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Environmental Hazards
ISSN: 1747-7891 (Print) 1878-0059 (Online) Journal homepage: https://www.tandfonline.com/loi/tenh20
Normalised insurance losses from Australian
natural disasters: 1966–2017
John McAneney, Benjamin Sandercock, Ryan Crompton, Thomas Mortlock,
Rade Musulin, Roger Pielke Jr & Andrew Gissing
To cite this article: John McAneney, Benjamin Sandercock, Ryan Crompton, Thomas
Mortlock, Rade Musulin, Roger Pielke Jr & Andrew Gissing (2019): Normalised insurance
losses from Australian natural disasters: 1966–2017, Environmental Hazards, DOI:
10.1080/17477891.2019.1609406
To link to this article: https://doi.org/10.1080/17477891.2019.1609406
© 2019 The Author(s). Published by Informa
UK Limited, trading as Taylor & Francis
Group
Published online: 24 Apr 2019.
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Normalised insurance losses from Australian natural disasters:
1966–2017
John McAneney
a,b
, Benjamin Sandercock
a,c
, Ryan Crompton
a,b
, Thomas Mortlock
a,b
,
Rade Musulin
a,d
, Roger Pielke Jr
a,e
and Andrew Gissing
a,b
a
Risk Frontiers, St Leonards, Australia;
b
Department of Environmental Sciences, Macquarie University, Sydney,
Australia;
c
Department of Applied Finance & Actuarial Studies, Macquarie University, Sydney, Australia;
d
FBAlliance Insurance, Schaumburg, IL, USA;
e
Sport Governance Centre, University of Colorado, Boulder, CO,
USA
ABSTRACT
The paper updates normalisation of the Insurance Council of
Australia’s Disaster List in the light of debate about the
contribution of global warming to the rising cost of natural
disasters. Normalisation estimates losses from historical events in
a common year, here ‘season’2017 defined as the 12-month
period from 1 July 2017. The number and nominal cost of new
residential dwellings are key normalising factors and post-1974
improvements in construction standards in tropical cyclone-prone
parts of the country are explicitly allowed for. 94% of the
normalised losses arise from weather-related perils –bushfires,
tropical cyclones, floods and severe storms –with the 1999
Sydney hailstorm the most costly single event (AUD5.6 billion).
When aggregated by season, there is no trend in normalised
losses from weather-related perils; in other words, after we
normalise for changes we know to have taken place, no residual
signal remains to be explained by changes in the occurrence of
extreme weather events, regardless of cause. In sum, the rising
cost of natural disasters is being driven by where and how we
chose to live and with more people living in vulnerable locations
with more to lose, natural disasters remain an important problem
irrespective of a warming climate.
ARTICLE HISTORY
Received 3 January 2019
Accepted 11 April 2019
KEYWORDS
Australia; Climate Change;
Insurance; Natural disaster
costs; Loss normalisation
Introduction
Despite broad agreement in the scientific literature and assessments by the Intergover-
mental Panel on Climate Change (IPCC) that there is little evidence that insurance or econ-
omic losses arising from natural disasters are becoming more costly because of
anthropogenic climate change (IPCC, 2012;2014), the topic remains highly politicised
(Pielke, 2018). Many commentators assume a direct causal relationship between disaster
losses and rising global air temperatures (e.g. http://www.insurancebusinessmag.com/
© 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License
(http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any
medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.
CONTACT John McAneney john.mcaneney@riskfrontiers.com Risk Frontiers, Level 8, 33 Chandos Street, St Leo-
nards, NSW 2065, Australia; Department of Environmental Sciences, Macquarie University, NSW 2109, Sydney, Australia
ENVIRONMENTAL HAZARDS
https://doi.org/10.1080/17477891.2019.1609406
au/news/breaking-news/australian-insurers-not-keeping-pace-with-climate-change–
report-92398.aspx). Our study re-examines the evidence for this notion in the Australian
context and discusses policy implications of our findings.
Regardless of the degree to which various types of extreme weather events may or may
not be changing, climate change resulting from the emission of greenhouse gases is an
issue that can no longer be avoided by Boards of Directors of financial service providers.
Encouraged by signals arising from the 2015 World Climate Change Conference in Paris,
the Australian Prudential Regulatory Authority (APRA) is now seeking more systematic
monitoring and disclosure …of climate change risks from its regulated entities, which
include insurers and reinsurance companies. APRA considers it’s unsafe …to ignore
risks just because there is uncertainty, or even controversy and expects climate change
risks to be explicitly considered and managed as appropriate (G. Summerhayes, 17 February
2017: http://www.apra.gov.au/Speeches/Pages/Australias-new-horizon.aspx).
In its statement, APRA draws a distinction between physical and transitional risks where:
(1) physical risks stem from the direct impact of climate change on our physical environment
–through, for example, resource availability, supply chain disruptions or damage to assets
from severe weather, [and]
(2) transition risks stem from the much wider set of changes in policy, law, markets, technol-
ogy and prices that are part of the now agreed transition to a low-carbon economy.
