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Ocean
dead zone near African coast shows lowest oxygen levels ever recorded
5
May, 2015
The
dead zones are spreading. No, it’s not a sign of the zombie
apocalypse, though the consequences could be just as dire. A recent
study by
the European Geosciences Union’s journal Biogeosciences describes
a dead zone off the coast of Africa which contains the lowest levels
of oxygen ever observed in the Atlantic. To complicate matters, the
Atlantic-African dead zone is on the move, threatening all life in
its path.
Often
located in coastal waters, dead
zones are
caused by the runoff of chemicals and fertilizers used in
agriculture, though poorly
designed disposal of liquid human waste also
contributes to the problem. A particularly infamous zone lurks in the
Gulf of Mexico, a deadly consequence to farming runoff down the
Mississippi River. Nitrogen and phosphorus rich runoff settles in
river deltas or in the ocean, where it feeds the growth of algal
blooms. As the algae dies, it becomes food for bacteria, which in
turn consumes the oxygen present in the water. This environment is
extremely inhospitable to marine life. Oxygenless water is usually
diluted by current and tidal movement, yet the presence of enormous
eddies in the Atlantic-African dead zone prevents this dispersal.
“The
fast rotation of the eddies makes it very difficult to exchange
oxygen across the boundary between the rotating current and the
surrounding ocean. Moreover, the circulation creates a very shallow
layer – of a few tens of meters – on top of the swirling water
that supports intense plant growth,” says Johannes
Karstensen,
lead author of the report. “From our measurements, we estimated
that the oxygen consumption within the eddies is some five times
larger than in normal ocean conditions.”ithin the eddies is some five times
larger than in normal ocean conditions.”
Eddies
slowly move westward and if these particular eddies make landfall, it
would spell disaster for the local marine ecosystem. “Given that
the few dead zones we observed propagated less than 100 km north of
the Cape Verde archipelago, it is not unlikely that an open-ocean
dead zone will hit the islands at some point. This could cause the
coast to be flooded with low-oxygen water, which may put severe
stress on the coastal ecosystems and may even provoke fish kills and
the die-off of other marine life,” says Karstensen.
The
outlook is not all doom and gloom. Dead zones can be rehabilitated,
as demonstrated by the transformation of the Black Sea dead zone.
Previously the largest in the world, the Black Sea dead
zone disappeared
in the decade following the collapse of the Soviet Union,
which made fertilizers cost prohibitive for farmers. Although this
revitalization was coincidental, deliberate efforts have been made to
eliminate dead zones along the Hudson
River and
in San
Francisco Bay.
However, no clean-up will be able to revive now-extinct organisms
that have perished in the dead zone.
Military
Could Step in Over Brazil Drought Chaos
5
May, 2015
An
engineer for Sao Paulo state’s water company said that “scenes
from the end of the world” would ensue if the city ran out of
water. The drought in the Brazilian metropolis of Sao Paulo has
become so severe that local authorities are considering bringing in
military personnel to cope with the possible social chaos.
With
over 11 million residents, Sao Paulo is Brazil's most populous city
and the country's economic center. But senior officials at Sao
Paulo's water facility said residents might soon be evacuated because
there is not enough water, to bathe or to clean homes.
The
water crisis is the worst is the last 84 years, and the dry season
has only just begun, with less water in the dams than in 2014, when
restrictions on water began and the authorities began to realize the
seriousness of the disaster.
Last
week, a conference between academics, military employees and local
councils to discuss how to handle the coming five months in the case
that reserves run out, and the city might go up to five days without
water.
Paulo
Massato, engineer at the state water company, told the conference
that water supplies could run out as early as July, if emergency
works are not finished in time.
Engineers
are working to create infrastructure to connect various reservoirs,
which, if completed, would mean that there would be enough water to
last until October.
On
being asked what would happen in the worst case scenario, with no
rain and incomplete works, Massato replied, “It would be terrible.
No would be no food, no would be no electricity … It would be a
scene from the end of the world.
There
a thousands of people, and it could cause social chaos. It would not
only be a problem of water shortage, it would be much more than
that.” Last year the smaller city of Itu suffered a similar
April
2015 Arctic sea ice is second-lowest on record
This is the Agham fluvial terrace, located roughly 400 m above the current river level of the upper Shyok valley, NW Himalayas, India. See related article by J.H. Blöthe and colleagues.
Large
landslides are an important process of erosion in the
Himalaya-Karakoram ranges. These high-relief landscapes are
characterized by steep slopes that are prone to frequent landsliding.
By mapping nearly 500 large (greater than 0.1 km2) landslides in the
HKR, geologists have found that the vast majority of these mass
movements lie in the lower portions of the landscape, whereas
glaciers and rock glaciers occupy the higher elevations almost
exclusively.
A
Canadian advisory panel on Wednesday approved a plan to bury nuclear
waste at a site just steps away from Lake Huron, saying it had
concluded the project would pose no danger to the environment.
The
Joint Review Panel made its recommendation in a report to Canada's
environment minister, Leona Aglukkaq, who is expected to issue a
decision within 120 days.
The
forest fire near Chernobyl that broke out a week ago has spread
radionuclides, notably plutonium, over eastern Europe, Asia, Alaska,
and is now moving in over the west coast of the US.
This
image from the downloaded Windows HYSPLIT atmospheric dispersion
model shows the spread of this plume, as of 2 PM Eastern time on May
7.
And the world's climate change deniers
Australia’s
education minister, Christopher Pyne, has vowed to find another
university to host the Bjorn Lomborg “consensus centre” and is
seeking legal advice about a decision by the University of Western
Australia (UWA) to hand back $4m in federal government funding
awarded for it.
UWA
handed back the funding and dropped its connection with Lomborg,
saying that lack of support among its academics made the centre
untenable.
What
If Humans Disappeared?
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