* Heatwave bakes central, northern Australia
* 2013 hottest year recorded in Australia
* Farmers slaughtering cattle, heatwave health warnings
By Matt Siegel and Colin Packham
SYDNEY, Jan 3 (Reuters) - A searing heatwave is baking central and northern Australia, piling more misery on drought-hit cattle farmers who have been slaughtering livestock as Australia sweltered through the hottest year on record in 2013.
Temperatures have topped 40 degrees Celsius (104 Fahrenheit)in large parts of Australia's key agricultural regions for most of the past week, with the mercury topping 48 degrees Celsius in the central west Queensland town of Birdsville.
The heatwave is moving east across Australia, prompting health warnings on Friday in some of the country's biggest cities and firefighters were already battling bushfires.
But it is in the outback that soaring temperatures have had the most devastating impact, especially on cattle farmers in Queensland, which accounts for about 50 percent on the national herd.
"Water supplies are fast diminishing and whatever feed supplies that were left are cooking off to the point where there won't be any left," said Charles Burke, a beef farmer and chief executive of Agforce, a Queensland cattle industry group.
"This drought is shaping to be an absolute disaster."
Monsoon rains in Australia's north failed last summer and the entire continent endured its hottest year since records began in 1910, the Bureau of Meteorology said on Friday.
Average temperatures were 1.2 degree Celsius above the long-term average of 21.8 degree Celsius, breaking the previous record set in 2005.
"The new record high calendar year temperature averaged across Australia is remarkable because it occurred not in an El Niño year, but a normal year," David Karoly, a climate scientist from the School of Earth Sciences, University of Melbourne, said in an emailed statement.
The El Nino weather pattern is a warming of ocean surface temperatures in the eastern and central Pacific and usually brings hot, dry, and often drought conditions to Australia.
FRIED EGGS AND THIRSTY FLIES
In the remote town of Marree, 700 kms (435 miles) north of Adelaide in South Australia, one resident tested the folklore that you can fry an egg on the road during an outback heatwave.
"You hear stories of people frying an egg on a shovel, so we set up a shovel this morning out the front and sure enough we've got an egg there that's slowly frying away," publican Phil Turner told the Australian Broadcasting Corporation.
"So yep, we fried an egg on a shovel."
Faced with such tough conditions, farmers are being forced to slaughter more cattle in the current 2013/14 season.
Australia's cattle herd will fall to 25 million head during the 2013/14 season, the lowest since the 2009/10 season, due to increased slaughtering, the Australian Bureau of Agriculture and Resource Economics and Sciences said.
"Even the flies are sticking close to the house ... thanks to the air-conditioner coming out the windows," said Jo Fogarty from Lucy Creek cattle station in the Northern Territory.
"(We are) leaving sprinklers on for the dogs and birds at the moment. We are quite lucky we have got a good supply of water at the homestead," Fogarty told local media.
Australia is the world's third largest beef exporter, with sales during the 2013/14 season tipped to reach A$5.4 billion ($4.82 billion).
Should Australian farmers continue to send cattle to slaughter due to the heatwave, future exports could fall as farmers eventually rebuild stocks when conditions improve.
The soaring temperatures have also renewed focus on climate change policy in Australia under the new government.
While Australian Prime Minister Tony Abbott has said he accepts the reality of climate change, he abolished the country's Climate Change Commission in September, and rejected any link that global warming was responsible for a series of bushfires across New South Wales state in October.
One of Abbott's major policies is to overturn the previous government's carbon tax, which was aimed at reducing greenhouse gas emissions in an effort to tackle climate change.
"On the science perspective, which is the basis for taking action, you're getting very very mixed messages from this government," Will Steffen, an adjunct professor at The Australian National University, said in an interview.
"I think the first challenge needs to be absolutely clear and consistent messaging from this new government that they understand the science, they accept the science, they accept the risk and they accept the lead to take vigorous and decisive action in getting emissions down."
(Editing by Michael Perry)