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BOM annual climate statement shows 2017 was Australia's third-warmest year on record

Kate Doyle, Wednesday January 10, 2018 - 17:40 EDT
Audience submitted image
A wet beginning and end of the year bookended a warm, dry winter in 2017. - Audience submitted

The Bureau of Meteorology (BOM) has confirmed 2017 was Australia's third-warmest year on record, with temperatures almost a degree above the 1961-1990 average.

With a rundown of the year's temperatures, rainfall, climate drivers, major weather events and enough maps to make an atlas, the is a late Christmas present for weather lovers.

In 2017 the main climate drivers, the Indian Ocean Dipole and the El Nino Southern Oscillation, were in neutral for much of the year.

But despite there being no El Nino, usually associated with warm temperatures, 2017 was still the third-warmest year on record, at 0.95 degrees above the 1961 to 1990 average.

BOM head of climate monitoring Karl Braganza said the figures showed how much Australia had warmed.

"We have seen that warming across the land surface temperatures and in the ocean surrounding Australia, so they have both warmed by a similar amount and that's consistent with global warming as well," he said.

Seven of the 10 warmest years on record have been recorded since 2005 and only one year was below the 1961 to 1990 average in the past decade.

"Odds [now] favour warmer-than-average temperatures more often than in the past," Dr Braganza said.

Queensland and New South Wales recorded their hottest years on record.

South Australia recorded its fifth-warmest year, while for Victoria it was the sixth-warmest, and for Tasmania it was the equal 10th-warmest.

Daytime temperatures were particularly hot around Australia, coming in as the second-warmest on record at 1.27 degrees above average.

Coral bleaching two years running for first time

The heating has not just been restricted to the land. Last year saw record warm ocean temperatures, especially on the east coast and around Tasmania.

These warm ocean temperatures brought about a mass coral bleaching event on the Great Barrier Reef in March.

This follows the bleaching event in 2016, making it the first time two mass bleaching events have been recorded two summers in a row.

Dr Braganza acknowledged that mass bleaching events were not recorded prior to the 1980s, but noted, "Certainly in the oral tradition, the traditional owners, there's no real recording of bleaching events, and we haven't seen bleaching events that were back-to-back."

It didn't rain and it poured

A wet beginning and end of the year bookended a warm and dry winter.

Without the major climate drivers to mix things up, a strong subtropical ridge and positive helped keep the rain-bearing fronts and troughs south of the continent.

This led to clear skies, high daily maximums, cool frosty nights, and little rain in the south of Australia during winter.

September was the driest on record for NSW and for the Murray-Darling Basin as a whole.

"That's consistent with the … we have seen a gradual decline of about 10 to 20 per cent in the rainfall during that time of year, so that is consistent with that longer-term trend," Dr Braganza said.

The dry came to an end with above or near average rainfall in the last three months of the year.

This wet weather coincided with the beginning of a weak La Nina system, but the system did not bring about the heavy rainfall usually associated with strong La Nina events.

Events of 2017

Cyclone Debbie in March and April was the stand-out event of the year. It brought about flooding and heavy rainfall to parts of Queensland and New South Wales.

Other noteworthy events included a long period of warmth in November in Victoria and Tasmania, which Dr Braganza said was associated with slow-moving high pressure systems and the very warm sea surface temperatures that were around the coast at the time.

Dr Braganza also put the high May to September daytime temperatures in the Northern Territory on the short list of significant weather events of 2017.

What's next in 2018?

BOM's for January to March suggests the weak to moderate La Nina will stay until early autumn.

Above-average rainfall is likely in the east and the west, but low to near-median stream flows are likely in parts of southern Australia where soils are still dry.

Temperatures are likely to be below average for most of Australia for January to March, with the major exception the very south and Tasmania, which are highly likely to be hotter than normal.



© ABC 2018

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