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The International Programme on the State of the Ocean Report

 summary on major ocean impacts and stressors, released June 20th 2011

Life in the oceans is at imminent risk of the worst spate of extinctions in millions of years due to threats such as climate change and over-fishing, a study showed on Tuesday.

Time was running short to counter hazards such as a collapse of coral reefs or a spread of low-oxygen "dead zones," according to the study led by the International Programme on the State of the Ocean (IPSO).

"We now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation," according to the study by 27 experts to be presented to the United Nations.

"Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, over-exploitation, pollution and habitat loss, the next globally significant extinction event in the ocean," it said.

Scientists list five mass extinctions over 600 million years -- most recently when the dinosaurs vanished 65 million years ago, apparently after an asteroid struck. Among others, the Permian period abruptly ended 250 million years ago.

"The findings are shocking," Alex Rogers, scientific director of IPSO, wrote of the conclusions from a 2011 workshop of ocean experts staged by IPSO and the International Union for Conservation of Nature (IUCN) at Oxford University.

Fish are the main source of protein for a fifth of the world's population and the seas cycle oxygen and help absorb carbon dioxide, the main greenhouse gas from human activities.


Jelle Bijma, of the Alfred Wegener Institute, said the seas faced a "deadly trio" of threats of higher temperatures, acidification and lack of oxygen, known as anoxia, that had featured in several past mass extinctions.

A build-up of carbon dioxide, blamed by the U.N. panel of climate scientists on human use of fossil fuels, is heating the planet. Absorbed into the oceans, it causes acidification, while run-off of fertilizers and pollution stokes anoxia.

"From a geological point of view, mass extinctions happen overnight, but on human timescales we may not realize that we are in the middle of such an event," Bijma wrote.

The study said that over-fishing is the easiest for governments to reverse -- countering global warming means a shift from fossil fuels, for instance, toward cleaner energies such as wind and solar power.

"Unlike climate change, it can be directly, immediately and effectively tackled by policy change," said William Cheung of the University of East Anglia.

"Over-fishing is now estimated to account for over 60 percent of the known local and global extinction of marine fishes," he wrote.

  • Human actions have resulted in warming and acidification of the oceans and are now causing increased hypoxia. Studies of the Earth’s past indicate that these are three symptoms that indicate disturbances of the carbon cycle associated with each of the previous five mass extinctions on Earth
  • The speeds of many negative changes to the ocean are near to or are tracking the worstcase scenarios from IPCC and other predictions. Some are as predicted, but many are faster than anticipated, and many are still accelerating. Consequences of current rates of change already matching those predicted under the worst case scenario include: the rate of decrease in Arctic Sea Ice  and in the accelerated melting of both the Greenland icesheet  and Antarctic ice sheets ; sea level rise ; and release of trapped methane from the seabed. The ‘worst case’ effects are compounding other changes more consistent with predictions including: changes in the distribution and abundance of marine species, changes in primary production changes in the distribution of harmful algal blooms increases in health hazards in the oceans and loss of both large, long--]lived and small fish species causing widespread impacts on marine ecosystems, including direct impacts on predator and prey species, the simplification and destabilization of food webs, reduction of resilience to the effects of climate change
  • The magnitude of the cumulative impacts on the ocean is greater than previously understood Interactions between different impacts can be negatively synergistic (negative impact greater than sum of individual stressors) or they can be antagonistic (lowering the effects of individual impacts). Examples of such interactions include: combinations of overfishing, physical disturbance, climate change effects, nutrient runoff and introductions of non-native species leading to explosions of these invasive species, including harmful algal blooms, and dead zones; increased temperature and acidification increasing the susceptibility of corals to bleaching  and acting synergistically to impact the reproduction and development of other marine invertebrates ; changes in the behavior, fate and toxicity of heavy metals with acidification ; acidification may reduce the limiting effect of iron availability on primary production in some parts of the ocean ; increased uptake of plastics by fauna , and increased bio availability of pollutants through adsorption onto the surface of microplastic particles ; and feedbacks of climate change impacts on the oceans (temperature rise, sea level rise, loss of ice cover, acidification, increased storm intensity, methane release) on their rate of CO2 uptake and global warming .
  • Timelines for action are shrinking. The longer the delay in reducing emissions the higher the annual reduction rate will have to be and the greater the financial cost. Delays will mean increased environmental damage with greater socioeconomic impacts and costs of mitigation and adaptation measures.
  • Resilience of the ocean to climate change impacts is severely compromised by the other stressors from human activities, including fisheries, pollution and habitat destruction. Examples include the overfishing of reef grazers, nutrient runoff, and other forms of pollution (presence of pathogens or endocrine disrupting chemicals  reducing the recovery ability of reefs from temperature--]induced mass coral bleaching. These multiple stressors promote the phase shift of reef ecosystems from being coral--dominated to algal dominated. The loss of genetic diversity from overfishing reduces ability to adapt to stressors.
  • Ecosystem collapse is occurring as a result of both current and emerging stressors. Stressors include chemical pollutants, agriculture run--off, sediment loads and over--]extraction of many components of food webs which singly and together severely impair the functioning of ecosystems. Consequences include the potential increase of harmful algal blooms in recent decades; the spread of oxygen depleted or dead zones ; the disturbance of the structure and functioning of marine food webs, to the benefit of planktonic organisms of low nutritional value, such as jellyfish or other gelatinous--like organisms  dramatic changes in the microbial communities with negative impacts at the ecosystem scale ; and the impact of emerging chemical contaminants in ecosystems . This impairment damages or eliminates the ability of ecosystems to support humans.
  • The extinction threat to marine species is rapidly increasing. The main causes of extinctions of marine species to date are overexploitation and habitat loss . However climate change is increasingly adding to this, as evidenced by the recent IUCN Red List Assessment of reef-forming corals . Some other species ranges have already extended or shifted pole-wards and into deeper cooler waters ; this may not be possible for some species to achieve, potentially leading to reduced habitats and more extinctions. Shifts in currents and temperatures will affect the food supply of animals, including at critical early stages, potentially testing their ability to survive.

