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Active Projects
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Title: Avoided Deforestation as a Natural Climate Solutions for the United States
Principal Investigator: Joe Fargione (The Nature Conservancy)
Co-Principal Investigator: Christopher A. Williams (Clark University)
Funding Source: US Climate Alliance subaward
Dr. Williams is involved in a scientific collaboration with The Nature Conservancy’s Science Director for North America focused on mapping opportunities to mitigate climate change with avoided deforestation. Williams’ team is providing detailed estimates of the carbon emissions that could be avoided by slowing or halting deforestation in the United States, along with high resolution maps of where forests are being lost and what they are being replaced by. Our new work will significantly improve on prior estimates with new mapping of forest losses, new assessment of deforestation emissions, detailed assessment of albedo offsets to mitigation, mapping of disturbance risks for future forests and forest carbon sequestration, and the costs of conservation for climate protection.
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Title: Decision Support Tools for Global Assessment of Albedo Impacts on Natural Climate Solutions (NCS)
Principal Investigator: Christopher A. Williams (Clark University)
Funding Source: Bezos Earth Fund award to The Nature Conservancy
Lead TNC Earth Fund Principal Investigator: Peter Ellis (The Nature Conservancy)
The project’s aim is to provide the data and decision support tools needed for quantifying the albedo component of assessments evaluating climate change mitigation opportunities from reforestation and agroforestry, avoided deforestation, and possibly also improved forest management. The work will contribute to all three science categories of the Applied Science to Catalyze Natural Climate Solutions Prime Grant – (a) global assessments of mitigation potential, (b) an online web platform that serves data to users and allows them to compare and contrast opportunities, and (c) project design and evaluation within the NCS Prototyping Network – with primary emphasis on part (a). Dr. Williams will lead the Grantee’s team in its delivery of quantitative assessments of the albedo-induced radiative forcing (RF) and associated CO2 equivalent (CO2e) emissions that would be caused by avoiding forest conversion (deforestation), reforesting (expanded forest cover), or improving forest management.
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Recently Completed Projects
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Title: Bringing Forest Carbon into Focus: Improved Estimates of Carbon Benefits from Avoided Forest Conversion in New England
Principal Investigator: Laura Marx (The Nature Conservancy, Massachusetts Chapter)
Co-Principal Investigator: Christopher A. Williams (Clark University)
Funding Source: US Climate Alliance and The Nature Conservancy
Dr. Williams is involved in a scientific collaboration with The Nature Conservancy to provide detailed estimates of the size of the opportunity of avoided deforestation as a climate change mitigation pathway for states in New England plus New York. In addition to mapping forest conversion and associated carbon emissions and lost carbon sequestration across this region, the Williams lab is engaging in extensive outreach and communications with state partners and NGOs to facilitate broader understanding of our scientific findings and to deliver actionable data products and data analyses supporting state efforts.
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Title: Natural Climate Solutions for Canada
Principal Investigator: Ronnie Drever (Nature United), Susan Cook-Patton (The Nature Conservancy)
Co-Principal Investigator: Christopher A. Williams (Clark University)
Funding Source: The Nature Conservancy
Dr. Williams is involved in a scientific collaboration with The Nature Conservancy’s carbon and climate science team focused on land management and land use solutions to mitigate climate change in Canada. Williams’ team is providing detailed estimates of the albedo offsets to carbon-related climate mitigation associated with a host of opportunities, principally those involving avoided forest losses or enhanced forest gains. This work is soon to be published in a leading science journal.
