Proxy Calibration: An Example Emiliania huxleyi is one of 5000 or so species of phytoplankton Emiliania huxleyi is one of 5000 or so species of phytoplankton Most abundant coccolithophore on a global basis, and is extremely widespread Most abundant coccolithophore on a global basis, and is extremely widespread  Occurs in all except the polar oceans Produces unique compounds Produces unique compounds  C 37 -C 39 di-, tri- and tetraunsaturated methyl and ethyl ketones

Emiliania huxleyi Blooms E. huxleyi can occur in massive blooms E. huxleyi can occur in massive blooms  100,000 km 2  During blooms E. huxleyi cell numbers usually outnumber those of all other species combined  Frequently they account for 80 or 90% of the total number of phytoplankton SeaWiFS satellite image of bloom off Newfoundland in the western Atlantic on 21 July 1999

Emiliania huxleyi Makes Alkenones

U K’ 37 Varies with Temperature Alkenone unsaturation global calibration Alkenone unsaturation global calibration  U K’ 37 determined in core top sediment samples  SST from from Levitus ocean atlas  Figure from Muller et al. (1998)

Global U K’ 37 SST Correlation

Laboratory U K’ 37 Calibrations

Ecology Potentially Affects U K’ 37 Highest alkenone biomass was found within the chlorophyll maximum in the western Mediterranean (Bentaleb et al., 1999) Highest alkenone biomass was found within the chlorophyll maximum in the western Mediterranean (Bentaleb et al., 1999) Alkenone export flux in sediment traps (1 km deep) in temperate NE Pacific traceable by its U K' 37 signature to chlorophyll maximum in overlying waters (Prahl et al., 1993) Alkenone export flux in sediment traps (1 km deep) in temperate NE Pacific traceable by its U K' 37 signature to chlorophyll maximum in overlying waters (Prahl et al., 1993) Temperature estimates from U K' 37 in surface sediments along a N-S transect (~50  N–15  S) in the Pacific (~175  W) fall near the lower limit or even below the annual range in SST (Ohkouchi et al., 1999) Temperature estimates from U K' 37 in surface sediments along a N-S transect (~50  N–15  S) in the Pacific (~175  W) fall near the lower limit or even below the annual range in SST (Ohkouchi et al., 1999)

Physiology Potentially Affects U K’ 37

Global U K’ 37 SST Correlation

Study Site: Station ALOHA HOT 1: 29 Oct – 3 Nov 1988 HOT 155: Jan 2004 HOT 124: Mar 2001 KOK 011: Jul 2001 HOT 131: Oct 2001 KOK 303: Feb 2003

Methods Alkenone export Alkenone export  Sediment trap particles  Determine U K’ 37 of alkenone export flux

Methods Alkenone standing stock Alkenone standing stock  Large volume in situ particle collection  Determine U K’ 37 of alkenone in suspended particulate matter Compare U K’ 37 and in situ temperatureCompare U K’ 37 and in situ temperature

Methods Determine alkenone production rate Determine alkenone production rate  In situ 13 C labeling experiments

Alkenone Production Rate Alkenone production rate (modified from Hama et al., 1993) Alkenone production rate (modified from Hama et al., 1993)  a is is alkenone 13 C atomic % (C 37:2 or C 37:3 ) at the end of the incubation,  a ns is alkenone 13 C atomic % of alkenone (C 37:2 or C 37:3 ) in the natural (nonincubated) sample,  a ic is CO 2 (aq) 13 C atomic % in the incubation bottle,  alkenone (t) is the alkenone concentration at the end of the incubation  t is the length of the incubation

In Situ Array Water collected from various depths Water collected from various depths Trace amount of H 13 CO 3 - added Trace amount of H 13 CO 3 - added Array deployed for 24 hours Array deployed for 24 hours Samples filtered and alkenone  13 C measured Samples filtered and alkenone  13 C measured  13 C uptake rate calculated

Sample Collection CTD CTD  Conductivity  Temperature  Depth Fluorometer Fluorometer  Chlorophyll a Oxygen sensor Oxygen sensor Sample bottles Sample bottles

Add H 13 CO 3 - (  13 C DIC = +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 37:2 ] ~1 - 4 ng L -1 [C 37:2 ] ~1 - 4 ng L -1 C 37:2 production <0.1 – 1.2 ng L -1 d -1 C 37:2 production <0.1 – 1.2 ng L -1 d -1  Maximum in excess DO maximum [C 37:2 ] & production lowest in chl. maximum [C 37:2 ] & production lowest in chl. maximum Depth of [C 37:2 ] and production maximum same Depth of [C 37:2 ] and production maximum same U K’ 37 T U K’ 37 T  < in situ in excess DO  > in situ in chl. maximum

Results – February 2003 [C 37:2 ] ~ ng L -1 [C 37:2 ] ~ ng L -1  Feb 03 >> Jul 01 C 37:2 production <0.1 – 0.9 ng L -1 d -1 C 37:2 production <0.1 – 0.9 ng L -1 d -1  Maximum in excess DO maximum  Feb 03 < Jul 01 [C 37:2 ] & production lowest in chl. maximum [C 37:2 ] & production lowest in chl. maximum Depth of [C 37:2 ] and production maximum same Depth of [C 37:2 ] and production maximum same U K’ 37 T U K’ 37 T  > in situ in excess DO  >> in situ in chl. maximum ~2ºC ~1ºC

