Awareness of environmental issues is growing globally. Environmentalist thinking has gradually grown since the first Earth Day in 1970. More concrete action needs to be taken to address environmental issues but there is a greater overall awareness of the impact of human activity on the earth's wellbeing.

However, one aspect of environmental degradation often eludes mainstream discourse: ocean destruction. Overfishing, acidification and pollution are having a devastating effect on marine life. Out of sight, out of mind, right? Not quite. Life on our planet is intricately connected to the wellbeing of our oceans and the life harbored within them. Ocean conservation has become more important than ever.

Here are five reasons why oceans are humanity's most precious common heritage

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 Home to ¼ of the World's Species

"Oceans sustain a stunning diversity of life, ranging from the majestic blue whale, the largest living animal, to the Great Barrier Reef – the largest living structure on earth. The latter is so enormous that it can actually be seen from the moon!"

Scientists estimate that there are 8.7 million different forms of life on earth. 2.2 million of these are harbored by oceans. Interestingly, 91% of the species in the oceans haven't been named or catalogued, according to a scientific study cited in the Guardian. Theories also point to life on earth originating from within oceans.

Oceans sustain a stunning diversity of life, ranging from the majestic blue whale – the largest living animal – to the Great Barrier Reef – the largest living structure on earth. The latter is so enormous that it can actually be seen from the moon! The Great Reef is extremely rich in biodiversity, home to some 9,000 species. There is much ocean life we are yet to discover– 6 new fish species were discovered in just 2016.

Heartbreaking Fact: Oceana, one of the biggest nonprofits fighting to protect the oceans, is stressing that human influence is altering marine ecosystems and destroying marine biodiversity. Less than 4% of oceans remain unaffected by human activity. Two-thirds of the Great Barrier Reef, for example, have been damaged by coral bleaching. Scientists believe this has been exacerbated by climate change. Overfishing and pollution are also putting immense pressure on marine ecosystems.

 Essential to Human Prosperity and Survival

Humans and oceans are inextricably linked for several reasons. The global economy relies heavily on maritime transport. In fact, 90% of world trade is conducted by sea. Oceans produce $2.4 trillion in value for us each year! A lot of us also are concentrated near oceans. Around 40% of the global population lives within 62 miles of coasts and half the US population resides in coastal areas. Billions of people rely on seafood as their primary source of nutrition – it is estimated that fish account for 16% of world animal protein consumption by humans. Finally, we can't breathe without oceans! Scientists suggest that 50-85% of the earth's oxygen comes from oceanic plants phytoplanktons.

Uplifting fact: Sustainable fishing can feed the burgeoning world population, as the book Perfect Protein argues. According to Oceana, there are at least 420 million hungry people in major fishing countries and 700 million could rely on a daily seafood meal by 2050 if we put an end to overfishing.

 Earth's Largest Habitat

Oceans are the earth's largest habitat. They make the our planet unique: No other planet in our solar system has liquid water. 71% of the earth – 140 million square miles – consists of oceans. The biggest oceans – by area and volume – are the Pacific Ocean, Atlantic Ocean and the Indian Ocean, in that order. Curiously, we have only explored less than 5% of the ocean realm!

Fun fact: The deepest part of the ocean, the Challenger Deep in the Mariana Trench, is almost 11 kilometers or 6.8 miles below sea level. By contrast, the average depth of the ocean is 2.3 miles. For perspective, you could vertically submerge 36 Eiffel Towers or 25 Empire State buildings in this part of the ocean!

 Keeping the Earth Healthy and Habitable

"Did you know that oceans have absorbed around half of the CO2 emitted by humans since in the Industrial Revolution?"

Oceans absorb most of the heat that the earth receives through sunlight and then distributes this heat across the earth through currents. In this way, oceans regulate and stabilize climate patterns. Without the oceans, climate patterns would be more extreme and most of the earth would be inhabitable: it would be much hotter nearer the equator and much colder nearer the poles.

Interesting fact: Chances are that you might be aware that humans are releasing greenhouse gases into the earth's atmosphere at an unprecedented rate, in large part due to extensive fossil fuel use. But did you know that oceans have absorbed around half of the CO2 emitted by humans since in the Industrial Revolution? Scarily, however, our impact on marine ecosystems means that oceans are becoming less able to perform this critical function of carbon dioxide absorption.

 Treasure Trove of Hidden Knowledge

Below the surface of the ocean, underwater archaeology has found shipwrecks and relics from distant times, and even lost cities! Underwater discoveries have the potential to utterly change our conception of human history.

Fun fact: The ruins of Thonis-Heraclion, an ancient Egyptian lost city, were located by French underwater archaeologist Franck Goddio in 2000. The port city has been compared to Venice because of its of network of canals and is said to have controlled a considerable amount of trade into ancient Egypt.