Believe it or not, it’s climate change.

By: Aidan Adams

Watching climate change unfold has turned all our faces green, and it turns out that’s not all. Believe it or not, the sea wasn’t always the murky colour it often is today. As far-fetched as it may sound, decades worth of research published by Wednesday in Nature show that 56% of the world’s Oceans have experienced colour change from 2002 to 2022.

Turns out our actions really do have consequences…

An article released by MIT news has revealed that the ocean’s colour is dependent on what makes up its upper layers, meaning that sediment in the water and decaying organic matter also have a role to play. But we’re not completely off the hook. The main factor concerning whether our waters take on a healthy blue hue is the population of phytoplankton, microscopic marine algae which float on the upper layer of the ocean.

Our oceans absorb an astounding 25% of the carbon dioxide that we produce, and crucially, the photosynthesis of Phytoplankton is largely responsible for this. But that’s not all, as a result of their photosynthesising, they produce almost half the oxygen we breathe!

Think of the oceans as a ‘hoover’, sucking up all of our ‘waste’, or carbon emissions.

So how does this relate to the changing colour of our seas? The Chlorophyll inside these Phytoplankton is the most important light-absorbing substance in the oceans. So, during the process of photosynthesis, they absorb primarily the red and blue portions of the light spectrum (yes, our sea really does have the colour red in it). Meaning the higher the density of phytoplankton, the greener the sea will appear to be, and only in areas of very low density will the sea appear a clear blue colour.

So what’s the problem? Phytoplankton absorb Carbon dioxide and clean up our mess, so the greener the ocean the better, right? Unfortunately it’s not that simple. Scientists say that the increased level of greening we are seeing in the ocean is not explained by the seasonal variation in phytoplankton population, instead, it is on account of increased carbon dioxide absorption. This means that the greener

the seas, the higher our carbon emissions are, and thus the more ‘waste’ that we are forcing into our ‘hoover’. This, however, signals a much more serious problem; our oceans already absorb nearly 25% of our carbon emissions, and they can’t keep cleaning up after us forever. Eventually, the ‘hoover bag’ will fill up, but unlike a hoover bag, we can’t simply replace our oceans. So when, in the inevitable future, they stop being able to absorb more, our carbon emissions will instead be distributed into our atmosphere. This would accelerate climate change to a frightening level.