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Topic last updated: 09 Nov 2023
    • Biology Biology
    • Ico Science Science
    • 14-16
    • 55

Ecosystems and ecology

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Biotic and abiotic factors and climate change

Global warming and climate change are affecting both biotic and abiotic factors, and this is leading to various species becoming extinct and endangered. This is because biotic and abiotic factors need to be balanced in a stable community and climate change is altering that balance.

For example, food availability is changing. This is because changes in the climate, such as more extreme weather events (like droughts or floods, which fall under the abiotic factor moisture levels) can affect the growing season of various plants and this can reduce the availability of food for herbivores/primary consumers. Competition (a biotic factor) therefore increases and this can make the number of individuals within the primary consumer population drop. This would have an impact on the secondary consumer too, as the number of primary consumers may decline. Essentially, the change to the growing season of the plants goes on to affect the whole food chain, causing some species to become extinct or endangered.

For example, phytoplankton prefer cooler water. The oceans are heating up because of climate change, meaning that some of the phytoplankton is dying. This is a change to an abiotic factor -temperature.

As the number of individuals in the phytoplankton population drops, this means that zooplankton (the primary consumer) has no food and could die. As fish eat zooplankton, this means that the fish (the secondary consumer) have no food, then the humans, the dolphins, and finally the killer whales.

Being extinct or endangered can also mean that the there will be lots of the animal or plant that the removed animal eats, as it isn’t being eaten any more. Therefore, food sources for the animal which there are lots of are spread further, and competition (a biotic factor) increases.

In the sea example, if the fish became extinct, there would be lots of zooplankton. Then, there might not be enough phytoplankton for all of the zooplankton to eat.

This means that climate change is putting food chains at risk. This is why we need to protect our habitats and look after the animals and plants that live in them.

The International Union for the Conservation of Nature (IUCN) have a set of criteria which they use to classify a species as endangered. For example, there should be ‘an observed, estimated, inferred or suspected population size reduction of ≥70% over the last 10 years or three generations, whichever is the longer.’ Further information on these criteria can be found on the IUCN website (IUCN, 2012).



IUCN (2012). IUCN Red List categories and criteria, version 3.1, second edition. Available at: (Accessed: 11th October 2023).