The remarkable weather extremes of the past decade were not directly caused by global warming, President of the Australian Meteorological and Oceanographic Society Professor Neville Nicholls said on Monday.

Professor Nicholls, who is one of Australia's most eminent climate scientists, said such extremes as the heat wave in Victoria of Australia that accompanied the Black Saturday bushfires, similar heat in Pakistan and Russia, and the devastating tornado ripped through parts of the U.S. earlier this year are, in many cases, unprecedented in modern times.

However, he said that global warming should not be blamed for these events.

"Whenever these things happen, people ask 'was it caused by global warming?' The short answer is no," Professor Nicholls told the International Union of Geodesy and Geophysics (IUGG) conference in Melbourne on Monday.

"They were all caused by well-known and reasonably well- understood weather and climate events, even with some predictability."

While global warming does not cause the weird weather, Professor Nicholls acknowledges its part in making some of the extreme weather more severe.

"Global warming doesn't produce these events, however, it's pretty hard to avoid the conclusion that global warming has exacerbated the frequency and the intensity of these heat waves," Prof. Nicholls, who is also a Monash University professorial fellow, said.

"It is much harder to make the connection to link those floods in Queensland in early 2011 to global warming," he said.

"There was a particular and very unusual meteorological sequence that led to those floods and it is very difficult to work out if climate change is exacerbating that situation at all."

He added that the cause of the recent floods in Australia, instead is a record-breaking version of La Nina.

The 25th general assembly of the International Union of Geodesy and Geophysics (IUGG) opened on Wednesday in Melbourne.

Almost 4,000 participants from about 100 countries will discuss recent natural disasters and the impact on human life and infrastructure at the eight-day conference.