major boogie with some of my scientific Gods. And man, can they move.

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Photo: Conference dinner/dance party at MONA

 

References

1 Gasser, T., Guivarch, C., Tachiiri, K., Jones C. D. & Ciais P. (2015) Negative emissions physically needed to keep global warming below 2 °C. Nature Communications 6, 7958.

2 Zeebe, R. E., Ridgwell, A. & Zachos, C. Z. (2016) Anthropogenic carbon release rate unprecedented during the past 66 million years. Nature Geoscience 9, 325–329.

3 Dupont, S., Hall, E., Calosi, P. & Lundve, B. (2014) First Evidence of Altered Sensory Quality in a Shellfish Exposed to Decreased pH Relevant to Ocean Acidification. Journal of Shellfish Research 33(3):857-861.

4 Doney, S. (2006) Oceanography: Plankton in a warmer world. Nature 444, 695-696.

5 Riebesell, U. & Gattuso, J-P. (2015) Lessons learned from ocean acidification research. Nature Climate Change 5, 12-14.
A fun infographic.

http://www.highco2-iv.org/wp-content/uploads/2016/04/OA20Facts.pdf