With this public policy context in mind, this paper examines one component of physical
risks using a time series of Australian insurance sector losses. While this loss metric ignores
damage arising from non-insured threats such as heatwaves (Coates, Haynes, O’Brien,
McAneney, & Dimer de Oliveira, 2014), changing rainfall patterns and drought, and
rising sea levels (IPCC, 2014), insurance losses possess the important attribute of being
explicitly measured rather than modelled, or just guessed, as is often the case for estimates
of economic losses. Our study updates previous loss normalisation studies (Crompton &
McAneney, 2008; Crompton, 2011) of the Insurance Council of Australia’s (ICA) Natural Dis-
aster Event List (hereafter ‘Disaster List’). Normalised losses are estimates of the cost if his-
toric events were to impact current societal and demographic conditions (Bouwer, 2019)
and loss normalisation is a necessary step before attempting to draw conclusions about
trends in the costs of natural disasters and/or climate change attribution (Pielke, 2018).
The ICA Disaster List now extends back to January 1966. The database is national in
terms of geography and multi-peril in line with most homeowner and contents insurance
policies in this country (McAneney, McAneney, Musulin, Walker, & Crompton, 2016). Perils
responsible for loss entries include bushfires (wildfires), earthquakes, floods, severe storms
including hailstorms and tropical cyclones (TC). Earlier Australian normalisation studies
(Crompton & McAneney, 2008; Crompton, 2011) enjoy wide currency amongst insurers
and reinsurers engaged in the Australian market and provided a framework for the
2014 Productivity Commission enquiry into natural disaster funding in this country (Pro-
ductivity Commission, 2015).
In what follows, event losses in the ICA Disaster List are normalised to season 2017,
defined as the 12-month period beginning 1 July 2017. Since the Crompton (2011)
study, two additional national Censi of Population and Housing have been conducted,
one in 2011 and a second in 2016, and, by virtue of these data improvements as well as
2J. MCANENEY ET AL.
cross-referencing Disaster List events with location data contained in Risk Frontiers’pro-
prietary database, PerilAUS, the granularity of the normalisation process is now much
improved.
1
After a discussion of the salient results, the study concludes with a brief discus-
sion of policy implications.
Loss normalisation methodology
Our methodology follows that of Crompton (2011) whereby an insured loss in season i(L
i
)
in the dollars of the day is converted to a season 2017 normalised loss (L
2017
) according to:
L2017 =Li×Ni,j×Di,k×Zi×Bi,a(1)
where,
.iis the 12-month ‘season’extending from 1 July year ito 30 June year i+ 1 during which
the loss event occurred. Employing seasons (Australian financial years) in this way rather
than calendar years serves to separate successive austral summers when most but not
all severe events occur.
.jis the set of Urban Centres/Localities (UCLs) impacted by the event. The UCL structure
is one of seven interrelated structures of the Australian Standard Geographical Classifi-
cation grouping of Census Collection Districts that together form geographical areas
defined by population size (Australian Bureau of Statistics (ABS) –www.abs.gov.au).
For more detail on UCLs, the reader is referred to Appendix 1.
.kis the set of States and Territories containing impacted UCLs. Where these were not
recorded in the Disaster List, these were identified by cross-referencing entries with
those in PerilAUS.
.ais the Wind Region defined by the Building Code of Australia and containing impacted
UCLs. These comprise four regions with different Ultimate Design windspeeds (3-s sus-
tained open terrain gust speeds at 10 m height) according to Australian New Zealand
Standard AS/NZ1170:2:2002: Region A –Normal (41 ms
−1
); Region B –Intermediate
(51.9 ms
−1
); Region C –Tropical cyclones (64.5 ms
−1
); and Region D –Severe tropical
cyclones (88 ms
−1
).
.N
i,j
is the dwelling number adjustment factor defined as the ratio of the total number of
residential dwellings in UCL j in season 2017 to the total number in season i. By way of
example, Tropical Cyclone Winifred (1985) impacted UCLs Innisfail and Babinda in
Queensland and the event dwelling number adjustment factor is calculated as the
sum of all dwellings in both Innisfail and Babinda in season 2017, divided by the
sum of all dwellings in season 1985.
.D
i,k
is the dwelling value adjustment factor, defined by the ratio of the nominal value of
new dwellings in State/Territory k in season 2017 to the nominal value of new dwellings
in State/Territory kin season i. In keeping with the Australian Bureau of Statistics’(ABS)
own approach, this study employed a Henderson Moving Average Filter with a term of
five (two seasons either side of the target season) to smooth dwelling values from
1966 to 2017 (www.abs.gov.au). At the endpoints, asymmetric weightings were
applied to maximise the amount of data that could be used. Changes in D
i,k
are due
to three main factors: inflation, improvements in the quality of housing stock and
changes in the average size of dwellings. These factors all contribute to the cost of
ENVIRONMENTAL HAZARDS 3
re-building after a disaster event. In keeping with the fact that damage to the land is not
covered by insurance, dwelling values exclude the price of land.
