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What is climate change?
Climate change, sometimes called “global warming”, is the most serious and most complex environmental issue ever to confront the international community.
The enhanced greenhouse effect
Global warming is caused, at least in part, by what is sometimes called the “enhanced greenhouse effect”. The earth’s atmosphere traps heat from the sun and makes our planet habitable – that is the “greenhouse effect”. But when we burn fossil fuels or release carbon dioxide (CO2) in other ways, such as deforestation, we increase CO2 concentrations in the atmosphere. This enhances the greenhouse effect, trapping more heat and causing average temperatures on the earth to rise.
The scientific evidence
A vast amount of research has been done on climate change, its causes and implications. There is virtually no argument that the climate is changing, and there is a growing international consensus that emissions from human activities are largely responsible.
Atmospheric concentrations of carbon dioxide and methane over the last few hundred years have been measured from air bubbles trapped deep in polar ice, and more recently, from instrument readings. The pattern is of steep increases of both these GHGs since pre-industrial times.
If global warming is allowed to proceed too far, there are feedback mechanisms such as increasing forest fires and loss of soil carbon which could create dangerous increases in GHG emissions in the second half of this century.
More detailed information regarding the current state of evidence of climate change is available from the website of the Intergovernmental Panel on Climate Change (IPCC) at www.ipcc.ch. You may also want to visit www.realclimate.org, a commentary site on climate science by working climate scientists for the interested public and journalists.
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