10 minute read
A land of drought and flooding claims
A wetter summer is forecast as La Nina looms, but will this provide a reprieve for insurers?
By Miranda Maxwell
Advertisement
As California and neighbouring states burn and Australia’s own horror bushfire summer is still fresh in the national memory, forecasts of a wetter summer sound comforting, even reassuring.
The climate influences this year are mercifully very different to those that led to the extreme dry conditions of 2019, something of a wry irony as the royal commission into Australia’s natural hazard management gets ready to deliver its findings by the end of October.
That verdict will be pored over by insurers who were swamped with 38,416 bushfire-related claims with losses estimated at $2.33 billion, a devastating fullstop to the years of widespread drought which had affected much of Australia since early 2017.
The latest key indicators signal the atmosphere is responding to changes in the ocean first detected some months ago. In September, the Bureau of Meteorology (BOM) declared an active La Nina, the ocean-atmosphere phenomenon that is the colder counterpart to El Nino, the two forces which have the strongest influence on year-to-year climate variability for most of Australia.
La Nina occurs when equatorial trade winds become stronger, changing ocean surface currents and drawing cooler deep water up from below. This results in a cooling of the central tropical Pacific Ocean, which the BOM says at the moment is 0.8°C cooler than normal and has resulted in changes to trade winds and pressure patterns.
The last significant La Nina, named after the Spanish for “little girl,” was in 2010-11, and that was Australia’s wettest two-year period on record and saw tropical cyclone Yasi cause widespread damage in far north Queensland.
Climate models indicate this latest La Nina will persist until at least January.
La Nina typically sees above average spring and summer rainfall over much of eastern and northern Australia. Also in play and suggesting wetter times ahead are a negative Indian Ocean Dipole (IOD) index in the Indian ocean and weakly positive Southern Annular Mode (SAM).
Both La Nina and negative IOD typically increase the chance of above average rainfall across much of Australia during spring and across eastern Australia during summer. Atmospheric indicators, including the Southern Oscillation Index (SOI), trade winds and cloud, are also at La Nina levels.
There are some benefits from the onset of a wetter summer, the Bushfire and Natural Hazards Co-operative Research Centre says. “Rainfall so far in 2020 has eased the fire risk for large parts of eastern Australia.”
Australia’s 2020-21 season bushfire risk has to date been deemed “normal,” with the notable exception of parts of Queensland.
But what is normal? And have we let our guard down to the risks of floods, cyclones and eastern lows in the coming natural hazards season to April?
Mark Leplastrier, the Executive Manager Natural Perils at IAG, says we cannot relax.
“It’s hard to say whether it will be better or worse,” Mr Leplastrier told Insurance News. “It only takes one event in a heavily populated area, and you never know where it will hit.”
Familiar sight: fire has once again ripped through California
The latest climate science promises Australia fewer cyclones this season, but says their intensity will be greater. Cyclone season continues through until the end of April and brings with it claims for wind, rain, hail and lightning damage.
This year, the storm risk is higher.
“The tropical cyclone season, which typically starts in November, is likely to be more active this season than in recent years for both Queensland and Western Australia due to the influence of La Nina,” the Bushfire and Natural Hazards Co-operative Research Centre says.
At a live stream to launch IAG’s Severe Weather in a Changing Climate research paper, the buzzword of the day was “amplitude” – the measurement from one point of the magnitude of a variable’s extreme values.
Working with the US National Center for Atmospheric Research (NCAR), an IAG team painstakingly researched the latest extreme weather event predictions, based on temperatures ranging up to 3 degrees warmer than pre-industrial times.
NCAR Senior Scientist Greg Holland says the study reveals that where a La Nina may have previously led to Australia having a “significant but not particularly bad” increase in the number of intense tropical cyclones in a La Nina year, that could “go up to being a substantially higher number of tropical cyclones” as small changes make a greater impact.
“With the onset and the continuing growth of climate warming, all of those changes are happening at a much greater amplitude,” Dr Holland says.
The joint research warns Australia will experience more frequent and intense extreme weather events. Tropical cyclones and giant hailstorms will move further south, threatening densely populated areas of the eastern Australian coastline and its largest cities.
Warming oceans off eastern Australia will see tropical cyclones retain higher intensities further south and penetrate further inland, increasing risks in south-east Queensland and north-east New South Wales.
“That’s not good, because it places major population centres like Brisbane in increasing potential danger,” Dr Holland says.
“Substantial increases in high surge occurrences, the really extreme ones – the ones we’re going to see a lot more of – that could be anything up to 10 or 20 times as many of those storms as we’ve observed in the past.”
Aon calculates cumulative insured losses show the tropical cyclone bill was going up $US3-5 billion a year globally before 2003, $US12 billion a year from 2005-2016, and since 2017, it’s been going up by $US25 billion a year.
IAG meteorology specialist Bruce Buckley agrees “this amplitude is a big issue”. The climate is changing “quite dramatically,” and this will alter the relationship of the impacts of El Nino and La Nina too.
“The key point is the amplitude. That is really one of the big issues here and one of the things you have to be careful of,” Dr Buckley says, noting that statistical techniques placing an accepted index value on impacts in Australia may quickly be superseded.
“That is fine if you have an unchanging climate. We have to bear in mind that relationships we have relied on historically between things like El Nino, the Indian Ocean Dipole, the Southern Annular Mode and all these other global measures will be changing with that changing climate.
