Many people are worried and frustrated about climate change and want to know what they can do to help. Studying the impacts of climate change and rising ocean temperatures on the Great Barrier Reef over the last decade has certainly convinced me that this is the most serious issue of our time. 

We hear quite a lot about what we can do in our own lives to reduce the carbon emissions into the atmosphere that drive climate change. Anything that lowers energy consumption helps reduce the need to burn fossil fuels and gives us time to transition to renewable energy sources such as wind and solar. For example, driving less by walking, riding or taking public transport where we can. Even what you eat makes a big difference (so maybe limit ‘BBQ Meatlovers’ to special occasions). We can go a step further and help remove carbon from the atmosphere by growing trees. The reason that Tasmania is currently removing more carbon from the atmosphere than it puts in (i.e. better than net zero emissions) is the natural regrowth of Tasmanian forests. 

One thing that I also like to do is avoid unnecessary generation of methane, which is much more potent than carbon dioxide as a greenhouse gas and responsible for more than 30% of the global temperature increase. If you dispose of food and garden waste with your garbage, it will be buried and breakdown without oxygen (anaerobic process) to produce methane that eventually escapes into the atmosphere. However, if you put organic waste into your home compost or council compost bin, microbes can access oxygen when breaking it down (aerobic process) thereby producing very little methane as well as compost that will help grow new carbon absorbing plants. 

Finally, we should all try to stay informed and express our views on what actions need to be taken. Students currently in college will be the ones asked to deal with the largest consequences of climate change. You’re entitled to have a say. 

The how and the why of climate change are very tightly linked, so tightly linked people as far back as 1896 had figured out the basics of how it works. Earth’s atmosphere keeps the world warm by trapping heat. It does this in a way similar to the way a greenhouse works (thus the name “greenhouse effect”). Sunlight (and warmth) can come through the atmosphere in the day time and warms up the land and sea areas. At night cooling occurs, with the heat escaping into the atmosphere, some of that leaks out into space again, but not all because the atmosphere traps some of the heat.  The key bit of the atmosphere that traps the heat are the greenhouse gases.  

Natural greenhouse gases are water vapor, carbon dioxide, methane, ozone and nitrous oxide. These chemicals are an important part of the world’s natural cycles. They cycle between the atmosphere, the ocean, soils and rocks. Human activities have changed those cycles, meaning more greenhouse gases have entered the atmosphere, trapping more heat and leading to global warming and climate change. 

Many human activities influence climate relevant cycles, but two of the most important are to do with carbon dioxide and methane. Fossil fuels contain carbon dioxide locked up millions of years ago, by bringing it to the surface and burning the fossil fuels human activity short circuits natural weathering and other cycles, creating one of the major sources of the excess carbon dioxide that is creating climate change.  

Agriculture is also a major contributor to climate change, producing about a quarter of all current greenhouse gas emissions. These emissions come from the fuels used by farmers, but also because of emissions from rice paddies and livestock, which produce methane. A particularly powerful greenhouse gas, over a 20-year period methane is 80 times more potent at warming than carbon dioxide. On top of this, the removal of native vegetation, like forests, to create space for agriculture reduces the amount of carbon drawn out of the atmosphere and stored in trunks and roots as trees grow (known as sequestration).  

As you can see there are many interconnected ways that human activities are influencing the biogeochemical cycles of Earth and thereby contributing to climate change. 

Good sources of climate information are https://climate.nasa.gov/ and the new IPCC climate atlas https://interactive-atlas.ipcc.ch/ 

Two good Australian information sources are the CSIRO https://www.csiro.au/en/research/environmental-impacts/climate-change/Climate-change-QA and the Academy of Science https://www.science.org.au/education/immunisation-climate-change-genetic-modification/science-climate-change 

You might also like to play with the simple climate model at en-Roads, explore options for reducing climate change https://en-roads.climateinteractive.org/scenario.html?v=21.10.0 

We’ve known about climate change and what causes it for a long time.

In fact, the first experimental observations of the effects of greenhouse gases were made by a female scientist, Eunice Foote, in 1856. In that year, she gave a talk at an American science meeting in which she described how glass jars containing different concentrations of water vapour, carbon dioxide and air heated up at different rates in the sun. Her research brought her to speculate that higher concentrations of carbon dioxide in the air could influence global temperatures.

Despite Eunice Foote’s discoveries Irish physicist, John Tyndall, is generally given the credit for first describing the 'Greenhouse Effect', in 1859. He published a series of studies showing how greenhouse gases such as carbon dioxide trapped heat in the Earth’s atmosphere.

