Learning from Climates of the Past Janice Lough April 2011 AIMS: - - PowerPoint PPT Presentation

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Learning from Climates of the Past Janice Lough April 2011 AIMS: - - PowerPoint PPT Presentation

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Learning from Climates of the Past Janice Lough April 2011 AIMS: Australias tropical marine research agency. OUTLINE value of proxy climate and environmental records understand nature of past changes and variability understand

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AIMS: Australia’s tropical marine research agency.

Learning from Climates of the Past

Janice Lough April 2011

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OUTLINE

  • value of proxy climate and environmental records
  • understand nature of past changes and variability
  • understand processes (ENSO, decadal, centennial)
  • detect changes and place in context
  • types of high-resolution proxy climate records
  • ice cores
  • tree rings
  • speleotherms
  • documentary sources
  • corals
  • examples from coral records
  • pulling it all together
  • Aus2k
  • Australasia Palaeohistory of the Quaternary
  • improving the value
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www.ncdc.noaa.gov/sotc/

Now can rapidly document climate anomalies worldwide

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We can also view and measure the world in unprecedented detail often in real time

www.imos.org.au www.aims.gov.au Coral Sea ocean glider – more data in 3 months than in 20 years! Remote sensing

  • cean

productivity “sensing” a reef environment at organism scale

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Satellite-tracked oceanic drifters April 2010 to January 2011

Craig Steinberg AIMS www.pmel.noaa.gov/co2/story/Heron+Island www.aims.gov.au

pCO2 sensor Heron Island southern GBR

Bronte Tilbrook CSIRO

New and improved sensors

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Can see weather as it is happening...........

Roger Beeden

AIMS Myrmidon Reef AWS post TC Yasi

AIMS Davies Reef AWS

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www.bom.gov.au/qld/townsville/

Network of consistent and reliable instrumental

  • bservations

ww.bom.gov.au

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www.bom.gov.au & www.csiro.gov.au

Instrumental observations: evidence of changing world

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BUT instrumental records only extensive back to 19th century → Proxy climate records

Central Meteorological Bureau 1981

  • biological, geological or human system affected by climate
  • leaves record of that influence
  • can be DATED and temporal resolution defined
  • can be measured and QUANTIFIED
  • can be REPLICATED in different samples
  • climate CONTROL(s) can be identified
  • single or integrated variables (e.g. rainfall, temperature, PDSI)
  • understand processes by which record formed
  • record can be CALIBRATED against instrumental data
  • seasonality can be defined
  • e.g. growing (tree) or accumulation season (ice)
  • CONSISTENT with other records?
  • UNCERTAINTIES can be quantified

“For now we see through a glass darkly”

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Red cedar Qld Ingo Heinrich Coastal cypress pine, WA Pauline Grierson Journal Lt William Dawes Royal Society London Joelle Gergis Liang Luar Cave, Flores, Indonesia Mike Gagan Clerke Reef WA Eric Matson

Many ways of retrieving the past...

Law Dome ice core Joel Pedro

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  • open cast gold mine, Waihi NZ
  • Kauri pit props late 19th-early 20th centuries
  • tree-ring chronologies 900-1400AD

And “windows” of more distant past

  • dredging for new marina, Magnetic Island
  • several corals – lived and died 6,000 years ago

Jonathan Palmer AIMS

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Ice Cores: Law Dome snowfall record

SLP correlation Precipitable water correlation

van Ommen & Morgan (2010)

  • Law Dome precipitation from 1250

AD

  • inverse link - SW WA rainfall
  • meridional circulation patterns
  • recent positive precipitation

anomaly unprecedented in past 750 years

  • possibly same for drought in SW

WA?

