Department of Geography (DoG) News and Events Where it's at!

IMAGE OF THE WEEK

Dry forest margins in the western United States may be more resilient to climate change than previously thought if managed appropriately, according to a study published by Lucas Harris and Alan Talyor in Ecosphere. See news story. Image: Lucas Harris.

GOOD NEWS

Jiayan Zhao successfully defended his dissertation on September 21.

Call for maps: Shelter: An Atlas endeavors to map shelter in its myriad contexts and conditions and at all scales of research and geography. As a project of Guerrilla Cartography, Shelter: An Atlas is a non-profit venture and will be financed through crowd-funding and grants. Money raised to fund the project will finance the printing and distribution of a full-color 12” x 12” bound volume.  All maps are due October 31, 2020, 11:59 PM PST. See submission guidelines here. 

Today, September 22 is National Bike There Day, part of Bike There Week, September 21–27, 2020, promoted by the League of American Bicyclists and Centre Regional Planning Agency.

September 25, the Thinking Spatially symposium will explore the topics of politics and polarization. The symposium is for everyone interested in politics, partisanship, idealism, voting patterns, racism, civil rights, community development, mapping, and more. View the full schedule, featured presenters, and register to attend. 9 a.m.-noon, via Zoom.

Anthony Robinson will serve as a panelist on the topic, “Social Engineering with Data: Disinformation & Destabilization of Geo-Political Order” at The Institute for Computational Data Sciences virtual symposium, “The Data Deluge: Opportunities and Challenges,” on October 22–23. Registration is open.

COFFEE HOUR

Coffee Hour with Qiusheng Wu
Using Google Earth Engine for interactive mapping and analysis of large-scale geospatial datasets

• 4:00 p.m., Friday, September 25, 2020
• Coffee Hour to Go on Zoom

Google Earth Engine is a free cloud computing platform with a multi-petabyte catalog of satellite imagery and geospatial datasets. During the past few years, Earth Engine has become very popular in the geospatial community and it has been used for numerous environmental applications at local, regional, and global scales. In this presentation, I will first introduce the geemap Python package (https://giswqs.github.io/geemap) for interactive mapping and analysis with Earth Engine. Then, I will introduce the Earth Engine plugin for QGIS along with 300+ Python examples. Lastly, I will demonstrate how Earth Engine can be used for automated mapping of surface water and wetland inundation dynamics with 1-m resolution aerial imagery and LiDAR data.

NEWS

Forest margins may be more resilient to climate change than previously thought

A warming climate and more frequent wildfires do not necessarily mean the western United States will see the forest loss that many scientists expect. Dry forest margins may be more resilient to climate change than previously thought if managed appropriately, according to Penn State researchers.

RECENTLY PUBLISHED

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

Seroussi, S. Nowicki, A. Payne, H. Goelzer, W. Lipscomb, A. Abe-Ouchi, C. Agosta, T. Albrecht, X. Asay-Davis, A. Barthel, R. Calov, R. Cullather, C. Dumas, B.. Galton-Fenzi, R. Gladstone, N. Golledge, J. Gregory, R. Greve1, T. Hattermann, M. Hoffman, A. Humbert, P. Huybrechts, N. Jourdain, T. Kleiner, E. Larour, G. Leguy, D. Lowry, C. Little, M. Morlighem, F. Pattyn, T. Pelle, S. Price, A. Quiquet, R. Reese, N. Schlegel, A. Shepherd, E. Simon, R. Smith, F. Straneo, S. Sun, L. Trusel, J. Van Breedam, R. van de Wal, R. Winkelmann, C. Zhao, T. Zhang, and T. Zwinger.
The Cryosphere
https://doi.org/10.5194/tc-14-3033-2020
Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and assess the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimates of the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes, forcings employed and initial states of ice sheet models. This study presents results from ice flow model simulations from 13 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015–2100 as part of the Ice Sheet Model Intercomparison for CMIP6 (ISMIP6). They are forced with outputs from a subset of models from the Coupled Model Intercomparison Project Phase 5 (CMIP5), representative of the spread in climate model results. Simulations of the Antarctic ice sheet contribution to sea level rise in response to increased warming during this period varies between −7.8 and 30.0 cm of sea level equivalent (SLE) under Representative Concentration Pathway (RCP) 8.5 scenario forcing. These numbers are relative to a control experiment with constant climate conditions and should therefore be added to the mass loss contribution under climate conditions similar to present-day conditions over the same period. The simulated evolution of the West Antarctic ice sheet varies widely among models, with an overall mass loss, up to 18.0 cm SLE, in response to changes in oceanic conditions. East Antarctica mass change varies between −6.1 and 8.3 cm SLE in the simulations, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional simulated mass loss of 28 mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the climate forcing, the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 climate models show an additional mass loss of 0 and 3 cm of SLE on average compared to simulations done under present-day conditions for the two CMIP5 forcings used and display limited mass gain in East Antarctica.

