Could today's plants and animals go the way of dinosaurs? New study says yes

Medill Reports: Could today's plants and animals go the way of dinosaurs? New study says yes
by Michelle M. Schaefer
March 04, 2011


The Earth may be on the verge of a sixth mass extinction, a new study finds. That means more than 75 percent of the world’s creatures could disappear in as little as 300 years.

The cause for this Armageddon isn’t an asteroid, believed to have driven the dinosaurs to extinction 65 million years ago. Human land use and climate change are directly to blame, according to study researchers.

“What we discovered is both good news and bad news. We have not caused so much extinction that we should lose hope. But the bad news is that, if we don’t slow down the highly elevated rates of extinction today, we could be looking at the sixth mass extinction in as little as three to 22 centuries,” said Tony Barnosky, a paleontologist at the University of California, Berkley, who led the study. The findings were reported this week in the journal Nature online.

“The cause of this mass extinction is clearly us. And the way we’re doing that is by fragmenting habitats, by climate change that is largely human caused, by moving species around the Earth so that invasive species take over places where the endemic species of an area would normally live," said Barnosky. Add to that the growing population on the planet and the resources we consume, he said.

A mass extinction is characterized by a short period of time when the Earth loses more than three-quarters of its species. The Earth has experienced five mass extinctions over the last 540 million years, the most commonly known being the extinction of the dinosaurs and other species in the fifth mass extinction.

The other four mass extinctions all occurred before the dinosaurs became extinct. Creatures lost during these extinctions impacted invertebrate marine animals, similar to clams, snails, coral and relatives of starfish.

Barnosky said no group of organisms is safe from the current extinction. Some of the current animals on the endangered species list include rhinoceros, elephants, giant pandas, whales, dolphins, tigers, marine turtles and tree kangaroos.

“There are species in just about every category of plants and animals that you are familiar with, so mammals reptiles, amphibians, birds, fish, many different kinds of plants. It seems like no matter what kind of group of organisms we do this assessment on, we come up with numbers that threatened species are in the range of 20 percent to 50 percent,” he said.

David Jablonski, a paleontologist at the University of Chicago in Illinois, who was not involved with the study, explained that this is one of the first rigorous attempts to compare the current extinction to that of the fossil record.

Researchers completed a mathematical analysis of the existing data for the modern record of species and the fossil record to compare the current rate of extinction to past mass extinctions.

“That’s actually a very difficult thing to do. The fossil record involves courser time frames and it involves a different kind of spatial coverage and at the same time of course it shows much more extreme extinction then we have so far. So the question is: What would it look like? What would today’s patterns look like if we extended them through a block of geological time?” Jablonski said.

The study estimated that four billion species have evolved on Earth over the last 3.5 billion years and about 99 percent of them are extinct. This shows that extinction is actually a common occurrence.

“So far we haven’t hit the massive amount of loss that we’d see in the fossil record, which is a very fortunate thing for all of us. But, at the same time, we’re doing our darndest to push the biosphere over into that kind of extinction spasm and that’s bad news,” he said.

A natural disaster could easily cause another mass extinction. However, current elevated extinction levels are linked to human activity and that gives people a choice, Barnosky said. He said the good news is, if people change their habits and implement effective conservation methods, there’s still time to save potentially threatened species.

“We still have most of earth’s biodiversity left to save and that’s actually in our grasp to do that. We can avoid this sixth mass extinction,” said Barnosky.