Impacts of maximum deforestation/reforestation on the regional climate in Europe STRADA Susanna and COPPOLA Erika ICTP-ESP section, Trieste (Italy) 9 th ICTP Wokshop on Regional Climate Models Trieste - May 31, 2018 Image credit: www.musee-moutiers.com
Introduction Methodology Mean climate Climate extremes Conclusions Land-use changes (LUCs) and surface-atmosphere interactions Land use changes modify biophysical and biogeochemical fluxes that link the land surface to the atmosphere Photosynthesis Re fl ected sunlight Evaporation Convective heat Biogenic emissions Dry deposition Jackson et al., Environ. Res. Lett. (2008) Focus of this talk: LUC-induced modifications on the surface energy and water balance and their impacts on atmospheric conditions
Introduction Methodology Mean climate Climate extremes Conclusions Land-use changes and climate Interactions across scales LUCs modify atmospheric conditions and thus influence climate at different scales, from local to regional and global scales Simulated percentage Cloud distribution Observed percentage change in rainfall change in rainfall Native forest : Native forest CLOUDS +20% -15% Intensive farming : NO CLOUDS Intensive farming South-western Australia Pitman et al., J. Geophys. Res. , (2004) IOCI (2002) Pielke et al., WIREs Clim. Change (2011) Average May-October rainfall over 1976-2001 Rainfall under current vegetation as a percentage of the as a percentage of rainfall average May-October over 1925-1975 under natural vegetation. Regional Climate Model: LRAMS .
Introduction Methodology Mean climate Climate extremes Conclusions Forests & climate: warming or cooling effect? Reforestation in the mid-latitudes: what is the regional effect? The main effect on climate of temperate forests is controversial compared to the warming/cooling effect of boreal/tropical forests (Bonan et al., 2008) Credit: temperateforestsinjapan.blogspot.co m In the framework of the LUCAS project (WCRP- CORDEX flagship), we aim to: Compare performance of regional climate models in representing the effects of LUCs on regional climate and extremes Assess the impacts that LUCs may have on the regional climate in Europe
Introduction Methodology Mean climate Climate extremes Conclusions METHODOLOGY
Introduction Methodology Mean climate Climate extremes Conclusions The coupled land-atmosphere regional climate model: RegCM4.6.1-CLM4.5 Domain set-up Modelled time period: 1985–2015 Domain: EURO-CORDEX (1985 as spin-up) Grid-cells: 128 × 128 Forcings: every 6h from Horizontal grid res.: 50 km ERA-Interim (0 . 75 ◦ × 0 . 75 ◦ ; Dee Vertical σ -levels: 23 et al., 2011) Surface Model Elevation (m) 4000 75°N 3000 70°N 2500 65°N 2000 Latitude (degrees) 1500 60°N 1200 55°N 1000 m 50°N 900 45°N 800 40°N 35°N 500 30°N 200 25°N 100 20°N 0 30°W 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E 70°E Longitude (degrees)
Introduction Methodology Mean climate Climate extremes Conclusions The coupled land-atmosphere regional climate model: RegCM4.6.1-CLM4.5 Model configuration RegCM4.6.1 → atmospheric model Hydrostatic, compressible, σ -p vertical coordinates CLM4.5 → land-surface model Rapid Radiative Transfer Model (RRTM, Mlawer et al., 1997) 17 Plant Functional Types (PFTs) Convection: Water-energy-carbon exchanges • Tiedtke (1996) Prescribed phenology and carbon • Bretherton et al. (2004) for cycle shallow convection Imposed vegetation distribution Multi-layer soil moisture scheme Resolved-scale precipitation: (10 layers) Subgrid Explicit Moisture (SUBEX, Pal et al., 2000) Ocean fluxes: Bulk aerodynamic algorithm of Zeng et al. (1997)
Introduction Methodology Mean climate Climate extremes Conclusions Simulations RegCM4.6.1-CLM4.5 Three fully coupled land-atmosphere simulations Simulation Climate Land cover distribution EVAL MODIS-based present-day (Lawrence and Chase, 2007) FOREST 1985–2015 Maximized forest cover according to potential vegetation GRASS Grasslands replace all forests 1-year spin-up (1985) All simulations consider the same fraction of bare soil In the FOREST (GRASS) simulation shrub-lands and crop-lands have been completely replaced by forest (grass)
Introduction Methodology Mean climate Climate extremes Conclusions Idealized land-use changes Maximum reforestation/deforestation over Europe 100 100 80 80 60 60 40 40 20 20 5 5 % % -5 -5 -20 -20 -40 -40 -60 -60 -80 -80 -100 -100 Increase in forest cover: +174% 100 100 80 80 60 60 40 40 20 20 5 5 % % -5 -5 -20 -20 -40 -40 -60 -60 -80 -80 -100 -100 Increase in grass cover: +336%
