Environment Forum

Is Earth due for a mass extinction?

extinction2_h1It has all the signs of a sick good-news/bad-news tale. The bad news is that Earth may be ripe for a mass extinction, where 75 percent or more of the life on the planet vanishes forever.

The good news is it’s unlikely to happen for at least three more centuries.

Scientists writing in the journal Nature warn that we could be on the brink of a mass extinction, the kind of species loss that has happened just five times in the last 540 million years.

“If you look only at the critically endangered mammals–those where the risk of extinction is at least 50 percent within three of their generations–and assume that their time will run out and they will be extinct in 1,000 years, that puts us clearly outside any range of normal and tells us that we are moving into the mass extinction realm,” Anthony Barnosky, an integrative biologist at the University of California at Berkeley said in a statement about the study he co-wrote.

extinction3_h2Are humans to blame? Possibly.

“A modern global mass extinction is a largely unaddressed hazard of climate change and human activities,” said H. Richard Lane of the National Science Foundation, which funded the research.

Polar bears, sure. But grolar bears?

RUSSIA/Most people have seen a polar bear, usually at the local zoo. And most zoo-goers know that wildlife advocates worry about the big white bears’ future as their icy Arctic habitat literally melts away as a result of global climate change. But apparently more than the climate is changing above the Arctic Circle.

The new mammal around the North Pole is the grolar bear, a hybrid created when a polar bear and a grizzly bear mate. Then there’s the narluga, a hybrid of the narwhal and beluga whale. The presence of these two new creatures and others produced by cross-breeding may be caused when melting sea ice allows them to mingle in ways they couldn’t before, according to a comment in the journal Nature.

These hybrids could push some Arctic species to extinction, the three American authors said in their Nature piece. They identified 22 marine mammals at risk of hybridization, including 14 listed or candidates for listing as endangered, threatened or of special concern by one or more nations.

So long, sardines? Lake Tanganyika hasn’t been this warm in 1,500 years

lake_tanganyika1_hEast Africa’s Lake Tanganyika might be getting too hot for sardines.

The little fish have been an economic and nutritional mainstay for some 10 million people in neighboring Burundi, Tanzania, Zambia and the Democratic Republic of Congo — four of the poorest countries on Earth. They also depend on Lake Tanganyika for drinking water.

But that could change, according to research published in the online version of the journal Nature Geoscience. Using samples of the lakebed that chart a 1,500-year history of the lake’s surface water temperature, the scientists found the current temperature — 78.8 degrees F (26 degrees C) — is the warmest it’s been in a millennium and a half. And that could play havoc with sardines and other fish the local people depend on.

The scientists also found that the lake saw its biggest warm-up in the 20th century.

Will Obama like his lichen?

A scientist at the University of California, Riverside has named a newly discovered lichen after President Obama, a gesture he clearly intends as an honor.

Kerry Knudsen, lichen curator at UCR’s Herbarium, says he discovered the hardy orange organism on Santa Rosa Island,  off the California coast, and “named it Caloplaca obamae to show my appreciation for the president’s support of science and science education.”

Lichen is a plant-like growth that looks like moss.

Knudsen,  an ardent supporter of Obama, says he made his final collections of the presidential lichen, which grows on soil and was almost driven to extinction by cattle ranching on the island during the final weeks of the presidential election.

Greenhouse gases: saints, villains or future saviours from an Ice Age?

 It’s not often that greenhouse gases spewed out by human activities get praise as potential saviours of the planet in a leading scientific journal — they’re normally viewed as villains for causing global warming.

But a study in Nature today shows that heat-trapping gases such as carbon dioxide can help avert an even worse problem in thousands of years’ time — a shift to a freeze worse than an Ice Age that could blanket much of the northern hemisphere with ice (see picture on the left and story here).

The scientists say that the Earth is close to a natural tipping point, partly based on shifts in the orbit around the sun, that could abruptly end swings between warm periods, like the present, and Ice Ages like the one that ended 10,000 years ago.

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