The total number of species on Earth is difficult to determine precisely, as new species are still being discovered, and many remain undiscovered. The estimated number of described species varies among different scientific estimates and is subject to ongoing revision. According to the Catalogue of Life, an extensive database of known species, there are over 1.8 million ~ 2.16 million described species of living organisms, including plants, animals, fungi, and microorganisms.

Regarding the number of extinct species, it’s also challenging to provide an exact figure. Throughout Earth’s history, numerous species have gone extinct due to various factors such as natural events, environmental changes, and human activities. The fossil record provides evidence of past extinctions, but it is likely that many species have become extinct without leaving a fossil record.

It’s worth noting that the rate of extinctions has increased significantly in recent times due to human activities, such as habitat destruction, pollution, climate change, and overexploitation. The International Union for Conservation of Nature (IUCN) maintains the Red List of Threatened Species, which assesses the conservation status of various species. As of September 2021, the IUCN Red List includes over 38,000 species, with more than 31,000 species classified as threatened with extinction.

To obtain the most up-to-date and accurate information on the number of species and extinctions, I recommend referring to scientific sources, research papers, or reputable databases that specialize in cataloging and tracking biodiversity.

The main causes of extinction are habitat loss, overexploitation, invasive species, and climate change. Habitat loss is the most significant factor, as it destroys the natural homes of plants and animals. Overexploitation occurs when too many individuals of a species are harvested, such as for food or medicine. Invasive species are non-native species that disrupt the ecosystems they are introduced to. Climate change is a relatively new threat, but it is already causing the extinction of many species that are unable to adapt to the changing environment.

The loss of biodiversity is a serious problem, as it has a number of negative consequences for the planet. These include the loss of ecosystem services, such as pollination and pest control, the loss of genetic diversity, and the increased risk of pandemics.

There are a number of things that can be done to prevent extinctions, such as protecting habitats, reducing overexploitation, controlling invasive species, and mitigating climate change. It is important to take action now to protect the remaining species on the planet, as we may not have another chance.