Increased albedo Decreased solar radiation absorption Decreased net

Increased albedo Decreased solar radiation absorption Decreased net radiation Reduced vegetation cover Reduced soil water Figure 27. 1 Decreased latent heat flux Decreased sensible heat flux Reduced water vapor Reduced boundary layer heating Decreased clouds and convection Increased solar radiation Ecological Climatology © 2008 G. Bonan

Decreased roughness length Increased aerodynamic resistance Reduced vegetation cover Reduced soil water Figure 27. 2 Decreased latent heat flux Increased surface temperature Decreased sensible heat flux Reduced boundary layer heating Reduced water vapor Decreased clouds and convection Ecological Climatology © 2008 G. Bonan

Desert planet Green planet Atmosphere 421 000 km 3 71 000 km 3 464 000 km 3 Ocean 31 000 km 3 Land 37 000 km 3 137 000 km 3 443 000 km 3 Ocean 108 000 km 3 Land 28 000 km 3 125 W m-2 75 W m-2 23 W m-2 18 W m-2 130 W m-2 52 W m-2 8 W m-2 Net solar Net Sensible Latent radiation longwave heat flux radiation Land surface air temperature, 9. 1 C Figure 27. 3 410 000 km 3 62 W m-2 Land surface air temperature, 7. 9 C Ecological Climatology © 2008 G. Bonan

Mexico-U. S. Difference (W m-2) 10 0 9 -13 August 1988, 1100 local time Latent Heat Sensible Heat -10 -20 -30 -40 -50 -60 -70 2 3 4 5 6 Mexico-U. S. Difference ( C) Days Since Rain 3. 5 3. 0 2. 5 2. 0 1. 5 1. 0 0. 5 0. 0 -0. 5 -1. 0 -1. 5 Air Temperature Surface Temperature 2 3 4 5 6 Days Since Rain Figure 27. 4 Ecological Climatology © 2008 G. Bonan

Figure 27. 5 Ecological Climatology © 2008 G. Bonan

Figure 27. 6 Ecological Climatology © 2008 G. Bonan

Overgrazing Drought Reduced vegetation cover Less rainfall Increased albedo Decreased clouds and convection Subsidence Figure 27. 7 Decreased net radiation Surface cooling Ecological Climatology © 2008 G. Bonan

(mm day-1) Precipitation Difference 20 N -1 -0. 5 15 N -1 -3 10

6 13 10 8 6 Annual Albedo 0. 50 0. 40 0. 30 0. 20 0. 10 Annual Precipitation (mm) 2000 1750 1500 1250 1000 750 500 250 0 Arid Semi-arid Dry subhumid Moist subhumid Humid 11 6 Arid Semi-arid Dry subhumid Moist subhumid Humid Wooded grass Crop 9 4 Annual Albedo 0. 50 0. 40 0. 30 0. 20 0. 10 Open shrub Figure 27. 9 Closed shrub Grass Wooded grass Crop Annual Precipitation (mm) 2000 10 1750 1500 1250 1000 750 500 250 0 Open shrub Closed shrub Grass Ecological Climatology © 2008 G. Bonan

Atmosphere-Ocean 100 50 0 -50 -100 Atmosphere-Ocean-Land 100 50 0 -50 -100 Figure 27. 10 1995 1990 1985 1980 1975 1960 1955 1970 Atmosphere-Ocean-Land-Vegetation 100 50 0 -50 -100 1950 Annual Rainfall Anomaly (mm per year) Observed 100 50 0 -50 -100 Ecological Climatology © 2008 G. Bonan

Remaining Forest Open Woodland Brisbane Remaining Woodland Brisbane Woodland Remaining Mallee Other Vegetation Unchanged Saltbush Some Tree Loss Grassland Crops Pasture Greatest Tree Loss Sydney North Melbourne Adelaide Sydney North Melbourne 500 km Area (thousand km 2) 64 40 500 km Area (thousand km 2) 58 162 199 349 124 143 54 533 Figure 27. 11 82 324 Ecological Climatology © 2008 G. Bonan

Legend 1, trees to shrub 2, trees to grass 3, shrub to trees 4,

January Latent Heat Flux Difference July Latent Heat Flux Difference 15 S 18 S 21 S 24 S 27 S 30 S 33 S 36 S 39 S 120 E <-40 W 130 E m-2 <-20 W 140 E m-2 120 E 150 E >20 W m-2 -5 to -10 W January Temperature Difference m-2 140 E >10 W 150 E m-2 July Temperature Difference 15 S 18 S 21 S 24 S 27 S 30 S 33 S 36 S 39 S 120 E <-0. 2 C Figure 27. 13 130 E >0. 2 C 140 E 150 E >0. 8 C 120 E 130 E 140 E 150 E <-0. 2 C Ecological Climatology © 2008 G. Bonan