The Effects of Visual Realism on Spatial Memory and Exploration Patterns in Virtual Reality

Jiawei Huang and Alexander Klippel
26th ACM Symposium on Virtual Reality Software and Technology (VRST ’20) https://doi.org/10.1145/3385956.3418945
Understanding the effects of environmental features such as visual realism on spatial memory can inform a human-centered design of virtual environments. This paper investigates the effects of visual realism on object location memory in virtual reality, taking account of individual differences, gaze, and locomotion. Participants freely explored two environments which varied in visual realism, and then recalled the locations of objects by returning the misplaced objects back to original locations. Overall, we did not find a significant relationship between visual realism and object location memory. We found, however, that individual differences such as spatial ability and gender accounted for more variance than visual realism. Gaze and locomotion analysis suggest that participants exhibited longer gaze duration and more clustered movement patterns in the low realism condition. Preliminary inspection further found that loco-motion hotspots coincided with objects that showed a significant gaze time difference between high and low visual realism levels. These results suggest that high visual realism still provides positive spatial learning affordances but the effects are more intricate.

IMAGE OF THE WEEK

Friday, Sept. 11 was the kickoff Coffee Hour lecture for the fall 2020 semester.  If you missed it and would like to view the recording of Kaitlin Harbeck’s talk on ICESaT-2 or view any previously recorded Coffee Hour lectures, you can go to the Department of Geography Coffee Hour Channel. Each recent semester of Coffee Hour is saved as a playlist, so you can easily find the speaker or topic of interest.

GOOD NEWS

Mikael Hiestand was quoted in the article, “Introducing Students to Scientific Python for Atmospheric Science,” in the September 2020 issue of the Bulletin of the American Meteorological Society.

Welcome to Tatiana Gumucio who has joined as a post-doctoral scholar on Helen Gretrex’s AXA-XL grant on humanitarian weather response in Somalia.

COFFEE HOUR

Coffee Hour with Qiusheng Wu is on Friday, September 25, 2020
Using Google Earth Engine for interactive mapping and analysis of large-scale geospatial datasets

Google Earth Engine is a free cloud computing platform with a multi-petabyte catalog of satellite imagery and geospatial datasets. During the past few years, Earth Engine has become very popular in the geospatial community and it has been used for numerous environmental applications at local, regional, and global scales.

NEWS

Peirce F. Lewis, 1927–2018

by Ben Marsh & Joseph Wood in the Annals of the American Association of Geographers

All geography rests, finally, upon the land. Few geographers have stayed as connected to the land throughout their professional careers as Peirce F. Lewis, few relished the immediacy of being in the field more than he did, and few imbued that deep love into as many students and students-of-students as he was able to. Land is in the very name of the discipline that he championed for over five decades: cultural landscape. That term refers to the world of human experience, “nearly everything we can see when we go outdoors” (Lewis 1979a, 12).

50+ years of Coffee Hour

Fall 2018 was the fiftieth anniversary of the Department of Geography Coffee Hour, weekly socializing and a lecture on Friday afternoons. Although the methods have modernized, Coffee Hour remains true to its purpose, which Peirce Lewis and Wilbur Zelinksy described in a 1987 article in the Professional Geographer as “creating and preserving a sense of intellectual and social community within the department.”

