POLLUTION haze from Asia may be the reason for increased rainfall in central and northwestern Australia.

But once the aerosol pollution eases later this century, the rain in Australia could decrease, CSIRO research has found.

"Sooner or later these emissions will be cleaned up and then a trend of increasing rainfall in the northwest and centre could be reversed," Marine and Atmospheric Research scientist Leon Rotstayn said.

"This is potentially serious, because the northwest and centre are the only parts of Australia where rainfall has been increasing in recent decades."

The elevated particle emissions are cooling the Asian continent and nearby oceans.

This increases the tendency of monsoonal winds to flow to Australia. Dr Rotstayn said climate simulations responding to increased greenhouse gases did not reproduce the rainfall increase over northwestern and central Australia. "A likely reason for this failure was the omission of modelled responses to Asian aerosols."