More than one in five Australians believe global warming is a hoax and more than one-third think aliens have visited Earth.

Essential Research has surveyed about 1000 Australians on various beliefs to reveal some eyebrow-raising results.

While 21 per cent of respondents believed global warming was a hoax perpetrated by scientists, 68 per cent did not believe that statement.

It found 21 per cent believed global warming was a hoax perpetrated by scientists - with 9 per cent strongly believing in the statement and 12 per cent somewhat believing. Another 11 per cent were not sure.

One Nation Senator Malcolm Roberts has been among those to doubt climate change science, with a senior NASA official last year rejecting his claims the agency had falsified data to exaggerate warming in the Arctic.