Impact of global warming on biodiversity
Glossary
biodiversity. A measure of the variety of life. It is usually calculated from the number of species of organisms – although genera, families, classes and phyla can all be counted too.
carbon dioxide fertilisation effect. Increased concentrations of carbon dioxide stimulate the growth of many different types of plant. A doubling of atmospheric carbon dioxide has been shown to stimulate leaf photosynthesis rate by up to 50 per cent depending on temperature. Experiments show that the fertilisation effect of increasing concentrations of carbon dioxide eventually reaches a saturation point. This means that other vital ingredients such as water and nutrients become limiting.
endemic. Describes a species (or other unit of classification) that occurs in one particular region in all months of the year, and in all years. For example, the platypus is endemic to southeast Australia, and malaria is endemic to parts of Africa.
global warming. An increase in the average temperature of the Earth's surface. Global warming is one of the consequences of the enhanced greenhouse effect and will cause worldwide changes to climate patterns.
greenhouse gas. A gas that is transparent to incoming solar radiation and absorbs some of the longer wavelength infrared radiation (heat) that the Earth radiates back. The result is that some of the heat given off by the planet accumulates, making the surface and the lower atmosphere warmer. The most common greenhouse gases are water vapour, carbon dioxide, methane and nitrous oxide. For more information see The greenhouse effect (CSIRO Atmospheric Research, Australia).
groundwater. Water stored naturally below the land surface in a saturated zone of the soil. The top of this groundwater is called the watertable. For more information see What is groundwater? (Connected Waters, University of New South Wales, Australia).
Intergovernmental Panel on Climate Change (IPCC). An organisation established in 1988 by the World Meteorological Organization and the United Nations Environment Programme to provide the most widely accepted information available about climate change. The IPCC does not conduct new research or monitor climate-related data, its mandate is to assess existing data and to produce balanced and objective publications. For more information see Intergovernmental Panel on Climate Change (Switzerland).
photosynthesis. The biochemical process in which green plants (and some microorganisms) use energy from light to synthesise carbohydrates from carbon dioxide and water. Photosynthesis can be shown as:
CO2 + H2O + energy → [CH2O] + O2
recharge or discharge. The recharge rate is the rate at which an aquifer is replenished or topped up with water (inflow). The other important variable for groundwater management is the discharge rate, or the rate at which water is taken out of the system (outflow). In some cases aquifers can discharge naturally to rivers and springs and so the water is not being removed from the system. The two variables determine the water balance, which is part of the larger water cycle involving the journey of water as it falls from the sky, onto land or sea or aquifer, and back again.
thermal expansion. Global warming causes the water in oceans and seas to expand in volume as it warms. The IPCC projects that thermal expansion will be the main component of expected sea-level rises over the 21st century.
Posted October 2005.