.Z
i
=S
i,total
/S
i.new
adjusts for the changing size of new dwellings vis-à-vis the total build-
ing stock after accounting for demolitions (Crompton, 2011). (Insurance policies gener-
ally require re-building to be undertaken to the same size as the original home, so we
account for this.) S
i,total
is the ratio of the average size of all existing dwellings in season
2017 to the average size of all dwellings in season i, and S
i,new
is the ratio of the average
size of new dwellings in season 2017 to the average size of new dwellings in season i.
Dwelling size data is available on a national level and has been drawn from Building
Activity Reports (ABS –www.abs.gov.au).
.B
i,a
is the building code adjustment factor, which defaults to unity for all natural peril
events other than TC. For any particular TC, B
i,a
is calculated by first considering the pro-
portion of the total damage caused by wind or wind-induced rainfall ingress vis-à-vis
cyclone-induced flooding and then applying damage functions to the former to esti-
mate the percentage damage to dwellings built before and after new construction
regulations. Depending on location, these regulations were introduced in 1974, 1975
or 1980, after TC Tracy destroyed Darwin in Christmas 1974 (Walker, 1975). The
approach adopted here is identical to that described in Crompton and McAneney
(2008) and employs damage functions first published by Walker (1995) and reproduced
in Crompton and McAneney (2008).
Results
Changes to the Disaster List: Crompton (2011) normalised 195 Disaster List events, 178 of
which had normalised losses of more than AUD 10 million, whereas our current study
considered 297 events, 245 of which had normalised losses in excess of the same
threshold. A substantial number of the additional event losses are from older events
that have been recovered from archival document searches by ICA staff(K. Sullivan,
ICA,pers.com.);intotal,wehavenormalised102newevents,73ofwhichoccurred
since 2011. Most significant of the changes to the Disaster List since our previous
studies include entries for TCs Elsie, Dinah, Barbara and Elaine, all of which occurred
during the 1966 season.
Normalised losses: Table 1 ranks the top 10 most costly loss events normalised to 2017
values with the 1999 Sydney hailstorm the most expensive at AUD 5.6 billion. Six different
perils contribute to these top 10 losses: hailstorm, tropical cyclone, bushfires, floods, one
earthquake and an East Coast Low storm (extra-tropical cyclone).
The aggregated ‘seasonal’raw losses in dollars of the day and the normalised losses are
given in Figure 1(A,B), respectively. The key result is that our normalisation methodology is
successful in explaining the increase in nominal losses as evidenced by the absence of any
significant trend in the normalised losses. The regression in Figure 1(B) explains less than
1% of the variance about the trend line and its slope is slightly negative because the
largest seasonal loss (1966) is also the first of the time series. (McAneney, van den
Honert, and Yeo (2017) demonstrate the dependence of regression statistics on the
choice of start and finish dates and the bias that this can introduce in attribution
studies.) If the time series is begun in 1967 (data not shown) the slope of the trendline
becomes marginally positive but the trend is still not statistically significantly different
4J. MCANENEY ET AL.
from zero (p= .67). That conclusion is also unchanged if only weather-related perils are
considered (Figure 2), whereupon the p-value reduces to .46.
The average annual loss for the Disaster List is AUD 1.8 billion across its 52-year period.
Since the Disaster List accounts for about 90% of the industry claims experience –not all
insurers are members of the ICA –the annual average insured cost of natural disasters is
∼AUD 2 billion with an standard error of the same magnitude.
Table 2 shows the breakdown of normalised losses by State and Territory. Since 1966
events in Queensland, closely followed by New South Wales, have been most costly.
Together these two states account for 70% of the national normalised losses.
Table 3 shows the breakdown of the accumulated normalised losses by peril category.
TC and hail have been the most costly and responsible for 29% and 27% of the aggregated
normalised losses respectively. The remainder of the losses are roughly equally spread
between floods, bushfires and storms, and then earthquakes, which account for 5% of
the total normalised losses. As discussed below, we believe storm losses to have been
underestimated.
Coherence of normalised losses with underlying peril activity: Appendix 2 shows time
series of the normalised insured losses broken down by peril and aggregated by
seasons and in Appendix 3 we explore changes in the activity of the underlying peril, in
other words, changing numbers of severe hailstorms, for example, as opposed to
changes in the losses caused by hail. For losses due to severe storms, flooding and hail
(Figures A1,A2, and A5), no statistically significant trends emerge. In the case of
flooding losses (Figure A2) the result is curious given that insurers have not consistently
covered riverine flood damage and a priori we might have expected to find an increase
in losses over time, especially in recent years. Nonetheless, the result is consistent with
the lack of trends in modelled flood discharges going back to 1900 (Figure A6).
For damage from severe storms (Figure A1) no events are listed prior to the mid-1970s.
We believe this to be a feature of the under-reporting of smaller event losses in the early
administration of the Disaster List and also the use of a fixed event threshold for inclusion
in the Disaster List of AUD 10 million (formerly AUD 5 million). It should be noted that an
event loss of AUD 5 million in 1966 could translate to a normalised loss today up to AUD
500 million depending upon where it took place. It is also possible that some storm losses
Table 1. Top 10 most expensive normalised losses.
