6.1 Background
Our global climate is rapidly changing because of human activities. Climate change is the most significant environmental challenge facing people around the world.
Climate change is caused by increases in the amounts of greenhouse gasesA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. in the Earth’s atmosphere. Over the past 150 years, since the beginning of the industrial era, human activities have added greenhouse gasesA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. to the air. This includes burning fossil fuels (such as petrol, coal and gas) and clearing land for cities and agriculture. Our atmosphere now has the highest levels of greenhouse gasesA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. for at least the past 800,000 years. This increase in greenhouse gasesA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. has been the main cause of changes to the world’s climate since the 1950s.
It doesn’t matter what activities cause the emissions, or where they are released from – they end up in the Earth’s atmosphere. Greenhouse gasA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. emissions from the ACT have an impact on global climate, and emissions from around the world have an impact on the ACT climate.
This makes climate change a global problem: we are all in this together.
Century-old science
Swedish scientist Svante Arrhenius explained over 100 years ago that any increase in greenhouse gasesA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. would be linked to an increase in temperature. ‘Double the concentration of carbon dioxide in the atmosphere and the average surface temperature will rise by 4.9°C to 6.05°C,’ he reported in a paper published in the Philosophical Magazine and Journal of Science in 1896. For well over a century, scientists have been reporting that any changes to the levels of atmospheric greenhouse gasesA gas in the atmosphere (such as carbon dioxide, methane and nitrous oxide) that absorbs and emits energy, warming the Earth. Greenhouse gas emissions from human activities are the main cause of climate change. would warm the planet.
Warmer and warmer
Climate change is accelerating faster than most scientists expected. The world has warmed by 1.1°C over the past 100 years. At current rates, global warming is likely to reach 1.5°C in the next 10 to 30 years and 3°C later this century. The world’s environment, and how it supports us, will be challenged if we don’t keep global warming below 1.5°C to 2°C.
Here are some fast facts about our warming climate on a global scale and in Australia:
- 2023 was the world’s warmest year on record.
- The world’s warmest years on record have all occurred in the 21st century, with the last ten years (2014-2023) being the hottest.
- 2019 was Australia’s warmest year on record.
- Of the eleven years from 2013–2023, eight rank among the ten warmest years on record for Australia.
