Proxy Calibration: An Example Emiliania huxleyiEmiliania huxleyi is one is one

of 5000 or so species of of 5000 or so species of phytoplanktonphytoplankton

Most abundant Most abundant coccolithophore on a coccolithophore on a global basis, and is global basis, and is extremely widespread extremely widespread Occurs in all except Occurs in all except

the polar oceansthe polar oceans Produces unique Produces unique

compoundscompounds CC3737-C-C3939 di-, tri- and di-, tri- and

tetraunsaturated tetraunsaturated methyl and ethyl methyl and ethyl ketonesketones

Emiliania huxleyi Blooms E. huxleyiE. huxleyi can occur can occur

in massive bloomsin massive blooms 100,000 km100,000 km22

During blooms During blooms E. E. huxleyihuxleyi cell cell numbers usually numbers usually outnumber those outnumber those of all other of all other species combinedspecies combined

Frequently they Frequently they account for 80 account for 80 or 90% of the or 90% of the total number of total number of phytoplanktonphytoplankton SeaWiFS satellite image of bloom off

Newfoundland in the western Atlantic on 21 July 1999

Emiliania huxleyi Makes Alkenones

UK’37 Varies with Temperature

Alkenone unsaturation Alkenone unsaturation global calibrationglobal calibration UUK’K’

3737 determined in determined in core top sediment core top sediment samplessamples

SST from from SST from from Levitus ocean atlasLevitus ocean atlas

Figure from Muller Figure from Muller et al.et al. (1998) (1998)

Global UK’37 SST Correlation

Laboratory UK’37 Calibrations

Ecology Potentially Affects UK’37

Highest alkenone biomass was found within Highest alkenone biomass was found within the chlorophyll maximum in the western the chlorophyll maximum in the western Mediterranean (Bentaleb Mediterranean (Bentaleb et al.et al., 1999), 1999)

Alkenone export flux in sediment traps (1 km Alkenone export flux in sediment traps (1 km deep) in temperate NE Pacific traceable by its deep) in temperate NE Pacific traceable by its UUK'K'

3737 signature to chlorophyll maximum in signature to chlorophyll maximum in

overlying waters (Prahl overlying waters (Prahl et al.et al., 1993), 1993) Temperature estimates from UTemperature estimates from UK'K'

3737 in surface in surface

sediments along a N-S transect (~50sediments along a N-S transect (~50N–15N–15S) S) in the Pacific (~175in the Pacific (~175W) fall near the lower W) fall near the lower limit or even below the annual range in SST limit or even below the annual range in SST (Ohkouchi (Ohkouchi et al.et al., 1999), 1999)

Physiology Potentially Affects UK’37

Global UK’37 SST Correlation

Study Site: Station ALOHA

HOT 1: 29 Oct – 3 Nov 1988 HOT 155: 20-24 Jan 2004

HOT 124: 19-23 Mar 2001KOK 011: 16-23 Jul 2001

HOT 131: 21-26 Oct 2001 KOK 303: 17-22 Feb 2003

Methods

Alkenone exportAlkenone export Sediment trap Sediment trap

particlesparticlesDetermine UDetermine UK’K’

3737 of of alkenone export alkenone export fluxflux

Methods Alkenone standing stockAlkenone standing stock

Large volume Large volume in situin situ particle collectionparticle collectionDetermine UDetermine UK’K’

3737 of of alkenone in alkenone in suspended suspended particulate matterparticulate matter

•Compare UCompare UK’K’3737 and and

in situin situ temperaturetemperature

Methods

Determine alkenone Determine alkenone production rateproduction rate In situIn situ 13 13C labeling C labeling

experimentsexperiments

Alkenone Production Rate Alkenone production rate Alkenone production rate (modified from (modified from

Hama Hama et al.et al., 1993), 1993)

aaisis is alkenone is alkenone 1313C atomic % (CC atomic % (C37:237:2 or C or C37:337:3) at the ) at the end of the incubation, end of the incubation,

aansns is alkenone is alkenone 1313C atomic % of alkenone (CC atomic % of alkenone (C37:237:2 or or CC37:337:3) in the natural (nonincubated) sample,) in the natural (nonincubated) sample,

aaicic is CO is CO22(aq) (aq) 1313C atomic % in the incubation bottle, C atomic % in the incubation bottle, alkenone (alkenone (tt) is the alkenone concentration at the ) is the alkenone concentration at the

end of the incubationend of the incubation tt is the length of the incubation is the length of the incubation

t

t

aa

aa

nsic

nsis )( alkenone Rate Production

In Situ Array Water collected from Water collected from

various depthsvarious depths Trace amount of Trace amount of

HH1313COCO33-- added added

Array deployed for Array deployed for 24 hours24 hours

Samples filtered and Samples filtered and alkenone alkenone 1313C C measuredmeasured 1313C uptake rate C uptake rate

