THE WORLD OF WATER: A PERSONAL JOURNEY – Part II: The Ocean and its Waves

For any alien traveller, Earth would be a beacon in the vastness of space. Of all the planetary bodies in our solar system, the blue marble we live on is the only one with liquid water covering most of its surface. It is common cause amongst biologists that the presence of liquid water is a sign for the possible existence of life on any planet in the universe. Therefore, to a traveller through space Earth stands out as a likely home for the organic complexity we call life.

Water covers over 70% of Earth’s surface, an expanse of approximately 361 million square kilometres. With an average depth of between three to four kilometres, the single ocean of our planet holds about 1, 34 billion cubic kilometres of water. So, a watery world indeed, but salty too. The ocean that comprises over 97% of Earth’s water has accumulated dissolved minerals throughout its more than four billion-year existence, so that of seawater’s mass today 3, 5% is made up of dissolved salts and other minerals.

Our planet’s single ocean forms over 90% of the biosphere, that thin, tenuous layer of the Earth’s surface that can sustain life. It is no surprise then that the ocean is home to more than 93% of all presumed life-forms on our planet. Presumed living species that is, because we have hardly bothered to explore this vast realm, most of which exists in complete darkness – sunlight can not penetrate seawater to a depth greater than a hundred metres or so. It is an indictment to the often-misguided human endeavour that we know less about our ocean than we know about the moon or the surface of Mars; we have explored only around 6% of this immense and vitally important region of our own home.

We owe our existence to the ocean. The first organisms, the first living beings, evolved in seawater between 3, 5 and 4 billion years ago. These are our ancestors. Since the evolution of photosynthesis, first be cyanobacteria and much later by algae, the surface waters illuminated by sunlight made available the production and release of oxygen into the atmosphere as a waste product of this process. For aeons algae have absorbed vast amounts of carbon dioxide from the atmosphere, thereby mitigating (up until recently in Earth’s history, that is) the accumulation of heat by the planet.

The majority of sunlight striking exactly half of the Earth’s surface at any moment in time irradiates the ocean. As the ocean surface heats up, currents and transfer of heat to the atmosphere redistribute this energy, driving the planet’s climate systems and thus doling out precipitation around the globe. Like a gigantic conveyor belt of energy, the ocean helps regulate Earth’s land temperatures, acting as coolant in summer and heater in winter. Without this global re-distribution of heat, surface temperatures on land would be unbearable for the substantial majority of terrestrial organisms.

Other than the fathomless immensity of the ocean, the most spectacular feature of this underappreciated waterworld are its waves. As the ocean is ruffled by the nudging and shuddering of the dynamic rocky planet on which it rests, and as it is whipped by winds of its own making, the surface water undulates. These wrinkles travel over the expanse of the ocean, the upper water column bobbing up and down as it is lifted into crests and dropped into troughs. When the undulations reach shallower water at the margins of islands and continents, as though wishing to greet the land first, the crests bend forward as a result simply of the deeper water slowing down as it rubs and scours over the ocean floor in these shallow zones.

For me personally, waves represent a myriad of marvels. The process of wave action is well understood scientifically; it is a continual process and relatively simple in mechanism. Yet each wave is unique. The encounter of each wave while ‘wave-watching’ is unique too. The experience ranges from perception of the susurrations of gentle wavelets lapping at sandy beaches to the thunderous cacophony of invincible titans assaulting the very continents themselves. Depending on the time of day, the quality of sunlight, the mood of the tides, and the weather, my experiences and the concomitant thoughts and emotions provoked by the watching of waves flit from tranquil bliss to atavistic fear. And all the while the waves remind me of my own, very special history on Earth: from my ocean-borne ancestors billions of years ago to my present insignificance on this unique planet, Earth.