Shift happens

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 much more recently, 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.

And about 250 million years ago, about 95 percent of all the life on the planet suddenly went extinct, and over the millions of years that followed, all new species slowly evolved to take its place.

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 soft spoken, but he’s kind of a big deal, and has 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. Back in 2000, when Vermeij was awarded the Daniel Giraud Elliot Medal by the National Academy of Sciences, they praised him for “extracting major generalizations about biological evolution from the fossil record, by feeling details of shell anatomy that other scientists only see.”

When he sat down for an interview with SN&R, 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 much thinner, 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. UC Davis mathematician Alan Hastings also worked on it, too, adding research on the mathematics of regime changes.

Had Vermeij been the lead author, the study might have had a grabbier headline. “I think style is important,” he said with a little smile. Not that the study’s conclusions need a lot of dressing up.

“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,” according to 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 per-capita 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 on the Earth has been converted to agriculture or urban use. And 50 percent of the Earth’s terrestrial 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,” said Vermeij.

Like Vermeij, UC Davis mathematics Hasting said he thinks this state shift is probably irreversible. “By the time you see the effects, it’s really too late,” he said.

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 the equivalent to an asteroid striking the Earth” and lead to the loss of 75 percent of the biodiversity on the planet.

The authors could be wrong. Probably not wrong about climate change or overpopulation or overconsumption.

After all, there is scientific consensus on these issues, said Bradley Cardinale, a University of Michigan professor of ecology.

“No reasonable scientist doubts that humans are transforming the planet in a way that is not sustainable,” Cardinale told SN&R.

The question is just how fast these transformations are taking place, and “whether they are linear and continuous, vs. abrupt thresholds from which there is no return.”

Cardinale acknowledges there is “solid theoretical evidence” that tipping points may occur in ecosystems. But he cautions that there is “very little data from real systems” to prove tipping points and thresholds truly exist.

And he worries that the Nature article is “seriously overstating their certainty on the issue when, in fact, there is an ongoing scientific controversy.”

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,” said Vermeij.

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