Climate Sense

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overnance

and

olicy

an adjacent building

–

remains an ongoing challenge.

Through careful archiving and analysis, however,

Australia now has sufficient data to represent, with a

fair degree of accuracy and on at least a daily basis, the

variations of weather and climate across the breadth of

the land for the past 100 years.

In 1967 drawing on more than 60 years of monthly

rainfall records from around 6,000 locations around

Australia, W.J. Gibbs and J.V. Maher of the Australian

Bureau of Meteorology developed a method of using

rainfall deciles as drought indicators. For any location

or region where the aggregated rainfall over a period

of three calendar months or more was below the first

decile (lowest 10 per cent of all historical rainfalls

for that period), the rainfall was considered to be

seriously deficient. Interestingly, in the announce-

ments that followed the delineation of extended

areas of seriously (or severely) deficient rainfall, the

term ‘drought’ was not used. There was recognition

that lack of rainfall alone might not be adequate for

determining that agriculture was being stressed to

the point where government assistance was required.

Nonetheless, the Australian Drought Watch Service,

which continues to operate on the same basic princi-

ples, represents one of the first examples of a routine

systematic community service based on the rigorous

use of climatological data.

A lesson learnt

The management of Australia’s water data was not

centralized following the federation and remained

the responsibility of individual states and territories,

devolving down in fact to more than 200 individual

agencies and authorities across the nation, with a

consequential set of disparate standards for recording

and reporting on water resources. In its centenary year,

following an extended period of rainfall decline across

the southern Murray-Darling Basin

–

Australia’s major

agriculturally productive region

–

the Water Act 2008

was passed, which gave responsibility for the develop-

ment of national water accounts and water resource

assessments to the Bureau of Meteorology. The actual

recording and primary collection of water data remains

a devolved responsibility, but the standards and regu-

lations for carrying out these functions are set and

maintained by the Bureau of Meteorology, which is

now archiving the data in a central repository called

the Australian Water Resources Information System.

Synoptic climatology

Another critical outcome of the systematic collection

of meteorological and related data (including from

oceanic regions) was the ability to study the nature

and ultimately the causes of Australia’s highly vari-

able climate. While it had been thought by some that

external forces such as sunspot activity and even

periodic meteorite showers were a possible cause of

recurrent drought over Australia, it was the linking

of the atmosphere-based Southern Oscillation to the

locality. Responding to the general characteristics of weather

conditions at different times of the year is a fundamental

rhythm in all living systems, and human societies have always

sought to understand and use knowledge of the seasonal cycle

to their advantage. The increasing rigour in the application of

scientific method throughout Europe and elsewhere following

the Enlightenment, saw the beginning of systematic recordings

of meteorological variables such as rainfall, wind and tempera-

ture. In addition, a wide range of phenological data relating to

climatic events

–

such as the first and last dates of frost, the

thawing of rivers and the migratory habits of birds

–

began to

accumulate in Europe and in other advanced civilizations.

All this collecting of data resulted in the conception of ‘the

climate’, which once defined would provide a strong guide on

what it was feasible to do and when it could be done, across a

wide range of human activities sensitive to the prevailing weather.

The early history of climatology saw the development of system-

atic characterizations of climate in terms of the natural vegetation

that it supported. The first comprehensive attempt to classify

world climate along these lines was that of a Russian climatolo-

gist, Wladimir Köppen at the beginning of the 20th century, with

later modifications by the German climatologist Rudolf Geiger.

An American climatologist, Charles Thornthwaite, with access to

an increasing body of archived meteorological data, was able in

1948 to incorporate factors such as evapotranspiration rates to

help delineate different climatic zones.

Climate is variable

Once devised, these climatic classifications were essentially

static, underpinned by the notion that climate could be relia-

bly defined by around 30 years of data

–

the period over which

climatic ‘normals’ were derived. As the data collections grew over

time it became clear that there could be significant differences

between the climatic statistics of consecutive 30-year normals for

any location, and hence there was potential for changes in the

vegetation and broader ecosystems that could be supported. The

notion that climate significantly varied only on glacial/intergla-

cial timescales had to be well and truly set aside.

The inherent variability of climate across all timescales was

no more evident in reality than in Australia. Since the arrival

of the first settlers at the end of the 18th century, the norms

of European agriculture were time and again confounded by

recurrent and crippling periods of drought. Indeed the history

of Australian agriculture has been one of good years and not

so good years, punctuated every so often by multiple years of

drought with catastrophic crop failures.

Establishing a climate service

In 2008 the Australian Bureau of Meteorology celebrated its 100th

year of existence, having been formed shortly after the federation as

the national agency for: ‘taking and recording meteorological obser-

vations’. One of the most significant outcomes of this transfer of

responsibility to a single national authority was the standardization

of how meteorological observations should be made. Hitherto there

was a wide variation between the Australian State authorities in the

way meteorological instruments were exposed and how recordings

were made. Ensuring that meteorological records truly reflect the

prevailing weather and climate and are not contaminated by local

effects

–

such as growth in nearby vegetation or the erection of