Climate change is already impacting biodiversity

Mike Read Crane Cam is providing outstanding views of Sandhill Cranes Zoom In

The climate of our planet is changing rapidly because of human activities, especially the burning of fossil fuels. We can already see many direct impacts on biodiversity, and other threats may be made much worse.

Our planet's climate is changing rapidly

The Earth is undergoing profound changes to its climate. There is now little doubt that this results from human activities, mainly the burning of fossil fuels (see box 1). Climatic changes have occurred throughout Earth’s history. However, these recent changes are different because they are taking place faster and are unlikely to be reversed by natural processes.

Climate change affects all biodiversity

The effects of climate change on biodiversity are far-reaching and operate at many different levels – from individuals to ecosystems. At the species level, climate change affects particular species in different ways. It may alter their distribution, abundance, behaviour, phenology (the timing of events such as migration or breeding), morphology (size and shape) and genetic composition. Many such effects have already been documented in a wide range of species (box 2). Birds provide some of the clearest examples, in both single species and multi-species studies (box 3).

Climate change makes other threats worse

Climate change may affect species directly, for example through changes in temperature and rainfall. Often, however, the indirect effects are even more important. There may be increased pressure from competitors, predators, parasites, diseases and disturbances (such as fires or storms). Climate change will often act in combination with major threats such as habitat loss and alien invasive species, making their impacts considerably worse (box 4).

Boxes: case studies and scientific analyses

Download SOWB pp.46–47 (PDF, 331 KB) containing the following:

1. The world's climate has changed significantly over recent decades, and much larger changes are predicted

2. There is good evidence that climate change is already impacting many species
Changes in phenology and distribution detected among almost 500 species are overwhelmingly in the direction predicted from climate change

3. Climate change is already affecting birds in diverse ways

4. In Hawaii, climate change will increase the impact of disease
The area of forest with medium and low malaria risks for native bird species in forest reserves on three Hawaiian islands is predicted to decrease substantially following a temperature rise of 2 degrees Celsius