How Global Warming Affects Marine Life

My family and I moved to India in 2008. I vividly remember my father telling me that Bangalore was one of the only cities in India where we could make do without air conditioners in the summer. The memory never fails to surface as the temperature increases each summer.

Scientists estimate that global warming is increasing the temperature of our planet's surface by 0.2°C per decade due to past and ongoing emissions. Data has revealed that the planet’s average temperature has risen by 0.85°C between 1880 and 2012. The earth has warmed by 0.87°C in the decade 2006-2015. While this increase in temperature manifests itself in our increased usage of the air conditioner, did you know that it also negatively impacts marine life?

Polar ice caps melting is often the first thought that crosses our minds when we think about climate change. Recent studies show that Antarctica is melting from underneath. This phenomenon is due to submerged ice melting rapidly as the oceans warm up. When land-based polar ice melts, it finds its way to the sea. Ice that forms in the polar seas, however, does not affect the sea levels when they melt. Water expanding when it is warm is also one of the unsung causes for the rise of sea levels. Sea level rise is accelerating at an estimated rate of about one-eighth of an inch every year. 10% of the world's population are directly threatened by sea-level rise because they live below sea level. Small island nations stand to be wiped off the map. The people of the island Kiribati are among the first of the island nations to seek refuge against sea-level rise.

The melting of the polar ice caps also has a significant impact on aquatic wildlife. Algae, the foundation of the Arctic food web, directly depends on the presence of sea ice. As the ice diminishes, so does the population of algae. Thus, affecting the Arctic food chain. Walruses, seals, penguins, and other species relying on ice lose habitable areas for their survival. Antarctic krill, the source of food for many seabirds, relies on ice for its survival. The population of Antarctic krill has declined due to the melting of sea ice. Thus, also resulting in the decline of the species that rely on them.

In more tropical climates, higher temperatures and warmer waters cause coral bleaching. Microscopic algae(zooxanthellae) live in symbiosis with their host organisms(polyps) that reside on the coral. Coral bleaching is a process by which the coral colonies lose their colour. This can happen either due to the loss of pigments from the zooxanthellae or because the zooxanthellae have been expelled. Coral reefs die due to this. When reefs die, the reef ecosystems which people and wildlife depend on, deteriorate. Warmer water also threatens to cause mass migration of marine species like most fish and cephalopods (species such as octopus and squid). Mass migration of marine life negatively affects the lives of the 3 million people relying on them for income.

We know that carbon dioxide emissions have increased drastically over the last decade. As a result, oceans have been absorbing excessive amounts of carbon dioxide. The water then becomes carbonic acid which lowers the pH value of the water to 2.52. This acidic water is fatal to the fish and other aquatic life that call the ocean home. On a brighter note, an unexpected result of the global pandemic is the dramatic decrease in the amount of carbon dioxide released into the air. This phenomenon has also led to lesser absorption of carbon dioxide by seas and oceans.

Is there a lesson for us in all this? Will we be more aware when our life returns to some semblance of normality? Hopefully, politicians and governments will pay more attention to climate change in the future. Do I think that will happen? Maybe. Do I hope that will happen? Definitely.


Author: Aditi Krishnan

Editor: Arjun Krishnan

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