ROME • Never before has a single species become the top predator on land and sea, and human dominance over the natural environment has caused shifts in world ecosystems unprecedented in the last 500 million years, researchers said on Tuesday.

Human activity is leading to an international decline in the variety of plants and animals through extinction, as organisms not useful to human needs are killed off by ecosystem changes or over-exploitation, according to a new study.

The biggest immediate losers will be large predators like tigers and lions, while creatures domesticated by humans, including house cats, will thrive in the new world, said Professor Jan Zalasiewicz, an expert in palaeobiology at the University of Leicester in central England and co-author of the study.

Big extinctions or climate shifts are nothing new, as evidenced by the ice age and the disappearance of dinosaurs, but current environmental changes represent something different, researchers said. "Some human-made changes have genuinely not been seen before on planet earth," Prof Zalasiewicz told the Thomson Reuters Foundation.

The research was published in the academic journal The Anthropocene Review on Monday.

In the past, volcanic eruptions, complex ecological breakdowns and meteor strikes caused structural changes to the planet, he said. In contrast, today's shifts - including climate change and loss of biodiversity - have created a "new kind of nature", Prof Zalasiewicz added.

"Global warming as a phenomenon is just beginning," he said. "Species extinctions and other changes are far more advanced."

Since 1900, extinction rates for vertebrates have been 10 to 100 times higher than normal, he said, and at least 468 creatures have been eliminated since then. "When global warming really bites, that will ratchet up the changes currently taking place," he said.

REUTERS