Paris, the City of Light dimmed last night as a five-minute "lights-out" campaign was held to express concern over climate change.

Even the Eiffel Tower, with its 20,000 sparkling bulbs usually lighting up the Paris skyline nightly, went dark between 7:55pm and 8pm local time.

The countrywide lights-out, the brainchild of France's Alliance for the Planet conservation group, was timed before the release Friday of a major climate change report warning that the Earth will keep getting warmer.

Climate change awareness is considered crucial worldwide, particularly in Australia.

The Commonwealth Scientific and Industrial Research Organisation warns that if residents in Sydney do not cut water consumption by more than 50 per cent over the next 20 years, the city will become unsustainable.

The report also warns that temperatures could rise 5C above the predicted global average, which would leave the city facing an almost permanent state of drought.

By the year 2070, if climate change goes unchecked, the city is in threat of severe droughts nine out of every 10 years, a dramatic rise in the number of bush fires, and freak storm surges which could devastate the coastline.

Scientists predict that rainfall will fall by 40 per cent by 2070, not only creating a massive water crisis, but producing double the number of bush fires. Heat-related deaths, meanwhile, could soar from a current average of 176 a year to 1,300.

Climate change issues will become a top priority for Australians, as the change is predicted to destabilise the Asia-Pacific region, exacerbate food, water and energy shortages and threaten Australia's security.