Get Regular Updates!
|A brighter future: how whitening the Wheatbelt could cool the climate



Getty Images

A brighter future: how whitening the Wheatbelt could cool the climate

A brighter future: how whitening the Wheatbelt could cool the climate

There aren't many things humans have made that are visible from outer space. WA's wheatbelt is one of them - and it could help us fight climate change.

A brighter future: how whitening the Wheatbelt could cool the climate

The Wheatbelt. 150-odd thousand square kilometres of Australia’s south-west where dark, native vegetation has been replaced with lighter agricultural crops. The difference in colour is something you can see from orbit, but it might also be something you can feel from right here on Earth.

Like an enormous mirror, those crops bounce solar radiation back out to space. That means WA’s Wheatbelt – and the wheat growing there – could become a crucial part of how southwestern WA adapts to climate change.

View Larger
From space, the line between crops and native vegetation is stark.

Simulations show that, just by growing slightly lighter-coloured crops, we could reduce monthly mean daily maximum temperatures by 1.01.2°C. To understand how a seemingly tiny change could make such a huge difference, we need to understand albedo – and an emerging field of climate science called geoengineering.

Let’s start with albedo

Albedo is a measure of how colour affects temperature by reflection and absorption of radiation.

“I often use the analogy of wearing a black shirt on a really hot day,” says Dr Jatin Kala, Senior Lecturer in Atmospheric Science at Murdoch University’s Harry Butler Institute.

The lighter the colour, the higher the albedo and the more light it reflects. Scientists compare the albedo of different surfaces by giving them a number between 0 and 1.

“Albedo 0, you absorb everything, albedo 1 you reflect everything,” Jatin says.

The same physics makes black cars hotter than white ones. On a larger scale, it can affect the temperature of cities, countries and even our entire planet.


Getty Images

Jatin says the difference between ploughed and unploughed soil, or irrigated and unirrigated land, can have a similar effect.

Jatin says the difference between ploughed and unploughed soil, or irrigated and unirrigated land, can have a similar effect.

Our polar ice caps reflect a huge amount of radiation. As they melt, they expose the dark soil beneath, which absorbs more heat so ice melts even faster.

(This is called polar amplification. It’s one of the horrifying arrays of unforeseen feedback loops that we’re discovering as climate change intensifies.)

Messing with the system

What Jatin is proposing is the same concept but on purpose – and on a much smaller scale.

“It comes from this idea of geoengineering,” Jatin says. “Basically, some people have thought, ‘Well, we’ve been messing with the climate system, let’s mess some more to cool it down.’”

As far as geoengineering projects go, changing the colour of WA’s entire agricultural region is actually pretty modest.

“People are starting to propose ideas such as putting aerosols in the stratosphere to mimic what happens when there’s a volcanic eruption. Or let’s put mirrors out into space – things which have got a whole bunch of us very nervous,” Jatin says.

But humans have been changing the land we live on for a while already.

“We are changing the properties of the land surface just by the fact that we’ve developed agriculture, we build cities, we live in suburbs.”

“If we pay attention to the colour of things, that is something we can actually manage. If we grow huge areas of crops, let’s just make all of the crops more reflective and see what happens.”

Light simulator

Of course, that doesn’t mean going out and painting the entire Wheatbelt overnight. If climate change has taught us anything, it’s that messing with systems without some serious forethought can have disastrous consequences.

In this case, that forethought is coming from a climate model. It’s a complex calculation incorporating everything from vegetation to soil type – including how reflective they all are.

Video|NASA Goddard Space Flight Center
Daisyworld is a simple simulation of how colour, climate and crops can affect each other.

Each 10 square kilometres of land can be represented by a square on a grid in a climate model. The air above each square is divided the same way. The model calculates how the temperature of the atmosphere changes as you change the land below it.

Then, starting from the actual climate data, Jatin re-ran the past few years of WA’s weather inside a computer – with a twist.

“Basically, I said let’s simulate the past few years of the climate and let’s pretend that all of the crops were more reflective.”

Global models, working with much bigger grid cells, had never showed much change, but zooming in on just WA made a surprising difference. With an increase of just 0.1 to the crops’ albedo, average maximum temperatures over WA dropped by about three times more than the global models predicted.

Solution or stopgap?

Like most geoengineering projects, painting the Wheatbelt is no replacement for reducing the amount of carbon we put into the atmosphere in the first place.

“It does matter, but it’s not going to change global climate,” Jatin says. “What it will change is regional climate.”

It’s a part of the same toolkit as green spaces in cities and reflective rooftops in suburbs. It won’t fix the problem, but it might help keep places liveable for longer.

View Larger
It’s easy to see where the agricultural land and the adjacent National Park begins.

Colour is also just one part of an already pretty complex calculation for farmers.

“They want crops that are resilient to drought, and they want crops that are high yield, right? And more and more with genomics, people are trying to develop crops which are going to adapt better to lower rainfall and higher temperature and give us decent yield,” Jatin says.

“But something else we should think of is if you have two crops and they overall give you the same yield and they have the same drought tolerance, go for the paler one.”

Particle Puns


Creative Commons Logo

Republishing our content

We want our stories to be shared and seen by as many people as possible.

Therefore, unless it says otherwise, copyright on the stories on Particle belongs to Scitech and they are published under a Creative Commons Attribution-NoDerivatives 4.0 International License.

This allows you to republish our articles online or in print for free. You just need to credit us and link to us, and you can’t edit our material or sell it separately.

Using the ‘republish’ button on our website is the easiest way to meet our guidelines.


You cannot edit the article.

When republishing, you have to credit our authors, ideally in the byline. You have to credit Particle with a link back to the original publication on Particle.

If you’re republishing online, you must use our pageview counter, link to us and include links from our story. Our page view counter is a small pixel-ping (invisible to the eye) that allows us to know when our content is republished. It’s a condition of our guidelines that you include our counter. If you use the ‘republish’ then you’ll capture our page counter.

If you’re republishing in print, please email us to let us so we know about it (we get very proud to see our work republished) and you must include the Particle logo next to the credits. Download logo here.

If you wish to republish all our stories, please contact us directly to discuss this opportunity.


Most of the images used on Particle are copyright of the photographer who made them.

It is your responsibility to confirm that you’re licensed to republish images in our articles.


All Particle videos can be accessed through YouTube under the Standard YouTube Licence.

The Standard YouTube licence

  1. This licence is ‘All Rights Reserved’, granting provisions for YouTube to display the content, and YouTube’s visitors to stream the content. This means that the content may be streamed from YouTube but specifically forbids downloading, adaptation, and redistribution, except where otherwise licensed. When uploading your content to YouTube it will automatically use the Standard YouTube licence. You can check this by clicking on Advanced Settings and looking at the dropdown box ‘License and rights ownership’.
  2. When a user is uploading a video he has license options that he can choose from. The first option is “standard YouTube License” which means that you grant the broadcasting rights to YouTube. This essentially means that your video can only be accessed from YouTube for watching purpose and cannot be reproduced or distributed in any other form without your consent.


For more information about using our content, email us:

Copy this HTML into your CMS
Press Ctrl+C to copy

We've got chemistry. Want something physical?