Chapter 37, Problem T27.1BYB

Summary Introduction

To analyze:

The cause for the current extinction crisis.

Introduction:

Our planet is experiencing the sixth wave of mass extinction of plants and animals in the half-billion years. Since the extinction of dinosaurs about 65 billion years ago, we are experiencing the worst spate of die-offs. Sometimes, it could be a ‘natural phenomenon’. However, unlike the past which was caused by volcanic eruptions or asteroid strike, the current crisis is due to humans.

Explanation of Solution

The most recent period, the Cretaceous-Paleocene extinction event, that occurred 66 million years ago, was a mass extinction of plants and animal within a short period of time. Around 99% of threatened species are at risk of human activities that are causing a habitat loss, global warming and introducing hybrid or exotic species. In this complex ecological web, the extinction of one species affects the other species in line.

The diversity of species in the ecosystem provides resilience and communities know how to withstand the stress. The biodiversity areas are such as coral reefs, rainforests, tundra, grasslands, polar seas wherein loss of biodiversity could be irreversible.

Causes

Climate change − Climate change has a huge impact on extinction rate. The species in biodiversity are not capable of handling this drastic change in temperature and climate, like long seasons or changing chemical make-up of surroundings. Besides, it allows many bacteria and virus to survive the warm climates making it easier for the spread of disease and epidemics.

Sea-levels or current changes − The melting freshwater is the cause for changes in the sea levels. Ocean floor spreading causes a rise in the sea level which displaces water to the land. The denser salty water sinks form currents that marine life depends on. Besides, volcanic eruptions expel chemicals that get absorbed by water making it unsuitable for life.

Acid rain- When sulfur dioxide or nitrogen dioxide is released from chemical industries, it mixes with water vapor in the atmosphere and falls on earth as acid rain. This increases the acidity of soil affecting the pH of the soil and thus the plant life. It also disturbs the lethal levels in rivers and lakes.

Epidemic/diseases- As global warming affects the climate, species lose their immunity to defend against diseases. They become susceptible to epidemics and prone to disease.

Spread of invasive species- Due to invasive species from the outside territory, occupying the native habitat, it creates competition for the species to survive, leading to extinction.

Conclusion

Extinctions happen most of the time, but they are balanced by ‘survival of the fittest’ and the arrival of new species. However, mass extinction happens when the balance is disturbed. This extinction of species happens at an alarming rate, which is caused by man and politics around it.