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Climate change is altering the colour of our oceans

As climate change continues to throw marine ecosystems out of balance, MIT research shows that the colour of our oceans are physically changing.

When we talk about natural wonders of the world, we typically associate rich colour with health and vitality – particularly with fauna and flora.

In the case of our oceans, however, the aesthetically pleasing ‘deep blue sea’ generally means organic life isn’t overly prosperous. Despite being markedly less desirable for holiday-goers and Instagram models, greener hues usually indicate areas where the most activity is occurring.

Though green can also be a symptom of pollutants, it’s predominantly a bi-product of tiny microorganisms called phytoplankton which provide sustenance for small fish and crustaceans. In essence, the ocean’s colour is ‘a literal reflection of the organisms and materials in its waters,’ says a research team at the MIT.

In a recent study published in nature, they revealed that constant shifts in the balance of these marine ecosystems, due to human-induced climate change, have been reflected by colour changes in the world’s oceans over the last two decades.

Though changes are sometimes visible to the naked eye, subtle differences in shade are only discernible from satellite data using wavelength and light measuring technology. ‘These are changes that you really do need sensors to see, and you need long periods of time,’ says team member Stephanie Dutkiewicz.

Colour changes can happen organically as weather patterns shift between seasons, as phytoplankton vitality depends on energy harvested from sunlight.

Severe wind events like El Nino and storms can also drastically affect the abundance of such organisms, though researchers claimed to have negated both factors by recording colour outside of periods of natural variability.

The team discovered that colour changes were occurring in 56% of the globe’s oceans, and the reality paired up nigh-on identically with virtual greenhouse gas simulations previously completed by Dutkiewicz. ‘It is definitely sobering to actually see it happening in the real world,’ she said.

The most drastic transformations were observed in tropical regions in close proximity to the equator, while samples nearer the poles were harder to separate from factors of natural variability.

As eluded earlier, the ocean’s spectrum of changing hues has been attributed to the natural balance of organisms being thrown off-kilter. In terms of phytoplankton, certain areas are too rich or sparse, or have types too big or small for the established order of their habitat.

Dutkiewicz compares the phenomenon to having too much rain in areas that aren’t accustomed, leading to flooding; or too little in places that expect it, threatening potential drought.

‘It’s taken millions of years for our ecosystem to be in balance,’ she explained. ‘If you now suddenly perturb it, that’s going to have consequences. And many of them are not going to be good.’

We already know that phytoplankton are instrumental in allowing oceans to capture atmospheric carbon, so it’s essential we begin to learn where and why these organisms’ levels are changing so drastically.