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The Earth’s molten interior is cooling faster than expected, which could turn the planet into a cold, inactive world similar to neighboring Mercury and Mars sooner than previously thought, researchers have warned.
The study, published in the Earth and Planetary Science Letters journal, examined how well bridgmanite – the primary mineral found at the boundary between the planet’s core and mantle layers – conducts heat from the hot, molten core to the surface.
Researchers irradiated a bridgmanite crystal with pulsed lasers on a diamond anvil press to simulate the effects of intense heat and pressure at the boundary. They found that the rate at which the mineral conducted heat was “about 1.5 times higher than assumed.”
The findings mean that the cooling of the Earth’s core is speeding up, and it is “becoming inactive much faster than expected.”
The rapid cooling could in turn lead to an earlier slowing-down of processes like plate tectonics, which are related to the movements of large underground slabs composed of the crust and outer mantle layer, and volcanic activity.
This heat exchange from the planet’s core helps generate the Earth’s magnetic field, which is understood to be protecting the planet’s atmosphere from solar radiation and allowing life to thrive.
The rapid cooling may accelerate even more in the future, since cooled bridgmanite transforms into a mineral known as post-perovskite, which conducts heat even more quickly.
“Our results could give us a new perspective on the evolution of the Earth’s dynamics. They suggest that Earth, like the other rocky planets Mercury and Mars, is cooling and becoming inactive much faster than expected,” said ETH Zurich Earth scientist Motohiko Murakami, who led the study.
However, it remains unclear exactly how long it will take for thermal convection currents within the mantle to stop entirely. Murakami said that not enough is known about such events to “pin down their timing.”
Besides a better understanding of mantle convection in “spatial and temporal terms,” Murakami noted that any predictive timeline would also need to account for how mantle dynamics are affected by the decay of radioactive elements in the core, which is a key source of the Earth’s internal heat.
Courtesy of rt.com
A team of Chinese researchers says a period of global cooling could be on the way, but the consequences will be serious. Photo: Xinhua
A new study has found winters in northern China have been warming since 4,000BC – regardless of human activity – but the mainland scientists behind the research warn there is no room for complacency or inaction on climate change, with the prospect of a sudden global cooling also posing a danger.
The study found that winds from Arctic Siberia have been growing weaker, the conifer tree line has been retreating north, and there has been a steady rise in biodiversity in a general warming trend that continues today. It appears to have little to do with the increase in greenhouse gases which began with the industrial revolution, according to the researchers.
Lead scientist Dr Wu Jing, from the Key Laboratory of Cenozoic Geology and Environment at the Institute of Geology and Geophysics, part of the Chinese Academy of Sciences, said the study had found no evidence of human influence on northern China’s warming winters.
“Driving forces include the sun, the atmosphere, and its interaction with the ocean,” Wu said. “We have detected no evidence of human influence. But that doesn’t mean we can just relax and do nothing.”
Moon Lake, a small volcanic lake hidden in the deep forest of China’s Greater Khingan Mountain Range, where a team of scientists spent more than a decade studying the secrets hidden in its sediments. Photo: Baidu
Wu and her colleagues are concerned that, as societies grow more used to the concept of global warming, people will develop a misplaced confidence in our ability to control climate change. Nature, they warned, may trick us and might catch us totally unprepared – causing chaos, panic, famine and even wars as the global climate system is disrupted.
There are already alarming signs, according to their paper, which has been accepted for publication by the online Journal of Geophysical Research: Atmospheres.
Wu and her colleagues spent more than a dozen years studying sediments under Moon Lake, a small volcanic lake hidden in the deep forests of the Greater Khingan Mountain Range in China’s Inner Mongolia autonomous region. They found that winter warming over the past 6,000 years had not been a smooth ride, with ups and downs occurring about every 500 years.
Their findings confirmed an earlier study by a separate team of Chinese scientists, published by online journal Scientific Reports in 2014, which first detected the 500-year cyclical pattern of China’s summer monsoons and linked it to solar activity.
The 2014 research, which drew on 5,000 years’ worth of data, suggested the current warm phase of the cycle could terminate over the next several decades, ushering in a 250-year cool phase, potentially leading to a partial slowdown in man-made global warming.
Wu said the latest study, with 10,000 years’ worth of new data, not only helped to draw a more complete picture of the 500-year cycle, but also revealed a previously unknown mechanism behind the phenomenon, which suggested the impact of the sun on the Earth’s climate may be greater than previously thought.
According to Wu, the variation in solar activity alone was usually not strong enough to induce the rapid changes in vegetation the research team recorded in the sediment cores of Moon Lake. Instead, the scientists found the warming impact was amplified by a massive, random interaction between surface seawater and the atmosphere in the Pacific Ocean known as the El Nino-Southern Oscillation.
As a result of the research findings, Wu said she was now more worried about cooling than warming.
“A sharp drop of temperature will benefit nobody. The biggest problem is, we know it will come, but we don’t know exactly when.”
Courtesy of scmp.com