Land Use Change and Land-Atmosphere Feedback Processes as Regulators of Regional Climate Change

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Information about Land Use Change and Land-Atmosphere Feedback Processes as Regulators of...

Published on December 23, 2016

Author: NIFA_IBCE

Source: slideshare.net

1. Pis David Lawrence1, Paul Dirmeyer2, Ahmed Tawfik1, and Liang Chen2 1National Center for Atmospheric Research, Boulder, CO Co-chair CESM Land ModelWorking Group 2George Mason University Land-Use Change and Land-Atmosphere Feedback Processes as Regulators of Regional Climate Change Collaborative Research: EaSM3, NSF/NIFA

2. Land-Use Change and Land-Atmosphere Feedback Processes as Regulators of Regional Climate Change Collaborative Research: EaSM3, NSF/NIFA

3. Problem statement 1. Land-use and land-cover change (LULCC) impacts on climate and weather are significant, but complex and remain uncertain 2. LULCC impacts are likely to be modulated by the tightness of local land-atmosphere coupling, which is itself uncertain 3. Land management can be as impactful as land cover; different types of land management have unique impacts

4. 1. Land-use and land-cover change (LULCC) impacts on climate and weather are significant, but complex and remain uncertain 2. LULCC impacts are likely to be modulated by the tightness of local land-atmosphere coupling, which is itself uncertain 3. Land management can be as impactful as land cover; different types of land management have unique impacts Problem statement

5. … as highlighted by LUCID … de Noblet-Ducoudré et al. 2012, Boisier et al. 2012 • Uncertainty in LULCC impact on temperature larger than for CO2 • Models do not agree on sign of impact on evapotranspiration Earth System Models exhibit wide range of responses to LULCC

6. Lee et al. 2011 Radiative forcing due to changes in albedo Energy Redistribution due to changes in surface roughness Energy Redistribution due to changes in Bowen ratio Slide courtesy Liz Burakowski Diagnosing sources of LULCC impacts Intrinsic biophysical mechanism (IBPM)

7. Diagnosing dominant mechanisms for land-cover change impact on temperature using paired flux towers Chen and Dirmeyer, 2016

8. Method applied to climate model simulation Global deforestation Chen and Dirmeyer 2016 CESM1 JJA

9. 1. Land-use and land-cover change (LULCC) impacts on climate and weather are significant, but complex and remain uncertain 2. LULCC impacts are likely to be modulated by the tightness of local land-atmosphere coupling, which is itself uncertain 3. Land management can be as impactful as land cover; different types of land management have unique impacts Problem statement

10. Land-atmosphere coupling strength modulates deforestation response Land-atmosphere coupling strength forT Lorenz et al., 2014

11. Soil moisture – precipitation feedback in models Warm colors show positive soil moisture-precipitation feedback Models show wet soil  more rain Koster et al. 2004

12. Soil moisture influence on precipitation inconsistent in observations and models Drier soils have a higher probability of rain in obs…

13. Soil moisture influence on precipitation inconsistent in observations and models Taylor et al., 2014 ObsParameterizedExplicit Models w/o explicit convection show ‘incorrect’ soil moisture  precip relationship Convective triggers • Convective Available Potential Energy (default) • Heated Condensation Framework with subgrid threshold (Tawfik et al. 2016) - Improved diurnal phase, intensity of precip - Improved propagation of mesoscale complex

14. * indicates significant change at the 95% confidence level No significant feedback in the CTRL simulations. With the HCF trigger PRECT↓ Chen et al., 2016; Chen et al., in prep Representation of convective trigger alters land-cover change response

15. 1. Land-use and land-cover change (LULCC) impacts on climate and weather are significant, but complex and remain uncertain 2. LULCC impacts are likely to be modulated by the tightness of local land-atmosphere coupling, which is itself uncertain 3. Land management can be as impactful as land cover; different types of land management have unique impacts Problem statement

16. Land management Erb et al., GCB, 2016 ~80% non-ice land area under land management ~25% non-ice land area undergone anthropogenic land-cover change

17. Set of land-only historic (1850 – 2014) simulations with one-at-a-time modification of particular aspects of land management 1 Land historical all management 2 Year 1700 instead of 1850 start 3 No LULCC change 4 Alternate land use histories 5 No shifting cultivation 6 Crop and pasture as unmanaged grassland 7 Crops with crop model but no irrigation/fertilization 8 No irrigation 9 No fertilization 10 No wood harvest 11 No grazing on pastureland 12 No human fire ignition/suppression 13 Constant 1850 CO2 14 Constant 1850 climate Land Use Change ✗✗ ✗ Land Use Model Intercomparison Project (LUMIP) for CMIP6 Land management experiments Lawrence et al., 2016

18. Corn* Soy* Wheat** Sugarcane Cotton Rice * Temperate and tropical varieties CLM-Crop ** Spring wheat only in CLM4.5; Winter variety available in CLM5

19. Objective Chen and Dirmeyer, 2016

20. Objective Glacier Lake River Routing Runoff River discharge Urban Land Use Change Wood harvest Disturbance Vegetation Dynamics Growth Competition Wetland Crops Irrigation Flooding Understand and quantify the nature of land-atmosphere interactions • as they exist today • as they may be modulated by the radiatively-driven component of climate change • as they may evolve with changing land use

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