This is a great question – which has several parts to it. If we stop putting large amounts of greenhouse gasses that cause climate change (like carbon dioxide and methane) into the atmosphere, it would still take several decades for warming to slow down and stop. This is because the high levels of these gases already in the atmosphere will take a long time to breakdown (in the case of methane) or be absorbed into the ocean and forests (in the case of carbon dioxide). Sea level will also continue to rise for many decades, even if we stop emitting these gases today. Stopping carbon dioxide emissions would help slow down ocean acidification, benefiting marine life and fisheries.

If climate change itself were to suddenly stop – which would be great if you had a magic wand – there are some positive things that would happen. The Earth would stop warming, and we would no longer experience the increasing temperatures and heatwaves associated with climate change. The rate of sea-level rise would also slow down. Melting glaciers and ice sheets, which are major contributors to sea-level rise, would decrease their rate of melting. The Arctic region, which has experienced significant ice loss, would start to recover. Sea ice would become more stable, which is important for the functioning of polar ecosystems. If climate change stopped completely tomorrow, many ecosystems that have been disrupted by climate change, such as coral reefs, forests, and polar environments, would have a better chance of recovering.

There would be good things that are very important to humans. Stopping climate change could improve food security by reducing crop failures and the negative impacts on agriculture caused by intense floods and droughts. Human health risks would also be reduced, as there would be less exposure to extreme heat – and many people can die during intense heatwaves.

It's important to note that while these are positive outcomes, stopping climate change would not necessarily reverse the effects that have already occurred. Many changes to ecosystems and landscapes are irreversible, and some consequences, such as the loss of certain species, may be permanent. Furthermore, global climate change is a complex process, and a sudden stop could also have unintended consequences. I hope you can think of some of these unintended consequences!

Thousands of years ago, when sea levels where much lower than today, the Torres Strait was a land bridge between Australia and Papua New Guinea. Rising sea levels turned it into a series of islands. As climate change continues to cause more sea level rise, these islands will get smaller. Parts of the islands are more than 100 m above sea level, so there is no risk of the entire island disappearing. But, as the sea level rises, high tides and storm surges become much bigger problems. A storm surge is the increase in sea level that happens during a cyclone or other large storm. Sea level rise is already making the impact of these extreme events much more severe, and this will continue to get worse as the sea level rises.

Climate change is caused by natural processes but also increasingly by human activities. The main driver of climate change is the greenhouse effect. Some gases in the atmosphere have a similar function to the glass in a greenhouse. The glass walls of a greenhouse let heat and light from the Sun in, which warms up the air inside. Similarly, greenhouse gases let the incoming heat from the Sun pass through to the Earth’s surface, where it is trapped. Many of these gases occur naturally, and natural causes of changes to the greenhouse effect include solar radiation and volcanic activity. But human activities are increasing the concentrations of some greenhouse gases in the atmosphere, in particular carbon dioxide, methane, nitrous oxide and fluorinated gases, leading to an enhanced greenhouse effect and warmer temperatures.

The main human activities causing these changes are:

1. Burning of fossil fuels such as coal, oil and gas, which produce carbon dioxide and nitrous oxide
2. Deforestation, which means that there are less trees to help absorb carbon dioxide from the atmosphere, and carbon stored in the trees is released to the atmosphere
3. Increasing livestock farming, which is problematic as cows and sheep, for example, produce large amounts of methane when they digest their food
4. Fertilisers containing nitrogen, which produce nitrous oxide emissions
5. Fluorinated gases, which are emitted from equipment and products that use these gases, such as refrigerators, air conditioners and heat pumps

While natural processes play a role in how the climate changes, what we are currently experiencing cannot be explained by natural processes alone. Since at least the mid 20^th century, humans are unequivocally causing climate change, and unless we modify how we live and how we interact with the environment around us, this will continue to be the case.

Stopping, or reducing climate change, known as mitigation, is something that is really important so I’m very glad you’ve asked how to do this. 

Reducing climate change will involve lowering the level of greenhouse gases in the atmosphere. This means reducing the emission of heat-trapping greenhouse gases. This is done by reducing the use of fossil fuels and moving to renewable energy sources, like wind, solar and ocean wave energy instead. The effectiveness of these energy sources is improving all the time and around the world (especially in Australia) they are becoming a major source of energy already. Increasing efficiency and finding ways of reducing energy use and waste is also very important. Around the world businesses and governments are making commitments to reduce the use of fossil fuels and to transform manufacturing, food production and transport (e.g. trucks, cars, trains and shipping) to electricity or other fuels (like hydrogen). 

Another way to help mitigate climate change is to support processes that actively remove carbon out of the atmosphere. Healthy oceans, forests and soil are great carbon stores. This means restoring and protecting these environments and supporting sustainable practices will help. Growing trees is a great way of helping remove carbon from the atmosphere. This effect is so large that the natural regrowth of Tasmania’s forests means that the state is currently a carbon sink – meaning more carbon is removed from the atmosphere than is emitted. This means as a state Tasmania is doing better than the net zero emissions target governments around the world are talking about.  

Rather than just letting the trees do all the heavily lifting though we can help Australia and the world by reducing our individual emissions. On a personal level that means turning lights and appliances off when you’re not using them; putting on a jumper rather than turning the heating up to full; and walking, cycling, or using public transport if we can. Also finding out about what you eat and changing to options that contribute less to climate change can also help. Agriculture is a major producer of greenhouse gases so look for low carbon meals, such as sustainable seafood and local seasonal foods, and try having at least a couple of red meat free days a week.  

In addition to reducing energy use we can also consume less (e.g. use clothes for longer rather than chasing the latest fashion look), increase recycling and appropriately dispose of organic waste (e.g. food scraps). Methane is a powerful greenhouse gas, over twenty years it is about 80 times more potent at warming than carbon dioxide. When food and garden waste is buried with general garbage the microbes and chemical processes that break the waste down cannot easily access oxygen and so they produce a lot of methane (known as anaerobic breakdown). However, if you put the organic waste into a compost bin (at home or one provided by the council) the microbes can access oxygen and so they use a process that produces much less methane (known as aerobic breakdown). The nutrient rich compost that results also means more plants can be grown (absorbing carbon) and less energy is needed to make artificial fertiliser. A win-win-win. 

The biggest thing you can do to help climate change is to stay informed, to help share useful information and to think about your actions – each little bit really does help. Around the world innovations and action by young people is helping accelerate action to reduce climate change. 

For starters, you might like to find out how Tasmania’s tree growth is helping our carbon budget. NASA also has a great page on climate change, which mentions some solutions. The United Nations also has some high-level information on different activities around the world.  

You might also like to play with the simple climate model at en-Roads, explore options for reducing climate change