I have been asked a lot about how climate change works – what is it, how does it happen, and what happens to the Earth with global warming. To answer this I’ll start by talking about the difference between weather and climate. As I’m sure you know, weather is the changes in temperature, rainfall and wind that we see outside from day to day, while climate refers the usual weather of a place. Tasmania has a cool temperate climate overall, but the west coast has a wetter climate than the east coast, and the central regions have a cooler climate than the coast. The Earth also has a climate; Earth’s climate is what you get when you combine all the climates from around the world together. 

Climate change is a change in the usual weather of a place. While the weather can change in just a few hours (as it often does in Tassie!), climate change occurs over many years. And in fact the Earth’s climate has always been changing. As I’m sure you know, there have been times in the past when the Earth was much hotter than it is today, and also times when it has been much cooler. But an important difference with climate change caused by human activities is that the change is occurring much, much faster than we have ever seen before. 

There are lots of different things that can cause climate to change – volcanic eruptions, changes in the world’s oceans, and changes in the activity of our sun. Climate change caused by humans is due to the gases we release into the atmosphere – particularly carbon dioxide from burning fossil fuels, but also methane and other gases. These gases cause a green-house effect which traps more of the sun’s energy in Earth’s atmosphere and so warms the planet. This warming also causes changes in other features of our climate such as rainfall. 

Earth's temperature will keep going up for at least the next 100 years. This will cause more snow and ice to melt and sea levels to rise. Some places will get more rain and others will get less rain. There will be more heatwaves and some places might have stronger storms. The sooner we can stop emitting greenhouse gases and implement solutions to take excess carbon dioxide out of the atmosphere, the better chance we have of minimising the impacts of climate change on our Earth. 

Thanks for asking this important question. In order to solve a problem, first, we must identify and define the problem. 

Even though the science of global warming was discovered as far back as 1856, climate scientists only started to use the term ‘global warming’ in the 1980s. Global warming refers to the average global surface temperate increase caused by human emissions of greenhouse gases. Global warming is mainly understood as temperature rise, but it’s a bit more complicated than this.  The warming leads to changes in weather patterns and air and water currents, which can mean that in a few places, colder weather is sometimes caused by global warming. The term confused some people, so scientists started to use a different term, ‘climate change’. 

Climate change refers to the long-term change in the Earth’s climate.  It is a more comprehensive term because it includes side effects of warming such as melting glaciers, heavier rain and storms, more frequent drought, frequent bushfires, changes in ocean circulations and ocean acidity. So climate change describes how weather patterns will be affected differently around the globe. 

If you’d like to keep up with the latest news in climate science, scientists have started to use new terms:

Climate disruption, climate crisis and climate emergency are a few of these. The common feature of these terms is that the rising average global temperature has consequences (for example disruption) and requires urgent action.  These terms may be more effective to get the message out because climate change action is urgent. 

What will happen to animals? The answer is- it depends. Some will move around to find new places to live. Some will evolve to the new climate conditions where they currently live. And some species will die or go extinct. Let’s look at how species might respond and why this means that even with evolution and moving, some will still die.   

Species are evolving and moving in response to climate change. Examples of evolution are changes in how a species can tolerate extreme temperatures – known as thermal ranges. Some species will die at particular temperatures. For example in late 2018 many flying foxes died in an extreme heat wave in northern Australia. Marine heatwaves result in mass coral reef deaths.   

But if individual plants or animals within a species happen to have or abilities to survive at higher temperatures, then, over time, those traits will become widespread within the species, because those individuals survive and reproduce.  In fact, scientists are selectively breeding coral reefs for their ability to tolerate higher temperatures and then farming these corals to improve the health of the Great Barrier Reef.   

Some species can also move around in order to follow suitable climate conditions (like the right temperature or rainfall for them). Plants use wind to move seeds kilometres away, birds can fly long distances to find the next suitable tree hollow to live in, and mammals can follow habitat corridors like rivers and tree lined fences to find the next forest to live in. In this way, some species can continue to adapt and follow changes in their habitat to survive. Scientists call this ‘species on the move’ and it’s a big area of current research. These scientists estimate that so many species will move or redistribute themselves, the types of plants and animals you see out your back door today may well be different in the future. 

But evolving, or moving, takes time. Evolution is a multi-generational process. And species tend to move anywhere from a few metres to 10s of kilometres each year depending on how big and how mobile they are. If climate change outpaces the speed at which species can move or change, then they are at risk of dying.  

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.  

The species that are most likely to be at risk of extinction are those that are on islands (like New Zealand and Australia) where there’s not enough space for species to move or track their preferred climate.  So here in Australia, we will have more species extinctions due to climate change relative to other parts of the world. 

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.