A cheat's guide to understanding climate change.

by ANNA ROSE

If you had 97-98% of doctors telling you had cancer, would you ignore them just because there were a handful of doctors (who weren’t cancer experts) telling you to wait and see?

Well the same principle applies to climate change. The problem is that a lot of us don’t really understand much about how the earth is warming. And we should. Here’s quick way to get your head around the facts…

The basics of global warming:

Imagine a blanket around the Earth. This is the atmosphere, and it’s the reason we have life on this unique blue and green planet. From rainforests, coral reefs, the pyramids, New York, inventions like the hair straightener and other wonders of civilization: we owe it all to the atmosphere.

For a long time, though, people took the atmosphere for granted. We assumed that, like a loyal long-term boyfriend, it’d always be there for us no matter how badly we treated it.

Sadly, the atmosphere is more fragile than we initially assumed. Imagine a beach ball covered in a layer of nail polish. The tiny layer of nail polish is the relative size of the atmosphere compared to the Earth.

Before people started pumping carbon pollution into it, the atmosphere was made up of just the right concentration of gases (called greenhouse gases) that trap heat in the atmosphere. These gases allowed just enough heat from the sun to warm our planet so we weren’t freezing cold and devoid of life (like the Moon) but reflected excess heat back into space (so we don’t turn into, say, Mars).

But then people burning fossil fuels – coal, oil and gas – messed with this natural balance. Burning fossil fuels releases more heat-trapping greenhouse gases. And too much of a good thing, it turns out, messes up Earth’s climate.

What is the situation at the moment?

So now we have the equivalent of two or three blankets over Earth rather than the original one. We’ve increased carbon dioxide levels 40% since the Industrial Revolution and are pumping out over 25 billion tonnes of carbon pollution each year. And we all know what happens when you have too many blankets on the bed – things start to get a little uncomfortable.

To recap the basics: Since the Industrial Revolution, people have sharply increased the concentration of greenhouse gases. These greenhouse gases trap heat in the atmosphere. And since we’ve been pumping them out, global average temperatures have increased by a global average of 0.8 degrees C. This may sound small, but it’s enough to seriously mess with Earth’s system – and is far above anything that could be explained by natural climate variability.

The data below shows three separate official temperature records (including from NASA). The line is a bit jagged – but when scientists talk about “climate” (as opposed to weather), they’re talking about thirty year trends.

How do we know that people are the cause?

There are two reasons scientists know that people are the main explanation for this warming. Firstly, countries track and report their emission levels and they’re more than enough to account for the rising temperatures. Secondly, scientists track the isotopic signature of carbon dioxide in the atmosphere – so they can see that the 40% rise in carbon pollution comes from burning fossil fuels rather than natural processes.

But with all of this evidence, why do some parts of the media make out like the science isn’t settled?

Certain corporate-funded think tanks, mostly in the United States, have run a huge campaign to cast doubt on mainstream climate science. But the “debate” you hear on talkback radio simply doesn’t reflect the findings of the peer-reviewed scientific literature.

Every National Academy of Science of every major country in the world confirms the science of climate change, along with NASA, the CSIRO, the Bureau of Meteorology and hundreds more scientific bodies we have every reason to trust. There is no longer any reasonable doubt.

Several studies of scientific opinion have found that 97 – 98% of climate researchers most actively publishing in the peer-reviewed literature (as opposed to, say, blogs) support the basic principles of climate science. It’s about time we listened to them.

So what’s the bottom line?

Climate change is happening now. The World Health Organisation estimates that climate change is already killing 150,000 people a year (over what would have occurred without it). The Australian Medical Association calls it “a real and imminent threat to the health of Australians”.

Extreme weather events are on the rise all over the world, particularly due to the havoc climate change is wreaking with the water cycle. Warmer air holds more water vapour, so in dry areas water is sucked out of the soil faster. This creates harsher droughts and more severe bushfires. In wetter areas, because a warmer atmosphere holds more water, you get heavier rain and higher floods.

What does this mean for Australia?

In Australia, scientists are particularly concerned about food security. 40% of Australia’s food comes from the Murray Darling basin, yet scientists have warned us we’re facing a 92-97% decline in agriculture in the region by the end of the century if we don’t solve climate change. Our coastal infrastructure is also at risk from sea level rise, with over 85% of Australians living along the coast.

The good news is that with the carbon price, Australia has taken the first step to addressing climate change. It’s a simple idea. When it’s free to pollute, big businesses keep doing it. But when it costs something, heavy polluting businesses make an effort to stop. The carbon price gives them a reason to clean up their act and be more efficient with energy. It also raises $10 billion for renewable energy like wind and solar. That’s why 31 other countries, from New Zealand to England, have already put a price on pollution.

Anna Rose is the author of Madlands: A Journey to Change the Mind of a Climate Sceptic, you can check out her blog here and her twitter here.