calculatedcalculated

Sample Collection CTDCTD

ConductivityConductivity TemperatureTemperature DepthDepth

FluorometerFluorometer Chlorophyll aChlorophyll a

Oxygen sensorOxygen sensor Sample bottlesSample bottles

Add H13CO3-

(13CDIC = +190‰) & bag

bottles

Haul bagged bottles to rail and attached them to line

Deploy bagged bottles

Deploy floats, spar buoy & pray it all returns

Results – July 2001 [C[C37:237:2] ~1 - 4 ng L] ~1 - 4 ng L-1-1

CC37:237:2 production production <0.1 – 1.2 ng L<0.1 – 1.2 ng L-1-1 d d-1-1

Maximum in Maximum in excess DO excess DO maximum maximum

[C[C37:237:2] & production ] & production lowest in chl. lowest in chl. maximummaximum

Depth of [CDepth of [C37:237:2] and ] and production production maximum samemaximum same

UUK’K’3737 T T

< < in situin situ in in excess DOexcess DO

> > in situin situ in chl. in chl. maximummaximum

Results – February 2003 [C[C37:237:2] ~2 - 12 ng L] ~2 - 12 ng L-1-1

Feb 03 >> Jul Feb 03 >> Jul 0101

CC37:237:2 production production <0.1 – 0.9 ng L<0.1 – 0.9 ng L-1-1 d d-1-1

Maximum in Maximum in excess DO excess DO maximummaximum

Feb 03 < Jul 01 Feb 03 < Jul 01 [C[C37:237:2] & production ] & production

lowest in chl. lowest in chl. maximummaximum

Depth of [CDepth of [C37:237:2] and ] and production production maximum samemaximum same

UUK’K’3737 T T

> > in situin situ in in excess DOexcess DO

>> >> in situin situ in in chl. maximumchl. maximum

~2ºC

~1ºC

Results – February 2003 Water from 120 Water from 120

m, incubated at m, incubated at 100, 80 and 40 100, 80 and 40 mm

[C[C37:237:2] increase] increase 2.5-fold 80 m2.5-fold 80 m 4.7-fold 40 m4.7-fold 40 m

CC37:237:2 production production increaseincrease

3.8-fold 80 3.8-fold 80 mm

5.0-fold 40 m 5.0-fold 40 m UUK’K’

3737 T unaffected T unaffected Growth light-Growth light-

limited in chl. limited in chl. maximummaximum

ALOHA SST Time Series

Conclusions: UK’37 at ALOHA

Maximum alkenone production was found during all seasons Maximum alkenone production was found during all seasons in or just below the surface mixed layerin or just below the surface mixed layer

Minimum alkenone standing stock and production were Minimum alkenone standing stock and production were found in deep chlorophyll maximumfound in deep chlorophyll maximum Alkenone-producer growth light-limitedAlkenone-producer growth light-limited Expect minimal export flux to sedimentsExpect minimal export flux to sediments

Non-thermal physiological processes affect UNon-thermal physiological processes affect UK’K’3737

Nutrient depletion can lead to underestimation of actual Nutrient depletion can lead to underestimation of actual growth temperaturegrowth temperature

Light limitation leads to overestimation of actual growth Light limitation leads to overestimation of actual growth temperaturetemperature

Measurements of standing stock alone do not allow Measurements of standing stock alone do not allow conclusive interpretation of production and exportconclusive interpretation of production and export

Interstrain (or species) differences in alkenone biosynthesisInterstrain (or species) differences in alkenone biosynthesis

Guaymas Basin 2004-2005

Guaymas Basin 2004-2005

Comparison of AVHRR SST for 1996-97 with difference between UK’37

temperature measured in sediment trap particles and AVHRR SST (data

from Goni et al., 2001)

Historical Records Historical proxy data grouped into three Historical proxy data grouped into three

major categoriesmajor categories Observations of weather phenomenaObservations of weather phenomena

The frequency and timing of frosts or the The frequency and timing of frosts or the occurrence of snowfalloccurrence of snowfall

Records of weather-dependent natural or Records of weather-dependent natural or environmental phenomena environmental phenomena (parameteorological)(parameteorological)Droughts and floodsDroughts and floods

Phenological records of weather-dependent Phenological records of weather-dependent biological phenomenabiological phenomenaThe flowering of trees or the migration of The flowering of trees or the migration of

birdsbirds

Sources of Historical Data Sources of historical climate Sources of historical climate

information includeinformation include Ancient inscriptionsAncient inscriptions Annals and chroniclesAnnals and chronicles Government recordsGovernment records Estate recordsEstate records Maritime and commercial recordsMaritime and commercial records Diaries and correspondenceDiaries and correspondence Scientific or quasi-scientific writingsScientific or quasi-scientific writings Early instrumental recordsEarly instrumental records

Problems with Historical Data Accounts can be subjectiveAccounts can be subjective

How severe is a severe frost?How severe is a severe frost? Reliability of the accountReliability of the account

Did author have first-hand evidence of event?Did author have first-hand evidence of event? Is the account accurate and representative?Is the account accurate and representative?

