The ocean — at the heart of the Earth System, essential for human survival
It is very hard to overstate the importance of the global ocean, which encompasses every sea and ocean on our planet. A critical player in the Earth System, the ocean is central to climate regulation, the hydrological and carbon cycles and nutrient flows, balances levels of atmospheric gases, and is a source of raw materials vital for medical and other uses.- The ocean provides the oxygen in every second breath we take, has absorbed approximately 30% of the CO2 and 80% of the additional heat we have generated in the past 200 years, and is the primary source of animal protein for over 2.6 billion people.
If the Earth is thought of as a human body, the ocean is — among other things - the driver of its circulatory and respiratory systems. If it became unable to perform the host of essential functions we all count on, the planet would become uninhabitable.
As we grow ever more aware of the full extent of the impacts that human activities are having on the planet, some scientists are stressing the need to respect certain ‘planetary boundaries’ if we are to preserve the favourable conditions which have allowed human civilization to flourish, i.e. continue to enjoy ‘a safe operating space for humanity’. The ocean is a fundamental element in this analysis, and a healthy ocean is necessary to prevent us crossing tipping points into undesirable, potentially uninhabitable, and uncontrollable conditions.
The ocean must therefore be considered from a long-term, holistic perspective that respects its position within the entire Earth System, and its resources carefully managed and used in order to prevent further widespread damage to marine ecosystems and the vital functions they fulfill. Unfortunately, this is a realization that is only just beginning to take root, following many decades of relentless exploitation, and shortsighted and disjointed policies, which have left the ocean in a critical state of health.
The State of the Ocean: multiple threats, major challenges
The ocean is being pushed beyond the limits that the marine environment can sustain. Human activities — from overfishing to the increased use of plastics to the burning of fossil fuels — are subjecting it to a multitude of interconnected threats that are unprecedented in human history. The ocean has born the brunt of careless and unsustainable human exploitation for too long, and experts increasingly warn that unless action is taken urgently to address the most pressing threats and build the resilience of key marine ecosystems and species we risk catastrophic (and potentially abrupt and unpredictable) changes — such as mass coral bleaching, collapse of major fish stocks and devastating shifts in weather patterns — that will prevent the ocean from providing its life giving services to humanity and fulfilling its functions within the Earth System. Major threats include:
Ocean warming: increased temperatures in the ocean, caused by rising global temperatures as a result of climate change, have been detected at depths of more than 3,000m. There is strong evidence that warming ocean temperatures are responsible for increasing the intensity of tropical cyclones, as well as disrupting global fisheries by causing valuable fish stocks to migrate towards cooler waters nearer the poles. Warmer waters are also a major threat to coral reefs, making them both more vulnerable to bleaching and other damage, and more susceptible to the effects of acidification. Some researchers have indicated that at 1.7°C above pre-industrial temperatures, all warm-water coral reefs will be bleached, and by 2.5°C they will be extinct.
Ocean acidification: the ocean has acted as a giant buffer, helping to cushion the effects of climate change caused by our growing CO2 emissions by absorbing around 30% of carbon emissions since the Industrial Revolution. But at a huge - and not yet fully understood - cost to fundamental ocean chemistry and ecosystems. In the past 200 years, as a direct result of increasing levels of CO2 in the atmosphere — the ocean has experienced a 30% decrease in its mean pH levels. At current rates, pH will drop by up to 200% more by 2100, a rate of change ten times faster than anything else suffered by the ocean for 55 million years, and which will reduce the ocean’s capacity to absorb carbon in the future, and threaten the food security of communities reliant on vulnerable species of shellfish. The threat of ocean acidification is considered to be one of the nine so-called Planetary Boundaries which humanity must avoid exceeding, but which is currently not being addressed as global action to cut CO2 emissions flounders.
Unsustainable use of marine resources: FAO estimates that 85% of fish stocks are fully exploited, over exploited, depleted, or recovering from depletion—the highest proportion ever recorded. Additional climate-related fishing losses are being concentrated in tropical least-developed countries, many of them in Africa and South-East Asia, further effecting fishing communities. Illegal, unreported, and unregulated (IUU) fishing is responsible for the loss of between 11 million and 26 million tonnes of unaccounted for fish, out of a total world capture of approximately 80 million tonnes. Destructive fishing practices — including dragging nets the size of football fields across the sea bed — are causing tremendous damage to breeding, nursery and fishing habitats for marine life. Once abundant iconic marine species are disappearing from the ocean. Sharks are in particular trouble: studies estimate that up to 73 million sharks are killed every year to supply the fin trade, and they are often the victims of bycatch. Annual population declines as high as 70 to 80 percent have been reported for some species.
Hypoxia/Anoxia: agricultural run-offs mean that levels of nitrogen and phosphorus in the oceans have trebled since pre-industrial times, leading to massive increases in the numbers and expanse of deoxygenated coastal ‘dead zones’. There are well over 500 such zones, and this number is increasing fast, spurred on further by rising sea temperatures.
Sea-level rise threatens the very existence of some SIDS (small island developing states) and coastal cities, and could cause vast areas of land currently used for food production to become inundated. The pace of global mean sea level rise is accelerating: levels rose by approximately 1.8mm per year over the last 50 years, but doubled to 3.1mm per year in the 1990s, and were 2.5mm per year in the period 2003—2007. Estimates vary, but there is a growing consensus that mean levels could rise by over 2 metres before 2100 if further temperature increases stimulate the complex feedback loops which govern the patterns of polar ice melt. Summer sea ice in the Arctic has been decreasing by 7.4% per decade since 1978.