RECENTLY PUBLISHED

Desktop versus immersive virtual environments: effects on spatial learning

Jiayan Zhao, Tesalee Sensibaugh, Bobby Bodenheimer, Timothy P. McNamara, Alina Nazareth, Nora Newcombe, Meredith Minear & Alexander Klippel
Spatial Cognition & Computation
DOI: 10.1080/13875868.2020.1817925
Although immersive virtual reality is attractive to users, we know relatively little about whether higher immersion levels increase or decrease spatial learning outcomes. In addition, questions remain about how different approaches to travel within a virtual environment affect spatial learning. In this paper, we investigated the role of immersion (desktop computer versus HTC Vive) and teleportation in spatial learning. Results showed few differences between conditions, favoring, if anything, the desktop environment. There seems to be no advantage of using continuous travel over teleportation, or using the Vive with teleportation compared to a desktop computer. Discussing the results, we look critically at the experimental design, identify potentially confounding variables, and suggest avenues for future research.

Automatic detection of volcanic surface deformation using deep learning

Sun, J., Wauthier, C., Stephens, K., Gervais, M., Cervone, G., La Femina, P., & Higgins, M.
Journal of Geophysical Research: Solid Earth
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JB019840
Interferometric Synthetic Aperture Radar (InSAR) provides subcentimetric measurements of surface displacements, which are key for characterizing and monitoring magmatic processes in volcanic regions. The abundant measurements of surface displacements in multitemporal InSAR data routinely acquired by SAR satellites can facilitate near real‐time volcano monitoring on a global basis. However, the presence of atmospheric signals in interferograms complicates the interpretation of those InSAR measurements, which can even lead to a misinterpretation of InSAR signals and volcanic unrest. Given the vast quantities of SAR data available, an automatic InSAR data processing and denoising approach is required to separate volcanic signals that are cause of concern from atmospheric signals and noise. In this study, we employ a deep learning strategy that directly removes atmospheric and other noise signals from time‐consecutive unwrapped surface displacements obtained through an InSAR time series approach using an end‐to‐end convolutional neural network (CNN) with an encoder‐decoder architecture, modified U‐net. The CNN is trained with simulated synthetic unwrapped surface displacement maps and is then applied to real InSAR data. Our proposed architecture is capable of detecting dynamic spatio‐temporal patterns of volcanic surface displacements. We find that an ensemble‐average strategy is recommended to stabilize detected results for varying deformation rates and signal‐to‐noise ratios (SNRs). A case study is also presented where this method is applied to InSAR data covering Masaya volcano, Nicaragua and the results are validated using continuous GPS data. The results confirm that our network can indeed efficiently suppress atmospheric and other noise to reveal the noise‐free surface deformation.

IMAGE OF THE WEEK

NASA’s Ice, Cloud and land Elevation Satellite-2 (ICESat-2) was launched in September 2018 and became the highest-resolution laser altimeter ever operated from space. The satellite is now measuring the height of Earth’s surfaces in remarkable detail. A forested hillside in Mexico is visible in the elevation measurement above, acquired on October 19, 2018, by the Advanced Topographic Laser Altimeter System (ATLAS) on ICESat-2. For reference, the orbital path is laid over a natural-color image acquired on January 11, 2017, by the Operational Land Imager (OLI) on Landsat 8. Learn more about ICESat-2 at Coffee Hour on Friday, Sept. 11, with our speaker, Penn State Geography alumna Kaitlin Harbeck.

GOOD NEWS

The undergraduate clubs in the Department of Geography, GIS Coalition, Gamma Theta Upsilon, and UnderDoGS are holding combined meetings on Zoom this semester. The next meeting is on Monday, Sept. 14 at 7:30 p.m.

Alumna Sheryl Kron Larson-Rhodes, who earned a bachelor of science in 1985, received a State University of New York (SUNY) Chancellor’s Award for Excellence in Librarianship. The Chancellor’s Awards are “honors conferred to acknowledge & provide recognition for consistently superior professional achievement & to encourage the ongoing pursuit of excellence.” Larson-Rhodes is among nine librarians from SUNY’s 64 campuses to receive the Chancellor’s Award for the 2019–2020 academic year. She serves as the First Year Experience Librarian at SUNY Geneseo, & among the college departments she supports is (of course!) Geneseo’s Department of Geography, which in 2018 received the Award for Bachelors Program Excellence from the American Association of Geographers.

