Project Objective:

Peatlands are an important global source of atmospheric methane (CH4). Additionally, peatland soils currently store roughly one-third of the terrestrial soil carbon. Thus, the response of peatland carbon cycling to ongoing environmental change will have global implications. Given the high global warming potential of CH4, our ability to predict climate forcing by peatlands in the future hinges on our ability to incorporate CH4 dynamics into earth system models. However, CH4 dynamics are regulated by a complex set of controls, including plant and microbial activities, and the response of these controls to warming and elevated [CO2] are not well understood. This lack of appropriate mechanistic understanding of peatland CH4 dynamics represents a fundamental knowledge gap in our ability to predict if CH4 flux from peatlands will represent a positive feedback to anthropogenic global change. The overall objectives of this proposal are to provide a mechanistic understanding of how deep warming of peat and CO2 enrichment in a bog affect carbon mineralization and CH4 production, consumption, and transport (which together control CH4 emissions) and to incorporate that understanding into a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), which will then be used to improve predictions of CH4 emissions from boreal peatland ecosystems.

Our proposed work will leverage ongoing DOE research at the Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) experiment taking place in a black spruce-Sphagnum bog in northern Minnesota to address the following hypotheses: (H1) CO2 enrichment will enhance CH4 fluxes substantially because of an increase in root exudations. (H2) Warming will enhance CH4 production, but the mechanistic controls will be a complicated mix of the direct positive effects of warming on methanogens and indirect warming effects on interacting and competing anaerobic processes. (H3) Warming will seasonally reduce CH4 fluxes to the extent that it draws down the water table and thus increases CH4 oxidation. Alternatively, warming and a drawdown in the water table will increase the vascular component of the plant community over time. This will increase root exudation, the carbon quality of the surface peat, and plant transport of CH4, all of which will increase CH4 fluxes and partially offset the increase in CH4 oxidation due to a lower water table. We will address these hypotheses through a combination of controlled laboratory experiments as well as field measurements of key electron acceptors and carbon sources in porewater; stable isotope signatures (13C and D) of CH4 and CO2 to quantify CH4 production and oxidation pathways; and measurements of 14CH4 and 14CO2 to quantify the age of mineralized carbon. This increased mechanistic understanding of CH4 dynamics, and how they respond to key global changes, will be explicitly linked to the Terrestrial Ecosystem Model (TEM) in this proposal. Thus, this project will deliver valuable scientific data and models about the mechanistic controls of anaerobic carbon cycling, and CH4 dynamics in particular, in peatlands, a globally important ecosystem, in response to elevated temperature and [CO2].

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Project Objective:

Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges - as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research:

There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

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Project Objective:

This project will advance systems modeling approaches by developing a suite of stochastic modeling approaches, coupled with geostatistical and machine learning techniques. The new system modeling approach will utilize both in situ and satellite remotely sensed data to improve system model parameters and model structure. These novel developments, together with observed data, will advance ecosystem and environmental sciences through computational thinking. The proposed approach will be used to develop a cyber-enabled stochastic carbon-weather system to provide more adequate quantification of regional carbon exchanges, which is critical to better understanding carbon-climate-atmosphere feedbacks and facilitating climate-policy making.

The proposed approach will transform the current system modeling approach by (1) developing a stochastic version of the deterministic differential equation models of ecosystems and environmental systems; (2) developing geospatial statistical techniques to fully exploit multifaceted observational data to improve model parameterization; (3) developing advanced statistical and machine learning techniques to further utilize observational data to improve model structure; and (4) applying the improved model to examine the societal and biogeochemical impacts of land use change. Advantages of the proposed cyber-enabled terrestrial ecosystem model will include: (1) Efficiently quantifying regional net carbon exchanges and associated uncertainty and (2) Improving system model parameters and structure using advanced statistical and machine learning techniques and spatiotemporal data acquired over the U.S. Project deliverables include: (1) An innovative, cyber-enabled carbon-weather system that can quantify net carbon exchanges and associated probabilistic information at high spatial and temporal resolution for the continental U.S. and (2) a suite of transformative advanced mathematical, statistical and system modeling techniques that could be applied to other complex modeling fields (e.g., hydrological modeling). This project will significantly advance ecosystem sciences with computational thinking and will provide a unique opportunity to train a new generation of scientists in a highly interdisciplinary research environment.

