Healthy soil can protect land from soaring heat. But our map shows where soil is suffering

SYDNEY: (May 28) Imagine walking into a double-brick house on a scorching 40 degrees Celsius summer day – it feels cool almost straight away. Now imagine stepping into a corrugated tin shed – it feels like an oven. The difference is simple: some materials slow heat down, while others let it rush through.

Soil works in a similar way. Soil in fully functioning condition can act as a thermal buffer: a giant shock absorber for temperature. It holds water and organic matter such as leaf litter, and slows sharp changes in temperature.

But when soil becomes dry, bare or damaged, that protection weakens. During heatwaves, the roots of crop plants may be sitting in rapidly heating soil.