Transcript Slide 1

George Edwards Peacock, View of old Government House - Sydney - N.S.W., as it
appeared when vacated by Sir George Gipps in 1845, State Library of New South Wales,
ML 658, a128029.
Learning from the past
• Responses to drought in New South Wales were often ‘band aid’
solutions
• Moving cattle and sheep, importing food from other colonies and
overseas
• Repeated periods of long-term drought forced settlers to question the
sustainability of pastoral and agricultural practices
• Ways of living in arid regions were seen as long-term solutions to the
problems associated with periodic drought
J. W. Lewin, The Plains, Bathurst, ca. 1815-1816, State Library of New South Wales, a128133
From drought to flooding rains…
Source: Unknown artist, flood on the Hawkesbury River, June 1816, Sydney NSW. A rage for curiosity : visualising
Australia 1788-1830, Richard Neville. Sydney : State Library of New South Wales Press, 1997.
Lesser known 19th century wet periods
Brisbane Floods 1893, Source: State Library of Queensland
Above average rainfall 1870–1875
Anomalies calculated with respect to 1900–2009 average
A flood at Wagga Wagga, Illustrated Australian News, 18 June 1870.
RAIN (written during the Floods.)
Rain, rain
Nothing but rain!
Sapping the upland, flooding the plain;
Drowning our cattle, spoiling our grain-Rain, rain-Pitiless rain!
Rain, rain-Ne’er-ceasing rain!
Oh, for the sun to cheer us again-The gay blooming fields, and stout harvest wain-Rain, rain-Heart-breaking rain!
Rain, rain-Death-dealing rain!
Youth, manhood, and age alike you have slain-Stifled their wailings, embittered their pain-Rain, rain-Merciless rain!
Rain, rain-Wide-spreading rain!
Oft times a blessing, sometimes a bane;
All long for thy going, but longing's in vain-Still rain-Hope-crushing rain!
Charles Norton, Yarra River in Flood 1862, State Library of Victoria,
H88.21/59
Sydney Morning Herald, 23 May 1870
Samuel Calvert, Incident of the Late Flood, New South Wales,
1870, State Library of Victoria, IAN13/08/70/140
‘Sir,
The continued rains and floods remind us of the flood of forty
days we read of in Genesis, when “God saw the wickedness
of man was great in the earth.” If the wickedness of man then
caused that once great flood which covered the whole earth,
why should not our wickedness be the cause of the presentand recent floods. Think of our much unnecessary work on
Sundays, our general extravagance, particularly in drink and
ladies' dress, our propensities for money making, and our
self-neglect.
After our severe colonial droughts, only a few months back,
suspending the necessary supplies in an alarming degree
required for man and beast, God, in answer to private and
special public prayers in our necessity, sent rain for the good
of all animal and vegetable creation; and the fruits of the
earth were in superabundance granted to us... Yet this very
rare opportunity of setting apart a day for public thanksgiving
near the close of our harvests was overlooked. Oh! the sin of
ingratitude!
... if we obtain a public fast-day, general or limited, and
humble ourselves, the continued rains will probably cease,
and temporal and spiritual prosperity will yet be gained, and
that speedily.’
Sydney Morning Herald, 26 May 1870
Maitland (Hunter Valley) in flood, 1872. SLV Image H2010.134/85.
Floods at Sandhurst (Bendigo), 1873?, wood engraving, nla.pic-an10319478.
Map of Goyder’s Line, History South Australia, http://www.history.sa.gov.au/chu/programs/sa_history/sa_dry/map_goyders.htm
• South Australia 1866 - 1876
Image: National Library of New Zealand
• Area under wheat grew 166,200 ha to 363,700 ha
• Wheat production rose from 97,600 tonnes to 292,000 tonnes
http://www.bom.gov.au/iwk/
What about the natural world?
Tree growth rings
Biological and geological indicators capture natural
climate variability on seasonal–centennial timescales
e.g. tree rings, corals, ice cores, lake sediments, cave
records. Science known as ‘palaeoclimatology’
SEARCH used ‘high resolution’ i.e. monthly–annually
resolved palaeoclimate records to extend the
instrumental climate record centuries into the past
Provides estimates of pre-industrial
Ice laminations
or ‘natural’ climatic variations to
assess recent climate extremes
Palaeoclimate reconstructions are a tool
for comparison with climate models:
Assess the role of ‘natural forcing’ e.g.
solar, volcanic, internal ocean–
atmospheric processes (ENSO, SAM,
IOD) and anthropogenic greenhouse
gas forcing
Coral banding
Tree rings
Sources: NOAA WDC for Palaeoclimatology,
Matthew Brookhouse (ANU), Andrew Lorrey (NIWA)
Corals
Sources: NOAA WDC for Palaeoclimatology, Australian Institute for
Marine Studies (AMIS), Braddock Linsley (Columbia University)
Ice cores
Sources: NOAA WDC for Palaeoclimatology,
Australian Antarctic Division
Speleothems (cave deposits)
Sources: Janece McDonalad (University of Newcastle)
Russell Drysdale (University of Melbourne)
South-eastern Australian rainfall reconstruction
Corals
Trees
Ice cores
• ‘Proof of concept’ study using 12 well-dated, annually resolved records from
Australasia with published climate sensitivity (largely ENSO) to assess the
feasibility of developing an initial rainfall reconstruction for SE Australia
• Locations sensitive to large-scale climate modes associated with the Pacific,
Indian and Southern Ocean variability
Gergis et al. (2012), Climatic Change
Capturing large-scale, coherent rainfall variations:
(i) instrumental and (ii) palaeoclimate data
Instrumental
observations
Palaeocliamte
records
-Grid points where a statistically significant proportion of
the variations in May–April Australian rainfall can be
represented by 12-station observational network (left) and
first 3 leading modes of common variability (Principal
Components) of the palaeoclimate network (right)
- Palaeo network is able to capture the common signal
seen in the instrumental observations
Gergis et al. (2012), Climatic Change
SE Australian rainfall variability: 1783 –2009
Gergis et al. (2012), Climatic Change
Wettest period in instrumental record
(1950s and 1970s)
Driest period in instrumental ?
