What is the greenhouse effect?
To find out about the greenhouse effect and climate change, click on the links below.
- What causes the enhanced greenhouse effect?
- How do scientists measure and predict climate change?
- Frequently asked questions
- Is the scientific information reliable?
- Climate science, impacts and adaptation
Greenhouse effect
Greenhouse gases are a natural part of the atmosphere. They trap the sun's warmth, and maintain the earth's surface temperature at a level necessary to support life (approximately 15°C). This natural process is called "the greenhouse effect".
The earth's climate has been alternating between hot and cold periods (ice ages and interglacial periods) for at least the past million years. Records from polar ice cores show oscillating periods of glacial (ice ages) and interglacial (warm periods). We are currently in an interglacial period.
However, the observed warming since the 1970's cannot be explained by natural causes alone.
Most of the warming in the past 50 years is "very likely" (more than 90% in probability) due to the observed increase in greenhouse gas concentrations from human activities such as the burning of fossil fuels and land use change (IPCC 2007). These findings are reported in the Fourth Assessment Report released in 2007 by the Intergovernmental Panel on Climate Change.
An increase in greenhouse gases in the atmosphere traps more heat and raises the earth's surface temperature. This process is called the enhanced greenhouse effect.
As the earth's climate is a finely balanced system, any significant rise in atmospheric temperature, such as that caused by an increased concentration of greenhouse gases, is likely to produce changes to the climate worldwide. As a result, the enhanced greenhouse effect is often referred to as "global warming" or "climate change".
Scientists also warn that climate change impacts could occur very rapidly once certain thresholds are reached.
The enhanced greenhouse effect is a global problem where the effects of emissions are cumulative within the atmosphere. So, it does not really matter where the emissions are generated - they can still cause global warming and consequently climate change.
- Further information is provided in the frequently asked questions booklet on climate change science.
- Information sheets on hot topics related to climate change are also available
Last updated: 07 March 2008