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One of the astronomical phenomena is causing astronomers more concern than any other.
By the year 2182, these alignments may occur with a probability similar to flipping a coin 11 times and getting the same outcome each time.
While the likelihood of an impact is extremely low, a chilling new simulation has demonstrated precisely
A collision between Bennu and Earth, the planet would encounter an enormous amount of dust and debris raised by the comet, which would mix with the atmosphere, causing a two-year 'impact winter'.
predicted what would happen as Bennu emitted millions of tonnes of dust into the atmosphere.
If the world is blocked by dust, the planet would become bitterly cold and parched, with temperatures dropping by 4°C (7.2°F) and overall rainfall decreasing by 15 percent.
In certain regions, such as North America, precipitation would decrease by 30 to 60 percent, rendering it extremely difficult to cultivate crops.
Lead author Dr. Lan Dai remarks: 'This would most probably lead to significant disruptions in global food security.'
Unlike the massive asteroid that ended the reign of dinosaurs,
It is estimated that asteroids like Bennu have a 100,000- to 200,000-year impact frequency on Earth, so it is most likely that our early ancestors have already lived through at least one such disaster.
However, the point of similarity between Chicxulub and Bennu is the enormous disruption to global climate patterns.
Similar to the hypothetical concept of "nuclear winter" that would follow a nuclear war, an asteroid impact would send a massive column of dust into the atmosphere.
They estimate that if Bennu were to hit Earth, a quantity of dust ranging from 100 to 400 million tonnes would remain in the atmosphere for a period of approximately two years.
These dust particles would act like a vast global umbrella, shielding the Earth from the sun's radiation and reflecting heat back out into space.
At its peak, the amount of shortwave radiation reaching Earth would decrease by 28 percent in the most extreme case scenario.
Global temperature averages would decrease by 1.6°C (2.9°F), 2.7°C (4.9°F), 3.4°C (6.3°F), and 4.0°C (7.2°F) with injections of 100, 200, 300, and 400 million tonnes of dust, respectively.
As the dust accumulates in the northern hemisphere during winter, Eurasia and North America are expected to experience the most extreme and rapid cooling.
The simulation shows that a prolonged cooling period will last up to four years following the impact, with a gradual recovery process beginning after 24 months.
In the worst-case scenario, a rapid 'impact winter' could be equivalent to the disastrous global cooling resulting from the massive Toba eruption, which occurred approximately 74,000 years ago.
The Toba supervolcano triggered a six-year-long winter, resulting in widespread deaths and a nearly complete extinction of the entire human population.
In addition, the researchers forecast that the interference with the patterns of ocean evaporation will result in 'massive drying' in numerous regions of the world.
Within six months after the occurrence, the global mean precipitation will decrease by approximately 0.46 mm per day, which represents a reduction of roughly 15 percent.
However, this will be accompanied by significant increases in rainfall in some subtropical regions and severe droughts in others.
This situation is further complicated by the fact that the Bennu dust cloud will also lead to a rapid decline of the ozone layer, as radiation and heat become trapped in the upper atmosphere.
The researchers forecast a 32-per-cent depletion of the global ozone layer.
Although it will be masked by the widespread dust, this could lead to substantial rises in levels of UV radiation that lead to sunburns, blindness, and cancer.
In their paper, published in Science Advances, the researchers contend that these changes would 'severely diminish the living conditions suitable for humans'.
Dr. Dai comments, "The sudden 'impact winter' would create harsh climate conditions for plants to thrive, resulting in an initial 20-30% decline in photosynthesis in terrestrial and marine ecosystems."
In the first year after the impact, the net primary productivity, which measures how quickly ecosystems produce and store organic material, was projected to decrease by 36 percent on land and 25 percent at sea.
Meanwhile, crop yields in East Asia may decrease as much as 50% possibly leading to widespread food shortages.
Some of Earth's ecosystems may actually be able to use a disaster of this kind.
Although marine environments initially suffer the setback, the simulation indicates that they not only endure but flourish in the years that follow the collision.
Within a mere six months, ocean plankton would have begun to revive and continue to rise to levels beyond those experienced under regular climate conditions.
This unexpected bloom would be caused by a high proportion of iron dust on the asteroid.
Iron is an essential nutrient for plankton growth, but many locations, like the Southern Ocean and the eastern tropical Pacific, have naturally low iron levels.
As the dust from the asteroid clears, it would stimulate a large-scale growth of photosynthesizing diatoms, which in turn would attract massive quantities of zooplankton, small predators that feed on diatoms.
"The artificially induced excessive phytoplankton and zooplankton growth might be a boon for the ecosystem and could help mitigate the emerging food shortages resulting from the extended decline in land-based productivity," says Dai.
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