“So we have to be a little bit careful of just looking at simple numbers and trends, because the impacts themselves can vary and are likely to vary into the future.”
Complacency is never an option in dealing with Australia’s natural hazards, so famously dubbed the land of “droughts and flooding rains” in Dorothea Mackellar’s iconic poem My Country.
Since that was published in 1908, Australia’s climate has warmed by around 1.4°C, while southern Australia has seen a reduction of 10–20% in the April–October “cool season” rainfall in recent decades, according to the BOM.
While the total 2019-20 bushfire season bill of close to $2.5 billion dominated headlines, it was actually overshadowed in monetary terms by $3.07 billion in combined insured losses clocked up since November from storms and floods.
According to the Insurance Council of Australia (ICA), January hailstorms in the ACT, Victoria and NSW produced 129,201 claims with losses estimated at $1.625 billion, February east coast storms and floods in Queensland and NSW produced 100,384 claims with losses of $958 million, and November hailstorms in Queensland produced 29,782 claims with losses of $481.92 million.
The long-term warming trend means above-average temperatures now occur in most years.
Temperatures in Australia for 2019 were the warmest in 110 years of records, at 1.52°C above the 1961–1990 average.
Mr Leplastrier says Australia’s climate has always featured a variable swing from dry to wet to dry – what Ms Mackellar described as the “pitiless blue sky when sick at heart around us we see the cattle die”, followed by “the drumming of an army, the steady, soaking rain…over the thirsty paddocks”.
What is new is that as the average temperature gets warmer, periods described as “normal” – such as the coming bushfire season – are not completely reset and are “always slightly higher”.
“It’s off a different base,” Mr Leplastrier notes.
Cindy Bruyere, NCAR’s Director of Capacity Center for Climate & Weather Extremes, says the variability of extreme weather won’t change, but the intensity will.
“Some years we don’t have a lot of tropical storms and some years we do. That variability is going to remain going out into the future,” she says.
“It is not like we are suddenly going to have all years with a lot of tropical storms. We are still going to have the same variability. It is the severity of the storms that is important.
“That is the same for all the storms, including drought, so we are going to see bigger hailstorms, bigger tropical storms, more severe tropical storms, and more floods.”
University of Wollongong Research Fellow Hamish Clarke says Australia’s “very variable” climate will always mean there will be higher danger years and lower danger years, but adds: “There is an unmistakable upward trend in fire danger.”
What a difference a year makes: 2020 bushfire risk looks considerably lower so far
Still on alert: IAG’s Mark Leplastrier
Concerned about climate: NCAR Senior Scientist Greg Holland
It is this higher base experienced in the “down” years that is worrying, he says.
Parts of Queensland face above-normal fire potential in the south-east and central coast, extending to the north.
Despite above-average rainfall for much of south-eastern Australia and parts of the inland northwest and Northern Territory during one or more months this year, serious or severe longer-term rainfall deficiencies persist over very large areas.
“Normal bushfire risk does not mean there is no risk,” the Bushfire and Natural Hazards Co-operative Research Centre says.
While 2019 was the warmest and driest year on record for Australia, with many climate records set, 2020 has seen a shift away from drier conditions inmost of Australia. However, the past six months has seen drier than average conditions in Queensland and also large parts of Western Australia, which recorded its warmest June on record this year.
More than half of Australia remains in severe rainfall deficiency for the 29-month period from April 2018 to August 2020. The regions affected include south-east Queensland, pastoral South Australia, most of south-west WA, and much of the Northern Territory and central Australia.
“Persistent, widespread, above-average rainfall is needed to lift areas out of deficiency at annual and longer timescales and provide relief from the impacts of this long period of low rainfall, such as renewing water storages,” the BOM says.
The bureau’s climate model factors in the atmosphere, oceans, ice and land surface combined with millions of observations from satellites and on land and sea. It projects that the remainder of the year is likely to see above-average rainfall across much of the eastern two-thirds of the country, though parts of northern WA and western Tasmania are likely to buck the trend and be drier than average.
A greater than 75% chance is given for much of the eastern half of mainland Australia to experience wetter than average October to December weather. Days are likely to be cooler than average in western and southern WA, and eastern NSW.
Multiple years of below-average rainfall means that eastern SA and south west WA require a much longer period of above-average rainfall for the wider environment to fully recover. While water levels in storages across the northern Murray Darling Basin have increased in recent months, they remain at only 21% capacity.
June and July were largely drier than average nationally, especially in the south-west.
“Much of south-eastern Australia received above average rainfall for April, keeping these areas out of deficiency at slightly longer timescales including April, but have generally received below average rainfall since then,” the Bushfire and Natural Hazards Co-operative Research Centre says.
For this coming hazard season, insurers worn down by the COVID-19 pandemic will be summoning Australia to showcase “her beauty” and not “her terror” this summer and beyond.
Unfortunately, the research centre’s Chief Executive Richard Thornton warns that while the rainfall outlook is good news in the short-term for the bushfire risk, the rain could increase that risk come summer.
“While these wetter conditions in eastern Australia will help for spring, they may lead to an increase in the risk of fast-running fires in grasslands and cropping areas over summer,” Dr Thornton says. “Areas designated as normal fire potential will still see fires.
“When the wind is up and the weather is warm, fires can occur right across the country.”
