Impacts of maximum deforestation/reforestation on the regional - - PowerPoint PPT Presentation

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Impacts of maximum deforestation/reforestation

• n the regional climate in Europe

STRADA Susanna and COPPOLA Erika

ICTP-ESP section, Trieste (Italy) 9th ICTP Wokshop on Regional Climate Models Trieste - May 31, 2018

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

Reflected sunlight Evaporation Convective heat

Jackson et al., Environ. Res. Lett. (2008)

Photosynthesis Biogenic emissions Dry deposition

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

South-western Australia Rainfall under current vegetation as a percentage of rainfall under natural vegetation. Regional Climate Model: LRAMS.

Pitman et al., J. Geophys. Res., (2004) Pielke et al., WIREs Clim. Change (2011)

Native forest: CLOUDS Intensive farming: NO CLOUDS Cloud distribution

• 15%

+20% Observed percentage change in rainfall

Intensive farming Native forest

Average May-October rainfall over 1976-2001 as a percentage of the average May-October over 1925-1975

IOCI (2002)

Simulated percentage change in rainfall

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.com

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

Domain: EURO-CORDEX Grid-cells: 128 × 128 Horizontal grid res.: 50 km Vertical σ-levels: 23 Modelled time period: 1985–2015 (1985 as spin-up) Forcings: every 6h from ERA-Interim (0.75◦ × 0.75◦; Dee et al., 2011)

Longitude (degrees) Latitude (degrees)

20°N 25°N 30°N 35°N 40°N 45°N 50°N 55°N 60°N 65°N 70°N 75°N 30°W 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E 70°E

Surface Model Elevation (m)

100 200 500 800 900 1000 1200 1500 2000 2500 3000 4000 m

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 Rapid Radiative Transfer Model (RRTM, Mlawer et al., 1997) Convection:

• Tiedtke (1996)
• Bretherton et al. (2004) for

shallow convection Resolved-scale precipitation: Subgrid Explicit Moisture (SUBEX, Pal et al., 2000) Ocean fluxes: Bulk aerodynamic algorithm of Zeng et al. (1997)

CLM4.5 → land-surface model

17 Plant Functional Types (PFTs) Water-energy-carbon exchanges Prescribed phenology and carbon cycle Imposed vegetation distribution Multi-layer soil moisture scheme (10 layers)

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 1985–2015 MODIS-based present-day (Lawrence and Chase, 2007) FOREST 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

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Increase in forest cover: +174% 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)

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Introduction Methodology Mean climate Climate extremes Conclusions

Feedback loops in the presence of snow

Forest VS Grass

Reduce short-wave absorption Snowy grasslands: increase albedo Reduce net radiation Decrease Sensible and Latent Heat Fluxes Increase snow accumulation Decrease Air Surface T emperature Increase short-wave absorption Snow-masking forests decrease albedo Increase net radiation Increase Sensible and Latent Heat Fluxes Decrease snow accumulation Increase Air Surface T emperature

Introduction Methodology Mean climate Climate extremes Conclusions

Extreme reforestation in the mid-latitudes

Local and non-local effects during summer (JJA)

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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)

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Introduction Methodology Mean climate Climate extremes Conclusions

Non-local effects of reforestation in the mid-latitudes

Increase short-wave absorption Forests: reduce albedo Increase net radiation Decrease Latent Heat Flux Increase surface roughness Reduce water vapor Increase Sensible Heat Flux Reduce clouds Reduce daily minimum temperature Increase daily maximum temperature Decrease Surface Wind

Introduction Methodology Mean climate Climate extremes Conclusions

Change in the number of very warm days

Climate extremes

Longitude (degrees) Latitude (degrees) 35°N 40°N 45°N 50°N 55°N 60°N 65°N 70°N 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E

∆ Very Warm Days (Nb. days), GRASS - EVAL [1986-2015]

5 4 3 2 1 1 2 3 4 5

• Nb. days

Longitude (degrees) Latitude (degrees) 35°N 40°N 45°N 50°N 55°N 60°N 65°N 70°N 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E

∆ Very Warm Days (Nb. days), FOREST - EVAL [1986-2015]

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Very Warm Days: Percentage of days with a daily maximum T2m 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

Longitude (degrees) Latitude (degrees) 35°N 40°N 45°N 50°N 55°N 60°N 65°N 70°N 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E

∆ WET Freq. (Nb. days), GRASS - EVAL [1986-2015]

500 400 300 200 100 50 50 100 200 300 400 500

• Nb. days

Longitude (degrees) Latitude (degrees) 35°N 40°N 45°N 50°N 55°N 60°N 65°N 70°N 20°W 10°W 0° 10°E 20°E 30°E 40°E 50°E 60°E

∆ WET Freq. (Nb. days), FOREST - EVAL [1986-2015]

500 400 300 200 100 50 50 100 200 300 400 500

• Nb. days

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

Image credit: www.musee-moutiers.com

Thank you for your attention! Questions?

Contact: sstrada@ictp.it