Marine pollution is now a major problem in over half the total expanse of the global ocean, and is weakening the resilience of species and habitats to other threats, such as acidification, and reducing their capacity to cope with climate change. Plastic is becoming even more of a problem, as are chemical pollutants such as the flame-retardant chemicals and synthetic musks found in detergents which recent studies have traced in the polar seas. These chemicals can be absorbed by tiny plastic particles in the ocean and ingested by marine creatures such as bottom-feeding fish. Plastic particles can also transport algae from one location to another, increasing the occurrence of toxic algal blooms, which are also caused by nutrient-rich agricultural run-off.
Multiple Stressors: over 40% of marine ecosystems are already simultaneously facing several of the major pressures outlined above, creating a perfect storm of interconnected ‘multiple stressors’ which is placing the very chemical and thermodynamic foundations of the ocean in jeopardy, and increasing the risk of catastrophic outcomes — such as a mass extinction of vulnerable marine species. There are complex feedback loops at play in the ocean, and there is an urgent need to fill remaining knowledge gaps concerning how the different threats interrelate in different ecosystems. It is already evident that the co-existence of more than one threat can create impacts that are greater than the sum of their parts; this is known as a ‘synergistic response’. For example, the bleaching of coral reefs has been shown to occur more frequently in response to a combination of stressors acting simultaneously — and often synergistically. The combination of global stressors, such as increasing temperature and acidification, interacting with local stressors, such as pollution and deoxygenation, presents a particular danger to coral reefs and other vulnerable ecosystems.
The cumulative effect of overlapping threats is a key reason why their impacts are being observed at a faster rate than previously predicted. It is therefore paramount that they be addressed together and across all scales from local to global, instead of on an issue-specific basis as is the norm today.
Climate change: Rising emissions from fossil fuels is the direct cause of the global stressors impacting on the ocean — acidification, warming and sea-level rise, the effects of which are already exacerbating and accelerating the impacts of other threats such as pollution and overfishing.
The Value of the Ocean: what do we stand to lose?
As the life giving pump of the Earth System, and home to hundreds of thousands of species, the ocean itself is so vital to our lives and futures that it is impossible to assign a value to it. However, many of the services it provides do have a tangible — and in many cases massive — economic value, and, with every year that passes without strong action to reverse the tide of exploitation, the cost of preserving and rehabilitating a healthy ocean is rising. Ocean economics is a subject currently gaining increasing — and long overdue - attention.
The UN has calculated that over three billion people depend on marine and coastal biodiversity for their livelihoods, and estimates the market value of marine and coastal resources and industries at $3 trillion per year, or about 5% of global GDP.
The most widely recognised economic contribution of the ocean is fisheries. The global value of fish catches at landing is approximately $100 billion, and the wider economic activities related to fishing reach a value of about $240 billion. Marine fisheries directly or indirectly employ over 200 million people worldwide, and many coastal communities depend almost entirely on fishing for both their livelihoods and as their main source of protein, as well as it being the foundation of their cultural heritage and identity.
Poorly managed fisheries cause economic losses in the tens of billions of dollars every year. Subsidies for fishing are contributing to the rapid depletion of many fish species and are hindering efforts to save and restore global fisheries and related jobs, causing ocean fisheries to generate US$ 50 billion less per year than they could. In addition, illegal, unreported, and unregulated (IUU) fishing is responsible for the loss of $10 billion to $23 billion a year — the value of the 11 million to 26 million tonnes of fish that are unaccounted for, out of a total world capture of approximately 80 million tonnes.
Environmental degradation and mismanagement have other, less visible and still under-appreciated, economic consequences. For example, the destruction of habitats which protect the coastline, such as coral reefs and mangrove forests, causes enormous losses. Coral reefs alone have been estimated to provide goods and services worth up to $375 billion per annum; with the economic value of coastal protection from a coral reef calculated at $25,000 per hectare per annum. Reef-based tourism now brings in tens of billions of dollars every year.
Another emerging concept within ocean economics is that of ‘Blue Carbon’ — i.e. the value of the carbon stored in marine ecosystems such as mangroves, salt marshes and sea groves. Some experts believe that total carbon deposits per square kilometer in these ecosystems could be up to five times those stored in terrestrial forests. Today, these ‘Blue Carbon’ ecosystems are being degraded and destroyed at a rapid pace resulting in globally significant CO2 emissions. The UN estimates that between 1980 and 2005, 35,000 square kilometers of mangroves were destroyed globally — an area the size of Belgium. The management of these ecosystems, through conservation, restoration and sustainable use has the potential to be a major tool in reducing carbon emissions, but the value of this ‘Blue Carbon’ is not being awarded sufficient attention, and remains wholly unrecognised by many governments and sectors. The valuation of ‘Blue Carbon’ activities and ecosystems could be pursued by the UNFCCC and incorporated into other carbon financing mechanisms, as terrestrial forests already are.
2012 study coordinated by the Stockholm Environment Institute called ‘Valuing the Ocean’ has provided the first estimates of the ocean values we stand to lose if we do not address climate change. It calculates the cost of lost ocean value (in terms of impacts to services such as fisheries, storm protection and tourism) under different CO2 emissions scenarios. By 2100, the estimated annual cost of ‘business as usual’ policies, projected to lead to an average temperature rise of 4°C, is estimated to be US$1.98 trillion. By contrast, rapid emission reductions, whereby temperature increase is limited to 2.2°C, would ‘save’ almost $1.4 trillion a year. While these figures are preliminary — and tell just part of the story — by pricing the difference between “our hopes and our fears” this analysis hopes to encourage policy-makers to pay greater attention to the value of ocean services, and recognize that the cost of inaction increases greatly with time.
