Shift happens

UC Davis professor says we’ve pushed the Earth past its tipping point

photo illustration by priscilla garcia

Scientists think an asteroid smashed into the Earth 65 million years ago, wiping out the dinosaurs and most other large land animals on the planet. Another big-extinction event occurred during the last ice age that ended 10,000 years ago. That’s when about half of the large mammals in the world disappeared; scientists believe it was due to climate change.

In fact, the history of life on Earth is full of these dramatic “state shifts.” Over and over again, some force or forces, gradual or sudden, combined to push the Earth past a tipping point, to reshuffle the global biological deck, or maybe even throw all the cards up in the air.

“This one is unique in that we caused it,” said UC Davis paleontologist Geerat Vermeij.

Wait, “this one”?

Vermeij is talking about the state shift that he and some fellow scientists believe is happening right now.

Vermeij was born in the Netherlands and has maybe just a slight accent. He’s written books with sweeping titles such as Nature: An Economic History and The Evolutionary World: How Adaptation Explains Everything From Seashells to Civilization. He appeared in a PBS documentary, and his bio reads that “he probably knows more about molluscs and their shells than anyone alive.”

He’s also probably one of the few blind paleontologists around. When he sat down for an interview, he held a fat Braille copy of an article he recently worked on, plainly titled, “Approaching a state shift in the Earth’s biosphere.”

A non-Braille version of the article was published in the journal Nature in early June, just ahead of the Rio de Janeiro conference on climate change.

Vermeij was just one of 20 scientists who contributed research in their special disciplines.

“Humans are now forcing the biosphere toward another [state shift], with the potential for rapidly and irreversibly transforming Earth into a state unknown in human experience,” the authors conclude.

Human-driven climate change, overpopulation, overdevelopment, overfishing, the elimination of top predators in most ecosystems and overexploitation of resources—the list goes on. But the root causes are not surprising.

“Human population growth and per-capita consumption rate underlie all of the other drivers of global change,” reads the report.

The human population on Earth is somewhere around 7 billion now. It’s growing by 77 million people a year and is projected to be 9.5 billion by 2050.

It might be worse if not for education, birth control and a global rising standard of living. “We’re actually beginning to get a handle on population,” said Vermeij, “though it’s going too slowly.”

But all the trends on global consumption are headed steeply up. “It would help a lot if we could make it unfashionable to be a really big consumer,” said Vermeij.

More people, of course, means more of the planet has already been transformed by human use. Forty-three percent of the land has been converted to agriculture or urban use. And 50 percent of the Earth’s ecosystems will have undergone state shift by the year 2025.

The authors compared that to the fundamental transformation of the Earth’s surface during the last ice age, “when [about 30 percent] of the Earth’s surface went from being covered by glacial ice to being ice free.”

Meanwhile, the atmospheric concentration of carbon dioxide has increased by more than a third compared to pre-industrial levels. That’s leading to global warming and acidification of the oceans.

“It may not be completely obvious to us as urban individuals,” said Vermeij, “but all of the separate shocks to the system are acting in a positive feedback loop, increasing the possibility of a flip. We are having many effects, feeding upon one another in a sort of ghastly way.”

The paper’s lead author, UC Berkeley biology professor Anthony D. Barnosky, told the Los Angeles Times that in the worst-case scenario this state shift “could actually be equivalent to an asteroid striking the Earth” and lead to the loss of 75 percent of the biodiversity on the planet.

The question is just how fast these transformations are taking place. Even within the group of 20 authors of the state-shift article, Vermeij said, there’s some division between the optimists and the pessimists.

“It’s useful to be optimistic. People don’t react well to pessimism. They stop trying to help. So, I’d like to be optimistic. But I’m not,” he said.

“The best we can do is slow it down. If we can slow it down, then we have some chance of adapting to it.”