Introduction Methodology Mean climate Climate extremes Conclusions RESULTS
Introduction Methodology Mean climate Climate extremes Conclusions Extreme deforestation in the boreal region Change in the snow cover and its effects during spring (MAM) 300 80 60 200 40 100 20 50 10 25 5 -25 -5 -50 -10 -20 -100 8 -40 -200 6 -60 4 -300 -80 2 1 -1 -2 50 50 -4 40 40 -6 30 30 -8 20 20 10 10 2 2 -2 -2 -10 -10 -20 -20 -30 -30 -40 -40 -50 -50 100 100 80 80 60 60 40 40 20 20 5 5 % % -5 -5 -20 -20 -40 -40 -60 -60 -80 -80 -100 -100
Introduction Methodology Mean climate Climate extremes Conclusions Feedback loops in the presence of snow Forest VS Grass Snowy grasslands : increase albedo Reduce Increase snow accumulation short-wave absorption Decrease Reduce Air Surface T emperature net radiation Snow-masking forests decrease albedo Decrease Sensible and Latent Heat Fluxes Increase Decrease short-wave absorption snow accumulation Increase Increase Air Surface T emperature net radiation Increase Sensible and Latent Heat Fluxes
Introduction Methodology Mean climate Climate extremes Conclusions Extreme reforestation in the mid-latitudes Local and non-local effects during summer (JJA) 5.0 3.0 2.0 2.5 1.0 1.0 0.5 0.5 0.2 -0.2 -0.5 -0.5 -1.0 -1.0 -2.5 -2.0 -5.0 -3.0 50 50 50 80 40 40 40 60 30 30 30 40 20 20 20 20 10 10 10 10 2 2 2 5 -2 -2 -2 -5 -10 -10 -10 -10 -20 -20 -20 -20 -40 -30 -30 -30 -60 -40 -40 -40 -50 -50 -80 -50 100 100 80 80 60 60 40 40 20 20 5 5 % % -5 -5 -20 -20 -40 -40 -60 -60 -80 -80 -100 -100
Introduction Methodology Mean climate Climate extremes Conclusions Extreme reforestation in the mid-latitudes Changes in the cloud cover and its effects on temperatures during summer (JJA) 6.5 12 6.0 8 6 3.0 4 2.0 2 1.0 1 0.2 -0.2 -1 -1.0 -2 -4 -2.0 -3.0 -6 -8 -6.0 -12 -6.5 8 8 6 6 4 4 2 2 1 1 -1 -1 -2 -2 -4 -4 -6 -6 -8 -8
Introduction Methodology Mean climate Climate extremes Conclusions Non-local effects of reforestation in the mid-latitudes Forests : reduce albedo Increase Increase surface roughness short-wave absorption Decrease Surface Wind Increase net radiation Decrease Latent Heat Flux Reduce Increase water vapor Sensible Heat Flux Reduce clouds Reduce Increase daily maximum daily minimum temperature temperature
Introduction Methodology Mean climate Climate extremes Conclusions Change in the number of very warm days Climate extremes ∆ Very Warm Days (Nb. days), GRASS - EVAL [1986-2015] ∆ Very Warm Days (Nb. days), FOREST - EVAL [1986-2015] 5 5 5 5 70°N 70°N 4 4 4 4 65°N 3 3 65°N 3 3 2 2 2 2 Latitude (degrees) 60°N Latitude (degrees) 60°N 1 1 1 1 Nb. days Nb. days 55°N 55°N -1 -1 1 1 50°N 50°N -2 2 -2 2 45°N 45°N 3 -3 3 -3 40°N 40°N -4 4 -4 4 35°N 35°N -5 -5 5 5 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E Longitude (degrees) Longitude (degrees) Very Warm Days: Percentage of days with a daily maximum T 2 m greater than the 90th percentile of the daily maximum temperatures
Introduction Methodology Mean climate Climate extremes Conclusions Change in the number of wet days Climate extremes ∆ WET Freq. (Nb. days), GRASS - EVAL [1986-2015] ∆ WET Freq. (Nb. days), FOREST - EVAL [1986-2015] 500 500 70°N 70°N 400 400 65°N 300 65°N 300 200 200 Latitude (degrees) 60°N Latitude (degrees) 60°N 100 100 Nb. days Nb. days 50 50 55°N 55°N 50 50 100 100 50°N 50°N 200 200 45°N 45°N 300 300 40°N 40°N 400 400 35°N 35°N 500 500 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E Longitude (degrees) Longitude (degrees) Wet frequency: Number of days when daily precipitation is greater than 1 mm
Introduction Methodology Mean climate Climate extremes Conclusions Conclusions The effects of extreme land-use changes on regional climate maximize during the growing season (from spring to summer) Deforestation in boreal regions removes the masking of snow albedo by trees and significantly reduces mean surface temperatures, especially during spring, in agreement with previous studies (e.g., Betts and Ball, 1997; Bonan, 2008) Reforestation in Central Europe and the Euro-Mediterranean region leads to non-local effects with reduction of evaporation and changes in the cloud cover over the Mediterranean Basin
Thank you for your attention! Questions? Contact: sstrada@ictp.it Image credit: www.musee-moutiers.com
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