Rank Season Event Location
State/
Territory
Nominal loss
(Millions of AUD)
Normalised loss
(Millions of AUD)
1 1998 Sydney Hailstorm Sydney NSW 1700 5574
2 1974 Cyclone Tracy Darwin NT 200 5042
3 1966 Cyclone Dinah Multiple QLD/NSW 34 4685
4 1989 Newcastle Earthquake Newcastle NSW 862 4244
5 1973 Flooding Ex-Cyclone
Wanda
Brisbane QLD/NSW 68 3160
6 1982 Ash Wednesday
Bushfires
a
Multiple VIC/SA 176 2344
7 1984 Brisbane Hail Storm Brisbane QLD 180 2274
8 2010 Brisbane & Lockyer
Valley Flooding
a
SE Queensland QLD 2022 2260
9 2006 ECL Severe Storm
b
Multiple NSW 1480 2197
10 1966 Black Tuesday
Bushfires
Hobart & SE
Tasmania
TAS 40 2157
a
These events, which comprise two or more entries in the Disaster List, have been combined into a single event loss.
b
ECL is an East Coast Low, a severe storm impacting the eastern seaboard.
ENVIRONMENTAL HAZARDS 5
have been catalogued under hailstorms but deconstructing this history, even if this were
possible, lies beyond the scope of this study. If our supposition of underreporting in the
early part of the loss history is correct, then it means that our estimate of the average
annual normalised loss should more appropriately be considered a lower bound and
strengthens the conclusion that insured losses are not increasing in a normalised sense.
In terms of severe storm activity, only rainfall (Figure A7) shows any significant trend
and this is negative (p< 5%) but the main feature of this figure is the elevated incidence
of hail and heavy rain in seasons 2009–2011. By inspection it looks as if the incidence of
hail and heavy rain is mean-reverting but the short time series rules out more definitive
analyses. Severe windspeeds show no trend over time (p= .49).
Figure 1. (A) Annual aggregate losses by financial year in the dollars of the day; and (B) the annual
aggregate of losses normalised to 2017 societal and demographic conditions. The heavy black line
in the latter is the linear regression line considering all of the data; the dark grey area depicts the
95% confidence interval. Both graphs include losses from the 1989 Newcastle and other earthquakes.
6J. MCANENEY ET AL.
In the case of tropical cyclone losses (Figure A3), the regression trend is significant
(p= .04) and this is almost true of bushfire losses Figure A4 (p= .05) but both regression
lines have negative slopes and do not support expectations for an increase in normalised
losses. For bushfire this is consistent both with previous studies (McAneney, Chen, &
Figure 2. Normalised losses from weather-related events only. As for Figure 1(B), the slope of the
regression line is not significantly different from zero and the dark grey area depicts the 95% confi-
dence interval.
Table 3. Breakdown of normalised losses by peril category. Percentages have been rounded up to
single digit values.
Peril Nominal loss (millions of AUD) Normalised loss (millions of AUD) Proportion of normalised losses (%)
Cyclone 5384 26,132 29
Hail 9672 25,060 27
Flooding 5276 13,658 15
Bushfire 3067 11,184 12
Storm 5089 9475 10
Earthquake 941 4652 5
Tornado 263 357 0
Other 505 645 1
Table 2. Breakdown of normalised losses by State and Territory: New South Wales (NSW); Victoria (VIC);
Queensland (QLD); Western Australia (WA); Northern Territory (NT); Australian Capital Territory (ACT);
Tasmania (TAS).
State Nominal loss (millions of AUD) Normalised loss (millions of AUD) Proportion of normalised Losses (%)
QLD 11,704 34,354 38
NSW 9923 29,252 32
VIC 4533 10,817 12
NT 382 6448 7
WA 1950 4666 5
TAS 138 2374 3
SA 954 2053 2
ACT 350 839 1
ENVIRONMENTAL HAZARDS 7
Pitman, 2009; Crompton, McAneney, Chen, Pielke, & Haynes, 2010; Crompton, McAneney,
et al., 2011) and with the absence of trends in the numbers of bushfire ignitions and burnt
areas observed since 2001 (Appendix 3). No national databases of bushfire frequency or of
areas burnt exist prior to this year.
For tropical cyclone, the clear reduction in losses observed over time (Figure A3) is con-
sistent with declining numbers of landfalling cyclones observed since the late 1800s on
the eastern seaboard south of Cairns (Callaghan & Power, 2011). Other evidence points
to a longer-term decline in tropical cyclone activity in this area, beginning in the late
1700s/early 1800s (Haig, Nott, & Reichart, 2014). Whether human-caused climate change
is contributing towards this decline is unknown to this point, but given the level of inter-
annual, decadal and interdecadal variability, Callaghan and Power (2011) suggest it impru-
dent to assume that this decline in landfalling TC numbers will continue based on simple
extrapolation of past trends.
