Conference Agenda

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Session Overview
Session
107RB: Assessing, modelling, and analysing land use and land management impacts on the Earth system - Part B, including historical analyses
Time:
Thursday, 25/Apr/2019:
1:30pm - 3:00pm

Session Chair: Karlheinz Erb
Location: UniS-A 003
UniS Building, Auditorium A 003, ground floor, 178 seats + 54 seats on gallery on first floor
Session Topics:
What are the visions for the planetary land system?

Session Abstract

Currently, by far more than half of the Earth’s ice-free land surface are managed by humans for the provision of essential resources and services such as food, fibre, energy, and living space for about 7 billion people. These activities affect key processes of the Earth system, including biogeochemical and biophysical properties of the biosphere, and result in daunting sustainability challenges such as climate change or biodiversity loss. A central prerequisite to overcome these sustainability challenges is an improved understanding of the complex and dynamic interactions between the various Earth system components, as well as the various and ubiquitous influence of human activities.

Many remaining unknowns, however, relate to the extent and degree of human impacts on the natural components of the Earth system. While a relatively robust body of knowledge exists on the effect of land-cover conversions (i.e. the land-use induced change from one land cover type to another, for example deforestation), land-use activities that result in changes that occur within the same land-cover type (denoted “land management”) remain much less analysed. However, well-established insights, e.g. on the effects of fertilization or harvest activities, have been reinforced by recent evidence, suggesting the magnitude of management impacts to be substantial and of global proportion. Thus, omitting land management in assessing the role of land use in the Earth system may result in substantial difficulties to elucidate spatiotemporal dynamics and patterns of crucial Earth System processes. Furthermore, an improved understanding of management impacts on the Earth system is required to exploit the possibly large potentials of land use in mitigating the sustainability challenges while at the same time avoiding massive trade-offs or target conflicts that may reduce or even overturn the benefits of such strategies.

Two interacting impediments are responsible for this at least partial neglect: First, major knowledge gaps exist in our qualitative and quantitative understanding of the biogeochemical and biophysical impacts of land management. Second, substantial data gaps on the magnitude and pattern of various management practices prevail. This session assembles contributions that address these currently prevailing impediments in research from a multitude of disciplinary perspectives and spatio-temporal scales, including Earth System modelling, socioecological accounting or ecological case study research. It presents empirical and conceptual approaches aimed at assessing, modelling and analysing the impacts of land management on various components of the Earth system and will discuss novel approaches and databases. These findings are put into context of land use as a tool to mitigate sustainability challenges such as climate change. A particular focus will be on the trade-offs, but also synergies, that emerge when land-management is employed in such strategies.


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Presentations
Full talk
ID: 656 / 107RB: 1
107R Assessing, modelling, and analysing land use and land management impacts on the Earth system
Keywords: past land use change, land management, biogeophysical reconstruction

An historical data-driven reconstruction of land use change-induced impacts on temperature

Edouard Davin

ETH Zurich, Switzerland

An historical data-driven reconstruction of land use change-induced impacts ontemperature

Edouard Davin et al.

Land Use Change (LUC) has profoundly transformed the earth’s surface with biogeochemical (e.g. CO2 emissions) and biogeophysical (e.g. direct surface temperature effect resulting from albedo and evapotranspiration changes) consequences for climate. Historical reconstructions of LUC-induced carbon emissions based on bookkeeping models already exist (1,2). However there are still no data-driven estimates of the associated biogeophysical effect at the global scale, thus hindering a complete understanding of LUC influence on climate. The need for such reconstructions is particularly acute given that model-based estimates disagree on the sign and magnitude of past biogeophysical changes (3).

Here we use new observation-based estimates of the local temperature effect of various land conversions (4,5) combined with LUC reconstructions over the last millennium to derive a transient, high-resolution reconstruction of LUC-induced impacts on local surface temperature. We estimate the relative contributions of different types of LUC processes including land conversions (e.g. de/reforestation) and land management (e.g. irrigation and forest management). We further quantify uncertainties in the reconstruction using various combinations of biogeophysical and historical LUC data. The results show that in many hotspot regions, LUC has impacted surface temperature trends in the same proportion as CO2-induced climate change. Deforestation emerges as the main driver of these past changes, although in some regions irrigation had also an essential role. The conversion from natural grassland to cropland appears as the largest source of uncertainty in the reconstruction.

References:

(1) Houghton, R. A. and Nassikas, A. A.: Global and regional fluxes of carbon from land use and land cover change 1850–2015, Global Biogeochem. Cy., 31, 456–472, 2017

(2) Hansis, E., Davis, S. J., and Pongratz, J.: Relevance of methodological choices for accounting of land use change carbon fluxes, Global Biogeochem. Cy., 29, 1230–1246, 2015

(3) Lejeune, Q., S. I. Seneviratne, and E. L. Davin, 2016: Comparative assessment of mid-latitude land cover change effects on temperature in historical LUCID and CMIP5 simulations. Submitted to J.Climate.

