Mass Extinctions and Human Activity.pptx

A brief outline of mass extinctions for younger students. (11-15) Asking students if we are the cause of the next mass extinction and looking at the ways that we reduce biodiversity.

1. Mass Extinctions

2. Caused by a cooling of the earth. Ice caps grew and the sea level fell by hundreds of feet. This caused the see to be highly concentrated with toxic materials, killing most marine life. Killed 85% of life on Earth in 30 million years. Possibly caused by volcanic activity. Massive drop in ocean oxygen levels due to an algae bloom that suffocated most marine life. 75% of life on Earth killed over 20 million years. Known as “The Great Dying”. 95% of all life killed over about 60,000 years. All worlds forests were wiped out, not totally returning for 10 million years. Massive volcanic eruption.

3. Rapid warming due to volcanic activity, this also led to acidification of oceans meaning that invertebrates couldn’t build their shells as the calcium was dissolving. 80% of life killed by a 2-5 degree celsius rise in temperature 76% of all life killed by an asteroid and the following wildfires, hot ash worldwide and smoke that blotted out the sun. All land within 900 miles was set on fire. Global cooling and plants incapable of photosynthesising.

4. Are Mass extinctions a natural cycle of Earth? Extinction is a part of life, and animals and plants disappear all the time. About 98% of all the organisms that have ever existed on our planet are now extinct. When a species goes extinct, its role in the ecosystem is usually filled by new species, or other existing ones. Earth's 'normal' extinction rate is often thought to be somewhere between 0.1 and 1 species per 10,000 species per 100 years. This is known as the background rate of extinction. A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world's species being lost in a 'short' amount of geological time - less than 2.8 million years.

5. Are we the cause of the next mass extinction?

6. Human Activity People represent just 0.01% of all living things, according to the study. Yet since the dawn of civilisation (5,000 or 6,000 years ago roughly) humanity has caused the loss of 83% of all wild mammals and half of plants and insects.

7. So how does this happen?

8. Habitat Loss Urbanisation and Agriculture: Expanding cities, agricultural lands, and infrastructure projects lead to the destruction of natural habitats. Forests, wetlands, and grasslands are often cleared for development, leaving species without homes. Despite its green image, Ireland has surprisingly little forest. Across Europe, nations average around 35% forest cover but in Ireland the figure is just 11%, one of the lowest on the continent. This hasn't always been the case. Thousands of years ago, more than 80% of the island of Ireland was covered in trees.

9. Pollution Chemical Pollution: Pesticides, herbicides, and industrial chemicals can contaminate ecosystems, poisoning wildlife and disrupting reproductive and developmental processes. Plastic Pollution: Marine species often ingest or become entangled in plastic debris, leading to injury or death. Air and Water Pollution: Pollutants in the air and water can degrade habitats and harm species directly. For example, acid rain from air pollution can damage forests and aquatic ecosystems.

10. Climate Change Global Warming: Rising temperatures can alter habitats, making them uninhabitable for some species. For example, coral reefs are highly sensitive to temperature changes and can suffer from bleaching events. Changing Weather Patterns: Altered precipitation patterns and increased frequency of extreme weather events can disrupt ecosystems and the life cycles of species.