Ecosystems & Biogeochemical Dynamics Laboratory - LakeM - Department of Earth, Atmospheric, and Planetary Sciences - Purdue University Skip to main content
Ecosystems & Biogeochemical Dynamics Laboratory Department of Earth, Atmospheric, and Planetary Sciences

LakeM

Past methane from lakes in Alaska: Integrating proxy records and models

Duration:03/2020 - 02/2023
Award Amount:Dollar Amount of the Project

Participants
Dr. Zhuang as Collaborator with PI Dr. Maarten van Hardenbroek at Newcastle University,  Co-I: Dr. Jessica Whiteside and Prof. Mary Edwards

Project Objectives

Our aim is to quantify CH4 production from high-latitude lakes in Alaska across a range of environments during the warmer-than-present Holocene Thermal Maximum (HTM) 11-6 cal ky BP, and to use these proxy data, plus modern observations, to verify a process-based model of lake CH4 cycling. The model will then be applied to climate projections under IPCC (2013) to simulate future high-latitude lake CH4 emissions.
In order to achieve this aim, we will:
1) Produce proxy-based and model-based quantitative estimates of CH4 emissions from lakes in Alaska for climatically different periods in the Holocene. This will entail:
a. Creating proxy records for 8 lakes located in four climatically different zones in Alaska.
b. Undertaking a sensitivity analysis of Daphnia δ13C to quantify uncertainty: we will analyse δ13C of compounds that are specific for the two end-members of Daphnia diet: algae and methane-oxidizing bacteria. In addition we will fit the existing relationship between CH4 and Daphnia δ13C to Alaska using existing CH4 emission data from project partners and measuring δ13C values of Daphnia in surface sediment samples of 25 lakes in Alaska (see details in section 3.2).
c. Adapting an existing process-based model of lake-CH4 emissions to operate in the Holocene with TraCE21ka and with CMIP6 model simulations (see section 3.3).
d. Model refinement: adjusting parameterization to more closely reproduce the Holocene proxy records (see section 3.3).
2) Use palaeoenvironmental information on lake productivity, oxygen regime, and temperature derived from new analyses and existing data to:
a. Inform model experiments.
b. interpret proxy-derived CH4 flux estimates.
3) Assess whether temporal changes in CH4 emissions differ for lakes in four climatically different regions of Alaska.
4) Compare how proxy- and model-derived lake CH4 emissions estimates vary between sites in climatically different zones in Alaska.
5) Use high-latitude lake area data to estimate CH4 emissions for Alaska.
6) Produce future lake CH4 emission estimates for Alaska using the process-based model and CMIP6 predictions for future temperature and precipitation following IPCC scenarios.