Describe the probable causes of two mass extinctions?

Answer 1

The Permian-Triassic extinction event was probably caused by tremendous amounts of carbon dioxide that were released from a huge volcanic flow in what is now Russia. This carbon dioxide would have warmed the Earth 5 degrees Celsius (9 degrees Fahrenheit) on average, which would have been enough to evaporate deposits of methane on the ocean floor. This would have warmed the Earth an additional 5 degrees Celsius, for a total rise in average temperature of 10 degrees Celsius (18 degrees Fahrenheit). That would have caused catastrophic climate change, and may have also caused the oceans to lose oxygen content. This would have killed many marine species, and created an ideal habitat for bacteria that create hydrogen sulfide gas. This gas would poison many organisms, on top of damaging the ozone, so that UV light could harm any surviving organisms. 90% of species on Earth died out in this mass extinction.

The Cretaceous-Tertiary Extinction Event was probably caused in part by climate change due to volcanoes releasing carbon dioxide. This climate change weakened many of Earth's species. Then, when an asteroid impacted the Earth and covered the sky in a thick layer of dust, blocking nearly all sunlight, plants died, and so did the animals that depended on them. There is some evidence that the dinosaurs actually survived the first asteroid impact, only to be wiped out by a second impact only 200,000 years later.

Answer 2

The Permian-Triassic extinction, the largest mass extinction in Earth's history, was likely caused by intense volcanic activity leading to climate change and ocean acidification. The Cretaceous-Paleogene extinction, which wiped out the dinosaurs, was probably triggered by a massive asteroid impact that led to environmental disturbances like wildfires, tsunamis, and global darkness.