effects of documented land use change on climate in hungary workshop in landscape history, sopron,...
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Effects of Documented Land Use Change on Climate in Hungary
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Áron Drüszler University of West Hungary, Institute of Environmental
and Earth Sciences
Introduction
• Final aim of climate research: create correct forecasts of the changing climate
→ identifying all the different climate forcing processes
→ evaluating their impacts on the climate
• What do we call climate forcing processes?
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Climate System
• natural climate forcing processes:– solar variability– volcanic activity– changes in solar
orbital parameters
• Anthropogenic climate forcing processes:– greenhouse gases– aerosols– ozone depletion– jet contrails– land use change
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
(IPCC, 2007)
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Processes through which vegetation affects climate
• Indirect:– Greenhouse gases (CO2)
– Mineral dust aerosols
→ global climatic effects• Direct:
– Albedo– Evapotranspiration
→ Primarily regional effects
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Indirect Effects of Land Use Change
Carbon cycle in forests:• Sinks:
– plants take in carbon through photosynthesis
– Transfer of carbon to soil through litter fall → build-up of carbon in the soil
• Sources:– return carbon to the atmosphere through
autotrophic and heterotrophic respiration– Forest fire
net uptake of carbon by growth
→ Large scale changes in forest cover can affect climate
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Indirect Effects of Land Use Change
Mineral dust aerosols:• Less vegetated, dry landscapes can be significant sources of dust • Dust can exert climatic effects by:
– modifying the fractions of incoming solar radiation (cooling)– altering the absorption and transmission of outgoing terrestrial long wave
radiation (warming)→ The net climatic effect is still an open question
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
• Albedo
– Forests are generally darker than open land (lower albedo)
→ less sunlight is reflected→ more available energy (warming
effect)
• Evapotranspiration (ET)If the soil stores enough moisture then
the afforestation can increase evapotranspiration
→ greater proportion of the available energy flows to the atmosphere through latent heat
→ (cooling effect at the surface)
The rate of ET depends on: - current weather condition (moisture
availability) - vegetation-specific parameters (LAI,
roughness length, rooting depth, etc.)
Direct Effects of Land Use Change
(Sensible heat)
(Latent heat)
• Tropics:– Net carbon uptake (cooling)– The influence of increased transpiration (the moisture is nearly limitless
available) outweighs the impact of decreased albedo (cooling)
• Boreal Forests:– Rates of carbon storage is much slower then in the tropics (cooling)– The impact of decreased albedo is much higher than the effect of
increased transpiration (warming)
What can be the direct climatic effects of Hungarian land use change?
The Net Climatic Effects of Afforestation
The MM5 ModelThe Fifth-Generation NCAR/Penn State Mesoscale Model
- Equations of impulse-, mass- and energy conservation- Nonhydrostatic dynamic → Nowcasting- A number of physics options
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
OSU Land-Surface Model
• The lower boundary conditions are generated for two selected time period (1900, 2000)– The MM5 land use map for 1900 is based on different
maps (3rd Military Mapping Survey of Austria-Hungary, Synoptic Forestry Map of Hungarian Kingdom (1895) and on the database of Hungarian Central Statistical Office
– The MM5 land use map for 2000 is based on the CORINE 2000 land cover database
Investigation the Climatic Effects of Land Use Change with MM5
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
1900• Forest (12.50 %)• Urban (2.43 %)• Grassland (15.99 %)• Cropland (61.0 %) • Vineyard (2.49 %)• Water (2.26 %)• Wetland (3.22 %)
2000• Forest (21.07 %)• Urban (5.69 %)• Grassland (9.53 %)• Cropland (56.8%)• Vineyard (1.51 %)• Water (1.86 %)• Wetland (1.12 %)
Land Use Change in Hungary
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Investigation the Climatic Effects of Land Use Change with MM5
• The dynamical model has been run with the same detailed meteorological conditions of selected days from 2006 and 2007 but with modified lower boundary conditions (resolution 2.5 x 2.5km)
• The set of the 26 selected initial conditions represents the whole set of the macrosynoptic situations (Péczely, 1983) for Hungary.
• The effects of land use change under the different weather situations are further weighted by the long-term (1961-1990) mean frequency of the corresponding macrosynoptic types → Climatic effects
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Effects of Land Use Change on the Regional Climate
+ 0.14 °C - 0.03 °C + 0.06 mm
Temperature Dewpoint Precipitation
Average Temperature Difference (2m)
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
T (°
C)
Average Dewpoint Difference (2m)
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
T (°
C)
Average Precipitation Difference
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
Prec
(mm
)
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Average Precipitation Difference
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
Pre
c (m
m)
Average Dewpoint Difference (2m)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
T (°
C)
Average Temperature Difference (2m)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
T (°
C)
Average Precipitation Difference
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
Pre
c (m
m)
Average Dewpoint Difference (2m)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
T (°
C)
Average Temperature Difference (2m)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Timestep (hour)
T (°
C)
+ 0.32 °C - 0.12 °C + 0.31 mm
Pest county:
GyMS county:
+ 0.1 °C - 0.02 °C - 0.07 mm
Workshop in Landscape History, Sopron, Hungary, 22 April 2010
Land Use Change in the 20th Century
-80000
-60000
-40000
-20000
0
20000
40000
60000
80000
100000
Cropland Forest Grassland Urban Wetland Vineyard WaterAre
a(
ha)
GyMS
Pest, Budapest
Temperature
Temperature
Dewpoint
Dewpoint
Precipitation
Precipitation
Conclusions • Climatic effects of land use changes are not negligible
(especially regional)• In urban areas (e.g. Budapest) the changes are more
significant • Land cover differences can perturb the precipitation
fields
→ Further process studies are needed in this region:- New field and process-oriented studies that focus on processes critical to the temperate forests (length and frequency of droughts → new model running for longer time period)- Observing and improving vegetation-specific land surface parameters which influence the rate of evapotranspiration in the model results
Workshop in Landscape History, