Quantifying Arctic Holocene precipitation seasonality and relative humidity using leaf wax hydrogen isotopes in lakes with contrasting residence time: A case study on western Greenland
Abstract
Understanding past Arctic hydroclimate changes, including precipitation seasonality and relative humidity, allows us to examine mechanisms that caused past climate variability and better predict the potential effects of future climate trends. Lake water residence time dictates the seasonality of hydrogen precipitation isotope (d2H) signals in Arctic lakes during the summer growing season. Through-flowing lakes with short (<3 month) residence times reflect summer-weighted precipitation isotopes, whereas lakes with longer (12 month) residence times reflect annual mean precipitation isotopes, with minimal evaporative enrichment. We reconstruct Arctic Holocene precipitation seasonality through the comparison of aquatic plant leaf wax d2H records, which reflect growing season lake water d2H, from two lakes with contrasting residence times on western Greenland. Pluto Lake is dominated by a summer precipitation d2H signal since it has a short residence time. Aquatic leaf wax d2H in Pluto Lake therefore reveals information about local summer precipitation d2H, whereas terrestrial leaf wax d2H indicates summer precipitation with evaporative enrichment. We use the difference between aquatic and terrestrial leaf wax d2H to quantify changes in summer relative humidity at our study site. We compare our Pluto Lake leaf wax d2H records to published aquatic and terrestrial leaf wax d2H records at Lake N3, located 50 km to the south. Previously studied Lake N3 has a longer residence time, and thus its leaf wax d2H record reflects a mean annual precipitation isotopic signal. The difference between the mean annual and summer precipitation d2H records elucidates changes in winter hydroclimate on western Greenland during the Holocene. This case study will be an important step towards quantifying past hydroclimate seasonality in the Arctic.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP23D1521H
- Keywords:
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- 3335 North American Monsoon;
- ATMOSPHERIC PROCESSESDE: 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 4914 Continental climate records;
- PALEOCEANOGRAPHYDE: 4938 Interhemispheric phasing;
- PALEOCEANOGRAPHY