Results – February 2003 Water from 120 m, incubated at 100, 80 and 40 m Water from 120 m, incubated at 100, 80 and 40 m [C 37:2 ] increase [C 37:2 ] increase  2.5-fold 80 m  4.7-fold 40 m C 37:2 production increase C 37:2 production increase  3.8-fold 80 m  5.0-fold 40 m U K’ 37 T unaffected U K’ 37 T unaffected Growth light- limited in chl. maximum Growth light- limited in chl. maximum

ALOHA SST Time Series

Conclusions: U K’ 37 at ALOHA Maximum alkenone production was found during all seasons in or just below the surface mixed layer Maximum alkenone production was found during all seasons in or just below the surface mixed layer Minimum alkenone standing stock and production were found in deep chlorophyll maximum Minimum alkenone standing stock and production were found in deep chlorophyll maximum  Alkenone-producer growth light-limited  Expect minimal export flux to sediments Non-thermal physiological processes affect U K’ 37 Non-thermal physiological processes affect U K’ 37  Nutrient depletion can lead to underestimation of actual growth temperature  Light limitation leads to overestimation of actual growth temperature Measurements of standing stock alone do not allow conclusive interpretation of production and export Measurements of standing stock alone do not allow conclusive interpretation of production and export Interstrain (or species) differences in alkenone biosynthesis Interstrain (or species) differences in alkenone biosynthesis

Guaymas Basin

Comparison of AVHRR SST for with difference between U K’ 37 temperature measured in sediment trap particles and AVHRR SST (data from Goni et al., 2001)

Historical Records Historical proxy data grouped into three major categories Historical proxy data grouped into three major categories  Observations of weather phenomena  The frequency and timing of frosts or the occurrence of snowfall  Records of weather-dependent natural or environmental phenomena (parameteorological)  Droughts and floods  Phenological records of weather-dependent biological phenomena  The flowering of trees or the migration of birds

Sources of Historical Data Sources of historical climate information include Sources of historical climate information include  Ancient inscriptions  Annals and chronicles  Government records  Estate records  Maritime and commercial records  Diaries and correspondence  Scientific or quasi-scientific writings  Early instrumental records

Problems with Historical Data Accounts can be subjective Accounts can be subjective  How severe is a severe frost? Reliability of the account Reliability of the account  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? The data must be calibrated against recent observations and instrumental data The data must be calibrated against recent observations and instrumental data  This might be achieved by construction of indices (e.g. the number of reports of frost per winter) which can be statistically related to analogous information derived from instrumental records

Glaciological – Ice Cores Environmental conditions recorded as snow and ice accumulates on ice caps and sheets Environmental conditions recorded as snow and ice accumulates on ice caps and sheets Paleoclimate information is obtained from ice cores by three main approaches Paleoclimate information is obtained from ice cores by three main approaches  Stable isotopes of water  Dissolved and particulate matter in the firn and ice  Physical characteristics of the firn and ice, and of air bubbles trapped in the ice

Stable Isotope Analyses The vapor pressure of H 2 16 O > H 2 18 O The vapor pressure of H 2 16 O > H 2 18 O Evaporation of water results in vapor with less 18 O than the initial water Evaporation of water results in vapor with less 18 O than the initial water  The remaining water is enriched in 18 O During condensation, the lower vapor pressure of the H 2 18 O enriches water in 18 O During condensation, the lower vapor pressure of the H 2 18 O enriches water in 18 O During pole ward transportation of water vapor, isotope fractionation causes preferential removal of 18 O During pole ward transportation of water vapor, isotope fractionation causes preferential removal of 18 O  Water vapor becomes increasingly depleted in H 2 18 O Because condensation is the result of cooling, the greater the fall in temperature, the lower the heavy isotope concentration Because condensation is the result of cooling, the greater the fall in temperature, the lower the heavy isotope concentration  Isotope concentration in the condensate (water, snow, ice) can thus be considered as a function of the temperature of condensation

Physical & Chemical Characteristics Occurrence of melt features in the upper layers of ice cores provide climatic information Occurrence of melt features in the upper layers of ice cores provide climatic information  Horizontal ice lenses and vertical ice glands result from the refreezing of percolating water  Identified by their deficiency in air bubbles  Relative frequency of melt interpreted as an index of maximum summer temperatures or of summer warmth in general Other physical features of ices cores include Other physical features of ices cores include  Variations in crystal size  Air bubble fabric  Crystallographic axis orientation

Air Bubbles in Ice The atmospheric gas is trapped as air pores are closed off during the transition of firn to ice The atmospheric gas is trapped as air pores are closed off during the transition of firn to ice Considerable research has been devoted to the analysis of carbon dioxide concentrations of air bubbles trapped in ice cores Considerable research has been devoted to the analysis of carbon dioxide concentrations of air bubbles trapped in ice cores

Dissolved and Particulate Matter Variations of dissolved and particulate matter can be used as proxy paleoclimatic indicators Variations of dissolved and particulate matter can be used as proxy paleoclimatic indicators  Calcium  Aluminum  Silicon  Iron  Dust  Certain atmospheric aerosols

Dating Ice Cores Many different approaches used Many different approaches used  One of the biggest problems ice core studies is determining age-depth relationship  Accurate time scales for only last 10,000 years Age-depth relationship highly exponential and ice flow models needed to determine ages of deepest ice cores Age-depth relationship highly exponential and ice flow models needed to determine ages of deepest ice cores Absolute and relative dating techniques Absolute and relative dating techniques  Radioisotope dating ( 210 Pb, 32 Si, 39 Ar, 14 C) have been used with varying degrees of success  Characteristic layers provide valuable chronostratigraphic markers  Major explosive volcanic eruptions emit sulfur; increase acidity of ice