About Climate Change
What is climate change?
Our climate is changing, largely due to the observed increases in human produced greenhouse gases. Greenhouse gases absorb heat from the sun in the atmosphere and reduce the amount of heat escaping into space The Greenhouse Effect). This extra heat has been found to be the primary cause of observed changes (increases in global average air and ocean temperature, widespread melting of snow and ice and rising global sea levels) in the climate system over the 20th century. The extra heat in the climate system also affects atmospheric and ocean circulation, which in turn, influences rainfall and wind patterns (DCCEE, 2010).
Global warming and climate change
The terms 'global warming' and 'climate change' are often used interchangeably, but there is a difference(DCCEE, 2010):
- 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.
Greenhouse gases
Greenhouse gases have always been a natural part of the atmosphere. The chemical properties of greenhouse gases mean that they strongly absorb and re-radiate the sun’s warmth. This process maintains the earth’s temperature at 33°C warmer than it would otherwise be, allowing life on earth to exist (DCCEE, 2010).
Water vapour is the most abundant greenhouse gas. Its concentration is highly variable and human activities have little direct impact on its concentration in the atmosphere. The main greenhouse gases generated by human activity are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). There are also manufactured gases such as chlorofluorocarbons (CFCs), halocarbons and some of their replacements that make a small contribution to global warming (DCCEE, 2010).
Over the last 800,000 years, the amount of carbon dioxide in the atmosphere has varied between approximately 172 and 300 parts per million (ppm). Since industrialisation, carbon dioxide levels have risen sharply to about 386 ppm. Even in these amounts, the extra carbon dioxide is largely responsible for the increase in global temperatures of about 0.7oC (DCCEE, 2010).
Greenhouse gases and human activity
Greenhouse gases are produced by human activities, including (DCCEE, 2010):
- Burning fossil fuels, such as coal, oil or gas
- Using energy generated by burning fossil fuels
- Some aspects of farming, such as raising cattle and sheep, using fertilisers and growing some crops
- Clearing land, including logging
- The breakdown of food and plant wastes and sewerage
- Some industrial processes, such as making cement and aluminum.
Adapting to Climate Change
While there is no universally agreed definition of climate change adaptation, it can generally be defined as ‘actions taken in response to actual or anticipated climate change impacts that lead to a reduction in risks or realisation of benefits’. Adaptation represents a planned and proactive response to climate change and, as such, can be distinguished from reactive adjustments to climate change impacts after they have occurred.
For more information on how HCCREMS and its member councils are improving understanding and adaptation planning in response to climate change, visit History and Achievements and Current Activities.
Reference: Commonwealth Department of Climate Change & Energy Efficiency (DCCEE), 2010. http://www.climatechange.gov.au/en/climate-change.aspx.
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