COFFEE HOUR

Coffee Hour with Kaitlin Harbeck
ICESat2 – Measuring the Height of the Earth One Photon at a Time

• Friday, September 11, 2020
• Coffee Hour to Go on Zoom

NASA’s next generation laser altimeter mission, the Ice, Cloud and Land Elevation Satellite-2 (ICESat-2), launched on 15 September 2018, carrying the Advanced Topographic Laser Altimeter System (ATLAS) as its sole payload. ATLAS is a photon-counting lidar that directs laser beams (532 nm) at the Earth’s surface, fires a stream of light 10,000 times per second, and measures the distance between the illuminated ground surface and the instrument by precisely measuring individual photon times of flight.

NEWS

Bacastow appointed to US Geospatial Intelligence Foundation board of directors

Todd Bacastow, teaching professor in the College of Earth and Mineral Sciences at Penn State, has been appointed to the board of directors of the United States Geospatial Intelligence Foundation (USGIF) for a three-year term.

USGIF is a non-profit organization dedicated to promoting geospatial intelligence training and education and building a stronger community of interest across industry, academia, government, professional organizations and individual stakeholders. Since 2007, Bacastow has also served as a member of USGIF’s Academic Planning Committee.

RECENTLY PUBLISHED

Woody plant diversity changes of Abies-Tsuga forests during the natural regeneration of arrow bamboo (Bashania faberi) in the Wolong Nature Reserve

Zhu, T., Jinyan, H., Dian, L., Taylor, A.H., Hemin, Z.
Chinese Journal of Applied and Environmental Biology
DOI: 10.19675/j.cnki.1006-687x.2019.05002
We examined the response of woody plants to internal forest disturbance during subalpine succession and its underlying driving mechanism by comparing changes in woody plant diversity of Abies-Tsuga forests after the flowering and die-back of arrow bamboo (Bashania faberi). We calculated species diversity indices (a-diversity and β-diversity) for the survey data from six fixed plots in the area of the Wolong Nature Reserve, Sichuan Province, from 1984 and 2013 to understand changes in flora and species diversity over time, including the pro-phases and post-phases of the bamboo regeneration and restoration. The results showed that species and the diversity indices of the trees in the Abies-Tsuga forests did not change significantly before or after the regeneration and restoration of arrow bamboo but maintained relatively stable state (P > 0.05). In contrast, species diversity and the importance values of shrubs changed significantly between the pro-phase and postphase of the regenerative and restorative periods, and the species composition and diversity indices of the Abies-Tsuga forests slightly increased (P < 0.05). Variation was seen in woody plant tree diversity patterns, as changes in the tree species of the sample plots below 3000 m above sea level were small, but a significant change was seen in the sample plots above 3000 m above sea level. In contrast, the diversity of shrubs was significantly different among all plots and showed a slight increasing trend. At the same time, there were no significant differences in the tree species diversity of the Abies-Tsuga forests between different sites before or after the regeneration and restoration of arrow bamboo. Shrubs were significantly different with each other during the early stage. Only several plots and several indices were significantly altered during the later stage, and the rest presented no significantly statistical effects. In a word, these results reflect the stability of the species composition in climax communities, the variability of the species diversity of Abies-Tsuga forests during the process of bamboo regeneration and restoration, and the adaptation of diverse types of plants (e.g., tree species and shrubs) to environmental changes. This provides a basis for developing strategies for biodiversity conservation and the ecological restoration of wild giant panda habitats.

Strong Legacy Effects of Prior Burn Severity on Forest Resilience to a High-Severity Fire.

Harris, L.B., Drury, S.A. & Taylor, A.H.
Ecosystems
https://doi.org/10.1007/s10021-020-00548-x
Legacy effects from one disturbance may influence successional pathways by amplifying or buffering forest regeneration after the next disturbance. We assessed vegetation and tree regeneration in non-serotinous Sierra lodgepole pine (Pinus contorta var. murrayana) stands after a 1984 wildfire which burned with variable severity and again after a high-severity subsequent fire in 2012. The legacy effects of the 1984 fire were amplified; seedlings and saplings were abundant in areas initially burned at low severity (1267 stems ha⁻¹) despite high reburn severity, but regeneration was low in areas twice burned at high severity (31 stems ha⁻¹). Our results suggest that the severity of the 1984 fire may have influenced post-2012 tree regeneration by creating variable fuel loading, which may have affected soils, litter cover and shade after the 2012 fire and therefore affected seedling establishment and survival. A canopy seed bank of unburnt cones from trees killed by the 2012 fire potentially contributed to a strong effect of prior burn severity on regeneration after the 2012 fire despite a lack of serotinous or resprouting tree species, although the influence of this canopy seedbank was likely limited to the year following the fire. Our results suggest that a low- to moderate-severity fire increases forest resilience relative to a high-severity fire even when the next fire burns at high severity.

