Scientists simulate asteroid collision effects on climate and plants
Institute for Basic Science
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Climatic and ecological responses to dust injections of 400 million tons from a Bennu-type asteroid impact. Spatial changes of surface temperature (upper left), total precipitation (upper right), percentage change of terrestrial net primary productivity (lower left) averaged over the first 24 months, and percentage change of marine net primary productivity (lower right) averaged from 10 to 38 months after the impact relative to the control simulation.
view moreCredit: Institute for Basic Science
A new climate modeling study published in the journal Science Advances by researchers from the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea presents a new scenario of how climate and life on our planet would change in response to a potential future strike of a medium-sized (~500 m) asteroid.
The solar system is full of objects with near-Earth orbits. Most of them do not pose any threat to Earth, but some of them have been identified as objects of interest with non-negligible collision probabilities. Among them is the asteroid Bennu with a diameter of about 500 m, which, according to recent studies [Farnocchia et al. 2021], has an estimated chance of 1-in-2700 of colliding with Earth in September 2182. This is similar to the probability of flipping a coin 11 times in a row with the same outcome.
To determine the potential impacts of an asteroid strike on our climate system and on terrestrial plants and plankton in the ocean, researchers from the ICCP set out to simulate an idealized collision scenario with a medium-sized asteroid using a state-of-the-art climate model. The effect of the collision is represented by a massive injection of several hundred million tons of dust into the upper atmosphere. Unlike previous studies, the new research also simulates terrestrial and marine ecosystems, as well as the complex chemical reactions in the atmosphere.
Using the IBS supercomputer Aleph, the researchers ran several dust impact scenarios for a Bennu-type asteroid collision with Earth. In response to dust injections of 100–400 million tons, the supercomputer model simulations show dramatic disruptions in climate, atmospheric chemistry, and global photosynthesis in the 3–4 years following the impact (Figure 1). For the most intense scenario, solar dimming due to dust would cause global surface cooling of up to 4˚C, a reduction of global mean rainfall by 15%, and severe ozone depletion of about 32%. However, regionally, these impacts could be much pronounced.
“The abrupt impact winter would provide unfavorable climate conditions for plants to grow, leading to an initial 20–30% reduction of photosynthesis in terrestrial and marine ecosystems. This would likely cause massive disruptions in global food security,” says Dr. Lan DAI, postdoctoral research fellow at the ICCP and lead author of the study.
When the researchers looked into ocean model data from their simulations, they were surprised to find that plankton growth displayed a completely different behaviour. Instead of the rapid reduction and slow two-year-long recovery on land, plankton in the ocean recovered already within 6 months and even increased afterwards to levels not even seen under normal climate conditions.
“We were able to track this unexpected response to the iron concentration in the dust,” says Prof. Axel TIMMERMANN, Director of the ICCP and co-author of the study. Iron is a key nutrient for algae, but in some areas, such as the Southern Ocean and the eastern tropical Pacific, its natural abundance is very low. Depending on the iron content of the asteroid and of the terrestrial material, that is blasted into the stratosphere, the otherwise nutrient-depleted regions can become nutrient-enriched with bioavailable iron, which in turn triggers unprecedented algae blooms. According to the computer simulations, the post-collision increase of marine productivity would be most pronounced for silicate-rich algae—referred to as diatoms. Their blooms would also attract large amounts of zooplankton—small predators, which feed on the diatoms.
“The simulated excessive phytoplankton and zooplankton blooms might be a blessing for the biosphere and may help alleviate emerging food insecurity related to the longer-lasting reduction in terrestrial productivity,” adds Dr. Lan DAI.
“On average, medium-sized asteroids collide with Earth about every 100–200 thousand years. This means that our early human ancestors may have experienced some of these planet-shifting events before with potential impacts on human evolution and even our own genetic makeup,” says Prof. Timmermann.
The new study in Science Advances provides new insights into the climatic and biospheric responses to collisions with near-Earth orbit objects. In the next step the ICCP researchers from South Korea plan to study early human responses to such events in more detail by using agent-based computer models, which simulate individual humans, their life cycles and their search for food.
Journal
Science Advances
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Climatic and ecological responses to Bennu-type asteroid collisions
Article Publication Date
5-Feb-2025
Meteorite discovery challenges long-held theories on Earth’s missing elements
Arizona State University
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Planetesimal collisions during planet formation in the early solar system.
view moreCredit: Kouji Kanba
Understanding where Earth’s essential elements came from—and why some are missing—has long puzzled scientists. Now, a new study reveals a surprising twist in the story of our planet’s formation.
A new study led by Arizona State University’s Assistant Professor Damanveer Grewal from the School of Molecular Sciences and School of Earth and Space Exploration, in collaboration with researchers from Caltech, Rice University, and MIT, challenges traditional theories about why Earth and Mars are depleted in moderately volatile elements (MVEs). MVEs like copper and zinc play a crucial role in planetary chemistry, often accompanying life-essential elements such as water, carbon, and nitrogen. Understanding their origin provides vital clues about why Earth became a habitable world. Earth and Mars contain significantly fewer MVEs than primitive meteorites (chondrites), raising fundamental questions about planetary formation.
Published in Science Advances, the study takes a fresh approach by analyzing iron meteorites—remnants of the metallic cores of the earliest planetary building blocks— to uncover new insights.
“We found conclusive evidence that first-generation planetesimals in the inner solar system were unexpectedly rich in these elements,” said Grewal. “This discovery reshapes our understanding of how planets acquired their ingredients.”
Until now, scientists believed that MVEs were lost either because they never fully condensed in the early solar system or escaped during planetesimal differentiation. However, this study reveals a different story: many of the first planetesimals held onto their MVEs, suggesting that the building blocks of Earth and Mars lost theirs later—during a period of violent cosmic collisions that shaped their formation.
Surprisingly, the team found that many inner solar system planetesimals retained chondrite-like MVE abundances, showing that they accreted and preserved MVEs despite undergoing differentiation. This suggests that the progenitors of Earth and Mars did not start out depleted in these elements, but instead, their loss occurred over a prolonged history of collisional growth rather than incomplete condensation in the solar nebula or planetesimal differentiation.
“Our work redefines how we understand the chemical evolution of planets,” Grewal explained. “It shows that the building blocks of Earth and Mars were originally rich in these life-essential elements, but intense collisions during planetary growth caused their depletion.”
Journal
Science Advances
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Enrichment of Moderately Volatile Elements in First-Generation Planetesimals of the Inner Solar System
Article Publication Date
5-Feb-2025
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