The sooner we can reach net zero emissions the better it will be. Net zero means that the amount of greenhouse gases going into the atmosphere are no greater than the amount being absorbed out of the atmosphere. 

The term 'net zero' is important because it means we will no longer be contributing to increased global warming.

We have already seen a global temperature rise of over 1°C and we are experiencing the consequences of that increase already. The terrible bushfires of 2019-2020 and the three years of back to back coral bleaching on the Great Barrier Reef show us that our climate system is highly sensitive to even small changes in temperature. So, we cannot be sure that achieving net zero by 2050 will avoid exceeding the 2°C limit and 1.5°C target that we set ourselves in the Paris Agreement or that limiting warming to 1.5°C or 2°C will avoid serious harm.

The longer we wait, the higher the chance of failure. Most scenarios associated with the 2050 target only offer a 50 or 66 per cent chance of staying below the temperature limit. That isn’t very reassuring, and we should be doing all we can to increase our chances of success by bringing forward our decarbonisation commitments. Earlier action to arrest and reverse emissions trajectories will be much better than waiting until the last minute and possibly having a situation where temperatures overshoot the 2°C limit.

Finally, making the transition now will save us money in the long term. New energy and business opportunities will open up if we embrace decarbonisation now and we can avoid some (but not all) of the droughts, bushfires and heatwaves that cause so much economic loss, environmental damage and human suffering.

While Tasmania is net zero greenhouse gas emissions already thanks to protecting and not over-logging our vast forest reserves, this only masks that we still have similar levels of emissions per person from other sources such as transport, waste and industry as other Australians and people from other wealthy countries.  Therefore we in Tasmania can very much make a difference by making more sustainable choices at all levels of our community, from individuals, through to schools, businesses and governments.  By being good examples of how we can have a very good quality of life while impacting less on the environment not only can we be proud of ourselves but share how we have done that with other Australians and around the world so they can be inspired by our efforts (and we should be of other good roles model as well).

La Niña is part of a natural cycle called the El Niño-Southern Oscillation, or “ENSO.” La Niña, and its counterpart, El Niño, have a strong influence on the year’s weather for most of the country. It’s a weather pattern that occurs in the Pacific Ocean. When the circulation is in La Niña, it picks up the warm water near Australia, carries it over the ocean east towards South America where it descends, and the deep cold water from South America is pushed west towards Australia. (An El Niño happens when the circulation is weaker or pushing in the opposite direction.) 

La Niña is a weather pattern that occurs as a natural weather phenomenon. However, climate change impacts the severity and frequency of the impacts of La Niña such as increased rainfall, extreme temperature, earlier monsoon onset and tropical cyclones.

World Meteorological Organisation Secretary-General Prof. Petteri Taalas states, “human induced climate change amplifies the impacts of naturally occurring events like La Niña and is increasingly influencing our weather patterns, in particular through more intense heat and drought and the associated risk of wildfires – as well as record-breaking deluges of rainfall and flooding”.

Thanks for your question. Yes, air pollution (also called poor air quality) can make you sick, both physically and emotionally.

Air pollution is made up of very small particles. You can’t see each particle, but together they make a haze. You can sometimes smell air pollution, especially if it comes from bushfire smoke.

When you breathe these particles in, they can affect many systems in your body, especially your lungs and your heart. For example, if you have asthma, you might find poor air quality will make you feel wheezy or trigger an asthma attack. So it’s important to have your asthma medication with you on a smoky day.

When there is a lot of smoke in the air, some people can feel very nervous and anxious. If they have experienced a bushfire before, smelling or seeing smoke can trigger emotions or memories related to the previous fire.

Air pollution can come from burning wood (such as in a wood heater or a bushfire), burning coal or from petrol or diesel cars. Reducing these sources will help us all breathe easier.

Yes indeed! Putting your waste in a rubbish bin or recycling bin is much better than littering it into the environment. Keeping rubbish out of the environment is very important as the rubbish can cause harm to wildlife and our economy if it is in the environment. To understand some of the harms rubbish can have on the environment take a look at my answer to another of this year’s question!

Even better than placing your rubbish in the bin, is to look at different ways you can reduce and reuse the products and packaging you purchase. Take a look at one of last year’s questions to learn how you can reduce single-use plastic in the supermarket.

Absolutely - there is this potential! There is a long history of global social change which has come about when humans have united and worked together. Social movements historically have been able to create big structural change, the kind of big change we will need to face climate change. These movements in the past include things like the Suffragettes who worked to give women the vote and the Civil Rights Movement which worked to abolish segregation. Humans are cooperative beings, we work together – and we’ve seen this time and time again in history.

We are already seeing unity in responding to climate change in many ways. School Strike 4 Climate and Fridays For Future movements are examples of how local unity of young people is part of a global movement. The Paris Agreement is also an example of how lots of different countries can come together for a shared goal. The IPCC too is a whole bunch of scientists working together to learn more about and respond to climate change. We have the capacity as humankind to work together (just look at the changes we were able to make during COVID in a really short amount of time!).

There is also the potential that climate change will exacerbate conflict and cause greater competition over resources as they become scarcer. So, whilst climate change does have the potential to unite humanity, it also has the potential to cause conflict and further divide people in power from people who don’t. That’s why it is important that we are working to find ways to collaborate now as we look to the future.

You can be a part of this! Collaborating and working together to respond to climate change in a united way can include you. This can be small scale collaboration as a school, or community groups, as well as national and international collaboration. Finding practices to work well together to share learning, to care for one another, and to respond to the threats of climate change is really important.