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Project Objective :

The Arctic has been experiencing great warming and ecological changes in recent decades. The last pronounced warm period occurred about 11,000-9,000 years ago in Alaska. The warm and possibly dry climate resulted in unusual ecosystem types and processes, including novel poplar-willow deciduous forests in uplands, and rapid peatland expansion and growth in lowlands. The proposed research will test the hypothesis that the enhanced climate seasonality at that time played a major role in causing such contrasting responses of ecosystems on uplands and wetlands. To look into the past, the researchers will analyze microfossils preserved in peat. They will integrate their findings and test the hypothesis using simulation modeling. The project's objectives are to document ecosystem changes that occurred 10,000 years ago across Alaska and to assess effects of a warmer climate and different seasonality on nutrient and water cycling using the Terrestrial Ecosystem Model. This research addresses an important topic in global change, how a warming climate will interact with changing precipitation to influence ecosystem structure and functioning in the Arctic. An improved ability to model ecosystem processes will allow for better prediction of changes in carbon cycling under a changing climate in Alaska, and potentially for Pan-Arctic ecosystems in the future. In response to the public's keen interest in Arctic warming and its biological impacts, the investigators will disseminate results through the popular press. Undergraduates, graduate students, and a postdoctoral researcher will be trained on this project.

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Project Objective :

Northern Eurasia accounts for about 20% of the Earth's land surface and 60% of the terrestrial land cover north of 40°N. It contains 70% of the Earth's boreal forests and more than two-thirds of the Earth's land that is underlain by permafrost. The region is covered by vast areas of peatland, complex tundra in the north and semi-deserts and deserts in the south, including the Mongolia plateau. The surface air temperature has increased in the last half century and this increase will continue during this century. To date, studies have generally focused on analyzing climate change effects on biogeochemical processes and mechanisms governing the carbon and water dynamics in the region or potential changes in the distribution of natural vegetation. While we will also examine such issues, here we propose to investigate how patterns of land use in Northern Eurasia may change in the future due to: 1) Economic pressures for providing food, fiber and fuel to a growing global population; 2) Opportunities for expanding managed ecosystems into areas that experience a more favorable climate in the future; and 3) Abandonment of managed ecosystems in other areas that experience a less favorable climate. In our investigation, we will examine how these future changes in land use and land cover influence the exchange of CO2 and CH4 between terrestrial ecosystems and the atmosphere, terrestrial carbon storage and primary productivity, water supply and radiative forcing of the atmosphere through changes in surface albedo. We will also assess how human adaptation and quality of life may be impacted by these changes. To conduct this analysis, we will use a system of linked models that include the MIT Emissions Prediction and Policy Analysis (EPPA) model of the world economy, the SiBCliM bioclimatic vegetation model, and the Terrestrial Ecosystem Model (TEM). The land-cover/ land-use modeling and biogeochemical modeling will be based on current relationships observed by satellite and remote sensing data. Future climate change scenarios will be prescribed using existing spatially-explicit time-series data sets that have been developed with climate models using various IPCC SRES emission scenarios. Our multi-disciplinary US scientific team includes ecosystem scientists, biogeochemical modelers, and economists, which will be reinforced by international collaborators from Russian Academy of Sciences, International Institute of Applied Systems Analysis (IIASA) in Austria, National Institute for Environmental Studies in Japan, and Chinese Academy of Sciences.

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Project Objective :

Abrupt climate change is a potential menace that hasn't received much attention. That's about to change. Through its Climate Change Prediction Program, the U.S. Department of Energy's Office of Biological and Environmental Research (OBER) recently launched IMPACTS-Investigation of the Magnitudes and Probabilities of Abrupt Climate Transitions-a program led by William Collins of Berkeley Lab's Earth Sciences Division (ESD) that brings together six national laboratories to attack the problem of abrupt climate change. The research team also includes Purdue University

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Project Objective :

Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically forced climate warming, and the extent to which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes in the extent of wetlands and lakes, especially thermokarst (thaw) lakes, over the Arctic. Through a suite of global model experiments that encapsulate the fundamental processes governing methane emissions – as well as their coupling to the global climate system -we intend to test the following hypothesis:

There exists a climate warming threshold beyond which permafrost degradation becomes widespread and thus instigates strong and/or sharp increases in methane emissions (via thermokarst lakes and wetland expansion). These would outweigh any increased uptake of carbon (e.g. from peatlands) and would result in a strong, positive feedback to global climate warming.

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Abstract: The goal of this research is to develop realistic assessments of the economic and environmental impacts of regional and global policies designed to stimulate bioenergy production and use. We will build on the unique strengths of GTAP to analyze economic impacts of alternative bioenergy policies at regional and global levels. We will use the TEM model to help develop the land supply curves and to validate environmental consequences of these policies and check their feasibility from the environmental and land use perspectives. The following outputs will be accomplished during the study period:

    (1) Build and incorporate an explicit biomass energy sector within the GTAP analytical framework and data base. While GTAP has already been used for many environmental, energy, and climate change studies, there is at present no explicit biomass sector in GTAP. For future analyses, it will be imperative to have biomass sectors so that biomass for energy interactions can be incorporated with other land uses and so that biomass energy products will play in the energy markets like other energy products. Thus, all the production, substitution, consumption, and trade possibilities that currently exist for the other sectors will exist for biomass-based energy.

