Understanding Climate Change

Climate change refers to long-term changes (typically over decades, or longer) in average global or regional climatic patterns. Climate change can arise from both natural and human induced factors.

The greenhouse effect describes the process where-by a portion of the Sun’s energy is absorbed and re-radiated by greenhouse gasses (GHGs), rather than being reflected. The greenhouse effect is a necessary, naturally occurring process that results in warming of the surface of the Earth Human activities, such as clearing land, agricultural practices, and the burning of fossil fuels, release more GHGs, and therefore enhance this greenhouse effect, which is leading to global warming (DotE, 2013).

Climate Science

A certain level of variability in the Earth’s climate occurs naturally, as a result of internal (physical) and external interactions. These variations occur over a range of time and spatial scales, from daily (for example the passage of high and low pressure systems), through to seasonal (such as monsoon systems) and interannual (due to processes such as El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole) as well as  decadal differences (from processes such as the Interdecadal Pacific Oscillation).

Examples of external interactions include changes to atmospheric composition from volcanic activity, or changes in solar radiation or the Earth’s orbit (CSIRO, 2015).

The international scientific community accepts that increases in greenhouse gases due to human activities have been the dominant cause of observed warming since the mid-20th century.

– CSIRO and Bureau of Meteorology, Australia

Anthropogenic climate change, or the enhanced greenhouse effect, describes the Earth’s response to the long-term external radiative imbalance caused by human activities. At a global level this has led to increases in air and ocean temperature, sea level rise and ocean acidification. Overall, climate change inevitably will have long term implications on our natural resources and these require management, particularly at a regional level (DotE, 2014).

Climate scientists use long-term climate models to distinguish variations in the climate that are due to natural causes, from those that are induced by human activity. Watch the following video for further explanation.

The future of anthropogenic greenhouse gas and aerosol emissions (and hence their resultant radiative forcing) is highly uncertain, encompassing substantial unknowns in population and economic growth, technological developments and transfer, and political and social changes. The climate modelling community has developed Representative Concentration Pathways (RCPs) to explore credible future options (DotE, 2014).

Responding to Climate Change

The Australia Government’s Department for Climate Change (Campbell 2008) identified two broad categories of climate change responses:

  • Mitigation – avoiding or reducing greenhouse gas emissions and increasing sequestration of greenhouse gases.
  • Adaptation – making adjustments to natural and human systems to avoid and/or minimise the impacts of climate change.

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