Discussion
Methodological: Loss normalisation attempts to give a present-day perspective of historical
events. It requires credible adjustment factors to translate historical losses to current
societal conditions and having coherent data for these factors over the entire loss
history. Following on from Crompton and McAneney (2008) and Crompton (2011), but
in marked contrast with other normalisation studies, our approach deals explicitly with
improved construction standards of newer homes in TC-prone areas. McAneney et al.
(2007) suggest that these improvements have reduced insurance losses by some 67%. It
could be argued that similar adjustments might be necessary for riverine flood and
bushfire losses if risk-informed insurance premiums were to encourage more prudent
land use planning, but there is no evidence that this is happening yet, and just how
this might play out in the future is unknown. We’ll come back to this issue in later
discussion.
Limitations to our methodology were discussed in detail in Crompton and McAneney
(2008). Chief amongst these is our acceptance of the veracity of the Disaster List entries.
Beyond cross-referencing with contemporaneous entries in PerilAUS, which revealed no
anomalies amongst major events, and some research into the cost of individual key
events such as Cyclone Tracy (Mason & Haynes, 2010), there is little alternative but to
do so. As noted by Crompton and McAneney (2008), there has been a trend towards an
increasing number of smaller events being included in the Disaster List and it might be
timely that the ICA reconsiders its threshold cost for inclusion.
A second feature of our methodology is our use of normalisation factors developed for
residential properties to normalise damage to all insured assets, including commercial and
industrial buildings, motor vehicles, etc. In the absence of specific data on the breakdown
of losses by a line of business and the availability of alternative normalisation factors, this
shortcoming is unavoidable. Nonetheless for those events where we do have this detail,
damage to residential homes contributes a significant component –roughly one half
on average –of the total insured event loss and a lot more in particular cases (Roche, McA-
neney, Chen, & Crompton, 2013).
Some might argue that improving emergency management practices and resources, in
the case of bushfire for example, might mean the lack of trend in the normalised losses
8J. MCANENEY ET AL.
points to improving resilience and simply adjusting for increasing numbers and values of
property disguises the true extent of a purportedly worsening climate (Nicholls, 2011). This
view misses the key observation that most property losses take place under a few days of
so-called ‘catastrophic’conditions when fire behaviour is well beyond the control of fire-
fighting agencies (Crompton, McAneney, et al., 2010; Crompton, McAneney, et al. 2011).
This is being increasingly recognised since the 2009 Black Saturday fires in Victoria as
the early evacuation of at-risk populations and saving of lives takes precedence over prop-
erty protection, with the Wye River (2015) and the Sir Ivan (2017) fires two recent
examples.
Similar arguments can be made in respect of the role of improved weather forecasts
where there is no evidence that these have resulted in reduced property losses in
severe bushfires, although they have undoubtedly saved lives (Crompton, McAneney,
et al., 2011). The 2009 Black Saturday fires is a case in point of a bushfire disaster with
large losses despite near perfect weather forecasts.
Adjusting for the Consumer Price Index (CPI) (https://tradingeconomics.com/australia/
inflation-cpi) has been an oft-used normalisation methodology but one that performs
poorly in our case. Figure 3 shows how employing CPI results in an apparent increasing
trend in the adjusted losses post-2000. This increase is not matched by any comparable
trends in peril incidence and intensity (Appendices 2 and 3). We believe this to be an arte-
fact of CPI failing to correctly capture the full extent of changes in relevant societal and
demographic factors. In contrast, our chosen normalisation process is successful in
explaining the totality of the changes in demographics and wealth that have taken
place and which have collectively contributed to the increase in the nominal losses
over time (cf. Figure 1(A,B)). In particular, once we have normalised weather-related
losses for changes that we know to have taken place (Figure 2), no residual signal
remains to be explained by changes in the occurrence of extreme weather events, regard-
less of cause. And while more complicated adjustment models could be envisaged, they
Figure 3. Historical event losses adjusted by Consumer Price Index (CPI). The increasing trend is not
consistent with the underlying peril data (see text).
ENVIRONMENTAL HAZARDS 9
are not justified given the performance of our adopted approach. The coherence of the
normalised losses with the underlying peril data adds further confidence in the fidelity
of our chosen methodology.
Normalised losses: The key result emerging from our study is that normalised losses
aggregated by either season (or calendar year (data not shown)) exhibit no statistically sig-
nificant trend over time. This outcome should come as no surprise given identical con-
clusions drawn from many other similar studies across different perils and jurisdictions
(e.g. Pielke and Landsea, 1998; Pielke et al., 2008; Crompton and McAneney, 2008;
Barredo, 2009,2010; Di Baldassarre et al., 2010; Crompton et al., 2010; Crompton, McAne-
ney, et al., 2011 and others reviewed by Bouwer, 2011; Barredo, Saurí, and Llasat, 2012;
Barthel and Neumayer, 2012; Visser, Petersen, and Ligtvoet, 2014; Pielke, 2018; Mechler
and Bouwer, 2015; Chen et al., 2018; Ye and Fang, 2018; Weinkle et al., 2018; Bouwer,
2019). We conclude that the principal driver of the rising cost of natural disasters continues
to be societal factors such as where and how we choose to live.