Vegetation Evergreen broadleaf tree Deciduous shrub Crop Tall grass Short grass Semi-desert Soil color Soil texture Surface air temperature ( C) Soil surface temperature ( C) Precipitation (mm) Evapotranspiration (mm) Coarsest: 1, sand Finest: 12, clay Deforestation 1, lightest; 8, darkest Figure 27. 14 Ecological Climatology © 2008 G. Bonan

5. 0 16 14 12 10 8 6 4 2 3. 5 3. 0 2. 5 2. 0 1. 5 1. 0 Pasture Forest 0. 0 Solar Radiation 10 15 20 25 30 Days Since Rainfall 8 Dec Nov Oct Sep 6 Aug 7 Jul 1800 9 Jun 1200 10 May 500 11 Apr 1000 Pasture Forest 12 Mar 1500 0600 5 13 Pasture Forest 2000 0 Feb 2500 Reflected (S ) Net Upward Net Longwave Radiation (L -L ) (S -S +L -L ) Jan Incoming (S ) 0 4. 0 0. 5 0 Boundary Layer Height (m) 4. 5 Evapotranspiration (mm) Pasture Forest Diurnal Temperature Range ( C) Radiative Flux (MJ m-2 day-1) 18 Local Time (hours) Figure 27. 15 Ecological Climatology © 2008 G. Bonan

Intertropical Convergence Zone Strengthened Circulation Intertropical Convergence Zone More Convection Moister Air Low Transpiration Precipitation Increased Transpiration Dry Soil Increased Precipitation Wet Soil Summer Hemisphere (wet season) Shallow Roots Figure 27. 16 Winter Hemisphere (dry season) Equator Increased Soil Water Summer Hemisphere (wet season) Deep Roots Ecological Climatology © 2008 G. Bonan

Natural vegetation Grass (present-natural) Crop (present-natural) Present-day vegetation Broadleaf deciduous tree (present-natural) Needleleaf evergreen tree (present-natural) Other Mixed forest Grass Needleleaf evergreen forest Crop Broadleaf deciduous forest Forest crop Figure 27. 17 Ecological Climatology © 2008 G. Bonan

Figure 27. 18 Ecological Climatology © 2008 G. Bonan

6 40 4 0 -40 Forest Spring -80 2 3 2 1 0 0 8 80 6 40 -40 4 Forest Summer -80 0 J F MAMJ J ASOND Figure 27. 19 2 ET (mm day-1) 120 LAI (m 2 m-2) Net Radiation (W m-2) 4 3 2 1 0 Forest Summer J F MAMJ J ASOND ET (mm day-1) 3 2 1 0 0 J F MAMJ J ASOND Grass Winter J F MAMJ J ASOND 4 120 8 80 6 40 4 0 -40 Grass Spring 2 -80 J F MAMJ J ASOND 0 Forest Spring 2 ET (mm day-1) 80 ET (mm day-1) 8 LAI (m 2 m-2) Net Radiation (W m-2) 4 Grass Winter -80 J F MAMJ J ASOND 120 -40 4 3 2 1 0 0 J F MAMJ J ASOND 120 8 80 6 40 4 0 -40 Grass Spring J F MAMJ J ASOND 4 Grass Summer -80 2 0 J F MAMJ J ASOND ET (mm day-1) 0 0 Forest Winter 6 40 0 LAI (m 2 m-2) 1 8 80 LAI (m 2 m-2) -80 2 4 120 LAI (m 2 m-2) Forest Winter Net Radiation (W m-2) -40 4 2 Net Radiation (W m-2) 0 3 Net Radiation (W m-2) 6 40 ET (mm day-1) 8 80 LAI (m 2 m-2) Net Radiation (W m-2) 4 120 3 2 1 0 Grass Summer J F MAMJ J ASOND Ecological Climatology © 2008 G. Bonan

8 April 2000 Percent Land Covered By Green Vegetation 10 20 30 40 50 60 70 80 90 15 June 2000 Percent Land Covered By Green Vegetation 10 20 30 40 50 60 70 80 90 Figure 27. 20 Ecological Climatology © 2008 G. Bonan

36 32 32 34 Fort Collins 30 38 Greeley 34 34 36 36 30 n rga o M ort 28 30 F 32 30 34 36 32 38 34 38 36 Surface temperature ( C) at 13: 00, 1 August to 15 August 1986 Figure 27. 21 38 36 km Contour from 38 to 28 by 2 Ecological Climatology © 2008 G. Bonan

Present-day Land Cover Figure 27. 22 B 1: 2100 Change from Present A 2: 2100 Change from Present B 1: Land Use Temperature Difference ( C) A 2: Land Use Temperature Difference ( C) Ecological Climatology © 2008 G. Bonan