Information contained within this presentation is from a currently unpublished thesis, and should not be used or referenced without the expressed permission of the authors

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) Alex Wright & Dr. Orson van de Plassche

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) RELATIVE SEA-LEVEL: SEA-LEVEL VARIABILITY: with trends trends removed

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) NH TEMPERATURES: SEA-LEVEL VARIABILITY: Mann et al. (2003 trends removed

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) (BRIEF) TALK OUTLINE CONCEPT: Sea-level from salt-marshes METHODOLOGY: 5 Steps sea-level reconstruction, with examples (RESULTS & DISCUSSION) SUMMARY: Conclusions

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) CONCEPT: SALT-MARSHES Coastal wetlands Upper half tidal range (MTL-HHW)

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) CONCEPT: SALT-MARSHES AND SEA-LEVEL Surface vertically accretes - maintain position with rising sea level Sedimentary archive of palaeomarsh surfaces (PMS)

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) CONCEPT: VERTICAL DISTRIBUTION OF FORAMINIFERA Tidal inundation - strong environmental gradient - vertical distribution flora / fauna (MHW) Foraminifera occupy narrower vertical ranges More precise indicators of PRESENT and PAST marsh surface height (MHW)

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 5 STEPS TO SEA-LEVEL RECONSTRUCTION 1) Height PMS’s formed (relative to PMHW) 2) Time the PMS’s formed 1) + 2) = Relative PMHW 3) Sediment compaction correction 4) Palaeotidal range correction + 3) + 4) = Relative PMTL 5) Detrend millennial scale relative sea level (GIA) + 5) = PMTL

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY:1) Height PMS’s formed (relative to PMHW) Establish contemporary vertical foraminifera distribution Sample heights known (MHW) – TRANSFER FUNCTION foraminifera-surface height QUANTITATIVE PMS height reconstruction from FOSSIL foraminifera

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 1) Height PMS’s formed (relative to PMHW) Palaeo-record from core salt-marsh peat

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 1) Height PMS’s formed (relative to PMHW) Every (other) cm - assumed PMS Analyze for fossil foraminifera content

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 1) Height PMS’s formed (relative to PMHW) TRANSFER FUNCTION - PMS heights (PMHW) Variability from rate PMS accumulation or PMHW rise? PMS accumulation rate - CHRONOLOGY!

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 2) Determine time at which PMS’S formed Resample for datable PMS indicators Last ~200 yrs date sediment - HIGH PRECISION Remainder data 14 C of organics – LOW PRECISION

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 2) Determine time at which PMS’S formed PRECISION differences clear from age-PMS depth envelope High resolution sampling CHECKS record completeness

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) RECONSTRUCTIONS:

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 2) Determine time at which PMS’S formed CHALLENGE - Define within envelope PMS accumulation rate EXAMPLE - 2 LINEAR rates

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 2) Determine time at which PMS’S formed Illustrate importance…….

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY:COMBINE 1) + 2) = Relative PMHW PMS accumulation rate - PMS height variability due to PMHW Correct? Cannot resolve at this scale Combined - PMS accumulation rate defines (MULTI-)CENTENNIAL VARIABILITY

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY:COMBINE 1) + 2) = Relative PMHW reconstruction AGAIN - PMS accumulation rate defines (MULTI-)CENTENNIAL VARIABILITY Last ~200 yrs high precision chronology - constrains PMS Enables VALIDATION with instrumental records…..EXTENSION? (GEHRELS)

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) SUMMARY:

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 3) Sediment compaction correction COMPACTION – (post-depositional process) alters original PMS elevation CORRECTION APPLIED - LINEAR PMHW becomes CURVED decreasing trend (NON-)CORRECTION – impacts MULTI CENTENNIAL TRENDS

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 3) Sediment compaction correction CALCULATION? Comparison with basal reconstructed PMHW

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 4) Palaeotidal range correction, COMBINE 3) + 4) = Relative PMTL Rising relative sea level - coastline morphology - tidal range changes Solved with modeling - relative PMHW can infer relative PMTL

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) METHODOLOGY: 5) Detrend (GIA), COMBINE 5) = PMTL Reconstructed MTL once MILLENNIAL relative rise removed Past 1500 yr due to GIA? (assuming no SL trend) SCENARIO 1 / 2, extent to which SL is STABLE / RISING / FALLING Preferably long BASAL series with model prediction

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) SUMMARY:

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) RESULTS / DISCUSSION:Summary assessment of reconstructions

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) RESULTS / DISCUSSION:Summary assessment of reconstructions Falling SL trend? inc. ~1800 High freq. variability Falling SL trend & oscillation? inc. ~1900 Falling SL trend? inc. ~1800 / ~1900 inc. ~1900 High freq. variability, inc. ~1700 / ~1900 EROSION High freq. variability, inc. ~mid 1700 (PMS) / ~late 1800

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) SUMMARY: CONCLUSIONS 1) ARE RECONSTRUCTIONS COMPARABLE? Once specific differences in technique/approach are taken into account 2) MULTI-CENTENNIAL SCALE VARIABILITY? Dependant on the reconstructed PMS accumulation rates Most reliable reconstructions display no coherence in terms of a discernable influence of MWP / LIA Due to limitations of reconstruction?

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) SUMMARY: CONCLUSIONS 3) FALLING SEA LEVEL TREND LAST MILLENNIA? Still open Trends are the result of PMS rate, (non-)correction for compaction and detrending method SOLVABLE? Extrapolation of multi-millennial scale trends (basal and GIA) independent of data for recent ~1000 yrs compared to high resolution basal trends, e.g. DONNELLY, 2004, for this period 4) RECENT INCREASE LAST CENTURY? POSTER: Dr Roland Gehrels High precision dating past ~200 years, helps resolve rates of sea level rise for the last century that are higher than the trend for the last 1500 years Precise timing is problematic Defining such rates in past 1500 years beyond resolution achievable with conversational AMS 14C dating techniques

1500-yr-long sea-level reconstructions from North Carolina to Newfoundland (Iceland) ACKNOWLEDGEMENTS: Dr Orson van de Plassche Dr Roland Gehrels THANKS TO: Prof Kurt Lambeck UNESCO POSTERS: Wright & van de Plassche: Salt-marsh accumulation rates and relative sea-level changes during the past 1500 years for three sites along the east coast of North America Gehrels: Coupling instrumental and proxy records of recent sea-level change