With normalised losses approaching AUD 10 billion, 1966 emerges as the most costly of
all seasons (Table 4). Perils in that season include two tropical cyclones, a bushfire and a
flood; normalisation factors for these events are driven by the large increase in dwelling
numbers and dwelling values. TCs Dinah and Elaine caused significant destruction with
the former costing AUD 5.1 billion in normalised losses and inflicting the third largest
insured loss of all events in the Disaster List (Table 1). Elaine exacted a normalised cost of
AUD 2.3 billion and ranks at number 11. TC Dinah has a dwelling number adjustment
factor of 8.3 reflecting large population growth in South East Queensland since 1966 and
a dwelling value factor of 39.2. Dwelling value factors are very large for all seasons prior
to 1970, after which house values increased dramatically during a period of high inflation
that peaked at 17.5% in 1976 (https://tradingeconomics.com/australia/inflation-cpi).
Again in respect to the aggregated losses, only four seasons since 2000 rank in the top
10 (Table 4) with 2010 coming in at fifth, a reminder that recent years have not been
especially anomalous. The ranking of normalised losses is slightly different when these
are aggregated by calendar year with 1967 the most costly at AUD 11.3 billion; this
view is relevant for insurers whose reinsurance policies are aligned by calendar year.
Implications for policy
The question –is climate change, human-caused or other, responsible for some quantifi-
able part of the increasing cost of weather-related natural disasters? –is often incorrectly
Table 4. Top 10 seasonal aggregate normalised losses in millions of Australian Dollars (AUD).
Rank Season Nominal loss (millions of AUD) Normalised loss (millions of AUD)
1 1966 90 9681
2 1989 1293 6552
3 1998 1892 6285
4 1974 215 5449
5 2010 4151 4742
6 1973 114 4630
7 2014 3844 4229
8 1984 390 4097
9 2009 2190 3075
10 2016 2942 2993
10 J. MCANENEY ET AL.
conflated with a larger question as to whether or not anthropogenic climate change is real
(Pielke, 2018). The lack of positive trends in normalised event loss histories of insurance (or
economic losses), as observed here (Figure 2) is sometimes exploited by partisan actors to
argue that climate change is unimportant. Conversely, others attribute the rise in the
nominal value of weather-related event losses directly to climate change and then cite
these as proof positive that action in this space is urgent. Both interpretations are
misleading.
Rather, the results that emerge in this study and others like it simply reflect the fact that a
climate change signal in insured losses, if present, is expected to be small to this juncture,
and its detection in datasets characterised by large year-to-year and longer-term volatility is
fraught (IPCC, 2014;Benderetal.,2010; Crompton, Pielke, & McAneney, 2011). Even if we just
focus on the peril itself, attribution remains challenging: McAneney et al. (2017), for example,
were unable to detect changes in either the frequency of floods or their peak heights in a
high-quality, 122-year data set from the Ba River catchment of Fiji. The importance of that
study is that it deals with flooding in a region where low lying Pacific Islands are seen as
being particularly vulnerable to sea-level rise and which has seen contemporaneous
increases in air temperature (Kumar, Stephens, & Weir, 2014). With less self-consistent data-
sets, such as the North Atlantic hurricane record (HURDAT2 database), which is unavoidably
compromised by changes in observation platforms (Landsea, Harper, Hourau, & Knaff,2006;
Chen, McAneney, & Cheung, 2009;Landsea&Franklin,2013), and, even within the satellite
era, by improvements in coverage, resolution and signal processing (Landsea et al., 2006;
Klotzbach, 2006), the task is much harder (Klotzbach, Bowen, Pielke Jr, & Bell, 2018). Logic
suggests that any relationship between increasing mean global air temperatures and
extreme weather will be complex, and both peril and location-dependent.
Normalisation provides insight into how past events might look today; it does not fore-
cast the future and it would be incorrect to draw a conclusion from our work that changes
in the frequency or intensity of extreme events will have no impact on future losses or that
investment in proactive adaptation measures is unnecessary. At a minimum, a changing
climate introduces additional uncertainty into forecasts of the future, and since uncer-
tainty generally comes with an economic cost, proactive actions may make economic
sense even in the absence of increasing normalised disaster losses. Further, the relatively
slow turnover in housing stock combined with Australia’s skewed spatial distribution of
the population (Chen & McAneney, 2006) creates the possibility of a disaster ‘mitigation
gap’developing if future climate change effects materialise faster than building codes
can be enacted and housing stock fortified.
Lastly, insurance premiums are sometimes advocated as a driver of risk-reducing beha-
viours through the economic signals they send to property owners about exposure to risk
(Kunreuther, 1978,1996,2006; McAneney et al., 2016). This outcome, however, is not axio-
matic: rising insurance premiums in flood-prone areas, for example, may lead homeowners
not to insure against this peril. On the other hand, naïve confidence in the management of
upstream dams (e.g. van den Honert & McAneney, 2011) or in structural mitigation works
like levees might perversely encourage councils to allow more building in areas prone to
larger but less frequent floods (Burby, 2006; Gissing, van Leeuwen, Tofa, & Haynes, 2018).
