Creatures from the deep.
(photo credit: MBARI/Bloomfield Science Museum)
OSLO - 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 Program 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
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
A build-up of carbon dioxide, blamed by the UN 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, towards 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
"Over-fishing is now estimated to account for over 60 percent of the
known local and global extinction of marine fishes," he wrote.
Among examples of over-fishing are the Chinese bahaba that can grow 2
meters long. Prices per kilo (2.2 lbs) for its swim bladder -- meant to
have medicinal properties -- have risen from a few dollars in the 1930s