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Tree rings: Tasmanian summer temperatures

  • Huon Pine ring widths
  • living & dead trees
  • capturing multi-decadal

climate variability

  • wider temperature signal

Cook et al 2000

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Tree rings: Northern Territory rainfall

Baker et al 2008

1840 1860 1880 1900 1920 1940 1960 1980 2000

Number of c

20 40 60 0.0 0.5 1.0 1.5

  • Callitris intratropica (cypress pine), NT
  • ring width related to spring (October-December) rainfall
  • demonstrating the potential
  • and dispelling the myth about tropical tree rings
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Tree rings: southwest Australian rainfall

Cullen & Grierson 2009

  • Callitris columellaris (coastal cypress pine), Lake Tay
  • winter (March-September) rainfall 1655-2005
  • low-frequency variability, e.g. 20-30 year dry periods
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Tree rings: southeast Queensland rainfall

Brisbane Sydney Lamington N.P. NSW QLD Mackay Cairns

Heinrich et al 2009

  • Toona ciliata red cedar, Lamington National Park
  • March-June rainfall, 1854-2000
  • BUT we have removed most of these trees!
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Speleotherms: Australasian monsoon

Wetter

China Borneo Flores

Griffiths et al 2009

  • decadal to centennial time scales
  • reconstruct monsoon rainfall from

δ18O

  • wetter during Younger Dryas cooling

event – possibly southward shift of ITCZ

  • increased 7k-11k when sea level

rose rapidly – possibly increasing moisture supply

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Documentary sources: Sydney Cove, NSW

Joelle Gergis

  • meteorological journal of William Dawes
  • weather measurements 1788 to1791
  • 182 hand-written pages of up to 6 daily
  • bservations of temperature, barometric

pressure

Gergis et al 2009

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Historical perspectives from massive corals

Pocillopora Acropora Porites

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  • Clerke Reef ~17oS WA
  • 7 mm per year
  • started growing ~1770
  • now 2.5 m high

Matthew Flinders April 1803 Coral 25 cm tall Louis-François-Marie Aleno de Saint-Aloüarn March 1772 Coral was few cm tall when WA claimed for Louis XV

Growing through the Industrial Revolution

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Annual density bands – chronology of growth

Positive print of X-ray of slice through small Porites colony

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Lough 2008, in prep

Corals grow faster in warmer water!

  • 3
  • 2
  • 1

1 2 3 1979 1982 1985 1988 1991 1994 1997 2000 2003 std calcification anomalies Pandora Reef: 1979-2003

  • BUT thermal stress can

slow growth

  • 1998 bleaching event

followed by 4 years below average

healthy bleached

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Example growth hiatus

  • Tantabiddi, WA
  • 8 mm per year
  • 200 years of growth
  • very boring
  • EXCEPT for 1998
  • exceptional thermal stress

1998

NOAA DHW Feb-Apr 1998

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Recent slowing of coral growth on GBR

  • multiple coral growth records
  • throughout GBR (not just inshore)
  • 14% decline since 1990
  • unprecedented in at least 400 years
  • likely due to increasing temperature stress and maybe ocean chemistry
  • evidence from other coral reefs

De’ath et al 2009

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Winter 2008 Summer 2009

Macrossan Bridge: Burdekin River north Queensland

Corals as recorders of freshwater

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~17oS between Cairns & Innisfail ~19oS near Townsville ~23oS near Rockhampton

  • under UV light inshore corals show bright

luminescence lines

  • directly related to freshwater flood plumes
  • intensity varies with water depth/distance
  • ffshore
  • 1974 floods recorded in corals 800km apart

Robust and reproducible freshwater proxy

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Predictors Period R2 R2 10-year 17 cores 1891-1981 61% 66% 13 cores 1876-1981 67% 60% 9 cores 1844-1981 56% 66% 6 cores 1820-1981 49% 61% 4 cores 1783-1981 48% 66% 3 cores 1685-1981 47% 48% 1 core 1639-1981 45% 37% Lough in press

Reconstructing Queensland summer rainfall

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Insights from >300 year record 1639-1981

Period Very wet >90th percentile Very dry <10th percentile 1685-1784 12.5 years 9.1 years 1785-1884 25.0 years 14.3 years 1885-1981 5.4 years 7.5 years

Identifies ENSO pattern of correlation with tropical SSTs

Instrumental Reconstructed

  • drier & less variable rainfall1760s to 1850s
  • increased rainfall & variability since late 19th century
  • wet and dry extremes more frequent
  • 1973-74 wettest summer in 343-year record
  • consistent with a warming world

Lough in press

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Consistency between proxy climate records?