   (2) Examine changes in production, prices, consumption, trade, economic well being, etc. due to any policy or technical shock applied to the model. For example, we will be able to evaluate impacts of renewable fuel standards in the U.S. and E.U. In addition, we can couple GTAP with micro-level models to obtain estimates of the impacts of these shocks on household poverty in certain regions.

   (3) Assess the trade effects of bioenergy policy scenarios at regional and global levels. Analyzing the trade effects of bioenergy policies is a challenging task. The GTAP data bases and models provide a unique foundation to support this task.

   (4) Evaluate environmental impacts of alternative policies for bioenergy development. We will use the TEM model and its capabilities to:

      a. Help develop land supply curves for new lands, which will, in turn be used in the GTAP analysis
      b. Asses environmental consequences of policy scenarios,
      c. Check feasibility of alternative ways of producing bioenergy,
      d. Determine validation of alternative methods of producing bioenergy

See more information in the doc
Poster for DOE-BER workshop-2008 Poster

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Abstract: To predict future atmospheric composition and climate, more accurate biogeochemistry models used in Earth System Models are needed.  Here we propose to use available atmospheric data from satellite missions and in situ trace-gas networks and remote-sensing and in-situ data of terrestrial ecosystems and a 3D tropospheric chemistry model (GEOS-Chem) in a model-data fusion manner to improve a global biogeochemistry model (TEM) in simulating methane fluxes.  Simulated fluxes with the biogeochemistry model will be fed into the tropospheric chemistry model to simulate the gas concentrations.  The observed atmospheric concentrations will be compared to the estimates of the tropospheric chemistry model.  By altering parameters of the biogeochemistry model, the differences between the observed and the simulated atmospheric gas concentrations could be optimized.  Iterations of these steps will improve the biogeochemistry model by constraining its key uncertain parameters and suggesting alternative structures to the model.

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Abstract: The Boreal Forest contains about 1/3 of all global terrestrial carbon stored as vegetation and soil organic matter. The fate of this carbon, however, is uncertain because of the widespread degradation of permafrost, which plays a key role in sequestering soil carbon. If the climate warms another 5 to 8 C in Alaska, as predicted by the IPCC (2001), nearly all of the permafrost could be eliminated from this biome, causing dramatic changes in the water and carbon balance of boreal ecosystems.

The effects of permafrost degradation (thermokarst) on surface water and carbon is highly uncertain because of the spatial variability in terrain, topography, vegetation, fire regime, and permafrost characteristics. While field studies have begun to recognize the importance of thermokarst in carbon accumulation and subsequent methane emissions, current modeling approaches still assume a fairly homogenous soil landscape where thawing uniformly lowers the permafrost table and dries the soils. This assumption probably holds up well for permafrost-affected upland areas (23% of boreal landscape in Alaska), but is not valid for lowlands areas (41% of landscape), where thermokarst impounds water. Furthermore, the degradation of permafrost affects the export of carbon very differently in upland and lowland landscapes. In upland landscapes the loss of permafrost increases drainage, which eliminates or alters the seasonality of surface runoff. In contrast, thermokarst in lowland landscapes impounds water into isolated wetlands, thereby disrupting drainage and increasing storage capacity that in turn reduces runoff and increases the residence time of dissolve organic carbon in isolated wetlands. Thus, current modeling approaches neglect the varying ways in which permafrost affects water and carbon on the landscape.

To address these issues, this project will generate a new approach to modeling boreal forest systems by using research tasks designed to (1) assess interactive effects of climate change and fire on permafrost stability; (2) quantify how the varying modes of permafrost degradation initiate various thaw regimes on the landscape by affecting the microtopography, drainage, and soil thermal regimes of boreal systems; (3) determine how various thaw regimes such as drained or ponded systems affect carbon loss or accumulation in biomass and soils, and (4) characterize the export of dissolved organic carbon from watersheds in an effort to fingerprint the various thaw regimes induced by permafrost degradation. Using a replicated design, we will study age sequences of thaw history to capture changes in carbon and water over time since thaw. We will characterize temperature, moisture, water table of each thaw regime to parameterize the physical conditions of each thaw regime and will test model results based on the chemical finger print of thaw-water and on trace gas flux in one unique set of sites.

Broader Impacts: Realistic spatial biogeochemistry models must quantify the redistribution of water and carbon across the landscape that results from permafrost degradation. Process-based biogeochemistry and spatially-explicit permafrost models developed in this project will address interactions among climate, fire, permafrost, carbon and water for the boreal region. This proposal will unite modelers with field scientists. The project will be used to train a new generation of scientists in ecosystem sciences through graduate education at Purdue University and University of Alaska at Fairbanks. Public outreach will be achieved by participating in policy meetings and workshops. Project results will be communicated through scientific meetings and publications and will be distributed through Newsletters and Annual Reports of the Purdue Climate Change Research Center. In addition to the contributions to the global change research community, the knowledge of impact of permafrost degradation on ecosystem carbon and water cycling is critical to the management of fires and habitats on federal lands.

More on the project results