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The incredibly beautiful and, at times, frightening ocean is likely to be the largest moving phenomena most of us will ever witness.

Ocean waters tumble and cascade down ridges, creep abyssal plains, pinch off in crisp eddy rings that coalesce at the surface, rise in steep shoals and upwellings, crash and fold in on themselves and evaporate to the clouds. Ocean currents[1] are not stable or infinite – they have histories and may be shaken, diverted, and propelled at different speeds and in different directions by planetary wobbles, winds, celestial forces and Earth’s orbit. Through their global journeys and local upwellings, salty, wet, transitional currents animate the ocean’s complex liveliness. Enormous circulatory systems glide, wind and pump their way around the earth, crossing abyssal plains, massaging continents, breaking off into meandering currents and eddies that distribute warmth and nutrients before cycling back to be replenished.

Imagining the world through currents takes us offshore, away from terrestrial biases to consider our relations with ocean life and dynamics. Driven by transitional material exchanges, the surface currents, overturning circulation and biological pumps influence planetary climate systems and biological communities through myriad relations. They are thoroughly implicated and entangled with terrestrial events and intensifying human activities: fluxes of carbon, plastics and other materials arriving, transforming and leaving through river mouths, canal outlets, vehicle exhausts, rain freshened surfaces, holiday coastlines, beneath ice sheets and evaporating skyward. Currents send ashore the material missives of the local conditions through which they pass: washed up wrack, froth and spume from offshore sediment and kelp forests; as they also send warmth, seeds, remnant oil and plastic from one basin edge to another. As Neimanis observes of watery bodies (Neimanis 2014), the distributive capacity of currents is both situated and global. Currents stream material transitions, showing us where change comes from and where the effects of change are going.

Despite destructive tsunamis and powerful waves, the ocean is a generous provider of life conditions for humans and other animals. However, human exploitations of marine environments swirl as an undertow, challenging the very concept of human companionability with the seas. In an unequal exchange, the ocean’s biological communities, environments and dynamic systems are imperilled by overfishing (Pauly, 2010; Probyn, 2016); loss of marine biodiversity (Worm et al., 2006; Mitchell, 2009); sand depletions (UNEP, 2014); pollution from offshore petroleum extraction (Passow, 2015); threats of deep seabed mining (Hunter and Taylor, 2013; Rosenbaum and Grey, 2015); and global material flows of plastics that now speckle planetary currents (Cressey, 2016). Intensifying streams of our carbon emissions intersect with these issues and bring transition of an entirely different register. Planetary scaled ocean warming is deepening (De Lavergne et al., 2014; Hill, 2013), and this is significant for the flow and reach of ocean dynamics and the creatures and other systems reliant on them (Van Gennip et al., 2017; Brierley and Kingsford, 2009; Eissa and Zaki, 2011). Major overturning circulations are showing signs of slowing (See also Menezes, Macdonald, and Schatzman 2017 and Nace 2020). We humans are in a soak with the ocean – dependent on the very systems and materials that our actions imperil; and thoroughly implicated in, and affected by, their transitions.

Governance regimes fail to remove these ongoing threats. Particular systems amplify the ocean’s vulnerable state, such as the deep seabed mining regime inaugurated by United Nations Convention on the Law of the Sea (UNCLOS) and the International Seabed Authority. Seabed mining is an industry that may destroy some of the least understood ecosystems on the planet (Earle, 2016; International Seabed Authority, 2011). Under the extractivist regimes in which we are all differently implicated, conservation measures and principles may mitigate against the environmental harms of these activities. However, they have not yet prevented ocean transitions that augur less comfortable futures for differently vulnerable human and other animal communities.

The ocean that informed the long drafting of UNCLOS is not the same ocean today, yet their legal representations remain. UNCLOS’s foundational values instrumentalise a world for our use; one that is represented as exterior to, and situated outside the world of relations, rather than a world imagined from within its makings. The spatialised and territorialised realm that is the law’s ocean is structured as a background place where things happen – fish are harvested, sediments are mined, cables are laid, bombs are tested, chemicals are dumped, plastics circulate, waters warm and acidify (see also Steinberg, 2001). In this imaginary the ocean is instrumentalised as quarry, pantry, sink and sump.

To ‘sea truth’ and to live better with the ocean, we might understand more closely the material agency and transitional nature of the ocean’s dynamic systems and relations. Doing so offers a conceptual ground for understanding the nature of transition itself, so that finding ways to live better with the ocean might challenge us to live better with their transitions. Beyond their narrow taxonomic categories, or as subjects of siloed scientific research, how do ocean currents and other moving bodies shape the livable worlds that humans and other animals experience, albeit differently, across different localities. What might ecologically oriented imaginaries tell us of how our material appetites and carbon flows impact the ocean? How might we create imaginaries for more companionable ways to live well with the transitioning ocean in times of climate change?


Transitioning currents and carbon streams

Surface currents and winds work together to up-end our terrestrial assurances of place. Currents are described by the direction in which they move, whereas the winds that drive or buffer them are described according to the direction from which they come. Powerful westerly trade winds chase the easterly flowing Antarctic Circumpolar Current (ACC). Meanwhile, the East Australian Current (EAC) hugs the continent’s east while travelling the western boundary of the South Pacific Basin. The Leeuwin Current tracks along the west coast, travelling the eastern boundary of the Indian Ocean. Brushing, swirling, licking and sweeping the continents and islands, and their submarine shelf slopes, currents animate and transform the solid edges against which we orient ourselves: seaward of the eastern coast of Australia, for example, a concert of uniquely constituted rotating water masses, chains of eddy lenses and coalescences of cast-off rings stir and unsettle the western edge of the Pacific Basin.