What is the duration and extent of the event?What is the duration and extent of the event? The data must be calibrated against recent The data must be calibrated against recent

observations and instrumental dataobservations and instrumental data This might be achieved by construction of This might be achieved by construction of

indices (indices (e.ge.g. the number of reports of frost . the number of reports of frost per winter) which can be statistically related per winter) which can be statistically related to analogous information derived from to analogous information derived from instrumental recordsinstrumental records

Glaciological – Ice Cores Environmental conditions recorded as Environmental conditions recorded as

snow and ice accumulates on ice caps snow and ice accumulates on ice caps and sheetsand sheets

Paleoclimate information is obtained from Paleoclimate information is obtained from ice cores by three main approachesice cores by three main approaches Stable isotopes of waterStable isotopes of water Dissolved and particulate matter in the Dissolved and particulate matter in the

firn and icefirn and ice Physical characteristics of the firn and Physical characteristics of the firn and

ice, and of air bubbles trapped in the ice, and of air bubbles trapped in the ice ice

Stable Isotope Analyses The vapor pressure of HThe vapor pressure of H22

1616O > HO > H221818OO

Evaporation of water results in vapor with less Evaporation of water results in vapor with less 1818O than O than the initial waterthe initial water The remaining water is enriched in The remaining water is enriched in 1818OO

During condensation, the lower vapor pressure of the During condensation, the lower vapor pressure of the HH22

1818O enriches water in O enriches water in 1818OO During pole ward transportation of water vapor, isotope During pole ward transportation of water vapor, isotope

fractionation causes preferential removal of fractionation causes preferential removal of 1818OO Water vapor becomes increasingly depleted in HWater vapor becomes increasingly depleted in H22

1818OO Because condensation is the result of cooling, the Because condensation is the result of cooling, the

greater the fall in temperature, the lower the heavy greater the fall in temperature, the lower the heavy isotope concentrationisotope concentration Isotope concentration in the condensate (water, Isotope concentration in the condensate (water,

snow, ice) can thus be considered as a function of the snow, ice) can thus be considered as a function of the temperature of condensationtemperature of condensation

Physical & Chemical Characteristics

Occurrence of melt features in the upper layers Occurrence of melt features in the upper layers of ice cores provide climatic informationof ice cores provide climatic information Horizontal ice lenses and vertical ice glands Horizontal ice lenses and vertical ice glands

result from the refreezing of percolating result from the refreezing of percolating waterwaterIdentified by their deficiency in air bubblesIdentified by their deficiency in air bubbles

Relative frequency of melt interpreted as an Relative frequency of melt interpreted as an index of maximum summer temperatures or index of maximum summer temperatures or of summer warmth in general of summer warmth in general

Other physical features of ices cores includeOther physical features of ices cores include Variations in crystal sizeVariations in crystal size Air bubble fabricAir bubble fabric Crystallographic axis orientationCrystallographic axis orientation

Air Bubbles in Ice The atmospheric gas is trapped as air pores are closed The atmospheric gas is trapped as air pores are closed

off during the transition of firn to iceoff during the transition of firn to ice Considerable research has been devoted to the analysis Considerable research has been devoted to the analysis

of carbon dioxide concentrations of air bubbles trapped of carbon dioxide concentrations of air bubbles trapped in ice coresin ice cores

Dissolved and Particulate Matter

Variations of dissolved and particulate Variations of dissolved and particulate matter can be used as proxy matter can be used as proxy paleoclimatic indicatorspaleoclimatic indicators CalciumCalcium AluminumAluminum SiliconSilicon IronIron DustDust Certain atmospheric aerosolsCertain atmospheric aerosols

Dating Ice Cores Many different approaches usedMany different approaches used

One of the biggest problems ice core studies is One of the biggest problems ice core studies is determining age-depth relationshipdetermining age-depth relationship

Accurate time scales for only last 10,000 yearsAccurate time scales for only last 10,000 years Age-depth relationship highly exponential and ice flow Age-depth relationship highly exponential and ice flow

models needed to determine ages of deepest ice coresmodels needed to determine ages of deepest ice cores Absolute and relative dating techniquesAbsolute and relative dating techniques

Radioisotope dating (Radioisotope dating (210210Pb, Pb, 3232Si, Si, 3939Ar, Ar, 1414C) have been C) have been used with varying degrees of successused with varying degrees of success

Characteristic layers provide valuable Characteristic layers provide valuable chronostratigraphic markerschronostratigraphic markers

Major explosive volcanic eruptions emit sulfur; Major explosive volcanic eruptions emit sulfur; increase acidity of iceincrease acidity of ice