Recommendations from the workshop

  • Immediate reduction in CO2 emissions coupled with significantly increased measures for mitigation of atmospheric CO2 and to better manage coastal and marine carbon sinks to avoid additional emissions of greenhouse gases.

  • Urgent actions to restore the structure and function of marine ecosystems, including the coordinated and concerted action in national waters and on the High Seas (the high seas water column and seabed Area beyond national jurisdiction) by states and regional bodies to:

    • reduce fishing effort to levels commensurate with long]term sustainability of fisheries and the marine environment; 

    •  close fisheries that are not demonstrably managed following sustainable principles, or which depend wholly on government subsidies; 

    •  establish a globally comprehensive and representative system of marine protected areas to conserve biodiversity, to build resilience, and to ensure ecologically sustainable fisheries with minimal ecological footprint;  prevent, reduce and strictly control inputs of substances that are harmful or toxic to marine organisms into the marine environment; 

    •  prevent, reduce and strictly control nutrient inputs into the marine environment through better land & river catchment management and sewage treatment; 

    •  avoid, reduce or at minimum, universally and stringently regulate oil, gas, aggregate and mineral extraction; 

    •  assess, monitor and control other uses of the marine environment such as renewable energy schemes or cable / pipeline installation through comprehensive spatial planning and impact assessments procedures.


The current inadequate approaches to management of activities that impact the ocean have lead to intense multiple stressors acting together in many marine ecosystems. The impact of such stressors is often negatively synergistic meaning that the combination of the two magnifies the negative impacts of each one occurring alone. This is already resulting in large scale changes in the ocean at an increasing rate and in some regions has resulted in ecosystem collapse. The continued expansion in global population exerts ever increasing pressures on scarcer ocean resources and tackling this issue needs to be a part of the solution to current concerns. 

 The changes in the ocean that are coming about as a result of human CO2 emissions are perhaps the most significant to the Earth system particularly as they involve many feedbacks that will accelerate climate change. 

The resilience of many marine ecosystems has been eroded as a result of existing stressors, leading to increased vulnerability to climate change impacts and a decreased capacity for recovery. An example is coral reefs, the most biodiverse marine ecosystem and one of the most valuable in socioeconomic terms to humankind. 

Human interactions with the ocean must change with the rapid adoption of a holistic approach to sustainable management of all activities that impinge marine ecosystems. This has to be part of a wider re--]evaluation of the core values of human society and its relationship to the natural world and the resources on which we all rely. As such the current and future state of the ocean should form an integral part of the discussions on sustainable development at the Earth Summit in Rio, 2012.