Home to millions of plants and animals, the ocean is a very large part of our planet, covering more than 70% of the Earth’s surface – no coincidence we call it our blue planet!
Despite the importance the ocean play for our survival, from weather driver to carbon sink to source of sustenance and income for millions, about 80% of the ocean is unmapped and unexplored.
Today I want to explore its characteristics and share my next volunteering experience – the Ocean Lovers Festival, 22 to 24 April 2022 @Bondi Beach (Sydney, NSW, Australia).
Bear with me with the basics. I need to start from the rise of temperatures; you will understand why in a moment!
Earth is warming – The basics
Our planet is surrounded by the atmosphere, a thin layer of gases vital to life on Earth. When the sun’s radiation reaches the Earth, some of it is reflected back into space, and the rest is absorbed by lands and oceans heating the planet. This heat radiates from Earth to space, and some of it is trapped by the greenhouse gases (GHGs) such as carbon dioxide (CO2) and methane (CH4) in the atmosphere. It is the natural greenhouse effect, and it keeps the Earth warm. Without it, we would have an average temperature of –(minus) 18 °C – hard to sustain life as we know it!
And for a very long time (well before human civilization), the concentration of carbon dioxide in our atmosphere was between 200 and 280 parts per million (ppm).
The problem? Since the Industrial Revolution, our activities (the burning of fossil fuels and deforestation) have increased the amount of carbon dioxide (CO2) in that thin layer of gases (that is, the atmosphere).
Thanks to our activities, the amount of CO2 in the atmosphere is now past 410 ppm. As a result, GHGs are trapping extra heat, causing the Earth’s temperature to rise (this is the additional greenhouse effect due to human activities). We are past 1.2C of warming, headed towards 1.5C, which will happen sometime around 2040/2060 (IPCC scenarios).
The ocean’s role in absorbing the extra heat
The oceans and seas absorb more than 90% of the extra heat (additional greenhouse gas effect described above), causing ocean temperatures to rise.
Ocean water is constantly evaporating, increasing the temperature and humidity of the surrounding air to form rain and storms. Warmer oceans mean that storms are more severe, and cyclones and hurricanes become more powerful.
The ocean doesn’t just store solar radiation; it also helps to distribute heat around the globe through ocean currents: movements of ocean water in a continuous flow, mainly created by surface winds but also partly by temperature and salinity gradients, Earth’s rotation, and tides. The increase of freshwater (e.g., Greenland’s melting ice sheet) could disrupt the water cycle even more and reduce the ocean’s capacity to absorb more carbon and heat.
The increase in ocean temperatures poses a significant threat to coral reefs and marine biodiversity. Coral reefs are affected by increasing temperatures which cause coral bleaching and increase their risk of mortality. Researchers are seeking ways to preserve fragile, ailing ecosystems such as Australia’s Great Barrier Reef.
Ocean warming is also a serious risk to millions of people that rely on fish for food and income.
Sea level rise
As the ocean’s water warms, it expands, contributing to sea-level rise (thermal expansion). In addition, global warming is causing the loss of ice from glaciers & ice sheets. A large fraction of the Earth’s freshwater is frozen, stored in glaciers and the Greenland and Antarctic ice sheets. When this ice melts or breaks off at the glacier’s end, the water/iceberg goes into the oceans, resulting in rising sea levels.
If Greenland were to melt completely, it would cause the sea level to rise by seven meters. In addition, when the ice melts, the surface, once white (which reflects the sun’s radiation), becomes darker sea, which absorbs more sun rays. Since 1900, the global sea level has risen by 20 cm.
Rising temperatures also affect vegetation and reef-building species such as corals and mangroves, which protect coastlines from erosion and sea-level rise. Sea-level rise is a real threat; it will destroy housing and infrastructure, forcing people to relocate.
Building seawalls will not be enough to protect us from sea level rise. We will need to rely also on nature-based solutions for adaptation; coastal ecosystems like mangroves and coral reefs are natural barriers against rising seas and storms.
The ocean as carbon sink
About half of the CO2 we emit every year is absorbed by carbon sinks. Half of the CO2 stays in the atmosphere, heating our planet. Around a quarter of CO2 is absorbed by the ocean and the rest by the vegetation via photosynthesis.
When CO2 is absorbed by seawater, a series of chemical reactions occur, resulting in more acidic seawater (pH drop). When the pH drops, it becomes harder for calcium carbonate seashells, such as calcareous plankton and coral skeleton, to grow (because carbonate ions are less abundant). We are changing the chemical equilibrium, which can lead to severe consequences for marine life and potentially affect the whole ocean food chain (plankton is at the base of the ocean food chain).
Carbon is also sequestered by mangroves, seagrass, corals, and salt marshes. The more damage we do to our ocean and coastal areas, the harder it is for these ecosystems to offset carbon dioxide (for us) and remain resilient (protect communities from storms and provide food).
Plastic Pollution
And, of course, there is plastic pollution. Plastic pollution poses one of the biggest threats to the ocean. Plastic is mainly produced by fossil fuels, and it is not biodegradable. Over time, it breaks down into tiny pieces known as micro & nano plastics (depending on the size), which have significant negative impacts on marine life and us (humans).
Plastics directly harm animals as they ingest these tiny pieces, believing it is food, and have wide effects on biodiversity and ecosystem functioning.
What about the impacts on us?
New research shows that “people are inhaling microplastics through the air, consuming them through food and water and even absorbing them through the skin. Microplastics have even been found within our lungs, livers, spleens, and kidneys, and one study recently found microplastics in the placentas of newborn babies.”
The need to protect the ocean
Now we understand the ocean’s role in tackling climate change. We know that protecting and restoring oceans and coastal ecosystems is vital.
In 2021 we saw the launch of the UN’s Decade of Ocean Science for Sustainable Development, focused on the development of ocean-based solutions for the SDGs. In the next months, keep in mind two major international events: Our Ocean and the UN Ocean Conference.
Want something more local? Yes, Sydneysiders, talking to you!
Taking action: volunteering for the Ocean Lovers Festival
I will be volunteering with the United Nations Association of Australia NSW division at the Ocean Lovers Festival, an annual celebration of ideas, art, music, and solutions showcasing some of the latest innovations, science, state-of-the-art technology for helping the ocean.
If you are in Sydney, lock the date – 22 to 24 April 2022 – and join us at Bondi Beach for a weekend full of free activities & entertainment for the whole family. You will have fun and, as a perk, you will learn something more about the ocean.
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