In the 1950s and 1960s, scientists were developing a better understanding of what might be ahead of us in terms of climate change. Nobel Prize winning chemist, Glenn T. Seaborg warned in 1966 of a looming crisis, saying: "At the rate we are currently adding carbon dioxide to our atmosphere (six billion tons a year), within the next few decades the heat balance of the atmosphere could be altered enough to produce marked changes in the climate - changes which we might have no means of controlling”. In the 1950s, the New York Times reported that more carbon dioxide in the atmosphere “generated by man” was warming the climate.

In the 1970s the first global climate models were developed. They showed that it was impossible to increase carbon dioxide in the earth’s atmosphere and not have a global rise in temperature. In the 1980s, drilling ice cores deep into the Greenland and Antarctic ice allowed scientists to study bubbles of ancient air trapped there for thousands of years. This showed scientists that carbon dioxide concentrations in the Earth's atmosphere were historically much lower. This information helped confirm a remarkably consistent relationship between carbon dioxide in the atmosphere and Earth’s temperature.

In 1988, NASA scientist, James Hansen famously testified to the US Congress that “the greenhouse effect is here” and that “global warming has begun”. That same year, the Intergovernmental Panel on Climate Change (IPCC) was formed by the United Nations Environment Programme and the World Meteorological Organisation to study and report on climate change and its solutions. The IPCC and its thousands of scientists have since written numerous detailed reports on climate change, its impacts, and possible solutions. In 2007 it was awarded the Nobel Peace Prize for “efforts to build up and disseminate greater knowledge of man-made climate change, and to lay the foundations for the measures that are needed to counteract such change”. Today, more than 99% of scientists agree that global warming is anthropogenic – that is, caused by humans.

Despite centuries of science and decades of increasing evidence on the causes and consequences of climate change, plus growing consensus on the actions needed to mitigate it, there is one clear and crucial piece of evidence on the way humans have not dealt with the problem - and that is how carbon dioxide levels in the atmosphere keep rising. Carbon dioxide in the atmosphere was around 280 parts per million (ppm) in pre-industrial times (before we started burning a lot of fossil fuels). Today they are 420 ppm, and climbing.

This is not to say that we have ignored the science of climate change entirely. Some really important landmark decisions have been made on the strength of climate science – for example, the 2015 Paris Agreement where countries agreed to keep global temperature rise to no more than 2°C and to make the best efforts to keep it below 1.5°C. Climate scientists have been increasingly been sounding the alarm on the consequences of inaction. The IPCC’s Sixth Assessment report is the clearest yet on physical science behind climate change and warns of the severe consequences of not drastically cutting greenhouse gases this decade. The UN COP26 Climate Conference in Glasgow is now a crucial opportunity for policy makers to show they can finally take transformational action based on our very clear scientific understanding of climate change.

Great question! And the answer is yes, climate change can cause sickness in lots of ways. Illness from extreme heat, bushfires and bushfire smoke, and the spread of diseases like malaria are all linked to climate change. One of the biggest risks to athletes is having to play or train in extreme heat. As you probably know, climate change is making extreme heat events (or heatwaves) longer and more common. So it’s becoming more likely that most athletes will need to play or train in these sorts of conditions, especially sports that are normally played outside and over summer (like athletics, tennis or cricket).  

Exercising when its really hot can potentially make you very sick. Your body needs to stay within a certain temperature range (36.1°C-37.2°C) to operate effectively, and we have lots of mechanisms to make that happen (like sweating, for example). If the conditions we are training or playing in mean our body is unable to stay within that range, then we can get a heat-related illness. This can be mild, like a headache or feeling dizzy, and if we cool down, then our body can keep doing what it was doing before. However, if we can’t cool down adequately, then it becomes a problem. This is called heat stroke and it’s a very serious and life-threatening condition. If you want to see what this looks like, watch this clip of Scottish marathon runner Callum Hawkins competing in the 2018 Commonwealth Games on the Gold Coast. It’s a reminder that when we are training or competing in a hotter environment that usual, we need to take time for our body to get used to the new conditions. This is called acclimatising. 

Another impact of climate change is the increased risk of bushfires. These can generate a lot of smoke, and the smoke can travel a long way. We saw that in the Black Summer fires in 2019-20, when smoke from those fires travelled right around the world (watch this amazing clip from NASA!). If athletes are training or playing when the smoke levels are high, this can also make them sick. Its not good for your body to breathe in lots of smoke, especially when you are breathing hard, like when you are playing sport.  