Quantifying spatiotemporal variability of glacier algal blooms and the impact on surface albedo in southwestern Greenland

Shujie Wang, Marco Tedesco, Patrick Alexander, Min Xu, and Xavier Fettweis
The Cryosphere
https://doi.org/10.5194/tc-14-2687-2020
Albedo reduction due to light-absorbing impurities can substantially enhance ice sheet surface melt by increasing surface absorption of solar energy. Glacier algae have been suggested to play a critical role in darkening the ablation zone in southwestern Greenland. It was very recently found that the Sentinel-3 Ocean and Land Colour Instrument (OLCI) band ratio R_709 nm∕R_673 nm can characterize the spatial patterns of glacier algal blooms. However, Sentinel-3 was launched in 2016, and current data are only available over three melting seasons (2016–2019). Here, we demonstrate the capability of the MEdium Resolution Imaging Spectrometer (MERIS) for mapping glacier algae from space and extend the quantification of glacier algal blooms over southwestern Greenland back to the period 2004–2011. Several band ratio indices (MERIS chlorophyll a indices and the impurity index) were computed and compared with each other. The results indicate that the MERIS two-band ratio index (2BDA) R_709 nm∕R_665 nm is very effective in capturing the spatial distribution and temporal dynamics of glacier algal growth on bare ice in July and August. We analyzed the interannual (2004–2011) and summer (July–August) trends of algal distribution and found significant seasonal and interannual increases in glacier algae close to the Jakobshavn Isbrae Glacier and along the middle dark zone between the altitudes of 1200 and 1400 m. Using broadband albedo data from the Moderate Resolution Imaging Spectroradiometer (MODIS), we quantified the impact of glacier algal growth on bare ice albedo, finding a significant correlation between algal development and albedo reduction over algae-abundant areas. Our analysis indicates the strong potential for the satellite algal index to be used to reduce bare ice albedo biases in regional climate model simulations.

IMAGE OF THE WEEK

Keeping communities safe will take a collective effort. Help us spread the word to colleagues, family, friends and neighbors by taking a picture wearing a mask, posting to social media, and using the hashtag #MaskUpOrPackUp.

GOOD NEWS

Alumna Lettice Brown of York, Pa., who completed a bachelor of science in geography in 2006, was recently featured in an Allegheny Front story, “Nature Groups Address Environmental Justice in Pennsylvania.”

Mikael Hiestand will speak as part of the fall 2020 Climate Dynamics seminar series, on the topic, “Annual variations in latent and sensible heat fluxes under differing synoptic regimes in the U.S. Corn Belt,” on Sept. 30, from 11:15 a.m. to 12:30 p.m. via Zoom. For more information and link.

Thabiti Willis of Carleton College will speak as part of the African Studies Program fall 2020 speakers series on  “From East Africa to the Persian Gulf: Mapping Journeys of Slavery and Freedom in the Western Indian Ocean Region,” Sept. 9, at 12:30 p.m. All events will be live-streamed on Zoom. Links for the talks will be sent via email in advance of each presentation.

The AAG’s call for papers is now open. Anyone with an interest in geography may submit an abstract of up to 250 words, describing their presentation’s purpose, methods, and conclusions. Find out details on how to submit.

The undergraduate clubs in the Department of Geography: GIS Coalition, Gamma Theta Upsilon, and UnderDoGS are holding combined meetings on Zoom this semester. The next meeting is on Sept. 14 at 7:30 p.m.

NEWS

Students learn the power of collective voice while advocating for justice

Students discovered the power of community voice while working as interns over the summer through a social justice program facilitated by the Penn State Center Philadelphia, a Penn State Outreach service. Jaqueline Saleeby and Mackenzie Flanders both pivoted from their summer projects to assisting in the organization of a virtual symposium for the Penn State community that will be held in September and is focused on racial justice.

