A recent study on climate modeling has unveiled how climate and life on Earth could transform following a potential impact from a medium-sized asteroid (approximately 500 meters in size).
In an article published in the journal Science Advances, researchers from the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea have introduced a fresh scenario exploring how climate and Earth’s ecosystems might react to a possible strike from an asteroid measuring about 500 m.
The solar system contains numerous objects that orbit near Earth. While the majority pose no danger, a few have been flagged due to significant odds of collision. One such object is asteroid Bennu, which is around 500 m wide and has a predicted impact chance of 1 in 2700, particularly in September 2182, as indicated by recent research [Farnocchia et al. 2021]. This probability is comparable to flipping a coin 11 times and landing on the same side each time.
To explore the possible consequences of an asteroid collision on our climate and on both land and ocean plant life, the ICCP team devised a simulation of a hypothetical impact using advanced climate modeling techniques. The collision scenario includes a surge of hundreds of millions of tons of dust released into the upper atmosphere. In contrast to prior studies, this research also examines both terrestrial and marine ecosystems and the accompanying intricate atmospheric chemical reactions.
Utilizing the IBS supercomputer Aleph, the researchers tested several scenarios involving dust release from a Bennu-like asteroid collision with Earth. Their simulations revealed significant changes in climate, atmospheric chemistry, and global photosynthesis in the 3-4 years that followed the impact due to dust injections amounting to 100-400 million tons. The most severe scenario predicted a chilling of global surface temperatures by up to 4 degrees Celsius, a 15% drop in mean global rainfall, and a stark ozone reduction of about 32%, with regional impacts likely being even more severe.
“The sudden impact winter would create harsh conditions for plant development, leading to a 20-30% decrease in photosynthesis in both terrestrial and marine environments. This could significantly undermine global food security,” explained Dr. Lan DAI, the study’s lead author and a postdoctoral research fellow at the ICCP.
However, when the researchers analyzed data from ocean model simulations, they unexpectedly found that plankton exhibited a markedly different response. Unlike land plants, which faced a rapid decline followed by a slow recovery, ocean plankton bounced back within six months and even grew beyond levels typically seen in stable climate conditions.
“This unexpected outcome can be attributed to the iron content present in the dust,” noted Prof. Axel TIMMERMANN, ICCP Director and co-author of the study. Iron serves as a crucial nutrient for algae, but natural levels are often low in regions like the Southern Ocean and the eastern tropical Pacific. The iron from the asteroid, combined with terrestrial debris blasted into the atmosphere, can enrich these nutrient-deficient areas, leading to remarkable algae blooms. The simulations showed that this surge in marine productivity would be especially notable among diatoms, a type of silicate-rich algae, which would in turn attract large numbers of zooplankton that feed on them.
“These simulated explosions of phytoplankton and zooplankton could become beneficial for the biosphere and might mitigate the impending food scarcity driven by prolonged reductions in terrestrial productivity,” Dr. Lan DAI added.
“On average, medium-sized asteroids impact Earth every 100,000 to 200,000 years. This suggests that our early human ancestors may have encountered such transformative events, potentially influencing human evolution and even our genetics,” stated Prof. Timmermann.
This study published in Science Advances enriches our understanding of how collisions with near-Earth objects can affect climate and ecosystems. The next phase for the ICCP researchers will involve investigating early human responses to these events in greater detail through agent-based computer models that depict individual human lives, their lifecycles, and their quest for food.
