When the average pattern of weather changes over a long period of time, it's known as climate change.
Several gases that are naturally part of the Earth’s atmosphere act like a blanket, trapping some of the heat that would otherwise escape into space. This "greenhouse effect" maintains the temperature of the Earth’s surface within the perfect range to support life. Such greenhouse gases include water vapour, carbon dioxide (which consists of one carbon atom and two oxygen atoms), methane (which consists of one carbon atom with four hydrogen atoms), and enough nitrous oxide (commonly known as laughing gas).
Since the industrial revolution 250 years ago, there have been major changes in agriculture, manufacturing, mining, transportation and technology which have caused big rises in the emissions of these gases. The increased production of carbon dioxide has come mainly from using fossil fuels, and also from changing the way we use land (such as clearing forests). The increased methane and nitrous oxide have come from farming practices.
We are currently seeing changes in our climate that are happening more rapidly than ever before in the last 1800 years:
- Average temperatures around the world are rising
- Sea levels are rising
- Glaciers and sea ice are retreating
- Coral bleaching is becoming more common due to warmer oceans
- Animals are changing their mating and migration timings.
The majority of climate scientists believe it is more than 90 per cent likely that human activities have caused most of the global warming since 1950. And the problem is, it’s happening at an alarming rate – much faster than species could evolve to adapt to it.
- Snow depth in the Australian Alps has declined 40 per cent in the last 40 years.
- The number of record hot days in Australia has increased every decade for the last 50 years.
And when there’s more carbon dioxide in the atmosphere, more is absorbed by the oceans, making them more acidic. And that makes it harder for marine plants and animals like corals, crustaceans and molluscs to make their shells. As they often form the basis of global food chains, a large decline in their numbers could have dramatic consequences.