Threats to biodiversity

Scientists have so far described and classified around 1.3 million species of organisms that live on Earth today. However, they think that there could be as many as 8.7 million or more different species on Earth! Today, this incredible variety of species, the biodiversity on our planet, is under threat. There are five main reasons for this. One of the biggest threats to biodiversity is the loss of natural environment, the loss of habitat.

Habitat loss happens when an environment is changed so drastically that many species can’t survive there anymore. This change is sometimes caused by natural disasters, such as wildfires or droughts. But it is more and more often the result of human activity. For example, deforestation, cutting down trees and not replanting any, has a huge impact on biodiversity. Organisms that lose their habitat are either forced to move or they die.

Other major threats to biodiversity across the planet include pollution and changing climate. Plastic pollution is especially dangerous as it ends up in nature in enormous quantities. Many animals die because they eat plastic. Plastic also leaches chemicals into the environment when plastic breaks down. These chemicals might cause problems, such as fewer animals being born or animals getting health problems.

Climate change is also a serious threat to biodiversity, particularly because of rising temperatures and ever more extreme weather conditions. Species often can’t adapt to how quickly these changes happen. Species are disappearing at an alarming rate. People are harvesting plants, hunting and fishing at a rate faster than new organisms are being born. This is overexploitation and it’s another big threat to biodiversity.

Sometimes overexploiting one species can threaten the existence of other species too. For example overexploiting salmon means that eagles, bears and wolves that feed on salmon, won’t have enough to eat. Plants in forests might be affected too. Animals that eat salmon sometimes carry the fish with them into the forest, where any uneaten fish breaks down and returns nutrients to the soil, which plants need. Finally, there is a threat to biodiversity that affects specific areas, rather than the whole world.

Sometimes new species are taken by humans to parts of the world where they’ve never lived before, for example cats that came to New Zealand by ship. It might seem like one more added species means increased diversity, right? But in New Zealand, cats invaded the environment of animals that already lived there. Native birds had never met cats before, so they had no natural fear of them. Many bird species were therefore easily hunted by cats and wiped out completely.

Species, like the cats in New Zealand, that cause such problems in environments where they’re not naturally present, are called invasive species. They are a great threat to biodiversity in places where they are introduced. Biodiversity loss has a huge impact on different ecosystems, but it can affect our lives too. For example, we use between 50 and 70 thousand species of plants to produce medicine! As human activity is the main threat to biodiversity loss, we have the power and responsibility to change our activities to do the least harm possible.