The rate of weathering of silicate rocks plays a significant role in maintaining the climate on Earth
[Translation by Dr. Moshe Nachmani]
![The weathering process of silicate rocks is part of what is called the "carbon cycle" which preserves the temperature of the climate on the earth's surface for a long time. [Courtesy: © Universität Bern / University of Bern; Illustration: Jenny Leibundgut]](https://www.hayadan.org.il/images/content3/2021/03/Carbon-Cycle-Earth1.jpg.webp)
Researchers from the University of Bern studied the principles of the weathering process of silicate rocks in extrasolar planets. Their findings could influence the scientific interpretation given to signals coming from distant worlds - including those that imply the presence of life.
Everyone knows that the conditions on Earth are optimal for the existence of life (known to us). Most places on the surface of our planet are not too hot or too cold, and they allow the presence of water in a liquid state. However, this condition, and others required for the existence of life, depend delicately on the exact composition of the atmosphere. Too low or too high a concentration of certain gases - such as carbon dioxide - and the Earth could have turned into an ice block or a pressure cooker. Therefore, when scientists look for potentially habitable planets, one of the key elements must be the composition of the atmosphere on that planet. Sometimes, this atmosphere is primitive and consists mainly of those gases found during the formation of the stars - as in the cases of Jupiter and Saturn. On the other hand, in terrestrial planets such as Mars, Venus or Earth, such primitive atmospheres have already disappeared. Instead, their atmospheres are profoundly influenced by the geochemistry of the stars' surfaces. Geochemical processes, such as the weathering of rocks, may change the composition of the atmosphere and consequently affect the ability to sustain life on the planet. How this mechanism occurs, especially under conditions that are very different from those existing on Earth, is the question that scientists from the University of Bern asked themselves. Their research findings were published in the scientific journal The Planetary Science Journal.
Weathering on the Earth maintains a constant temperature of the climate over a long period of time
"We wanted to understand how the chemical reactions that occur between the atmosphere and the surface of the planets change the composition of the atmosphere. "On Earth, this process - the weathering of silicate rocks with the help of water - maintains a constant temperature of the climate for a long time," says the lead researcher. "When the concentration of carbon dioxide rises, the temperatures also rise due to the output of the greenhouse gas. Higher temperatures lead to lowering
heavier rains. As a result, the rate of weathering of the silicate rocks increases, which in turn reduces the concentration of carbon dioxide and leads to a lower temperature," explains the researcher.
However, this mechanism does not necessarily work that way in the other planets. The researchers used computer simulations to examine how different conditions affect the weathering process there. For example, the researchers found that even in very arid climates, weathering can be more powerful than on Earth if the chemical reactions occur fast enough. The type of rock also affects the process and may lead to very different weathering rates, according to the researchers. The team of researchers also found that at temperatures of about seventy degrees Celsius, contrary to popular scientific opinion, the rates of weathering of silicate rocks may slow down as the temperatures rise. "This finding shows that for planets with climate conditions very different from Earth's, the weathering process may play a very significant role," adds the lead researcher. If astronomers ever find a habitable world, it will most likely be in the so-called "habitable zone". This region is that region around the star within which the sun's radiation allows water to be in a liquid state. In the solar system this region is located between Mars and Venus. "Geochemistry has a profound effect on the feasibility of life on planets in the Hashiv region," says the lead researcher.
As the researchers' findings indicate, increasing temperatures can reduce the rate of weathering and its balancing effect on the other planets - what could have been an inhabited world could instead become a hotbed of hell.
As the lead researcher adds and explains: "Understanding geochemical processes under different conditions is not only important in order to assess the potential for life, but it is also essential for locating life. "Only if we gain a good understanding of geochemical processes under different conditions, we will be able to rely on biomarkers from biological activity that may be possible clues to the existence of life (such as the discovery of the substance phosphine on the planet Venus last year)."
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