Over the last two decades, a noticeable transformation has occurred in the colour of our oceans. The once vivid blue expanse is gradually shifting towards a more verdant green, a transformation attributed to the impacts of human-induced climate change.
According to the Mail & Guardian, this change in colouration carries far-reaching implications for the ocean’s well-being and the vital resources upon which we heavily rely, notably fishing and the production of oxygen.
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Spanning approximately 3 000 kilometres along its coastline, South Africa finds itself surrounded by three expansive oceans: the South Atlantic, the Indian and the Southern.
Within these marine realms, an estimated 12 000 diverse marine species call these waters home.
Yet, the changing temperatures are prompting these species to embark on migrations to different habitats, setting off a disruptive chain reaction within the intricate oceanic ecosystem.
This ecological upheaval challenges marine creatures as they grapple to secure sustenance, establish habitats, reproduce and ultimately survive.
In a study recently featured in the journal Nature, the phenomenon behind this shifting colour palette was revealed. As ocean temperatures rise, microscopic organisms known as microorganisms undergo directional shifts, culminating in the alteration of the ocean’s hues.
Matthew Germishuizen, a PhD candidate affiliated with the Mammal Research Institute Whale Unit within the Department of Zoology and Entomology at the University of Pretoria, has demystified the scientific intricacies underpinning this occurrence.
Germishuizen urges caution, asserting that merely two decades’ worth of data may prove insufficient in distinguishing the fingerprints of natural variability from those of climate change. Extended temporal perspectives are indispensable for comprehending the nuances of oceanic colour shifts in response to the evolving climate.
Central to this phenomenon is the presence of myriad single-celled algae called phytoplankton within the ocean. Through the process of photosynthesis, these algae harness sunlight, water and carbon dioxide to generate energy. This process is instigated by a green pigment within the algae known as chlorophyll, a phenomenon detectable solely via satellite imagery.
The productivity of these microscopic organisms propels the observable greening effect, which in turn intertwines with both climate fluctuations and the ocean’s circulation patterns. The latter phenomenon involves the intricate global transport of heat, carbon, nutrients and freshwater, influencing climate regulation on a planetary scale.
Amidst South Africa’s landscapes, a delicate tapestry of ecosystems flourishes, particularly evident within the tropical havens adorning portions of northern Kwa-Zulu Natal, where thriving coral reefs abound. The rapid greening phenomenon, however, looms as a potential threat to these vulnerable habitats, with the capacity to inflict considerable harm.
The ramifications of climate change reverberate throughout various sectors, including South Africa’s vital fishing industry, the Mail & Guardian reports.
This sector, which contributes a substantial R6 billion annually to the nation’s GDP, directly employs approximately 27 000 individuals in the commercial realm, as detailed by the Department of Agriculture, Forestry and Fisheries. In the face of continuing shifts in oceanic ecosystems, both the industry and the livelihoods reliant upon it face an ominous future.
Charlotte Scott, a PhD researcher immersed in the realms of locally-driven food systems and climate justice, underscores the importance of understanding climate change’s unique impact on small-scale fishers.
‘As our oceans get warmer, and our weather gets more extreme, coastal and fishing communities are likely to be impacted in multiple ways, compounding the existing challenges and inequalities they face.
We’re likely to see more intense and more frequent extreme weather events, meaning that fishers have fewer days to fish and might have to go fishing in worse conditions, putting them at a greater risk to make a living.’
As ocean temperatures continue to rise and weather patterns intensify, the ripple effects will cascade through coastal and fishing communities, amplifying preexisting challenges and inequities. The escalating frequency and severity of extreme weather events foreshadow fewer viable fishing days, possibly forcing fishers into treacherous conditions and imperilling their livelihoods further.
In tandem with the escalating temperatures blanketing Africa and the global sphere, the repercussions of the climate crisis are poised to strike with greater force. Vigilance towards these unfolding events is paramount.
Germishuizen’s statement rings true:
‘The ocean is critical to every single human on the planet. Changes to the ocean will affect everything from trade to water availability. The fear is that we will only realise how important the ocean is once it is too late. So, the key message is to change our ways faster and sooner rather than watch and wait.’
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Picture: Sebastian Wohlrapp / Unsplash