Did a magnetic field collapse trigger the emergence of animals?

The Ediacaran Period, spanning from about 635 to 541 million years ago, was a pivotal time in Earth's history. It marked a transformative era during which complex, multicellular organisms emerged, setting the stage for the explosion of life.

But how did this surge of life unfold and what factors on Earth may have contributed to it?

Researchers from the University of Rochester have uncovered compelling evidence that Earth's magnetic field was in a highly unusual state when the macroscopic animals of the Ediacaran Period diversified and thrived. Their study, published in Nature Communications Earth & Environment, raises the question of whether these fluctuations in Earth's ancient magnetic field led to shifts in oxygen levels that may have been crucial to the proliferation of life forms millions of years ago.

According to John Tarduno, the William Kenan, Jr. Professor in the Department of Earth and Environmental Sciences, one of the most remarkable life forms during the Ediacaran Period was the Ediacaran fauna. They were notable for their resemblance to early animals -- some even reached more than a meter (three feet) in size and were mobile, indicating they probably needed more oxygen compared to earlier life forms.

"Previous ideas for the appearance of the spectacular Ediacaran fauna have included genetic or ecologic driving factors, but the close timing with the ultra-low geomagnetic field motivated us to revisit environmental issues, and, in particular, atmospheric and ocean oxygenation," says Tarduno, who is also the Dean of Research in the School of Arts & Sciences and the School of Engineering and Applied Sciences.

Earth's magnetic mysteries

About 1,800 miles below us, liquid iron churns in Earth's outer core, creating the planet's protective magnetic field. Though invisible, the magnetic field is essential for life on Earth because it shields the planet from solar wind -- streams of radiation from the sun. But Earth's magnetic field wasn't always as strong as it is today.

Researchers have proposed that an unusually low magnetic field might have contributed to the rise of animal life. However, it has been challenging to examine the link because of limited data about the strength of the magnetic field during this time.

Tarduno and his team used innovative strategies and techniques to examine the strength of the magnetic field by studying magnetism locked in ancient feldspar and pyroxene crystals from the rock anorthosite. The crystals contain magnetic particles that preserve magnetization from the time the minerals were formed. By dating the rocks, researchers can construct a timeline of the development of Earth's magnetic field.

Leveraging cutting-edge tools, including a CO2 laser and the lab's superconducting quantum interference device (SQUID) magnetometer, the team analyzed with precision the crystals and the magnetism locked within.

A weak magnetic field

Their data indicates that Earth's magnetic field at times during the Ediacaran Period was the weakest field known to date -- up to 30 times weaker than the magnetic field today -- and that the ultra-low field strength lasted for at least 26 million years.

A weak magnetic field makes it easier for charged particles from the sun to strip away lightweight atoms such as hydrogen from the atmosphere, causing them to escape into space. If hydrogen loss is significant, more oxygen may remain in the atmosphere instead of reacting with hydrogen to form water vapor. These reactions can lead to a buildup of oxygen over time.

The research conducted by Tarduno and his team suggests that during the Ediacaran Period, the ultraweak magnetic field caused a loss of hydrogen over at least tens of millions of years. This loss may have led to increased oxygenation of the atmosphere and surface ocean, enabling more advanced life forms to emerge.

Tarduno and his research team previously discovered that the geomagnetic field recovered in strength during the subsequent Cambrian Period, when most animal groups begin to appear in the fossil record, and the protective magnetic field was reestablished, allowing life to thrive.

"If the extraordinarily weak field had remained after the Ediacaran, Earth might look very different from the water-rich planet it is today: water loss might have gradually dried Earth," Tarduno says.

Core dynamics and evolution

The work suggests that understanding planetary interiors is crucial in contemplating the potential of life beyond Earth.

"It's fascinating to think that processes in Earth's core could be linked ultimately to evolution," Tarduno says. "As we think about the possibility of life elsewhere, we also need to consider how the interiors of planets form and develop."

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Causes of the Qing Dynasty's collapse: Parallels to today's instability

The Qing Dynasty in China, after over 250 years, crumbled in 1912. Led by the Complexity Science Hub (CSH), an international research team has pinpointed key reasons behind the collapse, revealing parallels to modern instability and offering vital lessons for the future.

China is considered today to be the world's largest economy (in terms of PPP). However, this position is not new. In 1820, China's economy already held the top spot, accounting for 32.9% of the global GDP. In the interim, there was a period of decline followed by a resurgence. In 1912, after over 250 years in power, the Qing Dynasty collapsed despite being considerably wealthier at the time than modern-day China. "This clearly demonstrates that any economy must be vigilant as circumstances can change, and sometimes rather rapidly," emphasizes Georg Orlandi, the study's first author.

