The biggest contributors to climate change are greenhouse gas emissions, primarily carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), which trap heat in the Earth's atmosphere, leading to global warming. The levels of these gases is now higher than ever before in human history (800,000 years) is because we burn fossil fuels like coal, have cleared forests, and from farming.  All these things have helped make our lives more comfortable – but we have done too much and now need to reduce our impact on the planet if we want to reduce climate change. 

The burning of fossil fuels for energy production, including coal, oil, and natural gas, is a major contributor to CO₂ emissions. To reduce this, we can transition to cleaner energy sources - often called renewable energy (solar, wind, and hydro).

Clearing of forests (deforestation) for agriculture and development contributes to both CO₂ emissions and reduced carbon uptake as part of photosynthesis. We can combat this by protecting forests, implementing sustainable land use practices, and reforestation.

Agricultural activities release methane and nitrous oxide, mainly from livestock digestion and manure management. More sustainable agriculture practices, such as reducing meat consumption, improving livestock management, and using low-emission fertilizers, can help.

The transportation sector is a significant source of CO2 emissions. Transitioning to electric vehicles, improving fuel efficiency, and investing in public transportation can reduce emissions. Landfills emit methane due to the decomposition of organic waste. Reducing waste through recycling and composting and capturing methane from landfills can help reduce emissions.

Stopping climate change requires a multi-faceted approach that combines policy changes, technological advances, and individual efforts. The best alternatives depend on the specific sector and the region, but a combination of renewable energy, energy efficiency, sustainable land use, and responsible waste management are key components of climate change mitigation.

While scientists in Australia and elsewhere have collected lots of data and completed many experiments about a warming world, there are still aspects that remain uncertain or require further research.

For example, the long-term (say more than 100 years) consequences of climate change on species and habitats and people are still not fully known. How much damage to coral reefs can occur before the fish also disappear? Can there be sudden and irreversible changes, such as loss of species? How will human food production be affected? Will new diseases appear in places that have not had that disease before? For example, could malaria become more common in Australia?

Some of these changes are hard to understand because there are feedbacks between the atmosphere, ocean and land. How might melting of sea ice around Antarctica (ice reflects sunlight) result in even more warming (water can absorb more heat than ice)?

While there is a good understanding of global climate trends, predicting the specific regional and local impacts of climate change, including changes in precipitation patterns, extreme weather events, and sea-level rise, is challenging and uncertain. We know that the ocean will get warmer, but the speed of warming will be different on the east coast of Tasmania (fast) to the west coast (slower). What does this mean for species that might swim between the east and west coasts?

Understanding climate change gets even harder when we have to think about what humans might do. How individuals and societies will respond to the challenges posed by climate change is not fully predictable. How fast can technological innovation, such as solar power, wind farms, and electric vehicles help to reduce emissions. Can people in Hobart learn to adapt to days with temperatures over 40 C?

Scientists continue to work on these and many other aspects of climate change. We really want to address this global challenge and make the planet safer for everyone.

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!

There have already been some major problems caused by the changes in our climate. One big problem is that the Earth is getting warmer, and this is causing things like land and marine heatwaves (yes, we have heatwaves in the ocean too!), and more powerful storms and cyclones. Cyclones get some of their energy from the heat in the ocean, and a warmer ocean provides more heat, and so a stronger cyclone results. That is bad news for people living on coasts when cyclones hit.

The changes in our climate are having significant impacts on animals and their habitats – in both the land and the sea. One of these major changes is loss of habitat. As the Earth gets warmer, some areas where animals live are changing or disappearing. For example, penguins that need ice to breed are losing their sea ice habitat in the Antarctic which means many of the chicks can die, as happened in 2023 for Emperor Penguins. As the habitat changes, some species move to new areas. Fish that need warmer water, and used to live off New South Wales are now found in Tasmania. You can see a list of these species at the RedMap Australia website: https://www.redmap.org.au/region/tas/.

Climate change can affect the availability of food for animals. Changes in temperature can disrupt the timing of when plants bloom or when animals give birth, which can lead to food shortages for some species. This can result in animals struggling to find enough food to survive.

All these challenges can lead to a higher risk of extinction for some species. When animals can't adapt to the changing conditions or find new places to live, their populations may decline and, in some cases, they may go extinct.

In Tasmania, and many other places, scientists are working hard to understand and address these challenges by implementing conservation strategies, such as creating protected areas for wildlife. Additionally, you and your family can help by taking actions to reduce your carbon footprint and protect natural habitats.