That’s a great question, and the simple answer is ‘yes’, melting ice definitely makes the ocean less salty (or fresher, as we oceanographers say). What that means for the ocean depends on what type of ice melts, and where it melts, but the most important thing to understand is that salty water is heavier and will tend to sink, but fresh water is lighter and will tend to stay at the surface. This matters because sinking ocean water takes heat and carbon from the atmosphere to the deep ocean, and reduces the amount of climate change that we all deal with. So, by freshening the ocean surface and making it lighter, melting ice makes it difficult for the ocean to reduce the impacts of climate change.

In polar regions the biggest source of freshening by far is sea ice; this is frozen sea water that makes the ocean salty when it freezes, but fresher when it melts. Just in the Antarctic, an area of ocean two and half times the size of Australia freezes over in autumn and then melts in spring – every single year. This natural freshening/salting process helps to mix a lot of water between the surface and the deep ocean, and is very important both for our climate and for the marine life near Antarctica.

Another source of freshening, that is smaller than sea ice but getting bigger all the time, is melt water from the Antarctic ice sheets – this is ice on land that has formed from thousands of years of snowfall. As that ice melts into the ocean it causes the sea level to rise up, but it also freshens the surface and reduces that up-down pump of sea water. Scientists are still working to fully understand how this will affect the climate – it’s a new and fascinating part of my research.

That’s a great question! The majority of people who visit Antarctica do so by ship, so vessels play an important role in allowing humans access to the area. While the reduction in Arctic ice has led to the development of new shipping routes in the north, the Arctic is closer to where people live and such routes are therefore useful for trade purposes. Antarctica is far away from where most people live, so the vessels that head south have specific reasons for doing so. They might be undertaking a scientific expedition, taking tourists to experience Antarctica, undertaking permitted fishing in the Southern Ocean, or patrolling to detect illegal fishing. It can be dangerous to sail into the Southern Ocean because of the large waves that form, the notoriously strong winds (such as the furious fifties and screaming sixties), hazards such as icebergs, and the remoteness of the region.

Every year Antarctica doubles in area over the winter, as the sea ice forms on top of the ocean around the continent’s margins. Sea ice is different to icebergs. Icebergs are formed when ice sheets flow down to sea and float, turning into ice shelves, and then large chunks break off at the terminus. It’s sea ice that has a big impact on navigation. When there is less ice, vessels can travel further south along the coastline. This is why Antarctic tour operators tend to offer “Antarctic Circle” voyages that go south of 66 degrees south at the end of the season (February-March), because there is less sea ice around in the late summer and ships can travel further south. It’s also why National Antarctic Programs schedule resupply voyages to coastal stations near the end of summer. You may have seen reports about the discovery of Ernest Shackleton’s vessel Endurance in the Weddell Sea area in 2022 – this area was accessible due to a record low sea ice season, making it possible to travel further south. So to answer the question, changes in sea ice extent from year to year and over longer time scales impact on the accessibility of the region, but this has had more impact on shipping in the north. For up to date sea ice maps of both regions you can visit https://earthobservatory.nasa.gov/world-of-change/sea-ice-antarctic

This is an excellent question. Australia produces an astounding 70 million tonnes of waste annually and we need to deal with all this rubbish we create. In terms of plastic alone, in 2017-2018, some 3.4 million tonnes of plastic were used in Australia. Of that just 320,000 tonnes (only 9.4%) were recycled.

Historically, most of our waste has gone to landfill. About half of the waste we currently produce is able to be recycled, but Australia has recently seen a problematic breakdown in its recycling systems. We have partly dealt with the problem in recent years by shipping recyclables offshore to countries like China and Malaysia for processing. While dumping our rubbish in other countries is far from acceptable, shipping a “high quality” waste stream of recyclable material for effective processing and re-use is one way to make our global economy more circular. In 2018, though, China banned waste imports from Australia, and then in late 2020, Australia prohibited sending its own unprocessed waste overseas, partly to stimulate recycling systems in Australia.

Given we have so much waste to deal with, and only part of it can be recycled, much of the rest ends up in landfills. This is a problem in relation to climate change. Organic waste in landfills produces the greenhouse gas methane. Some landfills collect this for energy generation – not all – and the rest ends up in the atmosphere as a potent climate heating gas.

So could burning some of our waste be a better way to deal with it if it also produces energy from non-recyclable waste that would otherwise be sent to landfill? In terms of carbon accounting, waste-to-energy plants may potentially reduce greenhouse gas emissions. Australia’s biggest waste-to-energy plant at Kwinana in WA says it allows 486,000 tonnes of carbon dioxide emissions to be avoided each year. Australia now has two recently built state-of-the-art waste to energy plants, both in Western Australia. These plants emulate a technology that is becoming increasingly common in Europe and, if they are powered by material that is considered renewable – as designed to do – then they are considered by the Australian Renewable Energy Agency (ARENA) as a form of renewable energy. The ash which is the byproduct of this incineration process can be re-used, for example, in road building.

Despite being what sounds like a good solution to dealing with waste, incinerating rubbish is not without problems. There are certainly toxic chemicals associated with the process. Just one example, dioxins, a highly toxic and persistent organic pollutant, have been found in higher concentrations around waste incinerators. Above all, waste-to-energy plants ultimately also undermine a circular economy: they need us to keep producing large amounts of waste to keep going. If we are truly going to deal with waste in the most sustainable way, we need to produce less of it, and keep recycling materials. Needing waste to burn supports the continued production of waste, and ultimately, that’s not good for the planet. Overall, then, it's not a very sustainable practice - but it may have a use for some kinds of waste and in some places.