Plants and animals are threatened by lots of things like habitat loss from land clearing, or being hunted, fished or harvested. On top of these pressures are climate change impacts.  

Because there are so many interacting threats to biodiversity, we haven’t yet attributed many species’ extinctions only to climate change. Species that we have lost to date from climate change are species that occur only in one place, so they are very rare, and those places are exposed to immediate climate impacts such as flooding and sea level rise.  

The Bramble Cay Melomys was an Australian rodent that occurred only on one island in the Torres Strait. In 2016, it became the first recorded species extinction attributed to human induced climate change. The small sand island it lived on was affected by sea level rise and storm events. The extinction record by the State of Queensland said that extinction was caused by "ocean inundation of the low-lying cay, very likely on multiple occasions, during the last decade, causing dramatic habitat loss and perhaps also direct mortality of individuals" (1). There are likely other species that have been lost to a similar fate.  

The IUCN Red List of species is the best source for understanding global threats to species. Expert have listed climate change as a cause of decline for 19% of all species listed as near threatened or threatened. Climate change impacts that threaten species include increases in storms, flooding, extreme temperatures, drought, and sea level rise.  

As an example – Hooded seals are a species threatened directly by climate change. Their population has dropped in abundance by 90% in the northeastern Atlantic Arctic over the last 20 years. This decline is attributed to loss of sea ice which has reduced the number of places available for resting and raising pups.  

Looking into the future – One study estimated that if we follow our current, business-as-usual trajectory of climate change, which is projected to lead to a 4.3°C temperature rise, climate change would threaten one in six species (16%). This could as much as double our extinction rates.  

This is one of many reasons why people are calling for governments to limit climate change to 1.5°C, by ‘decarbonising’ our economy – or stopping emissions of CO2. If we do this, we can reduce the rates at which plants and animals become extinct. 

This is a really important question – with an “it depends” kind of answer. What we know for sure is that climate change is already, and will continue to, have really big impacts. The sorts of impacts that climate scientists expect that future generations will face include more extreme weather events, sea level rise, biodiversity loss, environmental degradation – all of which have complex and interrelated flow on effects. It is also important to remember climate change is not just a problem that is going to have impacts in the future. It is already having significant impacts to people’s lives right now!

What’s tricky about this question is that the kinds of impacts and extent of those impacts that future generations will experience however, depends on different mitigation scenarios. What that means is that if action is taken now to reduce greenhouse gas emissions and reach net zero CO2 emissions, then the scenarios for future generations will be less severe and dangerous then if action takes longer or doesn’t happen at all. What is also tricky about this question is that projections of what the future may look like depending on current actions could be much more severe and extreme if we reach ‘tipping points’ (some of the other experts have answered questions about these).

One of the really helpful things about these climate models and scenarios is that they show us really clearly what we need to do now to ensure a safer world for future generations. We can be a part of creating a more just and safe world for future generations by taking action now.

You could also read these articles about climate projections for 2500, and what the earth will be like 500 years from now.

We are experiencing climate change here and now. Some of the changes might be subtle things that we don’t readily notice – like small changes in average summer day time temperatures, or the number of extreme heat days a year. Each decade since 1980 has been warmer than the last - but often people don't remember how these things were different in the past - we suffer from ‘shifting baselines’ which means we only recollect what happened in the recent past like last week or last year as a comparison for what we experience today. This means that these subtle changes may be hard to notice.

Some of the changes we are experiencing are actually much more dramatic – these include extreme weather events like unusual and severe storms or prolonged heat waves.  Each year in Australia we are breaking lots of records. The Bureau of Meteorology puts out a great annual summary that you can refer to but I created a map collating notable examples for 2018 that gives you an idea of the types of climate change impacts and events we are currently experiencing. 

The impacts from these extreme events are being felt in different ways depending on who you are and where you live. But as examples – if your home is in a low lying coastal area the cost of flood insurance is often too high for the average home owner. And councils and state governments are considering planned retreats from the coast in terms of where they will support recovery from flood events versus where they will encourage home owners to move to as an alternative. Similar experiences are being felt in Australia’s fire prone city fringes where home owners have to monitor high fire danger index days and consider moving out of their homes on those days to protect themselves.

Other ways that individuals and families are already feeling the impacts are through their home environments.  Many are finding their homes aren’t built for our new extreme heat days in summer and so they have to install air conditioners or run the AC for much longer periods of time resulting in substantial electricity bill increases.  Individual, council, and state led adaptation measures are needed to make sure our built environments can cope with these changes from floods, fires, storms through to changes in heat.