Friday, January 15, 2016

In pitiful animal die-offs across the globe — from antelopes to bees to seabirds — climate change may be culprit

By Sarah Kaplan
January 13, 2016

On the chilly shores of Alaska’s Prince William Sound, tens of thousands of battered bird carcasses are washing up. The birds, all members of a species known as the common murre, appear to have starved to death, wildlife officials said Tuesday. Their black and white bodies lie strewn across the slick rock, or else bob in the shallow waters nearby.

Seven thousand miles away, on a sandy beach in southern India, more than 100 whales were discovered mysteriously stranded on shore this week. Already at least 45 of them are dead, according to the BBC, dried out and overheated by exposure to the sun. More may soon die if they can’t be safely returned to the ocean. The area hasn’t seen this big a stranding in more than 40 years.

These are two isolated incidents, but they’re not unlike others that have been reported in the past year — unexplained die-offs, abnormally large strandings, a worldwide coral bleaching bigger than almost anything else on record. Around the world, animal populations are vulnerable. Huge groups might be killed in a matter of days or weeks. In Kazakhstan in May of last year, more half of the world’s entire population of saiga antelope vanished in less than a month.

Incidents like these are often mysteries to be unraveled, with scientists sorting through various explanations — hunger, habitat loss, disease, disorientation — for the mass deaths. But in a swath of recent cases, many of the die-offs boil down to a common problem: the animals’ environments are changing, and they’re struggling to keep up.


Back in the U.S., the Los Angeles Times reported last August that the drought that has plagued western states for four years was causing a major die-off of vital fish populations like salmon, steelhead and the endangered delta smelt. Water levels were too low, and what’s more, water temperatures were too warm for fish and their offspring to survive.


And last July, researchers reported that global warming is working to “crush bumblebees in a kind of climate vice,” according to Nature.

“Bumblebee species across Europe and North America are declining at continental scales,” Jeremy Kerr, a biodiversity researcher at the University of Ottawa in Canada, told the scientific journal. “Our data suggest that climate change plays a leading, or perhaps the leading, role in this trend.”

It’s not only animals that are at risk. Researchers believe that the western drought killed 12 million trees in California’s forests, and estimated 58 million are so dry they’ve reached the brink of death, according to the San Francisco Chronicle. A study released that last month predicted that climate change would cause massive die-offs of the American southwest’s coniferous trees, like junipers and pinon pines, within the next half century.

In many ways, die-offs are an inevitable aspect of life on Earth. The ebb and flow of species’ success is part of the background noise of existence that drives evolution. Populations have risen and declined long before humans existed. They’re likely to continue to do so long after we’re gone.

But a study published in the Proceedings of the National Academy of Sciences last year suggests that the number of animal die-offs has gotten worse in recent years. And the researchers weren’t talking about small scale problems like the murres deaths or even the saiga die-offs either. They looked at more than 700 mass mortality events in which either 90 percent of the species was wiped out, more than a billion individuals were killed or 700 million tons (nearly 2,000 Empire State Buildings) worth of biomatter was destroyed.

What they found was not heartening. Mass Mortality Events (MMEs) are “rarely placed in a broader context,” the study’s authors reported. But they seem to be happening at an increased rate for birds, marine invertebrates and fish since the 1940s


These die-offs matter not just because of the inherent value of the creatures involved, the authors said, but because whole ecosystems may depend on that species to survive.


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