Australia

‘More frequent warm years’: 2020 Australia’s fourth hottest on record

Australia has recorded its fourth warmest year in history.The weather bureau has revealed the nation’s area-averaged mean temperature for 2020 was 1.15C above the 1961 to 1990 average.The country also experienced its warmest spring on record last year.The Bureau of Meteorology’s Annual Climate Statement for 2020 showed mean annual maximum and minimum temperatures were above…

Australia has recorded its fourth warmest year in history.

The weather bureau has revealed the nation’s area-averaged mean temperature for 2020 was 1.15C above the 1961 to 1990 average.

The country also experienced its warmest spring on record last year.

The Bureau of Meteorology’s Annual Climate Statement for 2020 showed mean annual maximum and minimum temperatures were above average for all states and the Northern Territory, while rainfall was close to average, which helped ease drought conditions in many areas across the country.

But some regions had below average rainfall, including the west of Western Australia, southeastern Queensland and western Tasmania.

Senior climatologist Lynette Bettio said last year followed Australia’s warmest and driest year in 2019.

She said Australia could no longer escape spring or summer heatwaves, even in La Nina years.

She said the last eight years had been in the top 10 warmest on record for Australia.

“2020 continues the run of well above annual temperatures for Australia,” Dr Bettio said.

“Globally, every year from 2013 onwards has been among the 10 warmest on record, with 2016 and 2019 being the hottest, and 2020 was among the top three despite the onset of La Nina, which has a suppressing effect on global temperatures.”

Dr Bettio said there were both wet and dry periods throughout 2020, and May to July was “notably” dry across the southern half of the continent.

“The year started with significant long-term drought affecting large parts of the country, but rainfall across the year saw these severe drought conditions ease in many areas,” Dr Bettio said.

“While water storages increased in the southern Murray-Darling Basin in 2020, northern basin water levels still remained low at the end of the year.

“By the end of the northern dry season, Darwin’s storage levels had dropped to their lowest level in 10 years.”

Dr Bettio said the shift from Australia’s driest year on record to more average conditions in 2020 reflected a significant shift in Australia’s climate drivers.

“The very strong positive Indian Ocean Dipole, which dominated our climate in 2019, broke down in early January,” she said.

“For winter and spring, it was close to negative Indian Ocean Dipole thresholds, favouring above average rainfall across Australia.

“La Nina slowly evolved during the winter and was declared under way by the bureau in late September and continued through the end of the year.

“The southern annular mode was in a positive mode for parts of winter, spring and at the end of the year. This reinforced the wet signal from La Nina in some areas.”

Dr Bettio said climate change continued to play a role.

“Australia has warmed on average by around 1.44C since 1910, meaning we are seeing more frequent warm years,” she said.

“We’ve also seen a 10 to 20 per cent decrease in rainfall across the April to October period for southern Australia in recent decades.”

Dr Bettio said some of the weather events experienced by the nation in 2020 included the extreme summer bushfires, which were aided by extreme heat across eastern Australia, extreme August heat in most of northern Western Australia, and a November heatwave across much of eastern Australia.

There was also a severe hailstorm in the ACT in January that dropped hailstones as large as 6cm in diameter. There were floods in eastern Australia in February, March and December, and southeast Australia was affected by thunderstorms in late October.

jack.paynter@news.com.au

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