Methane Production in the Arctic: Under-recognized Cold Season and Upland Tundra - Arctic Methane Sources-UAMS
Lead Research Organisation:
University of Exeter
Department Name: Geography
Abstract
In this project, we will use state of the art approaches and knowledge to better understand the current patterns of and controls on methane (CH4) release from the Arctic to the atmosphere and to improve major models to better simulate future releases of CH4 from the Arctic as the planet warms. Atmospheric methane (CH4) is the second most important greenhouse gas (after CO2) that has strong anthropogenic origins. High northern latitude terrestrial ecosystems account for ca. 50% of extra-tropical biogenic wetland emissions. More importantly methane emissions from the Arctic could increase dramatically in the future. The very large organic carbon stocks (>1,300 GtC) in the top 3 m of Arctic soils and the rapid climate change experienced and predicted in the Arctic, results in a very real possibility of large biogenic CH4 release from these soils in this century. Despite the importance of CH4 fluxes from the Arctic, now and in the future, biogenic and total natural CH4 emissions are poorly understood and very poorly modelled (Fisher et al., 2014).
In 2013, we updated five eddy covariance (EC) towers in Arctic Alaska to operate reliably year-round and measure CH4 fluxes. Initial measurements yielded two unexpected and highly significant findings: 1) cold season CH4 emissions account for >50% of annual emissions and 2) drier upland tundra are larger emitters of CH4 than wetter inundated tundra (Zona et al 2016 PNAS). These observations and processes are not now incorporated in leading global land-surface/carbon-cycle models used to calculate current and predict future CH4 emissions from the Arctic. Verifying this new understanding and incorporating this understanding into models used in the UK and elsewhere will revolutionize our ability to accurately calculate and model terrestrial CH4 fluxes. These results, if supported by the outputs of this project, are critical to verifying current baseline emissions, detecting a changing baseline, and for predicting, with confidence, biogenic CH4 emissions from the Arctic in the future. This project has two overarching objectives: (1) determining the patterns of, controls on, and importance of cold season and upland tundra in Arctic CH4 emissions; (2) incorporating this understanding into JULES, LPJ and TCF, thus significantly improving our ability to estimate current and predict future CH4 fluxes in the Arctic. This work is expected to impact policy through new information and model development, reported through conferences and publications and referenced in upcoming IPCC reports. In the project, we will continue year-round observation of methane release to the atmosphere, and the atmospheric and soil environment that corresponds to these fluxes. We will initiate new experiments and observations to understand the processes and conditions controlling the observed CH4 fluxes including a new system of measurement of CO2, CH4, and 222Rn concentrations that allow autonomous, year-round, determination of CH4 production, consumption, and flux by soil depth and snow layer. We will measure year-round [CH4] and d13CH4 will help identify the importance of methane oxidation in surface soil layers at different locations and seasons. And we will determine the role of GPP in controlling rates of CH4 production. We will also determine the importance of vascular plants in providing a conduit for CH4 produced at depth, to escape to the atmosphere past an oxidizing surface layer.
This new information will inform model development and improvement of models used by the Arctic community. Performance of these models will verified with unique data sets not used in model development. As a result, we intend UAMS to have a major impact on the communities' ability to calculate current and to predict with confidence future Arctic CH4 emissions in a changing world and thereby better inform policy decisions.
In 2013, we updated five eddy covariance (EC) towers in Arctic Alaska to operate reliably year-round and measure CH4 fluxes. Initial measurements yielded two unexpected and highly significant findings: 1) cold season CH4 emissions account for >50% of annual emissions and 2) drier upland tundra are larger emitters of CH4 than wetter inundated tundra (Zona et al 2016 PNAS). These observations and processes are not now incorporated in leading global land-surface/carbon-cycle models used to calculate current and predict future CH4 emissions from the Arctic. Verifying this new understanding and incorporating this understanding into models used in the UK and elsewhere will revolutionize our ability to accurately calculate and model terrestrial CH4 fluxes. These results, if supported by the outputs of this project, are critical to verifying current baseline emissions, detecting a changing baseline, and for predicting, with confidence, biogenic CH4 emissions from the Arctic in the future. This project has two overarching objectives: (1) determining the patterns of, controls on, and importance of cold season and upland tundra in Arctic CH4 emissions; (2) incorporating this understanding into JULES, LPJ and TCF, thus significantly improving our ability to estimate current and predict future CH4 fluxes in the Arctic. This work is expected to impact policy through new information and model development, reported through conferences and publications and referenced in upcoming IPCC reports. In the project, we will continue year-round observation of methane release to the atmosphere, and the atmospheric and soil environment that corresponds to these fluxes. We will initiate new experiments and observations to understand the processes and conditions controlling the observed CH4 fluxes including a new system of measurement of CO2, CH4, and 222Rn concentrations that allow autonomous, year-round, determination of CH4 production, consumption, and flux by soil depth and snow layer. We will measure year-round [CH4] and d13CH4 will help identify the importance of methane oxidation in surface soil layers at different locations and seasons. And we will determine the role of GPP in controlling rates of CH4 production. We will also determine the importance of vascular plants in providing a conduit for CH4 produced at depth, to escape to the atmosphere past an oxidizing surface layer.
