Biodiversity and Climate Change

Changing Oceans, changing species

The sea covers 71% of the globe. Approximately 51% of the earth's surface is covered by oceans over 3,000m in depth. They are critically important for biological diversity, commercial activities (such as fishing and tourism) and for their role in climate regulation. The impacts from human-induced climate change could potentially be disastrous.

Physical and chemical effects of climate change - the build up of greenhouse gases is causing a rise in air and sea temperatures. Marine life will be impacted directly by these warmer waters and indirectly by the secondary effects of other ocean conditions. Increases in water temperature have an effect on:

Deep-ocean circulation patterns
Wind patterns
Ocean stratification
Chemical composition
El Niño Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO)

Physical effects of ozone depletion and enhanced ultraviolet radiation - depletion of the earth's protective ozone layer has led to an increase in ultraviolet radiation with the effects of these harmful rays penetrating many metres below the ocean surface.

Effects on biodiversity - the impacts of climate change and ozone depletion on marine life in the oceans are likely to be seen right through the complex food web. Starting with the microscopic plankton that are consumed by fish and moving up to the larger animals such as seabirds and marine mammals. Their food source may be depleted while warmer waters and changing ocean currents will have quite an impact, and these factors may result in significant changes in species distribution and abundance.

Effects on important ecosystems - the impacts of warmer seas and increased ultraviolet radiation will be felt in many different areas of the world. Considerable information is available about the effects of increased temperatures on coral reef communities. The mass bleaching of corals that has occurred during extreme El Niño Southern Oscillation (ENSO) events in recent years has demonstrated the vulnerability of this ecosystem to climate change. Polar Regions are also feeling the effects of an increase in global temperatures leading to a reduction in the coverage and thickness of sea ice. In addition, the loss of ozone is most prominent at high latitudes. Our lack of knowledge about biodiversity in the deep sea makes it an important area for research if the impacts of human induced climate change are to be measured.

Source: Biodiversity and Climate Change Programme, UNEP World Conservation Monitoring Centre