Our climate is changing. Some changes may be natural but the majority of climate scientists agree the changes are very likely due to increases in human-produced greenhouse gases.
Today the majority of the debate among scientists is not whether climate change is happening, but how quickly it is happening and what the effects will be.
Our atmosphere and the role of greenhouse gases
Our earth is surrounded by an atmosphere that is made up of a collection of gases and vapours.
Greenhouse gases, as part of the atmosphere, play an essential role in absorbing and re-radiating the sun's heat. This process creates our climate and makes the Earth's temperature warmer than it would otherwise be, allowing life as we know it to exist.
There are many greenhouse gases. Many are naturally occurring, such as water vapour which is the main greenhouse gas. Its concentration is highly variable and human activities have little direct impact on the amount of it in the atmosphere.
However, there are several greenhouse gases generated by human activity such as:
- carbon dioxide (CO2)
- nitrous oxide.
There are also manufactured gases such as chlorofluorocarbons (CFCs), halocarbons and some of their replacements.
Greenhouse gases and climate change
Increased greenhouse gases absorb more heat from the sun within the earth’s atmosphere and reduce the amount of heat escaping back into space.
The effects of this captured heat include:
- increases in global average air and ocean temperature
- widespread melting of snow and ice
- and rising global sea levels.
The extra heat in the climate system also has other impacts, such as affecting atmospheric and ocean circulation, which influences rainfall and wind patterns.
The projected impacts of climate change in South Australia generally include warmer and drier conditions and more extreme weather events.
Global warming and climate change
The terms 'global warming' and 'climate change' are often used interchangeably, but there is a difference.
- Global warming is the gradual increase of the Earth’s average surface temperature, due to greenhouse gases in the atmosphere.
- Climate change is a broader term. It refers to long-term changes in climate, including average temperature and rainfall.
Climate change mitigation and adaptation
The terms 'mitigation' and 'adaptation' are often used when discussing climate change actions.
Climate change mitigation aims to reduce greenhouse gas emissions or remove greenhouse gases from the atmosphere to slow the rate of climate change. Common mitigation actions include:
- reducing the use of carbon-intensive fossil fuels for industrial processes or electricity generation
- switching to renewable energy sources
- using energy more efficiently
- developing and using low-carbon technologies
- expanding forests or carbon sinks to remove greater amounts of carbon dioxide from the atmosphere.
Climate change adaptation aims to reduce the vulnerability of natural and human systems to the current and potential effects of climate change. In South Australia these potential effects include warmer and drier conditions, more extreme weather events and an average sea level rise. Adaptation to these effects must take into account the economic, social and environmental impacts that will vary across each region.
Science of Climate Change - CSIRO
Climate Change - Australian Government
Weather and Climate Change - Bureau of Meteorology
United Nations Framework Convention on Climate Change
Science of Climate Change – Garnaut Review