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Title: Advancing Terrestrial Carbon Cycle Models with Atmospheric Carbon Data
Principal Investigator: Ken Davis (Penn State University)
Co-Principal Investigator: Christopher A. Williams (Clark University)
Funding Source: NASA EVS2 Atmospheric Carbon Transport – America
The overarching scientific goals of ACT-America are to reduce uncertainties in both mesoscale atmospheric transport and biogenic surface carbon flux estimates using targeted aircraft measurement campaigns and a regional inversion system, and to thereby improve constraint on surface biogenic carbon fluxes and associated ecosystem model parameters. These improvements will then be transferred to a multi-year, continental-scale inversion effort that will assess the sensitivity of the Orbiting Carbon Observatory column measurements to regional variability in tropospheric CO2. The Clark team was engaged to deliver ensembles of biogenic surface carbon fluxes with the CASA model to be used as priors for both the campaign, regional effort and the longer-term continental effort. The ensemble is being generated with a perturbed parameter ensemble of key CASA model parameters to which carbon balance and fluxes are sensitive. Several papers have already been published and suite are currently in review.
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Title: Terrestrial Carbon Sinks and Enhancement from Global Change
Leads: Christopher A. Williams (Clark University Geography); Trevor Keenan (UC Berkeley)
Funding Source: N/A
The terrestrial biosphere has been shown to be a large and growing sink for atmospheric CO2, helping to slow the pace of fossil-fuel driven climate change. However, identifying where and why ecosystems are soaking up CO2 remain poorly understood. This project aims to gather diverse sources of evidence evaluating support for sink enhancement, and critically evaluating the underlying mechanisms, which is key to understanding how long this biospheric uptake of carbon might be sustained.
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Title: Vegetation Decline and Recovery from the Millennium Drought in Australia: Novel Quantitative Analysis with Multi-Sensor and Higher Resolution Data
Principal Investigator: Christopher A. Williams (Clark University)
Co-Principal Investigator: Tong Jiao, PhD student (Clark University)
Funding Source: NASA FINESST
This PhD student fellowship is supporting Tong Jiao’s dissertation studies that are assessing the extent of vegetation decline and recovery ensuing throughout the decadal scale Millennium Drought in Australia. We are documenting (a) variability in ecosystem sensitivity to drought, (b) the extent of cumulative effects from one drought to the next, (c) the occurrence of persistent decline, and (d) the determinants of ecosystem recovery post-drought.
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Title: Natural Climate Solutions for the United States
Principal Investigator: Joe Fargione, Peter Ellis, Bronson Griscom (The Nature Conservancy)
Co-Principal Investigator: Christopher A. Williams (Clark University)
Funding Source: N/A
Dr. Williams is involved in a scientific collaboration with The Nature Conservancy’s Science Director for North America focused on land management and land use solutions to mitigate climate change. Williams’ team is providing detailed estimates of the carbon emissions that could be avoided by slowing or halting deforestation in the United States, along with high resolution maps of where forests are being lost and what they are being replaced by. This work was recently published in a leading science journal.
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Title: Translating Forest Change to Carbon Emissions/Removals Linking Disturbance Products, Biomass Maps, and Carbon Cycle Modeling in a Comprehensive Carbon Monitoring Framework
Principal Investigator: Christopher A. Williams (Clark University)
Co-Principal Investigators: G. James Collatz (NASA GSFC, Biospheric Sciences); Jeffrey G. Masek (NASA GSFC, Biospheric Sciences); Gretchen Moisen (US Forest Service)
Funding Source: NASA Carbon Monitoring System
Forests are a globally-significant store of carbon, but this store is vulnerable to release from disturbance processes such as harvesting or fires that oxidize forest carbon, releasing it to the atmosphere as CO2 and contributing to global warming. At the same time, intact forests serve as a major offset to rising CO2 concentrations as forest growth becomes stimulated by rising CO2 levels, enabling forests to absorb about one third of annual carbon emissions from fossil fuels and land use change. The balance of these processes is constantly changing and it varies widely from region to region. This project aims to quantify how much carbon is being released and taken up by each process over the entire United States, providing a new method for US reporting to the United Nations Framework Convention on Climate Change.
Historical forest clearing is responsible for about one third of all human-caused carbon emissions to date, with the rest coming from the combustion of fossil fuels. Avoiding further losses and protecting carbon uptake are both critical components of mitigating climate change. National and international policies aimed at protecting forest carbon storage rely heavily on high quality, accurate reporting (called “Tier 3”) that earns the greatest financial value of carbon credits and hence incentivizes forest conservation and protection. But methods for Tier 3 Measuring, Reporting, and Verification (MRV) are still in development.
