As we enter the 21st century, the world is facing an alarming number of environmental challenges. From the loss of biodiversity to the rising sea levels, each of these challenges possesses a significant threat to our planet and its inhabitants. Here is a list of the greatest environmental challenges facing the earth today.

1. Climate Change: The most significant challenge that our planet is facing today is undoubtedly climate change. The rise of global temperatures is causing extreme weather events, sea-level rise, water scarcity, and ecological destruction.

2. Loss of Biodiversity: The loss of biodiversity poses a great threat to our planet. This loss is caused by habitat destruction, climate change, and pollution. According to the IUCN Red List, over 37,000 species are facing extinction, putting our natural ecosystems and food security at risk.

3. Air Pollution: The exposure to air pollution is a leading cause of death, especially in developing countries. Toxic air pollutants such as nitrogen oxide and sulfur dioxide contribute to the depletion of the ozone layer and smog formation, compromising air quality.

4. Deforestation: Forests are crucial ecosystems that provide habitat for wildlife, regulate global climate, and store carbon. Despite their importance, deforestation is still occurring at an alarming rate. Forests are being cleared for human development, agriculture, and even for the production of palm oil.

5. Plastics Pollution: The overuse of plastic has become a significant environmental challenge. The accumulation of plastic waste in our oceans, ecosystems, and landfills is leading to severe ecological and human health issues. The Great Pacific Garbage Patch, the largest accumulation of plastic in the world, is now twice the size of Texas.

6. Water Scarcity: With the growing population, water scarcity has become a significant problem. It is estimated that by the year 2025, half of the world may face water scarcity. This scarcity is due to the depletion and pollution of our freshwater sources, increased demand for water, and climate change.

7. Loss of Coral Reefs: Coral reefs are one of the most biodiverse ecosystems on earth, supporting over 25% of all marine life. However, they are under severe threat from ocean acidification, pollution, overfishing, and climate change.

In conclusion, each of these environmental challenges poses a significant threat to our planet and its inhabitants. It is crucial to take immediate and decisive action to prevent further damage to our planet. We all have a responsibility to protect the environment and make our planet a better place to live.