Australia's deserts will expand southward and dry periods will lengthen as global warming alters key tropical circulations, according to new research by US scientists.

The researchers studied how the Hadley Circulation – the movement of warm air and moisture away from the tropics – will be affected if carbon-dioxide emissions continue to rise at the rate of 1 per cent per year.

Outlook: Climate change is affecting key tropical circulation patterns. Credit:Robert Rough

They found evidence of a so-called "deep-tropics squeeze", in which regions closest to the equator will experience increased convection as air rises faster.

Conversely, the drier sub-tropical regions characterised by descending air and resulting high-pressure systems will expand, according to the research published Tuesday in the Proceedings of the National Academy of Sciences.