This new information will inform model development and improvement of models used by the Arctic community. Performance of these models will verified with unique data sets not used in model development. As a result, we intend UAMS to have a major impact on the communities' ability to calculate current and to predict with confidence future Arctic CH4 emissions in a changing world and thereby better inform policy decisions.
Planned Impact
Knowledge of the impact of climate change and rising atmospheric [CO2] on greenhouse gas (GHG) emissions (especially of CO2 and CH4) is critical for setting targets for GHG emission reductions and to identify and promote mitigation strategies. The overarching aim of this project is to fill a major gap in knowledge and answer the question:
"What is the effect of climate change on CH4 fluxes from tundra ecosystems"? The information acquired by the field observations, will be used to test and refine models describing the response of the tundra C balance and GHG fluxes to climate warming. This will allow the models used to be improved, better constrained, and will thereby improve confidence in predictions of future responses. The new understanding will be build into the UK community model (JULES) and code made available to other land surface models. Overall, this project is critical to refining predictions of future feedbacks from the Arctic with anticipated global warming, and better inform policy on the sensitivity of the substantial C pool of arctic permafrost soils to climate change.
"What is the effect of climate change on CH4 fluxes from tundra ecosystems"? The information acquired by the field observations, will be used to test and refine models describing the response of the tundra C balance and GHG fluxes to climate warming. This will allow the models used to be improved, better constrained, and will thereby improve confidence in predictions of future responses. The new understanding will be build into the UK community model (JULES) and code made available to other land surface models. Overall, this project is critical to refining predictions of future feedbacks from the Arctic with anticipated global warming, and better inform policy on the sensitivity of the substantial C pool of arctic permafrost soils to climate change.
Publications
Arndt K
(2019)
Sensitivity of Methane Emissions to Later Soil Freezing in Arctic Tundra Ecosystems
in Journal of Geophysical Research: Biogeosciences
Arndt K
(2019)
Arctic greening associated with lengthening growing seasons in Northern Alaska
in Environmental Research Letters
Birch L
(2021)
Addressing biases in Arctic-boreal carbon cycling in the Community Land Model Version 5
in Geoscientific Model Development
Chang KY
(2021)
Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions.
in Nature communications
Chu H
(2021)
Representativeness of Eddy-Covariance flux footprints for areas surrounding AmeriFlux sites
in Agricultural and Forest Meteorology
Davidson S
(2017)
Upscaling CH4 Fluxes Using High-Resolution Imagery in Arctic Tundra Ecosystems
in Remote Sensing
Delwiche K
(2021)
FLUXNET-CH<sub>4</sub>: a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands
in Earth System Science Data
Hashemi J
(2021)
Seasonality buffers carbon budget variability across heterogeneous landscapes in Alaskan Arctic Tundra
in Environmental Research Letters
Irvin J
(2021)
Gap-filling eddy covariance methane fluxes: Comparison of machine learning model predictions and uncertainties at FLUXNET-CH4 wetlands
in Agricultural and Forest Meteorology
Liljedahl AK
(2017)
Tundra water budget and implications of precipitation underestimation.
