Climate change science
The oceans store a lot of the Sun's energy and transport this heat around the planet through massive currents. A slight temperature change in ocean surface waters can have a major impact on the atmosphere and rainfall patterns over vast areas.
Variations in Australian climate stem from changes in the Pacific, Indian and Southern Oceans. The effects of each of these can add to, or subtract from, each other.
The Indian Ocean Dipole is an important phenomenon. When it is present, the dipole consists of a warm water region in the area around Indonesia and New Guinea, and a relatively colder region in the central Indian Ocean west of Australia. The warm region is fairly common, particularly in La Niña years.
The Indian Ocean Dipole gives rise to rain-producing systems that extend across Australia from north-west to south-east. These north-west cloud bands are the principal means by which rain occurs in the dry centre, although most of the associated rain actually falls in the south-east of the country.
Global warming and ozone depletion (the ‘ozone hole') in the upper atmosphere (stratosphere) are two different problems. However, chlorofluorocarbons (CFCs) play a role in both. Chemical reactions involving CFCs destroy ozone in the stratosphere. As a result, more of the Sun's ultraviolet radiation reaches the Earth, increasing our risk of skin cancer. The Montreal Protocol, an international agreement to protect the ozone layer, has led to concentrations of atmospheric CFCs and related substances beginning to decrease. Stratospheric ozone is likely to be restored to 1960s levels by about 2050.
CFCs also act as powerful greenhouse gases in the lower atmosphere by trapping heat energy which would otherwise escape to space. Some CFCs can remain in the atmosphere for many centuries before being broken down, so their contribution to global warming will persist for a long time
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