Either way, the upshot is that future insured losses from floods may become less correlated
with the economic costs arising from this peril. A similar argument can be made in respect
of bushfire (wildfire) losses. As loss data does not reflect climate change and as insurers
ENVIRONMENTAL HAZARDS 11
usually issue short duration policies on physical assets, we posit that it’s unlikely that the
insurance system will drive needed adaptation measures.
It needs to be recognised that tackling climate change and reducing the cost of natural
disasters are both important issues but addressing these will require different policy
actions and societal responses. Moreover, large natural peril event losses will remain a
problem independent of the degree to which they might be influenced by changes in
the climate.
Note
1. PerilAUS contains information on natural peril events that have caused either loss of life or
material damage to property and is considered complete since 1900 (e.g. Coates et al.
(2014); Crompton et al. (2010) and Haynes et al. (2010)).
Acknowledgements
The authors acknowledge the financial support for this work from the Insurance Council of Australia
as well as the help and advice of a number of Risk Frontiers colleagues especially Drs Mingzhu Wang
and Salomé Hussein.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by Insurance Council of Australia.
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Appendices
Appendix 1. Dwelling value factors and urban centres/localities
Dwelling value factors (D
i
,
k
) were calculated using State/Territory data containing the impacted UCLs.
In cases where multiple States or Territories contain impacted UCLs, an arithmetic average of the
dwelling value factors for each State/Territory was used. The average nominal value of a new
dwelling is calculated by dividing the value of residential building work completed within a
season by the number of residential dwellings completed within the same time frame. Data for
the value of residential building work completed within a season and the number of residential
dwellings completed are available on a quarterly basis (Australian Bureau of Statistics (ABS) –
http://www.abs.gov.au).
Broadly, an Urban Centre is defined as a cluster of contiguous Statistical Area 1’s (SA1s) that are ‘of
urban character’with ‘an aggregate population exceeding 1000 persons contained within’(ABS –
http://www.abs.gov.au). A Locality is defined as a cluster of contiguous Statistical Area 1s (that do
not necessarily have to be ‘of urban character’) containing between 200 and 999 persons. The
number of dwellings in each UCL has been reported in all census years since 1966 in the Censi of
Population and Housing (ABS –http://www.abs.gov.au). All data points collected from censuses
are attached to the date of the census night. Dwelling numbers were linearly interpolated
between successive census years.
It is common for new UCLs to be created and existing UCLs to merge into other, larger UCLs.
For example, many older Western Sydney and Blue Mountains UCLs have been aggregated into
Sydney and Blue Mountains over time, as those urban areas have expanded and subsumed smaller
towns. Occasionally events in the Disaster List took place in UCLs that no longer exist today, or
conversely, occurred in places where there are now UCLs that did not exist in season i. Each of
these situations was examined on a case-by-case basis. In some instances where an UCL only
appears once in either 2017 or season i, data is ignored and the factor determined from the
remaining UCLs. Other cases requiring special attention include the 1968 Blue Mountains
bushfires that impacted what is now the Blue Mountains UCL. In 1968 this UCL did not exist;
in fact, there were few UCLs covering that area, none of which exist today. By way of a solution,
the Blackheath UCL was used as an approximation for the purposes of calculating the normalising
factors in the nearby impacted area. This approach must be done with care, as even geographi-
cally close towns can have quite different growth rates. In this particular case, the growth rate of
the Blue Mountains roughly matches that of Blackheath (which itself is in the Blue Mountains), and
as such is the best option given the available data.
ENVIRONMENTAL HAZARDS 15
Appendix 2. Times series of losses by weather-related perils
Figure A1. Normalised insurance losses caused by severe storms by financial year: 1966–2017. The
absence of losses prior to 1976 is discussed in the text but is believed to be due to underreporting.
Figure A2. As for Figure A1 but for flooding losses.
16 J. MCANENEY ET AL.
Figure A3. As for Figure A1 but for tropical cyclone losses.
Figure A4. As for Figure A1 but for bushfire losses.
ENVIRONMENTAL HAZARDS 17
Appendix 3. Time trends in the underlying climate-related perils
Confidence in the fidelity of the normalisation process is enhanced if the normalised loss history is
consistent with patterns of behaviour of the underlying perils. In what follows we examine the latter
for time periods when the data is considered complete.
Bushfires: There exists no consistent database detailing historical bushfire severity and frequency
over the time period of interest: 1966–2017. This being the case, we have created one using the
latest version of MODIS Burned Area product (Version 6) (NASA LP DAAC, 2018) to determine the
frequency of ignitions and the area burnt since 2001. No data exists prior to 2001. The MODIS
mapping algorithm detects the approximate date of burning on a per-pixel basis at 500 m resolution.
