Humpback whales at surface. Photo Credit: Lynsey Smyth/Wildscreen Exchange

Humpback whales at surface. Photo Credit: Lynsey Smyth/Wildscreen Exchange

Without life below water, there would be no life on land for wildlife or people. Every second breath that humans, elephants, rhinos, crocodiles, penguin, hyena and almost all life on earth needs, is thanks to the oxygen produced by the ocean. For us at Wild Tomorrow Fund, this is the key message for World Wildlife Day 2019, a day focused this year on ocean biodiversity.

While we more often marvel at the diversity of life on land: the herds of elephants, the spectacle of mass migration in the Serengeti, and the thrill of the hunt of a lion on land, underwater biodiversity numbers to the billions of species - an estimated 70% of all life on our planet. The mysterious ocean has its own incredible and unique array of life, much of it still unexplored. We know more about the moon than we do about the world below the waves.

It is microscopic life in the ocean that sustains life on Earth. Simple one-celled plants that live at the ocean’s surface, called phytoplankon, produce an incredible 70% of the air we breathe. Also known as microalgae, phytoplankton together with other marine plants such as kelp and plankton, produce oxygen as a byproduct of photosynthesis. One type of phytoplankton, Prochlorococus, is so small that millions can fit into a single drop of water, yet produces one fifth of our oxygen.

But the ocean is running out of breath, scientists warn. Climate change is putting the ocean’s phytoplankton in danger. Already, gradually warming ocean waters have killed off phytoplankton globally by a staggering 40 percent since 1950. “Climate change already poses serious problems for marine life, such as ocean acidification, but deoxygenation is the most pressing issue facing sea animals today,” said Dr Oschlies, an oceanographer at the Helmholtz Center for Ocean Research Kiel in Germany, whose team tracks ocean oxygen levels worldwide. After all, he says, “they all have to breathe.”

Not only is the ocean producing the air we and marine animals breathe, it has also been working overtime to absorb the increased carbon dioxide and other harmful greenhouse gases we have been emitting into the atmosphere. The ocean has been playing a disproportionately large role as Earth’s thermostat. Across the past 30 years, over 90% of warming has been absorbed by the oceans (Trenberth & Fasullo 2013).

Ocean warming is not the only clear and present danger to marine life today. Ocean life is already under threat due to unsustainable fishing, habitat loss, and pollution - including plastic pollution. These impacts are already impairing the ocean’s capacity to maintain the resilience of its marine ecosystems.

Abdoulaye Mar Dieye, UN Assistant Secretary General and Director of UNDP’s Bureau for Policy and Programme said, “Oceans regulate our climate, produce half the oxygen we breathe, provide nourishment for 3+ billion people, and absorb 30% of carbon dioxide released into the atmosphere and fully 90% of the heat from climate change. To ensure that oceans and marine species are preserved and protected, nature-based solutions that bring together public, private and civil society partners need to be replicated and scaled-up.”

To put it simply, the ocean is a life support system for Planet Earth. World Wildlife Day is an opportunity to think about oceans and their incredible importance to all life on earth, including our own. If global greenhouse gas emissions are not reduced, we will place even more stress on the oceans, which will impact the human species as well, who “sit as an unsustainable super-predator at the very top of the marine food web” (Darimont 2015). We must protect oceans and act on climate change, at our own peril.

All is connected in the wonderful diversity of life on Planet Earth, both on land and below the surface of the ocean, from the smallest single-celled phytoplankton to the heaviest elephants and the tallest giraffes. World Wildlife Day #WWD2019 is an opportunity to raise awareness of the role of the ocean in sustaining life on earth, and to work harder to protect it.


Darimont, C., Fox, C., Bryan, H. & Reimchen, T. (2015). The unique ecology of human predators. Science 349(6250): 858-860

Poppick, Laura. 25 February 2019. The Ocean is Running out of Breath Scientists Warn. Scientific American.

Trenberth, K. E. and Fasullo, J. T. (2013). An apparent hiatus in global warming?. Earth’s Future, 1:19-32.

Tseng, M., O’Connor, M. (2015). Predators modify the evolutionary response of prey to temperature. Biology Letters 11(12): 20150798.

Worm, B., Barbier, E B.., Beaumont, N., Duffy, J E. et al (2006). Impacts of Biodiversity Loss on Ocean Ecosystem Services. Science 3 November 2006: 787-790.

United Nations UNDP Press Release. 19 November 2019.

Wild Tomorrow Fund