Archiv: human evolution


25.10.2021 - 17:04 [ PRI.org ]

Scientists link Earth’s magnetic reversals to changes in planet’s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

20.09.2021 - 05:45 [ PRI.org ]

Scientists link Earth’s magnetic reversals to changes in planet’s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

21.02.2021 - 13:30 [ Sciencealert.com ]

Earth’s Magnetic Field Could Be Changing Much Faster Than We Ever Realised

(08.07.2020)

Quicker changes in direction seem to coincide with a local weakening of the magnetic field, the new research found. One shift in particular was highlighted: a movement of 2.5 degrees per year 39,000 years ago, right after the most recent Laschamp excursion flip, when the Earth’s magnetic field was weakened around the west coast of Central America.

21.02.2021 - 13:05 [ ScienceNews.org ]

50 years ago, scientists named Earth’s magnetic field as a suspect in extinctions

Excerpt from the November 21, 1970 issue of Science News

21.02.2021 - 12:40 [ Science Magazine ]

A global environmental crisis 42,000 years ago

(19.02.2021)

We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

21.02.2021 - 12:35 [ CNN ]

Reversal of Earth’s magnetic poles may have triggered Neanderthal extinction — and it could happen again

(19.02.2021)

Some 42,000 years ago, in an event known as the Laschamp Excursion, the poles did just that for around 800 years, before swapping back — but scientists were unsure exactly how or if it impacted the world.

Now, a team of researchers from Sydney’s University of New South Wales and the South Australian Museum say the flip, along with changing solar winds, could have triggered an array of dramatic climate shifts leading to environmental change and mass extinctions.