Reversal

Soundpiece 'Reversal' is a collaboration with producer and musician Jonny Nash for the installation 'Freq_wave', commissioned by TBA21 academy and curated by Carl Michael von Hausswolff for the research project Territorial Agency: Oceans in Transformation.

We were asked to create a sound piece within a 140-180 Hz frequency range for the 1st trajectory 'North Sea to Red Sea'. We drew inspiration from a sediment core obtained by Esmee and her NESSC colleagues during a Mediterranean research cruise winter in 2016. Our sound piece can be listened to and mixed with other frequencies using Mixer 1: North Sea to Red Sea (scroll down to select the item 'Mixer: North Sea to Red Sea', click play and adjust the frequencies to your liking).

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REVERSAL

The Levantine area, the birthplace of agriculture, has seen several climate oscillations since the beginning of the current geological period, the Quaternary, and has been a gateway for human migration waves, starting with the 'Out of Africa' dispersals ~120.000 years ago. Our freq_wave contribution Reversal aims to express the entanglement of factors that shaped the Levantine climate and our migration paths over the past 300.000 years.

What is pacing the recurrent floods, creating green corridors while depleting oxygen levels at the bottom of the sea, what is the forcing behind receding and advancing shorelines, what is leading and who is following?

Since entering the Quaternary glaciation ~2.6 Million years ago fluctuations in temperature, sea level and hydrological phenomena such as the monsoon system have largely been paced by orbital parameters: the orientation and tilt of Earth's rotational axis and the shape of Earth's path around the sun. Colder and warmer periods coincided with lower and higher sea levels. Wet and dry periods affected the Mediterranean thermohaline circulation, which slowed down during periods of enhanced Nile river outflow, depleting seawater oxygen levels. The recurring dark, peaty layers, buried in the seafloor sediments, remain the witness of these monsoon oscillations; human bones, stored in the soil, tell about the migration paths of our ancestors.

Reversal allows listening to the small steps of our species in the realm of large-scale climate-oscillations of the past. At the same time we are aware that human impacts, such as the construction of the Aswan dam, increasing atmospheric green house gases and concomitant rising sea levels, could tip future Mediterranean climate wiggles - paced by orbital parameters since ~2.6 Million years - into another amplitude and frequency range, that may exceed our bandwidth.

The sounds combined in this piece are amplitude- and frequency-modulated signals of the parameters seafloor de-oxygenation (recorded from the sediments collected from the eastern Mediterranean Seafloor), sea level, temperature and salinity (recorded from fossil shells), precession (the orientation of the Earths rotational axis), eccentricity (the shape of earth's path around the sun) and human migration events (reconstructed from archeological findings).

The timescale of Reversal reflects the signals reconstructed for the past 300.000 years, compressed into 60 seconds: 1 second hence reflects 5000 years, moving from past to present.

Acknowledgements

Reversal is dedicated to Rineke Gieles, who revealed the subtle colours of many sediment cores.

The Anoxia (Mo/Al ratio's of the sediment) and Levantine climate parameters (oxygen isotope ratios of foraminiferal shells) have been reconstructed using a sediment core retrieved during the Netherlands Earth System Science Center Mediterranean research cruise. We thank NESSC, the Pelagia-crew and all participants on board of cruise 64PE406, Rick Hennekam, Lynn Kruithof and other NIOZ colleagues involved in analysing core 64PE406-E1!

Orbital parameters calculated using: Laskar, J., Robutel, P., Joutel, F., Gastineau, M., Correia, A. C. M., & Levrard, B. (2004). A long-term numerical solution for the insolation quantities of the Earth. Astronomy & Astrophysics, 428(1), 261-285.

Human migration events based on: Demenocal, P. B., & Stringer, C. (2016). Human migration: Climate and the peopling of the world. Nature, 538(7623), 49-50.