record (late 1990s/early 2000s)
Rapid changes from wet to dry (and dry to wet)
evident through record
• Innovative statistical techniques used to generate an ensemble of 10,000 reconstructions – collaboration
with statisticians and meteorologists, robust uncertainty estimates (grey envelope)
Median of 10,000 member ensemble of rainfall reconstruction
• ‘Best estimate’
reconstruction
(black line) - 12
recordsfrom
capture
72% rainfall
of the observed
rainfall variations in
Observed
area-averaged
rainfall
AWAP
grid (1900–2009)
SEA (r = 0.85), distinct decadal scale wet and dry phases
Observed area-averaged rainfall from nine high-quality stations (1873–2006)
• Wet and dry cycles seen in the pre-industrial period (natural variability), since the 1970s there have
Gergisfewer
et al. (2012),
Climatic
Change
been
very wet
years
(human-caused temperature increases?)
How does the ‘Big Dry’ compare to rainfall
estimations reconstructed since 1783?
2.9%
According to our rainfall reconstruction ensemble, there is a
97% chance that the 1998–2008 decadal rainfall deficit was
the lowest since first European settlement of Australia
Gergis et al. (2012), Climatic Change
PAGES regional 2K network
- Global effort to consolidate regional palaeoclimate data that covers the last 2000 years
- Aim of the initiative is to produce high-resolution, proxy-based climate reconstructions for
comparison with high resolution Earth System Models: 1) temperature reconstructions for IPCC
AR5 release in 2013, 2) PAGES 2K synthesis book (all variables) by 2014
-‘Aus2K’ Australasian component: important area of southern mid-latitudes: El Nino–Southern
Oscillation (ENSO), Southern Annual Mode (SAM), Indian Ocean Dipole (IOD)
Source: http://www.pages-igbp.org/workinggroups/2k-network
Availability of palaeoclimate data in the Australian region
IPCC AR4 (2007)
Only 5 high
resolution records
available for the
Australasian region
for the last IPCC
report
Neukom and Gergis recently
compiled and reviewed 174
high-resolution records from the
Southern Hemisphere to
improve data availability for
climate analysis (doubling of
IPCC AR4 SH palaeo network)
Now over 50 sites from
Australasia available for
palaeoclimate reconstruction
Neukom and Gergis (2012), The Holocene
Australasian temperatures of past 1000 years
Gergis et al. (2011), Journal of Climate, in revision.
•
1000 year Australasian spring–summer (SONDJF) mean temperature anomalies (land and ocean): mean of
3000-member ensemble based on varying reconstruction parameters (28 records)
•
96.5% of our reconstruction ensemble members indicate that there are no other warm periods in the past
millennium that match or exceed post-1950 warming observed in Australasia
•
Three warmest decade of the past 1000 years occur consecutively in the 1980s, 1990s and 2000s
•
Model comparison show that atmospheric–ocean circulation and anthropogenic greenhouse gases have more
influence on reconstructed Australasian temperatures than solar and volcanic variations: increased greenhouse
gas concentrations since 1950 are now swamping the influence of ‘natural’ variability in our region
Climate change: Greenhouse gases
Concentrations in 2010
CO2 = 390 ppm, CO2-e = 470 ppm
From CSIRO/BoM (2012)
Climate change: Global temperature
Anomalies with respect
to 1961-90 average
From WMO, 2012
Indicators of global warming
from “State of the Climate 2009”, Bull Am Met Soc, 2010
Future climate change
- Continued emissions of
greenhouse gases will
lead to substantial further
warming, about 5C
above historical levels
- Rapid and substantial
reductions in emissions
are needed to minimise
dangerous climate change
- Projected changes in SE
Australia include more
hot extremes, reduced
rainfall in winter, and
continued variability, with
droughts and floods
Fig 5.1, The Science of Climate
Change, AAS 2010
What have we learned?
South eastern Australia has a naturally variable climate but is
starting to experience some rainfall and temperature extremes
that are highly unusual in a long term context
An incredible amount of climate information lies within historical
sources: provide a fascinating insight into how past Australian
societies have been influenced by climate variability and extremes
over time
Knowledge of past climate variability is critical for improving
estimates of the range of natural climate variability and how future
climate change will influence Australian prosperity in an
increasingly warm world
Sometimes the best way forward is through the past…
Source: National Gallery of Victoria
Help write Australia’s climate history
www.climatehistory.com.au