Currents are not undifferentiated ‒ in an ecological sense, each has their own histories, watery routes, marine passengers, physical characteristics and ways of responding and transitioning with the material conditions they meet. Nor are current flows assured or immutable, as Scher et al. (2015) have found in relation to the ancient westerly flowing origins of the ACC. Stefan Helmreich (2014), too, explores the physical variations of waves but with a focus more on their cultural significance. Currents have their own way of going about the ocean, meandering snug against rocky outcrops stubbled with crimson anemones, refreshing frilly green algae, or streaming through sediment plumes that rise from seabed excavations.

Currents act and can be acted upon with an inherently relational and ethical agency; subtly transforming the waters through which they pass, and in turn transformed by the waters that they meet, the particles collected, and the continents and seafloors they sweep. Human actions too materially transition with ocean currents, in the sense that Barad refers to as ‘intra-acting from within and as part of the world in its becoming’ (Barad, 2007, 396). Sticky, salt watery currents manifest ocean relationality, and carry our weathering agency, and streams of carbon and plastics, into thick time. Thinking with Haraway’s concept of ‘natureculture’ Neimanis argues that ‘[w]ater is eminently natureculture’ (Neimanis, 2014, 15). If this is the case, then so too is water’s myriad expressions as ocean currents. Temporalities and materialities of natureculture entangle currents: emissions and engine ignitions, wireless laptops, residential dwelling, bridges, chemicals and minerals, atmosphere and ocean skin, heat and volition – all co-producing the signal changes now coming into visibility. Transitioning relations of ocean currents carry plastics from river mouths and gather them in the grind of the North Pacific’s Great Pacific Garbage Patch, or as micro-plastics ingested by plankton. These transitions catch up with us in the Southern Ocean, where around 60 per cent of anthropogenic heat and almost half our carbon dioxide emissions are absorbed (De Lavergne et al., 2014). Carbon emissions and heat penetrate deepening levels of warming surface waters. The consequence of these transitions now measurably influence the distribution of temperature into ancient bottom waters and overturning – natureculture transitions carried in the long-term memory of ocean circulations. As watery bodies, currents convey what Neimanis describes as the ‘watery archives’ (2013, 32) of human consumption.

Emerging evidence of the thermohaline circulation’s transition through natureculture material entanglements offers a clarion call for more ethical approaches to ocean relations. The long-range temporal scale of the ocean’s overturning systems speak little of their vulnerability to changing material intensities. Their planetary scale belies the exquisite exchange and transitioning of materials at the heart of their movement. One stage of this transition occurs when ice forms around the polar region and, in the process, spits salt back into the sea. This dense, cold, saline water sinks and, then the water above moves in to replace the sinking water and eventually a current is created. The cold deep water of the thermohaline moves horizontally across the abyssal seabed until they[2] can rise again to the surface, usually around the equatorial regions. In the thick time of the thermohaline overturning, their watery archives move at the rate of a few centimetres per second. Some ancient water can take up to 1,000 years to complete the cycle, and as many years to see the sun (Mann and Lazier, 1996).

Equally planetary in scale, carbon and other greenhouse gases thicken the atmosphere and the ensuing warmer ocean sets in train a different type of transition. As carbon-plump surface waters melt polar ice, an excess of fresh water is poured into the thermohaline mix. These diluted polar waters enfeeble the thermohaline exchange to the extent that there may be real potential for a thermohaline circulation collapse (See also Keller et al., 2000, 19, Dalton 2023 and Morrison et al. 2023) Ecological knock-on effects of climate change are also transitioning the East Australian Current (EAC) and profoundly changing ocean relations. Unsuited to the warming waters, marine creatures such as yellow-tailed kingfish and coral trout retreat further south (Milman, 2015). Spiny sea urchins have arrived in Tasmania and are devouring underwater forests of the 30-metre-tall giant kelp, Macrosystis pyrifera (van Sebille et al., 2014). Tasmania’s cool waters creatures are caught unprepared by the arrival of new warm water predators (Kelly, 2011). As van Sebille et al. (2014) note, these creatures can only move so far before they meet the edges of the continental shelf – this is the end of the line as their next habitable shelf is about 3,000km south at Antarctica.

Continued in: Transitioning currents in times of climate change – Part Two

Adapted from: Reid, S. (2018). “Transitioning Currents in Times of Climate Change.” In Living with the Sea, 114–28. London: Routledge.


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[1] Broadly conceived here to encompass phenomena such as jet streams, gyres, eddies, cast-off rings, overturnings, upwellings and myriad biological pumps.

[2] This work intentionally uses the pronouns ‘they/their/them’ in recognition of ocean and current bodies not objects but as gender-neutral, collective planetary entities.

Video: AnthropoScene II : Tideline

Credit: Adam Sébire / Climate Visuals 

Gulf Stream Sea Surface Currents and Temperatures

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