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.
OXYGEN
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.
Conclusions
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.
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