Burnt areas and a number of ignitions were aggregated for each season (1 July to 30 June) both on a
national basis and also for latitudes less than −26 degrees. The latter categorisation was chosen to
correlate more closely with the spatial distribution of damaging events in Risk Frontiers’PerilAUS
database and, in particular, to eliminate fires in the Northern Territory where the fire is used as a
land management tool and, while large areas are burnt each year, little property damage occurs.
No significant linear relationship was found between areas burnt or numbers of ignitions and
time –all pvalues are greater than .05 (data not shown). This is unsurprising given the short 17-
year database.
Flooding: In respect of riverine flooding we use the daily gridded rainfall data from the Australian
Water Availability Project (AWAP) (Jones et al., 2009) in conjunction with a semi-distributed rainfall-
runoffmodel to derive a 117-year storm discharge history (1900–2017) for Australian river catch-
ments. These catchments are those that feature in the National Flood Information Database
(Leigh et al., 2010; McAneney et al., 2016). Catchments are aggregated by Australian Climate Zone
classifications (see below).
AWAP provides daily (24-h, from 9 am AEST the day before to 9 am the current day) rainfall maps
across Australia on a 0.05° grid (∼5km
2
) from 1900 to present (Jones et al., 2009). AWAP is derived
only from observations; it does not use a climate model. It uses all available rain station data across
the country held in the Australian Data Archive for Meteorology. Data quality at any location is
dependent on the density of observations.
Australian Climate Zones are distinguished by differences in rainfall totals and seasonal patterns
(Bureau of Meteorology [BOM], 2018). The median annual rainfall (based on the 100-year period from
Figure A5. As for Figure A1 but for hailstorm losses.
18 J. MCANENEY ET AL.
1900 to 1999) and seasonal incidence (the ratio of the median rainfall over the period November to
April to the period May to October) are employed to identify six zones: Summer dominant; Summer;
Uniform; Winter; Winter dominant and Arid. These six classification groups identify the season of the
highest rainfall in each area.
Figure A6. Number of proxy flood events register per climate zone per year: 1900–2107.
Figure A7. Number of severe storm events per ‘season’in Capital Urban Centre Localities (Appendix 1).
ENVIRONMENTAL HAZARDS 19
The rainfall-runoffmodel used a curve-number-based approach (Soil Conservation Service, 2002),
and incorporates simple physical catchment properties such as shape, hydraulic length, slope, land
use and hydrologic soil type, to model river discharge response.
Heavy precipitation days (>10 mm/24 h, as per the World Meteorological Organization’s
definition) were identified in the record and the peak discharge response retained. Catchments
were grouped according to Australian Climate Classification zones and the annual frequencies of
storm discharge events per climate zone calculated. We refer to riverine storm discharge during
heavy precipitation events as ‘proxy flood’events; over the long-term, the two phenomena are
closely correlated.
Figure A6 shows the annual frequency of proxy flood events per climate zone over the period
1900–2017. As can be seen, there are no significant (to 95% confidence interval) linear trends for
any of the six climate zones, although the time series exhibit pronounced interannual to multideca-
dal fluctuations. While not examined in any detail here, this volatility is likely the result of regional
climate forcing such as El Nino Southern Oscillation (ENSO), and the Interdecadal Pacific Oscillation
(IPO), both of which are known to be significant drivers of rainfall variability in Australia (Verdon et al.,
2004).
Tropical cyclones: Callaghan and Power (2011) document a declining number of landfalling
cyclones since the late 1800s (and perhaps from the late 1700s (Haig et al. 2014)) on the eastern sea-
board south of Cairns. Landfall numbers are in part modulated by decadal variability in El Niño-
Southern Oscillation and show a considerable variation on a multi-decadal timescale. This observed
decline is consistent with the direction of the projections of Knutson et al. (2015) under global
warming, but Callaghan and Power (2011) warn that to this juncture the role of global climate
change in this observed decline is unknown.
Severe storms: Severe storm data were sourced from the BOM Severe Storms Archive (www.bom.
gov.au/australia/stormarchive/about.shtml). For our purposes and in keeping with the Bureau’s
definitions, severe weather is defined as an event that has wind gusts in excess of 90 km/h or hail
in excess of 2 cm diameter or heavy rainfall likely to cause flash flooding. Thresholds for heavy rainfall
vary geographically but are often in excess of 50 mm/30 min. Windspeed is measured at 10 m
height. Storm events encompassing all three attributes are possible but for our purposes the
perils were examined independently.
These data were combined with Geographical Information Data from the 2016 census across Aus-
tralia between 1 January 1990 and 31 December 2017, with 1990 chosen as a start date to encom-
pass improvements in data recording that took place during the 1980s. To account for localised
reporting bias (more frequent reporting in areas with denser population), only events within
Capital City Urban Centre Localities (populations > 50,000) were analysed. ‘Seasons’again begin 1
July and end 30 June to incorporate southern hemisphere seasonality.
Figure A7 shows numbers of hail events, rain, and severe winds for Capital City UCLs. No signifi-
cant linear trends are observed although the period 2009 to 2011 stands out as particularly stormy at
least in terms of hail and heavy rain events.
20 J. MCANENEY ET AL.
