2015-01-21

Humanity as Invasive Species Edition:

NPR: Congress To Nutritionists: Don't Talk About The Environment

The impact [of producing food] will grow in the future, along with the world's population. So if people are thinking about their own personal environmental footprint, [Timothy Searchinger] says, "probably what you eat is more important than anything else."
-Dan Charles

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(Image credit: Screenshot of nytimes.com)
NYT: Ocean Life Faces Mass Extinction, Broad Study Says

Fragile ecosystems like mangroves are being replaced by fish farms, which are projected to provide most of the fish we consume within 20 years. Bottom trawlers scraping large nets across the sea floor have already affected 20 million square miles of ocean, turning parts of the continental shelf to rubble. Whales may no longer be widely hunted, the analysis noted, but they are now colliding more often as the number of container ships rises.

Mining operations, too, are poised to transform the ocean. Contracts for seabed mining now cover 460,000 square miles underwater, the researchers found, up from zero in 2000. Seabed mining has the potential to tear up unique ecosystems and introduce pollution into the deep sea.

The oceans are so vast that their ecosystems may seem impervious to change. But Dr. McClenachan warned that the fossil record shows that global disasters have wrecked the seas before. “Marine species are not immune to extinction on a large scale,” she said.

Until now, the seas largely have been spared the carnage visited on terrestrial species, the new analysis also found.

The fossil record indicates that a number of large animal species became extinct as humans arrived on continents and islands. For example, the moa, a giant bird that once lived on New Zealand, was wiped out by arriving Polynesians in the 1300s, probably within a century.

But it was only after 1800, with the Industrial Revolution, that extinctions on land really accelerated.

Humans began to alter the habitat that wildlife depended on, wiping out forests for timber, plowing under prairie for farmland, and laying down roads and railroads across continents.

Species began going extinct at a much faster pace. Over the past five centuries, researchers have recorded 514 animal extinctions on land. But the authors of the new study found that documented extinctions are far rarer in the ocean.

Before 1500, a few species of seabirds are known to have vanished. Since then, scientists have documented only 15 ocean extinctions, including animals such as the Caribbean monk seal and the Steller’s sea cow.

While these figures are likely underestimates, Dr. McCauley said that the difference was nonetheless revealing.

“Fundamentally, we’re a terrestrial predator,” he said. “It’s hard for an ape to drive something in the ocean extinct.”

Many marine species that have become extinct or are endangered depend on land — seabirds that nest on cliffs, for example, or sea turtles that lay eggs on beaches.

Still, there is time for humans to halt the damage, Dr. McCauley said, with effective programs limiting the exploitation of the oceans. The tiger may not be salvageable in the wild — but the tiger shark may well be, he said

-Carl Zimmer