Permian and Cretaceous Mass Extinctions
Assess the different hypotheses put forward for the mass extinctions at the end of the Permian and Cretaceous (KT) Periods.
A mass extinction is an event in which at least 25-75% of species in the global environment are eradicated in a short period of time. Where as a regional extinction event is when the extinction is confined to a specific zone. Five mass extinctions have occurred throughout time, two of the most well known of these are the Permian and Cretaceous extinction events.
There are several hypotheses that are used to explain the causes of mass extinctions. Climate change, the warming or cooling of global environments over a short period of time, can lead to other occurrences. Shifts in climate can cause extinction by moving or eliminating entire habitats. Global cooling most impacts the tropical areas as in the polar and deep-water flora and fauna have already adapted to cool environments. The major effect of global warning is on the circulation of ocean currents and the reduction of dissolved oxygen in water bodies. Anoxia, no or little dissolved oxygen in the sea, is the major cause of marine extinction. Anoxia is linked to global warming and sea levels rising.
Bolide, impact by asteroids or meteorites, can cause several environmental causatums. The dust from the impact can block out sunlight for years, creating permanent a winter, leading to the collapse of ecosystems. With no sunlight, plants cannot photosynthesis, so they will eventually die. Decaying plant and animal life leads to release of noxious gases, lessening the O2 levels in both atmosphere and lithosphere. The bolide impact can cause huge earthquakes and tsunamis. Molten debris raining down after the impact can start wildfires across the globe, further adding to the noxious atmosphere. The release of carbon dioxide and sulfur dioxide from mega-volcanoes can impact global temperatures, leading to global warming, sea level rises and acid rain. Volcanic eruptions have are
A mass extinction is an event in which at least 25-75% of species in the global environment are eradicated in a short period of time. Where as a regional extinction event is when the extinction is confined to a specific zone. Five mass extinctions have occurred throughout time, two of the most well known of these are the Permian and Cretaceous extinction events.
There are several hypotheses that are used to explain the causes of mass extinctions. Climate change, the warming or cooling of global environments over a short period of time, can lead to other occurrences. Shifts in climate can cause extinction by moving or eliminating entire habitats. Global cooling most impacts the tropical areas as in the polar and deep-water flora and fauna have already adapted to cool environments. The major effect of global warning is on the circulation of ocean currents and the reduction of dissolved oxygen in water bodies. Anoxia, no or little dissolved oxygen in the sea, is the major cause of marine extinction. Anoxia is linked to global warming and sea levels rising.
Bolide, impact by asteroids or meteorites, can cause several environmental causatums. The dust from the impact can block out sunlight for years, creating permanent a winter, leading to the collapse of ecosystems. With no sunlight, plants cannot photosynthesis, so they will eventually die. Decaying plant and animal life leads to release of noxious gases, lessening the O2 levels in both atmosphere and lithosphere. The bolide impact can cause huge earthquakes and tsunamis. Molten debris raining down after the impact can start wildfires across the globe, further adding to the noxious atmosphere. The release of carbon dioxide and sulfur dioxide from mega-volcanoes can impact global temperatures, leading to global warming, sea level rises and acid rain. Volcanic eruptions have are
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