Perilous Times
Oceans in distress foreshadow mass extinction
by Staff Writers
Paris (AFP) June 20, 2011
Runoff from nitrogen-rich fertiliser, killer microbes, and
hormone-disrupting chemicals, for example, have all contributed to
the mass die-off of corals, crucial not just for marine ecosystems
but a lifeline for hundreds of millions of people too.
Pollution and global warming are pushing the world's oceans to the
brink of a mass extinction of marine life unseen for tens of
millions of years, a consortium of scientists warned Monday.
Dying coral reefs, biodiversity ravaged by invasive species,
expanding open-water "dead zones," toxic algae blooms, the massive
depletion of big fish stocks -- all are accelerating, they said in
a report compiled during an April meeting in Oxford of 27 of the
world's top ocean experts.
Sponsored by the International Programme on the State of the Ocean
(IPSO), the review of recent science found that ocean health has
declined further and faster than dire forecasts only a few years
ago.
These symptoms, moreover, could be the harbinger of wider
disruptions in the interlocking web of biological and chemical
interactions that scientists now call the Earth system.
All five mass extinctions of life on the planet, reaching back
more than 500 million years, were preceded by many of the same
conditions now afflicted the ocean environment, they said.
"The results are shocking," said Alex Rogers, an Oxford professor
who heads IPSO and co-authored the report. "We are looking at
consequences for humankind that will impact in our lifetime."
Three main drivers are sickening the global marine environment,
and all are a direct consequence of humans activity: global
warming, acidification and a dwindling level oxygen, a condition
known as hypoxia.
Up to now, these and other impacts have been studied mainly in
isolation. Only recently have scientists began to understand how
these forces interact.
"We have underestimated the overall risks, and that the whole of
marine degradation is greater than the sum of its parts," Rogers
said. "That degradation is now happening at a faster rate than
predicted."
Indeed, the pace of change is tracking or has surpassed the
worst-case scenarios laid out by the UN Intergovernmental Panel on
Climate Change (IPCC) in its landmark 2007 report, according to
the new assessment.
The chain reaction leading to increased acidification of the
oceans begins with a massive influx of carbon into Earth's climate
system.
Oceans act as a massive sponge, soaking up more than a quarter of
the CO2 humans pump into the atmosphere.
But when the sponge becomes too saturated, it can disrupt the
delicately balanced ecosystems on which marine life -- and
ultimately all life on Earth -- depends.
"The rate at which carbon is being absorbed is already far greater
now than during the last globally significant extinction of marine
species 55 million years ago," when some 50 percent of deep-sea
life was wiped out, the report said.
That event, called the Paleocene-Eocene Thermal Maximum, or PETM,
may be an ancient dress rehearsal for future climate change that
could be even more abrupt and more damaging, some scientists fear.
Pollution has also taken a heavy toll, rendering the oceans less
resilient to climate change.
Runoff from nitrogen-rich fertiliser, killer microbes, and
hormone-disrupting chemicals, for example, have all contributed to
the mass die-off of corals, crucial not just for marine ecosystems
but a lifeline for hundreds of millions of people too.
The harvesting up to 90 percent of some species of big fish and
sharks, meanwhile, has hugely disrupted food chains throughout the
ocean, leading to explosive and imbalanced growth of algae,
jellyfish and other "opportunistic" flora and fauna.
"We now face losing marine species and entire marine ecosystems,
such as coral reefs, within a single generation," said Daniel
Laffoley, head of the International Union for Conservation of
Nature's (IUCN) World Commission on Protected Areas, and co-author
of the report.
"And we are also probably the last generation that has enough time
to deal with the problems," he told AFP by phone.