Recently, as asteroids approaching Earth have been discovered one after another, the possibility of a collision is once again drawing attention. Among them, the asteroid Bennu, with a diameter of 500 meters, is predicted to have a 0.037% (1 in 2,700) chance of colliding with Earth in 2182. Although the possibility is small, research has shown that if Bennu were to collide, it could have a tremendous impact on Earth's climate and ecosystem.
A research team led by Axel Timmermann, Director General of the Climate Physics Research Group at the Institute for Basic Science (IBS), and Postdoctoral Researcher Lan Dai analyzed the climate changes that would occur if the asteroid Bennu were to collide with Earth, using IBS's supercomputer Aleph. The research results were published on the 6th in the international journal Science Advances.
The researchers reported that there is a significant possibility that 100 to 400 million tons of dust would be ejected into the atmosphere upon Bennu's collision, simulating changes over three to four years based on four scenarios. Lan Dai, the leading postdoctoral researcher, noted to ChosunBiz, "There was a lack of observational data on dust emissions due to asteroid collisions, and the climate models were numerically unstable, which made the research challenging. However, we predicted the amount of dust that would be emitted in the event of a collision with a medium-sized asteroid like Bennu and applied it to the model."
According to the analysis, if up to 400 million tons of dust, aerosols, debris, and volcanic ash were emitted into the stratosphere, the sunlight would be blocked, causing Earth's average temperature to potentially drop by up to 4 degrees, with a likelihood of a 15% decrease in precipitation. Additionally, as dust particles absorb sunlight, the stratosphere would heat up, resulting in an approximately 32% reduction in the ozone layer. The research team predicted that this could lead to a global climate cooling phenomenon known as 'impact winter.'
The phenomenon caused by asteroid collisions is also expected to have a significant impact on Earth's ecosystem. The research predicts that terrestrial net primary productivity could decrease by up to 36%, while in the oceans, it could drop by up to 25%. This disruption could undermine the foundations of the ecosystem and severely impact agricultural productivity. The researchers estimated that it would take about two years for terrestrial ecosystems to recover.
On the other hand, some marine ecosystems may actually prosper. If Bennu were to release dust rich in iron, a key nutrient for algae, phytoplankton in the eastern Pacific and Southern Ocean could flourish for at least three years. Simultaneously, the population of animal plankton that feeds on phytoplankton is also likely to increase rapidly.
The research team noted, "Additional factors such as soot from wildfires and sulfate emissions were not included in this study," and added, "There is a possibility that the actual damage could be greater than expected during a collision."
Postdoctoral Researcher Lan Dai remarked, "Asteroid collisions have occurred multiple times throughout Earth's history, and early human ancestors might have experienced such events." He stated that there are plans to use computer models to analyze the effects of asteroid collisions on the evolution and genetic makeup of early humans in greater detail.
Meanwhile, an asteroid designated 2024 YR4, which has a collision probability of 1.2% with Earth in 2032, has been discovered. Postdoctoral Researcher Lan Dai commented, "The impact of asteroid collisions on the environment depends on the size of the colliding body," adding, "The small asteroid 2024 YR4, estimated to have a diameter of 40 to 100 meters, is likely to explode in the atmosphere with little damage to the surface."
Reference materials
Science Advances (2025), DOI: https://doi.org/10.1126/sciadv.adq5399