in Water resources research
| Title | Native children's view of Climate Change in the Arctic |
| Description | Our team worked with the Ukpeagvik Iñupiat Corporation (UIC), an Alaska Native Corporation which provides social and economic resources to over 2,900 Iñupiat shareholders, and their descendants. The collaboration with UIC has given us a good understanding of how to reach the local communities and involve them in our research. One of scientists in our team (David Lipson) and an artist (Kim Reasor) engaged fifth grade children in Utqiagvik and helped them to communicate to the rest of the world, in an emotionally resonant way, the direct impacts of climate change on their families in this Arctic region. Lipson, Reasor, and an outreach specialist (Erickson) of Inupiat heritage from a village in Alaska worked with four 5th grade classes of about 25 students each at Fred Ipalook Elementary in Utqiagvik, AK. The result was a poster showing historical and projected Arctic sea ice cover, with 100 beautiful paintings by children of things that are dear to them about their home being squeezed into a smaller region as the sea ice cover diminishes. The team scanned all the artwork to make a digital version of the poster and left the original with the school. These materials were converted into an interactive webpage where viewers can click on the individual painting for detail and get selected recordings of the children's statements about their artwork. |
| Type Of Art | Artistic/Creative Exhibition |
| Year Produced | 2020 |
| Impact | Subsistence hunting of marine mammals associated with sea ice is central to the Inupiat way of life. Furthermore, their coastal homes and infrastructure are increasingly subject to damage from increased wave action on ice-free Beaufort and Chukchi Seas. While the people of this region are among the most directly vulnerable to climate change, the subject is not often discussed in the elementary school curriculum. Meanwhile, in many other parts of the world, the impacts of climate change are viewed as abstract and remote. This activity served as a nucleus for communicating to other classes and adults about the real impacts of climate change in people's lives, in a variety of schools in Alaska and contributed to better understanding of the impact of climate change on the daily lives of native communities. |
| Description | We discovered a significantly latter soil freezing over the last 15 years that was associated with higher methane emissions. This matches NOAA observations for atmospheric methane and apparent Arctic biospheric controls on atmospheric methane. High resolution temperature measurement for active layer depth, water table, permafrost, snow depth, permafrost, and zero curtain. Diffusivity system for measuring CO2, CH4 soil concentrations and fluxes. Fall CO2 emissions and controls by summer GPP and zero curtain extent and duration. During the last summer season (2018) we initiated the collection of isotope data in Barrow and Atqasuk using a 24 hours sampling. The samples were shipped from Alaska to the Uk, and are currently being analyzed. |
| Exploitation Route | Broad application of technology. Broad application of results to modeling. |
| Sectors | Education,Environment,Government, Democracy and Justice |
| Description | Scientific Advisory panel of the CMCC Foundation |
| Geographic Reach | Europe |
| Policy Influence Type | Participation in a guidance/advisory committee |
| Impact | Walter Oechel was invited to join the Scientific Advisory panel of the CMCC Foundation, which supports modelling effort to refine the impact of climate change on ecosystems. |
| Description | Horizon 2020 project: INTAROS Proposal full title: Integrated Arctic Observation System Proposal acronym: INTAROS Topic: H2020-BG-09-2016 An integrated Arctic Observation System (2016) |
| Amount | € 528,752 (EUR) |
| Funding ID | Grant Agreement Number: 727890 |
| Organisation | European Commission H2020 |
| Sector | Public |
| Country | Belgium |
| Start | 04/2018 |
| End | 02/2022 |
| Title | Developing the technology needed to perform winter flux measurements |
| Description | An automatically heated sonic anemometer based on data quality has been developed and tested during the last few field campaigns. Commercially available heated sonic anemometers are activated either continuously or based on a temperature threshold (e.x. 4.5°C); as fall, winter and spring temperature are always below this value, the heating in these sonic anemometers biasing the sensible heat, and the flux calculation. To be able to activate the heating, we replaced this fixed threshoulds with a data quality threshold. The heater is coupled to the transducer for heating , an activation switch is configured to activate the heater when the measured quality of the collected data is less than a predetermined value. A deactivation switch is configured for deactivating the heater when the measured quality of the collected data reaches or exceeds the predetermined value. A status recording module is coupled to the data quality measurement module for indicating that the heater is heating the transducer. Heating of sonic anemometers is switched off automatically when not needed. Additionally, the increase in temperature of the bar of the sonic anemometer when heated continuously (and potential bias the data), is prevented when an intermittent heating is applied. The automatic heating system we developed and further tested within the UAMS project allowed to extend measurements in remotely located sites that cannot easily be manually operated, and where