2020 declared Australia’s fourth warmest year despite La Nina
The Bureau of Meteorology has confirmed that 2020 was Australia’s fourth warmest year on record with temperatures 1.15C above average.
Only 2019, followed by 2013 and 2005, were hotter. Climate scientists have said it was “unusual” to have such a warm year coincide with the La Nina climate driver that usually brings cooler and wetter conditions.
“We’re now seeing La Nina years that are warmer than we saw El Nino years in the past,” said head of climate services at the Bureau of Meteorology (BOM) Andrew Watkins.
The Bureau also said that despite the recent rain, it could take “months, even years” for some of Australia’s drought ridden regions to recover.
However, the presence of La Nina could lead to an overall wetter and cooler 2021.
This morning, the Bureau released its climate statement for 2020. In one word, last year was hot. Six of the 12 months of 2020 were among the 10 warmest on record, in a year that began with a horror bushfire season and saw Australia’s hottest November ever before La Nina brought the rains to the east.
Heatwaves were common including in populated areas of the south and east. Daytime temperatures were especially warm for Sydney, Hobart and Darwin.
Penrith, in Sydney’s west, topped out at 48.9C on January 4, the highest temperature reported in a metropolitan area since reliable records began. That was in contrast to the coldest temperature last year, when Liawenee in Tasmania’s Central Highlands dropped to a rather brisk -14.2C at 6am on August 7. That made it colder than Antarctica.
It amounted to a “significant” 63 degree difference in extreme temperatures in 2020, between blistering Penrith and bone chilling Liawenee, said Mr Watkins.
On January 14, Victoria had the worst air quality in the world as smoke from the bushfires spread.
Mr Watkins said that despite the strong La Nina emerging, it was still one of the warmest years on record.
“It is unusual to have such a warm year with a La Nina. But having said that, La Nina did start relatively late so the year was not dominated by La Nina.
“Normally you would have gone through more than half a year with La Nina, but last year it started very hot and dry so it really wasn’t influenced by enough of La Nina to make it cooler.”
The Indian Ocean Dipole, the negative Southern Annual Mode were the two dominate climate drivers in 2020 and together with the longer term effects of climate change it all came together to raise temperatures. Only South Australia and western inland parts of Victoria and New South Wales experienced average temperatures.
DROUGHT AREAS COULD TAKE YEARS TO RECOVER
Western Australia saw its second warmest year on record with rainfall below average in the west and above average in the north. Perth’s rainfall was 10 per cent below normal. The city has seen a festive run of punishing 30C-plus days.
Australia-wide, however, rain was 4 per cent above average in 2020 aided by some December deluges. That has added more moisture to Australia’s main drainage basins – but nowhere near enough to make up for years of drought.
The southern Murray Darling Basin, which covers southern NSW and northern Victoria, went from 42 per cent to a not shabby 65.8 per cent full over the year.
But it was less positive for the northern Murray Darling Basin, in southern Queensland and northern NSW. Dams there are only 23.6 per cent full.
“The environment of the (northern) basin has been hit by drought over a long period; it may take months, maybe years, to fully recover even if in the coming months we have above average rainfall with La Nina,” said BOM senior climatologist Lynette Bettio.
“We can’t just have one La Nina year and go back into drought. We need many years of rain in the system for it to draw breath.”
Looking ahead to 2021, the climatologists said we were likely in “peak La Nina” right now with rainfall due to drop off over the coming months. But the hope was some of that moisture would stick around so this time in 2022 we’re not talking about a record-breaking hot and dry previous 12 months.