(4) Duveiller, G., Hooker, J., and Cescatti, A.: The mark of vegetation change on Earth’s surface energy balance, Nat. Commun., 9, https://doi.org/10.1038/s41467-017-02810-8, 2018.

(5) Bright, R. M., Davin, E. L., O’Halloran, T., Pongratz, J., Zhao, K., and Cescatti, A.: Local temperature response to land cover and management change driven by non-radiative processes, Nat. Clim. Change, 7, 296–302, https://doi.org/10.1038/nclimate3250, 2017



Full talk
ID: 260 / 107RB: 2
107R Assessing, modelling, and analysing land use and land management impacts on the Earth system
Keywords: double cropping, land sparing, cropping intensity, harvest frequency, land use intensity, global crop production

Multiple cropping systems of the world and the potential for increasing cropping intensity

Katharina Waha1, Jan Philipp Dietrich2, Felix T. Portmann3, Stefan Siebert4,5, Philip K. Thornton6,7, Alberte Bondeau8, Mario Herrero1

1Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia; 2Potsdam Institute for Climate Impact Research (PIK), Germany; 3Goethe University Frankfurt, Germany; 4University of Göttingen, Germany; 5University of Bonn, Germany; 6CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), Kenya; 7International Livestock Research Institute (ILRI), Kenya; 8Institut Mediterraneen de Biodiversite et d’Ecologie marine et continentale (IMBE), France

Multiple cropping, defined as harvesting more than once a year, is an important characteristic of land management in tropical and subtropical agriculture. It can increase global crop production and spare land for other uses. However, the spatial patterns and extent of different multiple cropping systems has not been assessed so far. Here, we develop a framework for mapping multiple cropping systems globally to bridge this substantial data gap on the magnitude and pattern of harvest intensity.

We find multiple cropping systems on 134.5 Mha of global cropland (12%), 130.4 Mha under double cropping and 4.1 Mha under triple cropping. The majority of multiple cropping areas are located in East Asia (44.1 Mha) and South Asia (37.8 Mha), and in the lower middle income countries (91.3 Mha). 34%, 13% and 10% of the rice, wheat and maize area, respectively are under multiple cropping, demonstrating the importance of such cropping systems for cereal production. Harvesting current single cropping areas a second time could increase global harvested areas by 90-395 Mha, which is > 45% lower than previous estimates. Still, it could be enough land to avoid expanding physical cropland into other land uses but could come with high environmental costs and will depend on the crop yields attainable in the second cycle.

We envision future research to integrate the data set into global crop, agricultural or Earth System models and further analysis could include: (i) studying the biogeochemical interactions and fluxes between soil, crop, management and the atmosphere in multiple cropping systems and (ii) studying climate change impacts on crop production in multiple cropping systems globally. Currently, dynamic implementations of cropland management is limited to the timing of planting/sowing and harvest, crop selection, irrigation and fertilization.



Full talk
ID: 452 / 107RB: 3
107R Assessing, modelling, and analysing land use and land management impacts on the Earth system
Keywords: land use change, reconstruction, data harmonisation, land management

Towards a data-driven reconstruction of land use change and its linkage with land management at the global scale

Karina Winkler1,2, Richard Fuchs1, Mark Rounsevell1,3, Martin Herold2

1Karlsruhe Institute of Technology (KIT), Germany; 2Wageningen University & Research (WUR), The Netherlands; 3University of Edinburgh, UK

People have increasingly been shaping the surface of our planet. Land cover/land use change (LULC) and land management dynamics are highly interlinked and occur with the same order of magnitude. This human footprint on earth is one of the main contributors to greenhouse gas (GHG) emissions and biodiversity loss and, thus, key for current sustainability debates. For better understanding its underlying processes and associated environmental impacts, more accurate, spatially explicit and global-scale land change reconstructions are needed for feeding earth system and biodiversity models. Although more and more observational data (e.g. remote sensing products) have become available, considerable knowledge gaps related to the effect of human land change and management exist. Exploiting the growing potential of these data, we aim to develop a more comprehensive reconstruction of global LULC change from 1950-2015. The proposed model allocates land change based on a harmonised integration of multiple data sets, including satellite-based maps, statistical inventories, quantifying both net and gross LULC transitions at 1 km spatial resolution across the globe. Particularly, we will link the observed land transitions with information from land management inventories for croplands, pastures and managed forests across different world regions. Cropland expansion and intensification patterns as well as the underlying land change legacy will be analysed at the same time, gaining new insights into location and extent of land change-induced GHG emissions. With this approach, we address current research needs of the earth system modelling community by providing new layers of land use change and land management with unprecedented level of detail. Learning from the recent past, understanding how management and land cover dynamics interactively affect the climate, is essential for implementing measures of mitigation and sustainable land use policies. In this context, a solid information base can support informed decision-making.