SIMILAR ROOTS THEN AND NOW

"It's crucial to comprehend the origins of such instabilities. Assuming it's a thing of the past and can't recur would be a mistake. Such changes can indeed happen because the underlying mechanisms bear surprising similarities," CSH researcher Peter Turchin points out.

Scientists have been attempting to pinpoint the causes behind the fall of the Qing Dynasty for two centuries. Various factors had previously been proposed, including environmental disasters, foreign incursions, famines, or uprisings. However, "none of these factors provides a comprehensive explanation," notes Turchin.

THREE MAIN DRIVERS

Hence, in this study, researchers amalgamated various factors and discovered that three elements dramatically heightened socio-political pressures:

Firstly, there was a fourfold population explosion between 1700 and 1840. This resulted in reduced land per capita and caused an impoverishment of the rural populace.

Secondly, this led to increased competition for elite positions. While the number of contenders soared, the number of awarded highest academic degrees declined, reaching its nadir in 1796. Because such a degree was necessary for obtaining a position in the powerful Chinese bureaucracy, this mismatch between the number of positions and those desiring them created a large pool of disgruntled elite aspirants. The leaders of the Taiping Rebellion, perhaps the bloodiest civil war in human history, were all such failed elite-wannabes.

Thirdly, the state's financial burden escalated due to rising costs associated with suppressing unrest, declining per capita productivity, and mounting trade deficits stemming from depleting silver reserves and opium imports.

Collectively, these factors culminated in a series of uprisings that heralded the end of the Qing Dynasty and exacted a heavy toll in terms of Chinese lives lost.

THE QING WERE AWARE

According to the study's findings, social tensions had already peaked between 1840 and 1890. "Assuming that the Qing rulers were unaware of this mounting pressure would be erroneous," explains Turchin. The fact that the dynasty endured until 1912 rather underscores its institutional structures' robustness.

However, many of their attempted solutions proved short-sighted or inadequate to the task; for instance, the government raised the allowable quota for people passing certain degree exams but without increasing the number of available openings. This ended up exacerbating the already-building tensions. With the arrival of potent geopolitical challengers through the late 19th century, the rulers ultimately couldn't avert their downfall.

PREVENT INSTABILITY TODAY

We can draw valuable lessons from this historical process for the contemporary era and the future. Many nations worldwide are grappling with potential instability and conditions that closely resemble those of the Qing Dynasty. For instance, competition for top positions remains exceedingly fierce. Orlandi cautions, "When a large number of individuals vie for a limited number of positions, political decision-makers should view this as a red flag, as it can, at the very least, lead to heightened instability."

"Unfortunately, the corrosive impact of rising inequality and diminishing opportunities develop over longer time scales that make them hard to recognize," adds co-author and CSH Affiliated Researcher Daniel Hoyer, "let alone effectively combat within the short political cycles we see in many countries. Without long-term vision and targeted strategies to relieve these social pressures, many places are at risk of going the way of the Qing."

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Professors call for more research into climate-change related threats to civilization

An opinion piece published today in the Proceedings of the National Academy of Sciences, a peer-reviewed journal of the National Academy of Sciences, urgently calls for more research into the specific pathways by which civilization could potentially collapse due to climate change.

"Scientists have warned that climate change threatens the habitability of large regions of the Earth and even civilization itself, but surprisingly little research exists about how collapse could happen and what can be done to prevent it," says Dr. Daniel Steel of the School of Population and Public Health at the University of British Columbia.

"A better understanding of the risks of collapse is essential for climate ethics and policy."

In the article, Dr. Steel and his colleagues, Dr. C. Tyler DesRoches with Arizona State University's School of Sustainability and Dr. Kian Mintz-Woo from University College Cork, define civilization collapse as the loss of societal capacity to maintain essential governance functions, especially maintaining security, the rule of law, and the provision of basic necessities such as food and water.

The co-authors consider three civilization collapse scenarios:

1.     localized collapse of specific, vulnerable locations;
2.     the collapse of some urban and national areas while the remaining ones experience detrimental climate-related effects such as food and water scarcity;
3.     global collapse where urban areas around the world are abandoned, nations are no more, and global population falls.

It is not only the direct effects of climate change -- such as drought, flooding, and extreme heat -- that could create collapse risks, but also less-studied mechanisms.

As Dr. Steel and his co-authors explain, climate change may also have indirect effects on systems like trade and international cooperation, which might in turn lead to political conflict, dysfunction, and war. The authors also state that these effects may lessen civilizations' adaptability which would leave them vulnerable to other shocks, like pandemics.

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