The surface of our Blue Planet is 71% ocean – benign, mysterious and threatening in equal measure. Throughout the 4 billion years of their existence the oceans have been robust and durable, a source of constancy for Earth, acting as a buffer against climate extremes and an ever-efficient chemical recycling plant. Today, however, the oceans are in a state of change directly as a result of human actions. We harvest the seas for their abundant food, mineral, and energy resources. Ninety-nine percent of all internet communications are transmitted by submarine cables that stretch over hundreds of thousands of kilometres across the seafloor. The coastal regions are home to more than 3 billion people and that figure is set to double by 2050. Marine tourism is a booming multinational industry, from polar to tropical seas. The 10 billion people we expect to populate the planet by the end of this century will continue to need adequate and sustainable energy, mineral resources, and food supplies. These are among the most pressing issues of the 21st century and for each of them the oceans hold part of the solution.
In 2015, the United Nations set out 17 Sustainable Development Goals for the Planet. Goal number 14 is entitled Life Below the Water and sets out specific targets by which we must ‘conserve and sustainably use the oceans, seas and marine resources for sustainable development.’ Whereas we are still a long way from achieving most of these targets, it is both promising and significant that they are recognised and enumerated in this way. Once we know what is required it is always easier to set about achieving it.
Indeed, the seas are neither so large nor marine ecosystems so robust that they can withstand these pressures without change. The pressures on our coastline from urban sprawl, industrial development, and recreational demand, are without precedent. From microplastics and waste islands to organo-toxins and dead seas, the dumping of domestic and industrial waste into the oceans is rife. Sea levels are on the rise, as global climate warms and ice melts, with the most adverse effects on the world’s poorest and most vulnerable. Ocean acidification, coral bleaching, hotter seas, and extreme weather events are all on the increase. The oceans, rather than the diminishing rainforests, are the true lungs of the world, and yet they are losing oxygen at an alarming rate.
Whatever the societal challenge for the oceans, we need to be fully aware that marine ecosystems are profoundly fragile, that the current chemical, temperature and oxygen balance can be severely stressed, and that all resources have different limits to their renewability. Sustainability can only be achieved through a more equitable distribution of resources, a limit to excess and firm management of the Earth’s environment. If we understand the oceans and the changes they are undergoing, and act on this knowledge, then there is a clear window of opportunity that improved stewardship can lead to a more benign and sustainable future.