Month: July 2018

Enlarge (credit: Alfred Jacob Miller via Wikimedia Commons)

Layers of charcoal residue buried beneath the northern Montana prairie show that pre-Columbian indigenous hunters on the Great Plains once burned patches of grassland to stimulate new growth. This created a tempting feast for bison herds, which the hunters then used to lure the bison in for the kill. And that, archaeologists say, means that even relatively small, mobile groups of hunter-gatherers can have a bigger environmental impact than they’ve been given credit for.

It’s not the fall, it’s the sudden stop at the end

For a group of hunters on foot, like the ancestors of today’s Blackfeet people, one of the most efficient ways to take down large prey like the American bison is to simply chase a group of them off a cliff and then harvest the remains below. Various hunter-gatherer societies around the world have used versions of this tactic over the last several thousand years, leaving piles of animal bones (many with evidence of butchering or cracking to get at marrow) at the bases of ancient bluffs. It takes planning and coordination among many hunters—and a decent amount of luck.

In the uplands of north-central Montana, on what is today the Blackfeet Reservation, pre-Columbian hunters built mile-long stretches of rock cairns called drivelines, which hunters used to help them funnel buffalo herds from fertile grazing patches called gathering basins, toward the edge of a steep bluff overlooking a tributary of the Two Medicine River. At two different driveline sites, archaeologists have radiocarbon dated bison bones to between 900 and 1650 CE, with the majority of kills happening in the final 250 years of that period. (The sites are on a tributary flowing into the Two Medicine River from the north and another on a different tributary flowing in from the south.)

Enlarge / Legendary car executive Sergio Marchionne (credit: Pier Marco Tacca/Getty Images)

Sergio Marchionne, the CEO of Fiat Chrysler Automobiles and president of Ferrari, has died at the age of 66. The man who transformed the fortunes of his companies and took Ferrari public suffered an embolism during surgery. "Unfortunately, what we feared has come to pass. Sergio Marchionne, man and friend, is gone," said FCA chairman John Elkann in statement. He will be replaced at FCA by Mike Manley, who until now has been running the Jeep and Ram brands, and at Ferrari by Louis Carey Camilleri, a former chairman of Phillip Morris.

The first sign most of us had that all was not well was on Saturday morning, with reports that the FCA board had been called together hurriedly to discuss a successor to the ebullient executive. At first, reports merely stated that there had been complications with shoulder surgery leading to a longer-than-expected recovery. Yesterday, the Italian publication Lettera43 reported that Marchionne was actually being treated at the University of Zurich for an aggressive shoulder sarcoma and that he fell into a coma following an embolism.

Born in Italy, Marchionne grew up in Canada and joined the board of Fiat in 2003. Although he did not come from the automotive industry, he had earned a reputation as an executive with the ability to turn around companies. He demonstrated this to good effect after being appointed as CEO of Fiat the following year. "As part of my nature, I like to fix things and to be blunt, Fiat needs a fix right now," he said at the time.

Enlarge / The blue "warming hole" in the North Atlantic seems to be related to changes in Atlantic Ocean circulation. (credit: NOAA)

Last week, Nature published a climate science study that reached a very surprising conclusion—one that other climate scientists are taking issue with. Two other scientists penned a critical response and posted it at Real Climate the same day, outlining their issues with the study's findings.

This kind of argument could be left to play out among scientists, but the BBC News covered the study without skeptical counterweight, so we thought it would be worth explaining what the arguments are about.

AMOC run amok

The study by Xianyao Chen of the Ocean University of China and Ka-Kit Tung at the University of Washington focused on the large-scale movement of water in the Atlantic Ocean. In this section of the ocean “conveyor belt” that wraps around the world, surface water is carried toward the pole before mixing downward around Greenland and heading south along the ocean floor.