power is limited. This system allowed performing unmanned temperature, wind, or other measurements in remote areas where ice and freezing conditions occur for substantial portions of the year by automatically heating and/or de-icing the instruments. By automatically and selectively heating scientific equipment such as a sonic anemometer, more accurate measurements were obtained from the sonic anemometer even when the sonic anemometer is located in a remote location, where measurements are typically or necessarily performed in unattended, unmanned ways. Further, required power for heating the equipment was reduced. The automatic heating apparatus successfully de-iced the transducers of the sonic anemometer with minimal hours of activation, successfully reducing power consumption. Data recorded during the heating activations, as indicated by the automatic heating apparatus, were discarded, not affecting the final flux calculation. This development and testing was conducted in the most remote of our sites, and proved successfully in maintaining ice-free the sonic anemomenter during the cold period dramatically improving the data coverage. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2017 |
| Provided To Others? | Yes |
| Impact | The Arctic is undergoing warming twice that of the global average due to positive feedback loops involving snow and ice loss. This is resulting in shifting seasonality and altering greenhouse gas dynamics in tundra regions, where a large carbon reservoir exists in tundra soils. The effects of Arctic warming are most pronounced in the cold period (October - April). This is crucial as the cold period in Arctic tundra environments can account for half of annual emissions of methane (CH4), a powerful greenhouse gas with ~30 times the warming potential than that of carbon dioxide. The majority of cold season CH4 emissions occur in early winter, when soils are not completely frozen and temperatures hover around 0° C during the transition from liquid to solid. This is referred to as the zero-curtain period. There is uncertainty regarding whether CH4 emissions during the zero-curtain period are due to active microbial production of CH4 or merely the result of CH4 escaping that was generated during the prior summer season. Our study suggests that substantial CH4 occurs during the zero-curtain period, representing an important component of the annual budget.The ability to extend the flux measurements during the cold period is critical to develop better predictions of the impact of global warming on the Arctic carbon balance. |
| Title | High temporal and spatial temperature measurement for determine the position and extent of the zero curtain, water table, snow depth, permafrost level, active layer depth. |
| Description | High speed, high resolution thermocouple air, water, soil, snow temperature measurement recorded at 1 hz. |
| Type Of Material | Technology assay or reagent |
| Year Produced | 2017 |
| Provided To Others? | No |
| Impact | Better resolution of zero curtain, snow depth, water table, active layer, permafrost position and duration. |
| Title | Identifying the environmental and vegetation controls of heat penetration into the arctic soils |
| Description | To define the vegetation and environmental controls on the heat penetration into the soil, and the thawing the permafrost, temperature readings were collected from 5 cm above the surface (to collect air temperature) and from surface until 20 centimeters below-ground (every cm) on a weekly basis using a portable CR3000. These temperature profiles allowed to determine how the presence and thickness of the moss layer affected the heat penetration into the moss and soil layers. These 21 thermocouples were attached to a fiberglass probe which facilitated insertion in the moss layer and in the soil. Each point was measured for approximately 3 minutes given that this was the time it took for the temperature readings to stabilize. Given that heat penetration is affected by moisture, we also collected volumetric water content (%) weekly using a FieldScout TDR300 and a 5-cm probe. The FieldScout was calibrated using local water samples to account for nutrients which may influence conductivity. Thaw depth and water table levels (cm) were also collected weekly using a metal and wooden probe respectively with markings indicating intervals of 1-cm depths. Water table measurements were taken collected inside PVC pipes (with holes every 1 cm) previously installed along the transects (Zona et al., 2012) where the other measurements were collected. All described data collection was performed in 2-meter intervals for a total of 62 points at each 124-meter transects in both US-Ben, and US-Bec. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2022 |
| Provided To Others? | No |
| Impact | The tool developed is not published yet. Once it will be published in a peer reviewed publication, it will support the development of models trying to identify the controls on permafrost degradation. |
| Title | Data Base at SDSU |
| Description | Near real time data available on line form SDSU |
| Type Of Material | Database/Collection of data |
| Year Produced | 2017 |
| Provided To Others? | Yes |
| Impact | Numerous publications and model improvement. |
| Title | Development of CLM microbe |
| Description | The CH4 fluxes, soil DOC, CH4 and CO2 concentrations among different landscape types were simulated by the CLM-Microbe model with considerations of the specific soil hydrological conditions. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2020 |
| Provided To Others? | Yes |
