SCIENTIST Stephen Hawking yesterday described humans as "chemical scum on a minor planet".

Speaking at an international conference in India, Hawking said the human race would not survive another millennium if the greenhouse effect became irreversible.

The physicist urged the human race to start looking after the planet. He added: "I care whether our children's children have a future."

The professor said our atmosphere might become like that of Venus, raining boiling sulphuric acid.

He also warned that terrorists or an accident could trigger a nuclear calamity.