Climate change and global warming

Climate change is the term we use to describe changes in the world’s weather caused by global warming. But the big question is: why is the earth warming up?

Basically, the earth is warming up because of what’s known as the ‘greenhouse effect’. This is where ‘greenhouse gases’ (mostly carbon dioxide, water vapour, methane and nitrous oxide) build up in the Earth’s atmosphere and create a barrier through which excess heat can’t easily escape.

It’s called the greenhouse effect because global warming works in a similar way to traditional greenhouses, which make a tent-like cover over plants to keep them warm in cool conditions.

Human activities, such as cutting down forests and burning fossil fuels for energy, have increased the amount of greenhouse gases in the atmosphere and are enhancing the greenhouse effect.

This enhanced greenhouse effect is in turn, causing global warming and climate change.

Each of the greenhouse gases contributes to global warming to varying degrees so for measurement and comparison purposes they are converted to a ‘carbon dioxide equivalent’ unit (CO2e).

Climate change could have serious consequences

Climate change is significant, and it’s predicted to have far-reaching environmental consequences, such as rising sea levels, changing rainfall patterns, and more extreme weather events, like bushfires, storms and floods.

Social impacts of climate change are likely to include increased risk to human health, such as a higher number of deaths from extreme heat and an increase in infectious diseases like dengue fever from mosquitoes.

Economic impacts include the costs associated with an increased number of severe weather events, such as bushfires and floods, and also reduced agricultural productivity.

Targets to limit climate change

The earth’s average temperature has increased 0.74 degrees Celsius since the 1800s and, without action on climate change, it’s predicted to rise another 1.8 – 4 degrees by 2100.1

Some scientists argue that to avoid the worst effects of climate change we should limit global warming to about 2 degrees. Others scientists are pushing further, arguing for a limit of 1.5 degrees.


In Australia the generation of electricity makes up about 33% of total emissions.2


International negotiations

United Nations Climate Change Conferences are held annually and aim to establish a global agreement to address climate change, but negotiations progress very slowly.

Australia has pledged an unconditional 2020 target of reducing carbon emissions by 5 percent based on 2000 levels.3 This is quite an ambitious target because it represents about a 20 percent reduction based on the projections of what our emissions in 2020 would be if no action were taken to reduce them.4 That’s equivalent to a reduction of about 12 percent below 2005 levels.5

Prior to the G20 summit in 2014, the US and China announced they’d agreed on absolute limits for their emissions to peak by 2030 or earlier. This marked the first time China, the world’s largest greenhouse gas emitter has set an emissions target.

The G20 comprises of 20 leaders from 19 countries, including the European Union, that meet annually to discuss ways to boost the world’s economic growth and in turn improve global living standards. The next G20 summit will be held in Paris where emissions reduction targets for post 2020 will be set. You can read more about the G20 summit here.

Find out more about climate change at the Australian Academy of Science.

References

  1. United Nations Framework Convention on Climate Change 2013, Secretariat of the United Nations Framework Convention on Climate Change, Bonn, Germany .
  2. Department of Environment, Australian National Greenhouse Accounts, Quarterly Update of Australia’s National Greenhouse Gas Inventory June Quarter 2013, Department of Environment.
  3. As detailed in the United Nations Framework Convention on Climate Change 2013, Secretariat of the United Nations Framework Convention on Climate Change, Bonn, Germany.
  4. Department of Climate Change and Energy Efficiency 2012, Australia’s emissions projections, Commonwealth of Australia, Canberra.
  5. The Hon. Tony Abbott MP, Prime Minister, The Hon. Julie Bishop MP, Minister for Foreign Affairs, Assisting the global response to climate change, media release 10 December 2014.

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