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Why would an impact winter threaten plants and animals around the world?
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Earth impact hazard
An artist's rendering of the impact of a near-Earth object 66 million years ago in what is today the Caribbean region. Many scientists think that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of dinosaurs and many other species near the end of the Cretaceous Period.
An impact winter poses a severe threat to global life because it drastically alters the environment following a large-scale impact event. When a massive asteroid or comet strikes Earth, it ejects vast quantities of fine debris and dust high into the atmosphere.123
This global cloud of material acts as a barrier, preventing sunlight from reaching the surface for months or longer. The consequences for the biosphere are catastrophic:34
- Cessation of Photosynthesis: With sunlight blocked, photosynthesis cannot occur, leading to the widespread death of green plants.13
- Food Chain Collapse: The loss of plant life disrupts the base of the food chain, causing a ripple effect that results in starvation and disease among animals worldwide.13
- Temperature Depression: The reduction in solar energy leads to a prolonged, global drop in surface temperatures, creating harsh conditions that many species cannot survive.12
This environmental collapse is widely believed to be a primary driver of mass extinctions, such as the Cretaceous-Tertiary extinction that eliminated approximately 80 percent of all species 66 million years ago.234