Why the Seas are becoming more Blue

I’m sure we’re all used to hearing about climate change, and I don’t need to remind you about all of the causes and impacts. One of the indirect impacts of climate change relates to the idea that, as the global temperature increases, the seas are going to get more blue. Even though this simple fact seems superficial and irrelevant, this change would occur because of the decline of phytoplankton communities in the oceans. Today, I will be going through what phytoplankton are, how they’re affected by climate change, and what that means for our planet.

Phytoplankton are autotrophic microscopic organisms that live near the surface of water, in either fresh or salt water conditions. Autotrophs produce their own food, which phytoplankton do by photosynthesising, where they use chlorophyll in their cells to capture sunlight, and consume Carbon Dioxide, and produce oxygen and glucose, which is a form of chemical energy. Phytoplankton are a wide group of organisms, and members range from single-celled plants, to bacteria or protists. Phytoplankton are the foundation of the marine food web and they regulate key biochemical processes. They are the primary producers and the food for marine animals from microscopic zooplankton to blue whales. The growth of phytoplankton is dependant upon the accessibility of Carbon Dioxide, nutrients, and obviously sunlight. If these conditions were managed perfectly, phytoplankton populations can grow extremely rapidly, producing blooms, which can last several weeks, even though an individual phytoplankton can only survive a few days.

Climate change is causing the temperatures of the seas to rise, as you most likely already know. One of the indirect impacts of climate change is that, as climate change increases, the phytoplankton die and their numbers decrease. This happens because there are less nutrients present in the surrounding sea and therefore it is harder for the phytoplankton to find food. The increase in sea temperature also kills the phytoplankton, as they are not adapted to this greater temperature, and therefore less of them survive in these new changing conditions. However, the aspect of climate change that is having the greatest impact on phytoplankton is ocean acidification. The decrease in ocean pH makes the conditions of the sea even further from what the phytoplankton would prefer and be most adapted to. As I have just described three factors of climate change that lead to the decline in phytoplankton, you can see that they face multiple different environmental changes from climate change. The decline of the phytoplankton populations is one of the earliest warning signals that we, as a planet, are changing the ecology of our oceans.

What does this mean for the planet? Why does it matter if the populations of microscopic phytoplankton are decreasing? The most important reason is that the food webs that the phytoplankton support are struggling. The marine animals that rely upon the plankton for food would subsequently have much less food, resulting in other species decreasing rapidly in numbers too. Another big impact of the phytoplankton decline is that the seas are going to get more blue. As phytoplankton contain chlorophyll, they bring a hint of green colour into the seas, therefore with there being less phytoplankton, seas will look more blue than they do now. The areas near the equator and the poles are becoming even more green, with the areas in between becoming less green and gradually more blue.

It may not bother you that much that the seas are getting less green and more blue, but we need to be worried about what is actually going on that we can’t see as obviously. We need to concern ourselves with the microscopic organisms like phytoplankton that are dying as we speak, and we need to actively try and change this population decline and try and regain the populations of phytoplankton globally. Let’s not wait until it’s too late.