Drought-breaking La Nina made the continent cooler

AUSTRALIA did its best for global cooling in 2011 but it had nothing to do with the federal government's carbon tax.

AUSTRALIA did its best for global cooling in 2011 but it had nothing to do with the federal government's carbon tax.

Rather, back-to-back La Nina weather systems that caused widespread flooding and ended the 10-year drought also pushed temperatures below the 30-year average for the first time since 2001, resulting in the coldest autumn since at least 1950.

As with the economy and this year's start to summer, last year's weather was a two-speed affair.

According to the Bureau of Meteorology's annual climate statement for 2011, cooler temperatures in Sydney, the sub-tropics and tropics offset above-average conditions in Victoria, South Australia, Western Australia and Tasmania.

And for those looking to the figures to disprove climate change, the Bureau of Meteorology says Australia was the only continent to record cooling and the nation's 10-year temperature average trend was still up.

"In 2011, the La Nina and heavy rainfall acted like an evaporative cooler for Australia," said bureau climate change spokesman David Jones.

"The year 2010 was relatively cool in recent historical context and 2011 was cooler again."

Mr Jones said there was no evidence to link the strong La Nina weather systems with changing global temperatures.

"We have had this regular cycle of La Nina and El Nino," he said. "The strongest El Nino on record was in 1997 and we have seen one of the strongest La Ninas on record in 2010-11."

Mr Jones said the climate science was not very clear on what would happen with El Nino and La Nina patterns, particularly at this early stage of global warming.

"We have only seen one degree of warming so far but we will see substantially more as we move through the century, but it is probably too early to draw any concrete relationship between hotter temperatures and La Nina," he said.

"One simple thing we can say is we know La Nina are historically cooler for Australia but there is a big difference between variability and climate change."

The BOM climate statement said Australia's mean rainfall total for last year was 699mm, which was 234mm above the long-term average of 465mm, making it the third-wettest year since comparable records began in 1900.

The Australian area averaged mean temperature was 0.14C below the 1961-1990 average of 21.81C. Last year, maximum temperatures averaged 0.25C below normal across the country, while minimum temperatures averaged 0.03C below normal.

"Despite the slightly cooler conditions, the country's 10-year average continues to demonstrate the rising trend in temperatures, with 2002-2011 likely to rank in the top two warmest 10-year periods on record for Australia, at 0.52C above the long-term average," the bureau said.

"If you are interested in determining whether the planet is warming, you look at the global temperature," Mr Jones said.

"Australia follows the global trend closely, but it can vary."

Mr Jones said it was likely that the current La Nina weather pattern would decline this autumn and there would be a rebound in average temperatures.

Commenting on the start to summer, Mr Jones said "there has been quite a bit of bias in the perception of what summer has been like".

"Sydney and Brisbane have had a gloomy start to summer with a lack of high temperatures.

"The average has been quite low but more remarkable has been the lack of any spikes.

"If you were in Melbourne, Adelaide, Hobart or Western Australia there has been nothing remarkable about summer so far."