Scientists reveal when devastating asteroid could hit Earth, causing global 'impact winter'

A devastating asteroid impact could plunge Earth into a prolonged "impact winter," drastically reducing photosynthesis and triggering a long-term food supply crisis, according to new computer simulations. The asteroid Bennu, considered a near-Earth object, poses a minimal but non-zero risk of collision with our planet.

Scientists estimate a 0.037% chance that Bennu could strike Earth in September 2182. While this probability is exceptionally small, the potential consequences of such an event would be immense. Researchers used computer models to study the effects of an asteroid approximately 500 meters in diameter, similar in size to Bennu, hitting Earth.

Beyond immediate destruction at the impact site, the collision would launch between 100 and 400 million tons of dust into the atmosphere. This dust could disrupt global climate, alter atmospheric chemistry, and impair photosynthesis for several years. The simulations predict a potential drop in average global temperature by about four degrees Celsius, a 15% decrease in precipitation, and a 20-30% weakening of plant photosynthesis.

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The darkening of the Sun due to dust would cause a sudden global 'impact winter,' characterized by reduced sunlight, lower temperatures, and less surface precipitation.

The study also warns of a potential 32% reduction in the ozone layer, increasing exposure to harmful ultraviolet radiation. The impact itself would generate powerful shockwaves, earthquakes, fires, and thermal radiation, leaving behind a massive crater and vast amounts of ejected material. Scientists caution that the long-term climatic and ecosystem effects could severely jeopardize global food production, as unfavorable conditions would limit plant growth both on land and in oceans.

Bennu, composed of loose rocky material, is a remnant from the early solar system, formed about 4.5 billion years ago. NASA's OSIRIS-REx mission collected samples from Bennu in 2020, providing scientists with new insights into its composition, which includes chemical ingredients linked to the origin of life. Historically, asteroids have caused major catastrophes on Earth, with the most famous example being the impact 66 million years ago near the Yucatán Peninsula that led to the extinction of about three-quarters of plant and animal species.

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Such adverse climatic conditions would limit plant growth on land and in oceans.