How The Loss Of Phytoplankton Could Lead To Our Demise
By degrading the environment, humans have caused a decline in phytoplankton. This is a dangerous proposition — for the planet and for us.
The base of the entire aquatic food chain is the phytoplankton. Essentially what plants do on land, phytoplankton does in the ocean. It is the foundation on which the entire aquatic life is built. Any threat to this species would ultimately lead to a complete collapse of aquatic life. Unfortunately, the phytoplanktons are dying, and we are the ones killing them.
These microscopic algae have been critical in making life on Earth possible for a number of key reasons.
Oxygen
Phytoplankton are responsible for over 50% of all the oxygen in our atmoshpere.
These microscopic algae in our oceans are some of the most laborious workers in our ecosystem. Day and night, they absorb the carbon dioxide in the atmosphere and convert it into oxygen through photosynthesis.
Food
All the food in the ocean is ultimately produced by phytoplankton. Through photosynthesis, they produce carbohydrates which are in turn consumed by small fishes. These fishes are then consumed by larger fishes and so on.
Kill the phytoplanktons and the oceans will be left with no food.
Carbon Sequestration
Another important contribution of the phytoplankton is the fact that they sequester (remove and store) a large amount of atmospheric carbon. This reduces atmospheric carbon content and thereby mitigates the greenhouse gas effect.
Phytoplanktons are resilient enough to survive climate variations. They have done so for thousands of years, through the ice ages and back, when natural phenomena caused changes in the Earth’s temperature. They have, however, not been able to adapt to the changes being caused by humans. These changes have happened too fast when compared with natural planetary changes. Phytoplankton has simply not had the time to evolve.
Below you can see why the decline of phytoplankton is directly attributable to a changing climate.
Warming of the ocean
As the planet heats up, so does the water in our oceans. According to NASA, a warming ocean reduces the mixing between surface water and deeper nutrient-rich water in the oceans. This reduces the nutrients available near the surface. Hence, there are lesser nutrients available in the phytoplankton-rich top surface of the water.
A warming ocean creates conditions similar to growing food on barren land, meaning productivity would be extremely low.
Ocean Acidification
The increased carbon dioxide in the atmosphere increases the dissolved carbon dioxide in the ocean water. This further increases the acidic levels of the ocean. The pH levels of the oceans have already dropped significantly and a further drop is expected by the 2100s.
According to a team of researchers from MIT, this is having multiple negative impacts on the phytoplankton. Many species are expected to become extinct while some will have to migrate. These migrations are expected to be towards the poles, so densely populated zones of the tropical oceans will lose a major food source.
Increased Salinity
Climate change has increased ocean salinity by nearly 4%. While this figure may seem small, it is important to understand the vastness of the oceans. Causing a 4% shift in such a quantity of water would require significant greenhouse gas emissions. Unfortunately, we have done just that. If total global heating increases to 2–3 degrees Celsius, these figures could rise to nearly 25%.
Saline water is heavier and moves deeper into the ocean. This reduces the nutrients available at the ocean surface, which once again harms the phytoplankton population.
In half a century, we have managed to kill almost 40% of all phytoplankton in our oceans, and further warming would only make this worse.
If the phytoplankton were to indeed die, it would be the end of almost all marine life on Earth. With that, a major source of our food would disappear. That, however, is not the only concern. Without them, the capacity of our oceans to serve as carbon sinks will diminish greatly, which would further broaden the scope and impact of climate change. Not only this, the air around us will lose a lot of oxygen. Consequently, life on Earth itself would be challenged and humanity’s days would become numbered.
Saving the phytoplankton is therefore a significant step in maintaining the delicate balance of life on Earth. As long as we continue to emit large amounts of carbon, the conditions that are causing the demise of the phytoplankton will persist. Hence, the only way to save these organisms is to reduce our emissions. Even then, it will take decades for their numbers to increase.
Unfortunately, we cannot save the phytoplankton without stopping climate change, something that we seem all too determined to do nothing about. We are ultimately altering the basic conditions they need to survive. If they die, in time, so will we.
