The temperature forecast for next Monday (14 January) by Australia's Bureau of Meteorology is so unprecedented - over 52C - that it has had to add a new colour to the top of its scale, a suitably incandescent purple.

Australia's highest recorded temperature is 50.7C, measured in January 1960 in southern Australia. On Monday a new record was set for the hottest average day across the country, 40.3C, the highest for 40 years. "What makes this event quite exceptional is how widespread and intense it's been," said Aaron Coutts-Smith, the weather bureau's climate services manager.

Australia's Prime Minister, Julia Gillard, said: "While you would not put any one event down to climate change, we do know over time that as a result of climate change we are going to see more extreme weather events and conditions."

She is right to be cautious about linking individual weather events to the climate heating up, but she is also right that new colours will need to be added to scales across the world for heatwaves and other extreme weather events.

We already know that climate change is loading the weather dice. Scientists have shown that the European heatwave of 2003, which caused more than 40,000 premature deaths, was made at least twice as likely by climate change.

The Russian heatwave of 2010, which killed 50,000 and wiped out GBP10bn of crops, was made three times as likely.

The future looks even worse.

Mega-heatwaves like these will become five to 10 times more likely over the next 40 years, occurring at least once a decade, scientists predict.

Other research concludes it is 90% certain that heatwaves will increase further in length and severity, as will extreme high tides. It is 66% likely that hurricanes and typhoon winds will get faster - more new colours on charts - and that intense rain will increase.

There are uncertainties of course, but the basic physics is that carbon emissions are trapping more energy in the atmosphere, increasing climate chaos.

The two countries where the fringe opinions of so-called climate sceptics have been trumpeted most loudly - the U.S. and Australia - have now have been hit by record heatwaves and, in the U.S., superstorm Sandy. Extreme weather is the climate's alarm bell and is ringing more deafeningly than ever. Whether this leads to loud and clear political action to curb emissions or more shouting from sceptics and the vested fossil fuel interests supporting them remains to be seen.

©Guardian News & Media 2013