This project will offer a new approach to Tier 3 MRV, involving a combination of direct remote sensing, ground based inventorying, and computer modeling methods to track forest carbon emissions and removals at a 1 km scale across the US. Few existing approaches seek to combine all of these sources of information. Another major advantage of our approach is its specificity about the underlying processes driving carbon flows. This enables the framework to be used as a decision support tool to help test the relative benefits of various land management strategies and to examine how today’s carbon sources and sinks will trend over time.
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Title: Post-clearcut carbon, water, and energy fluxes and associated climate forcing
Principal Investigator: Christopher A. Williams (Clark University Geography)
Co-Investigators:Richa rd MacLean (Clark University Geography);
Funding Source: Clark University with additional support from NSF LTER through Harvard Forest
Ecological disturbances such as the clear cutting of forests are known to perturb ecosystem-atmosphere exchanges of water, carbon and energy in profound ways. However, the degree, character, and persistence of such perturbations are largely unknown but have important long-term implications for a host of ecosystem services such as carbon sequestration, wildlife habitat, and climate regulation. This project’s main objective is to quantify the full climate impacts of forest disturbances including the net ecosystem carbon balance, and energy and water forcings on atmospheric warming.
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Title: Albedo Trends Related to Land Cover Change and Disturbance: A Multi-sensor Approach
Principal Investigator: Jeffrey Masek (NASA GSFC Biospheric Sciences)
Co-Investigator: Feng Gao, Yanmin Shuai (Earth Resources Technology, Inc.)
Co-Is / Institutional PIs: Crystal Schaaf (Boston University Geography); Christopher A. Williams (Clark University Geography)
Funding Source: NASA The Science of Terra and Aqua
Numerous papers have highlighted how land-cover change and ecosystem disturbance can alter the surface energy balance through changes in albedo, surface roughness, and evapotranspiration. In some cases, these surface changes may constitute a larger radiative forcing than those arising from related carbon emissions. Past studies on post-disturbance albedo have been limited by the resolution of available MODIS data (500m), which is significantly coarser than the characteristic scales of ecosystem disturbance and human land use. Our project addresses this issue by creating high-resolution (30m) albedo maps through the fusion of Landsat TM/ETM+ directional reflectance with MODIS BRDF/Albedo (MCD43A) data. These maps permit trends in albedo to be evaluated at the characteristic scale of vegetation change (~1 ha).
Two algorithms are proposed to retrieve Landsat-resolution albedo: a “concurrent approach” which depends on overlapping MODIS and Landsat observations from the 2000-2010 period, and an “extended approach”, which uses an a priori BRDF table to extend retrievals back to the 1980’s. These fused products will be validated using in-situ Baseline Surface Radiation Network (BSRN) data. We will then evaluate the albedo trajectories for characteristic types of land cover conversion and disturbance across the globe. Specifically, we will (i) assemble a regional library of albedo values for IGBP land cover types; (ii) assemble time series of post-disturbance albedo from a latitudinal distribution of typical forest disturbance types (fire, insect damage, harvest); (iii) evaluate decadal trends in landscape albedo for “hotspots” of vegetation change; and (iv) assess the radiative forcing associated with historical (since 1700) and future (scenario-based) global land-cover change.
The outcome of the investigation will be an improved quantification of recent and historical albedo changes associated with land cover change and forest disturbance. Such information is needed to reduce uncertainties present in the current IPCC WG1 radiative forcing budget, and to forecast the effects of land management and land cover conversion on future climate.
