Record hot spells in Australia this month blurred the line between summer and autumn in another sign of rapidly advancing global warming, a Climate Council report says.

The first four days of March saw maximum temperatures in much of the country 4C above average – and 8C to 12C above average in most of southeastern Australia – the report said.

Despite summer being over, the New South Wales/Victorian border towns of Echuca and Tocumwal suffered the longest, hottest spell in their recorded history, with eight consecutive days of 38C or above.

It follows a summer that delivered Perth more 40C days than ever before and 39 consecutive days over 26C for Sydney, a record that more than doubled the previous high.

The Climate Council said the Australian findings reflected worldwide heat records that, among other impacts, threatened the Great Barrier Reef with widespread coral bleaching and drove a record low in Arctic sea ice cover last month.

The report linked prolonged local heat to destructive fires in Tasmania’s world heritage forests and a major algae outbreak in the Murray river.

It argued that evidence of escalating heat impacts lent urgency to climate mitigation efforts that remain politically contentious in Australia, including a moratorium on new coalmines.

“As Australians continue to suffer from more frequent and worsening extreme heat events, the path to tackling climate change is becoming more urgent: no new coalmines can be built, existing coalmines and coal-fired power stations must be phased out and renewable energy must be scaled up rapidly,” the report said.

The report’s release on Sunday came as the federal environment minister, Greg Hunt, took an aerial tour over the Great Barrier Reef to inspect the impact of coral bleaching.

Hunt was due to address reporters after the flyover with the chief executive of the Great Barrier Reef marine park authority, Russell Reichelt.

Tim Flannery, the former Australian climate commissioner who helped found the Climate Council after the commission was abolished by the Abbott government in 2013, said world heat records were an ominous sign the world had shifted from “climate change concern to climate change consequences”.

“Scientists have been voicing their concerns for decades and now we are seeing the consequences,” Flannery said.

“Our internationally renowned Great Barrier Reef is already experiencing widespread coral bleaching due to record sea surface temperatures.

“Our world heritage ancient forests in Tasmania have been razed by bushfires sparked by tinderbox conditions driven by climate change.

“And, just weeks after health experts warned of the grave dangers posed to Australians through more frequent and severe heatwaves, we’ve seen hospitals in Perth overwhelmed after four consecutive days over 40°C.

“The window of time we have to act is closing. The world is acting but Australia is so far behind.”

The Climate Council’s chief executive, Amanda McKenzie, said there had been no “substantive policy announcements” by the federal government since a UN summit in Paris agreed to rapidly cut fossil fuel emissions.

She called for an “orderly closure of our ageing and polluting coal-fired power plants” to make way for renewables.

McKenzie said extreme heat events affected farmers’ harvests and pushed Australia’s bushfire season “well into autumn”.

Heat records this month included 10 consecutive days above 30C for Canberra and Melbourne’s hottest March night on record at 38.6C.

Brisbane researchers this month predicted the world economy was on track to produce enough carbon emissions by 2020 to lock in a 1.5C rise above pre-industrial levels, and enough by 2030 to lock in a 2C rise.