A BID TO RESCUE VULTURE CULTURE
India faces a serious health threat as millions of vultures are in rapid decline. The vultures, a.k.a. nature’s garbage men, have been disappearing faster than any other bird in recorded history – some species by as much as 99 per cent since the early 1990s.
Cow carcasses are piling up (along with some human remains; in India, some groups, such as the Parsee, do not bury their dead), fuelling rats, pestilence and an explosion in feral dogs. The dogs, in turn, are spreading rabies – India has the world’s highest rate of human rabies – and threatening endangered Asiatic lions and tigers with distemper and other diseases.
The vulture decline was once pegged to a virus, but researchers now confirm in the Journal of the Bombay Natural History Society that diclofenac, an anti-inflammatory fed to cattle, is responsible. Analysis of tissue samples from vulture kidneys has shown the drug to be highly toxic to the carcass-eating birds. The manufacture of veterinary diclofenac was banned in 2006, but Chinese imports are still available.
Conservationists are trying to breed vulture populations back, but they reproduce very slowly. Some species, such as the griffon vulture, may be extinct within a decade.
THE SULPHATES SOLUTION
With greenhouse-gas emissions rising, and showing no sign of abating, many climate scientists think that it’s time to consider the use of “geo-engineering” – making grand-scale modifications to the planet itself in order to undo some of the damage.
One of the most popular ideas that scientists bandy about is to spray sulphate particles into the atmosphere. Sulphates – spewed by smokestacks and cars as well as natural sources such as volcanoes – reflect sunlight back into space and act as a brake on global warming. So perhaps we can cool the planet by putting more sulphur in the air. Sounds simple. But detractors point out that the sulphur would eventually fall back to the earth as acid rain.
Another criticism is that sulphates would enlarge the two holes in the ozone layer (one above each pole), because they facilitate the breakdown of ozone by chlorine-containing molecules, such as the infamous CFCs.
The ozone layer shields us from cancer-causing ultraviolet radiation. Thanks to the Montreal Protocol on Substances that Deplete the Ozone Layer, an international agreement in 1987 that kicked off the phase-out of CFCs, the holes were expected to have repaired themselves by the middle of this century (though the larger Antarctic hole would take longer because of differences in geography, weather and winds).
But artificially spraying the skies with sulphur would destroy up to 75 per cent of the ozone above the Arctic and delay the recovery of the Antarctic hole by up to 70 years, climatologists estimate in the journal Science.
“We don’t want to create another ozone hole trying to reduce climate change,” says Simone Tilmes at the National Center for Atmospheric Research in Colorado.
THE OZONE CONUNDRUM
But it gets even more complicated.
Even as the ozone layer shields the Earth from UV radiation, it also absorbs it – which further contributes to warming the climate.
Atmospheric scientists, led by Judith Perlwitz at the University of Colorado, calculate in the journal Geophysical Research Letters that once the hole in the ozone over Antarctica closes, the south pole will start to heat up.
So far, the southern continent has warmed less than expected, mainly because of wind patterns. But once the hole mends, increased heat-trapping could potentially lead to the meltdown of Antarctic glaciers and a catastrophic rise in sea levels.
So: Damned if we do, damned if we don’t? Should we maintain the holes in the ozone to keep the brake on global warming?
Of course not. “Without the ozone layer, life could not exist as we know it,” Dr. Perlwitz says. “What we need to do is limit our greenhouse-gas emissions.”
SAVE THE SHARKS
This month, two high-profile fatal shark attacks near California and Mexico have sent swimmers running from the water, coast guards on the hunt and the media into a frenzy.
“But we don’t need protection from sharks – they need protection from us,” says Richard Brill, a research scientist at the Virginia Institute of Marine Science. Humans are more likely to be killed by lightning than sharks, he notes, while more than 11 million sharks are killed every year as incidental by-catch in fishing lines.
Which is why he and other scientists are working on a way to deter sharks with small chunks of palladium neodymium metal attached to fishing nets. The metal creates an electric current in seawater that sharks avoid, says Dr. Brill, who presented their research to a workshop in Boston last month. Lab experiments with sandbar sharks are promising, and this summer they will do field tests in the Atlantic.
It’s not just the sharks that would benefit: Like all top predators, sharks are necessary for keeping ecosystems in balance. For example, research from Dalhousie University last year found that declines in the populations of large sharks have led to population explosions in smaller fish and rays, which in turn are wiping out scallops. “You can’t just take big hunks out of the ecosystem and expect it to work the way it should,” Dr. Brill says.