A pocket guide to climate change

Updated

The first step to being able to speak about climate change is to understand it. Not everyone learned about it in school, so here are the basics everyone should know.

You can tap on the following to jump between sections. We'll look at:

Why warming is impacting the weather

Why heat is being trapped

What are greenhouse gases

And how scientists figured out climate change is taking place

For deeper reading, tap any text that's underlined.

The planet's average surface temperature has risen about 1 degree Celsius since the late 1800s, a change mostly driven by increased carbon dioxide and other human-made emissions into the atmosphere.

That figure is calculated by combining data from weather stations from different countries across the globe on land and sea, and sometimes satellites.

One degree may not seem like much, but think about all the extremes we are already seeing — in nature, 1 degree matters a lot.

The extra warmth in places it doesn't belong (like the North and South poles) is causing normal air movements that rely on the difference between cold and warm air to propel them to slow down.

Slower streams of air mean more drawn out weather, which in turn upsets the balance of weather patterns and creates many of the extremes we keep experiencing.

The Earth's atmosphere is kept in place by the pull of gravity. This means that the gases that are produced as a result of all the chemical reactions on the planet (from breathing to fuel burning) surround us and don't drift off into space.

Heat, though, isn't a chemical. It's an energy, and light and energy can pass in and out of the atmosphere.

Heat from the Sun's rays enters the atmosphere as shortwave radiation and warms up the Earth's surface. When it's reflected back off the Earth, it turns into longwave radiation.

Greenhouse gases like carbon dioxide, methane and nitrous oxide are more complex than other gases in the atmosphere, so they absorb longwave radiation, which traps heat.

Carbon dioxide comes from naturally decaying and living things, and is produced when burning fossil fuels like coal and oil.

Methane is released naturally from wetlands, cattle and rice paddies, but is also produced when using natural gas and mining coal.

Nitrous oxide is a natural part of the nitrogen cycle in bacteria living in soil and the ocean, but it's also released by factories and fertilisers.

Overall, greenhouse gases are a good thing because without them, our planet would be too cold to sustain life as we know it. But the more greenhouse gases in the atmosphere, the more heat that is trapped.

There are a number of ways scientists have tracked greenhouse gases to come to the conclusion of climate change.

Ice at the poles of our planet has pockets of air trapped in it. The further down you go, the more ancient the air. Scientists are able to drill deep down and measure the chemical makeup of that air.

In 2017, scientists accessed an air pocket in Antarctica that was 2.7 million years old, so ice gives us a pretty long-running snapshot of the Earth. There are lots of complex ways scientists date ice, but one of the more simple ways is counting the annual layers (a bit like tree rings)

Speaking of tree rings, that's another way that scientists can measure changes in carbon levels.

Trees are sensitive to the weather, so the rings you see on a tree stump vary depending on the conditions it grows in.

By analysing the patterns, we can draw conclusions about how the climate has changed over the tree's lifetime.

Using modern technology like satellites, we can see more recent evidence too, like the shrinking sea ice.

We've also got recorded history that shows us a pattern of increasing extreme weather events that have been triggered by the sudden rise in greenhouse gases.

So now that you're up to speed on what climate change actually is, why not check out how the climate has changed since your childhood? Or how to navigate some of those myths that contradict climate science? And we'd love to hear your feedback on this piece.

Credits

Research and production: Jacqueline Howard

Jacqueline Howard Development: Nathanael Scott

Loading...

Topics: climate-change, drought, environment, australia

First posted