McGregor et al 2010

RF rec vs UEP # years Wet and La Niña 42 Dry and El Niño 32 BUT Wet and El Niño 23 Dry and La Niña 24 AND Wet and non-ENSO 40 Dry and non-ENSO 31

Yes and No!

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Coral geochemical tracers: stable oxygen isotope

Druffel & Griffin 1999; Kuhnert et al 1999; Lough 2004

  • δ18O mixed signal salinity and

temperature

  • most published records show

warming and/or freshening trends

  • coral δ18O overestimates

magnitude of observed warming

  • e.g. observed warming at 16 sites

= +0.2oC; corals = +0.7oC

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Coral geochemical tracers: Sr/Ca ratios

Javier Leon

Abram et al 2009

  • coral Sr/Ca records SST
  • multiple fossil corals Indonesia/PNG – edge Western Pacific Warm Pool
  • cooler < 6.8k and 5.5-4.3k BP = contraction WPWP, more northerly ITCZ

& stronger Asian summer monsoon

  • abrupt, brief warming 6.6-6.3k BP = southward migration of ITCZ &

expansion of WPWP

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Coral windows into the more distant past

Tudhope et al 2001

  • raised reef terraces Huon Peninsula, PNG
  • δ18O records inter-annual variability on ENSO

time scales

  • “windows” up to 130k
  • ENSO persistent feature
  • BUT 20th century ENSOs stronger compared to

both cool (glacial) and warm (interglacial) periods

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Combining proxy climate records

Turney et al unpublished

  • NH milder 1000-1300 = “Medieval Climate Anomaly”
  • NH cooler 1450-1850 = “Little Ice Age”
  • SH more heterogeneous; oceanic influences?
  • SH no widespread MCA or LIA
  • BUT both show significant warming since mid-20th century

SH NH

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Modelling the past

  • evaluate model capability to reproduce different climates of the past
  • multi-model ensembles
  • reproduce past = better confidence in future

pmip2.lsce.ipsl.fr

DJF rainfall DJF SST

6k-0k 6k-0k 21k-0k 21k-0k

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Improving understanding of Australian paleoclimates

www.pages-igbp.org/

  • climate history of the past 2,000 years Aus2k
  • synthesis of Palaeohistory of Australasia – Sandy Harrison & John

Dodson (eds) 0-125k

  • assemble data (e.g. NOAA Paleoclimate Data Center)
  • integrate data – consistency?
  • interpret and compare with model simulations
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  • more records
  • more locations
  • replication – improve dating & distinguish climate signal from

noise

  • site specific process studies – what are proxies responding

to?

  • apply various approaches to large-scale climate

reconstructions

  • greater use of climate modelling to understand & guide

sampling

  • REDUCE UNCERTAINTIES

Improving the contribution of proxy climate records

Russell Drysdale

monitoring speleotherms

Mark Curran

measuring snow accumulation

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SUMMARY

  • the past will always be an incomplete jig-saw puzzle
  • proxy climate records are only source of data BUT none are perfect
  • increasingly better spatial and temporal coverage but some locations

and variables will always be a mystery

  • increasingly sophisticated approaches to interpreting records
  • value of “process” and “forward modelling” studies
  • insights into inter-annual, decadal and centennial climate variability
  • for climate models to be more constrained about the future – need to

correctly model recent and more distant past (i.e. different boundary conditions)

  • evidence highlights unusual nature of current climate changes
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Mark Curran Mike Gagan AIMS

Thanks to Australian and international paleoclimate research community

j.lough@aims.gov.au www.aims.gov.au