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Title: Impacts of Disturbance History on Carbon Fluxes and Stocks in North America
Principal Investigator: G. James Collatz (NASA GSFC, Biospheric Sciences)
Co-Principal Investigators: Jeffrey G. Masek (NASA GSFC, Biospheric Sciences), Christopher A. Williams (Clark University)
Funding Source: NASA Terrestrial Ecology
Forests of North America are thought to constitute a significant long term sink for atmospheric carbon but the relative importance of underlying mechanisms is poorly understood. This project seeks to clarify mechanisms and quantify spatial and temporal variability in forest carbon sinks. The work extends a previously NASA-funded project that involved the development of a new modeling framework characterizing carbon consequences of forest disturbance and regrowth based on Forest Inventory and Analysis (FIA) data and remote sensing (Landsat) of forest disturbances. Prior results quantify with greater certainty the regrowth carbon sink in the conterminous US, indicating that it is about half of what is generally quoted. This current research project continues to develop and advance the modeling framework by delving deeper into the mechanisms and intensity of documented disturbances using the improved NAFD products, the Monitoring Trends in Burn Severity fire data set, and forest insect damage data sets. In addition, we are engaged in a broader synthesis on the subject by integrating perspectives from flux towers, forest inventories, satellite remote sensing, ecosystem carbon modeling, and atmospheric inversions. We are exploring: (1) mechanistic attribution of forest carbon sinks to disturbance legacies versus growth enhancements; (2) spatial patterns of the continent’s process-specific sources and sinks; (3) interannual fluctuations in forest carbon sources and sinks; and (4) implications for managing forests to sequester carbon. From this new work we will provide more accurate estimates of the carbon fluxes and stocks and their implications on current and future atmospheric CO2 concentrations.
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Title: Quantification of the regional impact of terrestrial processes on the carbon cycle using atmospheric inversions
Principal Investigator: Ken Davis (Penn State Atmospheric Sciences)
Co-Investigators: Christopher A. Williams (Clark University); G. James Collatz (NASA GSFC, Biospheric Sciences); Tristram West (Pacific Northwest National Lab); Stephen Ogle (Colorado State University Natural Resource Ecology Lab); Andrew Schuh (Colorado State University Atmospheric Sciences); Natasha Miles (PSU); Scott Richardson (PSU); Thomas Lauvaux (PSU); Martha Butler (PSU)
Funding Source: NASA Carbon Cycle Science
This project is examining the carbon balance of the southeastern US by adding new precision measurements of atmospheric CO2 concentrations in a regional network to inform advanced inverse modeling that can infer sinks and sources of carbon dioxide from measured concentrations in the atmosphere. This top-down approach will be combined with measurements and modeling of carbon fluxes from the ground up to examine consistency and explore possible biases in the various data sources.
Forests of the southeastern US are important for the North American carbon balance because the region is highly productive, is vigorously managed with intensive timber harvest, is sensitive to climate change, and is periodically inundated by severe storms that kill trees. The region also contains a pockets of intensive agricultural lands along with a range of urban and suburban hotspots of emissions. By combining a range of measurement and modeling approaches, this project will improve quantification of these carbon sources and sinks.
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Title: Carbon Dioxide and Water Flux Response to Extreme Weather and Climate Anomalies: A Fluxnet Syntheses
Principal Investigator: Christopher Williams
Funding Agency: National Science Foundation
In this project researchers will perform a synthesis motivated by findings at individual flux tower sites that extreme weather and climate events (e.g., droughts, floods, hurricanes, and ice-storms) lead to pronounced and protracted anomalies in key components of the measured local carbon and water budgets. The PIs will assess the degree of commonality across flux tower sites in the response of the ecosystem to extreme events, derive a coherent description of these responses, and use remote sensing data to extrapolate spatially coherent and persistent impacts on ecosystems, specifically on vegetation, that subsequently may impact carbon and water balances and climate trajectories on a larger spatial scale. The PIs will also assess the ability of land surface models spanning a wide range of complexity to simulate the observed response of terrestrial state variables and fluxes to extreme events when driven by observed meteorology. The project is composed entirely of a team of early-career scientists.
This work is supported under the NSF Carbon and Water in the Earth System solicitation, an interdisciplinary funding opportunity from the Directorate of Geosciences.