| Impact | improve model simulation of the sensitivity of carbon stored in the Arctic to climate change can affect policy |
| Title | Greenhouse gas flux measurements at the zero curtain, North Slope, Alaska, 2012-2021 |
| Description | Greenhouse gas flux measurements at the zero curtain, from five eddy covariance towers across the North Slope, Alaska, from 2012-2021 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2021 |
| Provided To Others? | Yes |
| Impact | Freely accessible data from the understudied arctic regions are critical for model development and to refine our knowledge of the impact of global warming on the carbon balance in the Arctic. |
| Description | Collaboration with NOAA |
| Organisation | National Oceanic And Atmospheric Administration |
| Country | United States |
| Sector | Public |
| PI Contribution | We are sharing data with NOAA to help help them interpret the atmospheric trace gas signal. New Collaborators added in 2021. |
| Collaborator Contribution | NOAA GMD is providing technical support at our CMDL site in Barrow Alaska. NOAA EPP is providing support for students, travel, and research support for this project. |
| Impact | Jointly published papers with NOAA personnel. Co-supervision of students' projects. |
| Start Year | 2016 |
| Description | Data Reduction of long term Eddy Covariance Record |
| Organisation | National Research Council |
| Department | Institute of Biometeorology (IBIMET) |
| Country | Italy |
| Sector | Public |
| PI Contribution | Cleaned, gap filled, Burba Collected data. |
| Collaborator Contribution | Gap filling, Data Cleaning, Burba Correction. |
| Impact | Manuscript in preparation. |
| Start Year | 2020 |
| Description | BARC science fair (1-3 August 2018) and to the Atqasuk Community Meeting (11 June, 2018) |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Media (as a channel to the public) |
| Results and Impact | In order to encourage the involvement of the local community with our research, we presented our research plans and results to the BARC science fair (1-3 August 2018) and to the Atqasuk Community Meeting (11 June, 2018). These were great opportunities for the scientists to explain in simple terms what are they researching in the Arctic, why the locals should care, and what the greater implications of their science results are for society. The fair gathered about 200-300 people from Utqiagvik, in northern Alaska, and the Atqasuk community meeting gathered about 80 people including locals (entire families joined the fair and the community meeting including elders and children), and scientists from a wide range of institutions across the world (US, Canada, Germany, etc.). In the science fair D. Zona discussed the importance of CH4 emissions and explained in simple terms the processes occurring during the cold period and what "zero curtain" is, and why an integrative approach to science is vital in understanding the complex impact of climate change on arctic ecosystems. D. Zona was also interviewed by a reporter (working for AccuWeather) and showed the reporter one of the research sites in Utqiagvik, describing how the instruments work, and what the importance of our research is for society. |
| Year(s) Of Engagement Activity | 2018 |
| Description | Press release of journal article |
| Form Of Engagement Activity | A magazine, newsletter or online publication |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Media (as a channel to the public) |
| Results and Impact | Embargoed until 21 March 10AM GMT Earlier snowmelt causing knock-on effects for Arctic carbon ? Arctic warming is causing earlier snowmelt and longer growing seasons in Arctic tundra ecosystems ? It was previously assumed that this would cause an increase in carbon sequestration in these regions ? New research has found that earlier snowmelt actually causes a loss in net carbon sequestration later in the year Earlier snowmelt and Arctic greening are affecting carbon sequestration later in the year in northern Arctic regions. New research has found that earlier snowmelt and a longer growing season, caused by climate change, are not causing a consistent increase in carbon sequestration as first thought. It has long been assumed that this longer period of growth and plant productivity would lead to an increase in the summer carbon sequestration, the process of capturing and storing atmospheric carbon. The findings published in Scientific Reports, however, show that whilst there is an increase in carbon sequestration during June and July, it leads to a loss in net carbon sequestration later in the season around August time. Dr Donatella Zona, from the University of Sheffield's School of Biosciences and the Department of Biology at San Diego State University and lead author of the research, said: "Climate change is having a major impact on the Arctic and Arctic warming, earlier snowmelts and Arctic greening are causing changes to the atmospheric carbon there. "Our results show that the expected increased CO2 sequestration arising from Arctic warming and the associated increase in growing length may not materialise if tundra ecosystems are not able to continue capturing CO2 later in the season. "The results should be considered when predicting the overall response of the Arctic carbon balance to climate change." The study was carried out using an extensive dataset from 11 sites in Arctic tundra ecosystems across Alaska, Canada, Greenland and Russia, allowing researchers to test the response of a wide range of sites to the earlier snowmelt. |
| Year(s) Of Engagement Activity | 2022 |