The Ocean is Changing Colour
- DHS ECO TEAM
- Nov 25, 2020
- 3 min read
By the end of the 21st century, the ocean will be in the process of changing in colour. 50% of it will be going from blue, shifting towards green and the other half would be shifting towards a deeper blue.
What makes the ocean appear blue?
Water has an intrinsically blue hue. This means that it absorbs some colour in the visible light spectrum, but has a weak absorption of blue, thus reflecting it and making the ocean appear blue.
Why will some ocean turn green, whereas some turns blue?
Phytoplankton, a type of microscopic algae in the oceans, are responsible for 50% of global photosynthesis and contain chlorophyll that have a green colour. The growth of phytoplankton due to climate change will be the direct leading cause of green bodies of water. Currently, some large expanses of sea, with high populations of phytoplankton, are already a deep blue-green colour which will have an intensified green colour in the next 80 years due to climate change.
These algal populations in the oceans can vary depending on the levels of CO2 in the atmosphere. Phytoplankton also undergo nitrogen fixation, the conversion of atmospheric nitrogen into organic compounds, which help with survival and reproduction. The higher the atmospheric levels of CO2 and nitrogen, the more rapid the growth of phytoplankton. This is because these gases will allow them to photosynthesize at a faster rate, providing them with more growth products and leading to phytoplankton blooms.
Therefore, due to the increased levels of greenhouse gases in the Earth’s atmosphere, phytoplankton populations will increase in high latitude areas, for example, in the ocean surrounding the Arctic Circle and the North Pole. However, other factors, such as increasing temperature, will stunt growth for phytoplankton. The phytoplankton growth will only occur in colder regions, as phytoplankton have an optimum temperature for growth which varies between 0°C and 14°C.
This means that phytoplankton would mass migrate to high latitudinal areas with temperatures below 15°C. Presently, the warmest ocean temperatures are at 35°C and are rising by approximately 0.13°C per decade. This could also contribute to lowered amounts of nutrient being transferred to the surface layer, where the phytoplankton live for maximum sunlight. Warming ocean temperatures will kill out swathes of this algal population in warmer oceans. The lack of phytoplankton between the Tropics will allow the water to return to its intrinsic colour and it will appear a deeper blue.
Why is this worrying?
As mentioned earlier, phytoplankton are responsible for 50% of global photosynthesis, and this may reduce if large populations of phytoplankton are wiped out by rising sea temperatures, one of the many results of harmful anthropogenic activities. This would then reduce the amount of CO2 being taken in by phytoplankton, increasing the atmospheric carbon dioxide. It would also mean less oxygen is given out by photosynthesis, a vital gas for the survival of much of the fauna on the planet.
The food web in the ocean, supported by phytoplankton, will also be negatively affected and could lead to fish populations dying out and other animals further along the food chains. This reduces the biodiversity in the ocean.
Evidence for changing ocean colours
Scientists used an updated computer model to investigate the influence of phytoplankton on reflected light with satellite measurements. With this model, they found that wavelengths of light of green responded quickest in areas with phytoplankton.
What can you do?
There are many things you, as an individual, can do to reduce your carbon footprint to help reduce carbon dioxide emissions. This includes limited vehicle use, less energy and water wastage and the use of recycled materials.
Tips to save the ocean
1) Reduce your carbon footprint.
The website link below allows you to calculate your carbon footprint, and you can use this as a guide as to where you can start on reducing your carbon footprint:
2) Use fewer plastic products.
Many plastics are not biodegradable, meaning they deposit in the ocean, kill marine animals and significantly reduce biodiversity. You could reuse your plastic items, for example, plastic water bottles and plastic bags.
3) Spend just 2 minutes taking care of the beach.
If we all clean up after ourselves and pick up any harmful plastics on the beach, we can make a huge positive impact on marine life. Check out this video on the BBC News website for more detail:
Thanks for reading and stay tuned for our next post!
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