Learning from Climates of the Past Janice Lough April 2011 AIMS: Australia’s tropical marine research agency.
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
Now can rapidly document climate anomalies worldwide www.ncdc.noaa.gov/sotc/
We can also view and measure the world in unprecedented detail often in real time “sensing” a reef environment at organism scale Remote sensing ocean productivity Coral Sea ocean glider – more data in 3 months than in 20 years! www.imos.org.au www.aims.gov.au
Satellite-tracked oceanic drifters April 2010 to January 2011 Craig Steinberg AIMS New and improved sensors pCO 2 sensor Heron Island southern GBR Bronte Tilbrook CSIRO www.pmel.noaa.gov/co2/story/Heron+Island www.aims.gov.au
AIMS Davies Can see weather as it is happening........... Reef AWS AIMS Myrmidon Reef AWS post TC Yasi Roger Beeden
Network of consistent and reliable instrumental observations www.bom.gov.au/qld/townsville/ ww.bom.gov.au
Instrumental observations: evidence of changing world www.bom.gov.au & www.csiro.gov.au
BUT instrumental records only extensive back to 19 th century → Proxy climate records • 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” Central Meteorological Bureau 1981
Liang Luar Cave, Flores, Clerke Reef WA Law Dome ice core Indonesia Eric Matson Joel Pedro Mike Gagan Coastal cypress pine, WA Journal Lt William Dawes Royal Society Pauline Grierson London Red cedar Qld Joelle Gergis Ingo Heinrich Many ways of retrieving the past...
• open cast gold mine, Waihi NZ • Kauri pit props late 19 th -early 20 th centuries • tree-ring chronologies 900-1400AD Jonathan Palmer • dredging for new marina, Magnetic Island • several corals – lived and died 6,000 years ago AIMS And “windows” of more distant past
Ice Cores: Law Dome snowfall record • Law Dome precipitation from 1250 Precipitable water correlation SLP correlation 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? van Ommen & Morgan (2010 )
Tree rings: Tasmanian summer temperatures • Huon Pine ring widths • living & dead trees • capturing multi-decadal climate variability • wider temperature signal Cook et al 2000
Tree rings: Northern Territory rainfall 60 1.5 40 1.0 20 0.5 Number of c 0.0 0 1840 1860 1880 1900 1920 1940 1960 1980 2000 • Callitris intratropica (cypress pine), NT • ring width related to spring (October-December) rainfall • demonstrating the potential • and dispelling the myth about tropical tree rings Baker et al 2008
Tree rings: southwest Australian rainfall • Callitris columellaris (coastal cypress pine), Lake Tay • winter (March-September) rainfall 1655-2005 • low-frequency variability, e.g. 20-30 year dry periods Cullen & Grierson 2009
Tree rings: southeast Queensland rainfall Cairns • Toona ciliata red cedar, Lamington National Park Mackay • March-June rainfall, 1854-2000 QLD • BUT we have removed most of these trees! Lamington N.P. Brisbane NSW Sydney Heinrich et al 2009
Speleotherms: Australasian monsoon China • decadal to centennial time scales Wetter • reconstruct monsoon rainfall from δ 18 O • wetter during Younger Dryas cooling Borneo event – possibly southward shift of ITCZ • increased 7k-11k when sea level Flores rose rapidly – possibly increasing moisture supply Griffiths et al 2009
Documentary sources: Sydney Cove, NSW • meteorological journal of William Dawes Joelle Gergis • weather measurements 1788 to1791 • 182 hand-written pages of up to 6 daily observations of temperature, barometric pressure Gergis et al 2009
Porites Historical perspectives from massive corals Acropora Pocillopora
Growing through the Industrial Revolution • Clerke Reef ~17 o S 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
Annual density bands – chronology of growth Positive print of X-ray of slice through small Porites colony
Corals grow faster in warmer water! • BUT thermal stress can slow growth • 1998 bleaching event followed by 4 years below average 3 Pandora Reef: 1979-2003 std calcification anomalies 2 1 0 -1 healthy bleached -2 -3 1979 1982 1985 1988 1991 1994 1997 2000 2003 Lough 2008, in prep
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
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
Corals as recorders of freshwater Winter 2008 Macrossan Bridge: Burdekin River north Queensland Summer 2009
Robust and reproducible freshwater proxy ~17 o S between Cairns & Innisfail • under UV light inshore corals show bright luminescence lines • directly related to freshwater flood plumes • intensity varies with water depth/distance offshore ~19 o S near Townsville • 1974 floods recorded in corals 800km apart ~23 o S near Rockhampton
Reconstructing Queensland summer rainfall R 2 10-year R 2 Predictors Period 17 cores 1891-1981 61% 66% 13 cores 1876-1981 67% 60% 1844-1981 56% 66% 9 cores 6 cores 1820-1981 49% 61% 1783-1981 48% 66% 4 cores 3 cores 1685-1981 47% 48% 1 core 1639-1981 45% 37% Lough in press
Insights from >300 year record 1639-1981 Instrumental Identifies ENSO pattern of correlation with tropical Reconstructed SSTs • drier & less variable rainfall1760s to 1850s • increased rainfall & variability since late 19 th century • wet and dry extremes more frequent • 1973-74 wettest summer in 343-year record • consistent with a warming world Very wet >90 th Very dry <10 th Period percentile 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 Lough in press
Consistency between proxy climate records? Yes and No! 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 McGregor et al 2010
Coral geochemical tracers: stable oxygen isotope • δ 18 O mixed signal salinity and temperature • most published records show warming and/or freshening trends • coral δ 18 O overestimates magnitude of observed warming • e.g. observed warming at 16 sites = +0.2 o C; corals = +0.7 o C Druffel & Griffin 1999; Kuhnert et al 1999; Lough 2004
Coral geochemical tracers: Sr/Ca ratios • 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 Javier Leon Abram et al 2009
Coral windows into the more distant past • raised reef terraces Huon Peninsula, PNG • δ 18 O records inter-annual variability on ENSO time scales • “windows” up to 130k • ENSO persistent feature • BUT 20 th century ENSOs stronger compared to both cool (glacial) and warm (interglacial) periods Tudhope et al 2001
Combining proxy climate records SH NH • 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-20 th century Turney et al unpublished
Modelling the past • evaluate model capability to reproduce different climates of the past • multi-model ensembles • reproduce past = better confidence in future DJF rainfall DJF SST 6k-0k 6k-0k 21k-0k 21k-0k pmip2.lsce.ipsl.fr
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