18 new NSF graduate researchers join the ranks at Penn State

Geographer Jeremy Diaz is among the new fellows

Eighteen students were named National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP) recipients for the 2020-21 academic year.

Faculty funded to study how people’s movement impacts COVID-19 transmission

Nita Bharti, Lloyd Huck Early Career Professor and assistant professor of biology at Penn State, and her collaborator Anthony Robinson, associate professor of geography at Penn State, have been awarded seed funding from the Huck Institutes of the Life Sciences at Penn State to study how monitoring the movement of people can potentially be used as a predictor or early indicator of COVID-19 transmission and guide health policy decisions.

RECENTLY PUBLISHED

Disclosing Influence: Hydraulic fracturing, interest groups, and state policy processes in the United States

Jennifer Baka, Arielle Hesse, Kate J. Neville, Erika Weinthal, Karen Bakker
Energy Research & Social Science
https://doi.org/10.1016/j.erss.2020.101734
This paper examines copy-and-paste regulating in hydraulic fracturing (HF) fluid disclosure regulation across US states. Using text analysis, cluster analysis and document coding, we compare HF regulations of twenty-nine states and two “model bills” drafted by the conservative American Legislative Exchange Council (ALEC) and the Environmental Defense Fund (EDF, an environmental NGO). In contrast to recent studies that have documented ALEC’s widespread influence across policy domains, we find limited evidence of ALEC influence in HF fluid disclosure regulations. Instead, elements of the EDF bill are more prevalent across state regulations. Yet, text similarity scores between states are higher than similarity scores between states and the EDF bill. In particular, Colorado and to a lesser extent Pennsylvania functioned as leader states for other states to follow. This indicates that state-to-state communication was a more influential channel of policy diffusion than interest group model bills in this instance. Future research should better examine processes of information sharing amongst state oil and gas regulators as regulatory text is but one channel of policy diffusion. The cluster analysis also reveals that contiguous states, often within the same shale basins, frequently have different regulations. This finding calls for a reconsideration of the current state-led environmental regulatory framework for HF, which has resulted in a patchwork of regulations across the US. Finally, through the use of novel text analysis tools, this paper adds methodological diversity to the study of policy diffusion within energy policy.

Robust paths to net greenhouse gas mitigation and negative emissions via advanced biofuels

John L. Field, Tom L. Richard, Erica A. H. Smithwick, Hao Cai, Mark S. Laser, David S. LeBauer, Stephen P. Long, Keith Paustian, Zhangcai Qin, John J. Sheehan, Pete Smith, Michael Q. Wang, Lee R. Lynd
Proceedings of the National Academy of Sciences
https://doi.org/10.1073/pnas.1920877117
Biofuel and bioenergy systems are integral to most climate stabilization scenarios for displacement of transport sector fossil fuel use and for producing negative emissions via carbon capture and storage (CCS). However, the net greenhouse gas mitigation benefit of such pathways is controversial due to concerns around ecosystem carbon losses from land use change and foregone sequestration benefits from alternative land uses. Here, we couple bottom-up ecosystem simulation with models of cellulosic biofuel production and CCS in order to track ecosystem and supply chain carbon flows for current and future biofuel systems, with comparison to competing land-based biological mitigation schemes. Analyzing three contrasting US case study sites, we show that on land transitioning out of crops or pasture, switchgrass cultivation for cellulosic ethanol production has per-hectare mitigation potential comparable to reforestation and severalfold greater than grassland restoration. In contrast, harvesting and converting existing secondary forest at those sites incurs large initial carbon debt requiring long payback periods. We also highlight how plausible future improvements in energy crop yields and biorefining technology together with CCS would achieve mitigation potential 4 and 15 times greater than forest and grassland restoration, respectively. Finally, we show that recent estimates of induced land use change are small relative to the opportunities for improving system performance that we quantify here. While climate and other ecosystem service benefits cannot be taken for granted from cellulosic biofuel deployment, our scenarios illustrate how conventional and carbon-negative biofuel systems could make a near-term, robust, and distinctive contribution to the climate challenge.