Climate Change - Climate Commission

Basics : Climate Change

‘Climate change’ refers to the way long-term weather patterns have been changing over many decades. One of the ways the Earth’s climate is changing is through increases in global temperatures, or ‘global warming’.

Climate change is a problem not only because of increasing average global temperature, which is leading to more record hot days and heatwaves, but it also leads to other changes in weather and climate, such as where and when rain falls, higher sea levels and the intensity of extreme weather events such as storms, fires and heavy rain. These changes are creating challenges for our water and food security, coastal communities, economy and way of life. They also put many of our native plants and animals at greater risk of extinction.

Climate change could lead to changes in where and when rain falls and the intensity of extreme weather events such as storms. Source: Flickr/Kimbo 79

Scientists have already observed increases in air and ocean temperatures across the globe, as well as rising sea levels and melting of snow and ice sheets. We have also seen an increase in some extreme weather events like heatwaves.

Australia is particularly vulnerable to a changing climate. Australia’s climate has always been one of extremes, and scientists are concerned that these extremes may be strengthening. In the past 50 years, the number of record hot days has more than doubled across Australia, increasing the risk of heatwaves and bushfires. Australians mostly live in coastal communities, many of which are vulnerable to rising sea levels.

Why is the climate changing?

We all need the sun’s warmth to stay alive. Greenhouse gases in the Earth’s atmosphere act like a blanket, trapping some of the sun’s heat close to the Earth’s surface and keeping the planet warm enough for us to live. This is known as the greenhouse effect. Right now we are adding greenhouse gases to this blanket, trapping more of the sun’s heat and causing the Earth’s temperature to rise.

Humans are using increasing amounts of energy to power our modern way of life, for example to power cars, planes, factories, computers and televisions. Much of this energy is generated by burning fossil fuels (coal, oil and natural gas). Burning fossil fuels adds carbon dioxide and other greenhouse gases to the atmosphere. Since the industrial revolution (in the mid-1700s), carbon dioxide levels in the atmosphere have increased by 40%, and are now the highest they’ve been for 800,000 years.

Deforestation also has an impact. Trees and plants store carbon in their branches, leaves, trunks and roots. When they are cut down or burnt this carbon is released into the air as a greenhouse gas.

How can we be sure?

Climate change is happening because of human activities, and scientists show this through a number of different ways.

Scientists take direct measurements of the atmosphere which show that greenhouse gases have been building up. They can also measure the make-up of these gases to show they have come from burning fossil fuels and not from natural sources.

Scientists have instruments, both on Earth and in space, that measure the heat reaching the Earth and going back into space. These measurements show that more heat is being kept in the atmosphere and less is escaping back into space. Scientists can prove this is happening due to carbon dioxide and other greenhouse gases by studying the particular wave lengths of the heat that is being trapped.

Scientists have studied past changes in the Earth’s climate, such as through ice cores, and have found that no natural processes can explain the extra heat in the Earth’s atmosphere and oceans. Source: NASA

Another way scientists can show human activities are causing the climate to change is by looking at the natural factors that also influence the climate. These natural causes include things like volcanic eruptions and even changes in the Earth’s orbit around the sun. Studies show that no natural processes can explain all the extra heat in the Earth’s atmosphere and oceans.

Scientists have also developed complex computer models of how the climate works and what affects the climate. When the models include only the natural drivers of climate, they do not show any long-term warming trend over the 1900-2000 period. When human-produced greenhouse gases are included along with the natural drivers, the models show exactly what the temperature observations show – a clear warming trend over the last half-century.

How do we fix it?

The climate change problem is well understood and so is the solution. To lessen the risks to our economy, environment and our way of life, we must substantially reduce the amount of greenhouse gases we produce. This will require a transition away from relying on fossil fuels, like coal and oil, to cleaner forms of energy.

The good news is that we have all the technology to address climate change available right now. Although there’s a long road ahead, we will all benefit from a move towards more renewable energy, cleaner air, better health and new industries.

We can all contribute to creating a more sustainable Australia. Find out how here.