Full talk
ID: 788 / 107RB: 4
107R Assessing, modelling, and analysing land use and land management impacts on the Earth system
Keywords: Land-use change, Human Appropriation of Net Primary Production, Spatio-temporal dynamics, Long-term socio-ecological research

Quantifying and analysing global spatio-temporal patterns of land-use change: the role of natural vs. anthropogenic changes for the Human Appropriation of Net Priamary Production

Sarah Matej1, Thomas Kastner2, Maria Niedertscheider1, Matthew Forrest2, Thomas Hickler2, Jörg Steinkamp3, Christian Lauk1, Christoph Plutzar1, Simone Gingrich1, Helmut Haberl1, Fridolin Krausmann1, Karlheinz Erb1

1University of Natural Resources and Life Sciences, Vienna, Austria; 2Senckenberg Biodiversity and Climate Research Centre (SBiK-F); 3Johannes Gutenberg University Mainz

The last century experienced profound changes in global land-use driven by growing population, changing diets and affluence, and technological innovation. Capturing and understanding these changes is intricate due to lack of consistent historic land-use data and the complex interaction between natural and land-use processes. In order to analyse the spatio-temporal patterns of land-use changes, we constructed consistent databases on land-use types and biomass extraction at the global level (resolution 5 arcmin) for the last century. We calculated the indicator “human appropriation of net primary production” (HANPP), consisting of the indicator potential NPP (i.e. NPP prevailing in the absence of land-use but with actual climate), and two HANPP variables, i.e. HANPPluc (the difference between potential and actual NPP caused by land-use) and HANPPharv (the amount of biomass harvest). HANPP was calculated at the national level between 1910 and 2010, mainly from census statistics and global vegetation models, and downscaled to the 5 min grid. A decomposition analysis was performed, allowing to separate the relative importance of natural changes in NPPpot from direct anthropogenic (land-use) drivers of changes. Furthermore, land-use changes were decomposed in the relative effects of land-use type changes (e.g. from grazing land to cropland) and of land-management changes, i.e. intensity and efficiency changes that occur within land-use types. As not only best guess datasets, but several databases have been used to compile the spatially explicit HANPP time series, the importance of data and model uncertainty in the detection of hot- and cold-spots of land-use changes will be scrutinized. The presentation will discuss the role of individual drivers of land-use intensification and land cover conversions and explore past trade-offs, but also synergies in the land system that are important for the design of sustainability strategies around land-use, such as the increase of food security or land-based mitigation of climate change.



Full talk
ID: 848 / 107RB: 5
107R Assessing, modelling, and analysing land use and land management impacts on the Earth system
Keywords: land-use agriculture modeling ecosystems

Coupling a vegetation model and a land use model to estimate future impacts of land use and management adaptation on ecosystem service indicators

Sam S. Rabin1, Peter Alexander2, Roslyn Henry2, Peter Anthoni1, Thomas Pugh3, Mark Rounsevell1, Almut Arneth1

1Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research / Atmospheric Environmental Research; Garmisch-Partenkirchen, Germany; 2School of Geosciences; University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, United Kingdom; 3School of Geography, Earth & Environmental Sciences and Birmingham Institute of Forest Research; University of Birmingham, Birmingham, B15 2TT, United Kingdom

A future of increasing atmospheric carbon dioxide concentrations, changing climate, increasing human populations, and changing socioeconomic conditions means that the global agricultural system will need to adapt in order to feed the world. Cropland and pasture will expand and contract in different regions, farmers will change the kinds of crops they grow, and new fertilization and irrigation patterns will emerge. These changes will affect not only agricultural land, but terrestrial ecosystems as a whole—including their interactions with the climate. The complex interconnections among terrestrial ecosystems and society mean that these different parts of the Earth system must be examined as an interconnected whole.

To quantify the impacts resulting from interactions between future land use changes and terrestrial ecosystems, we have coupled the land-use model PLUMv2 with the global vegetation model LPJ-GUESS. LPJ-GUESS provides potential crop yields under different management levels in a variety of climatic futures, which PLUMv2 uses to generate land-use and -management trajectories under different scenarios of societal change. These are then fed back into LPJ-GUESS to simulate the future of the land system as a whole.

Here, we explore the impact of these trajectories on ecosystem service indicators such as the land carbon balance, runoff, nitrogen pollution, biodiversity, and albedo. We also test the relative contribution of different drivers to these impacts by holding individual variables, such as climate or land use, constant. Many variables are dominated by either the signal of climate change or land use, with some seeing strong interaction effects.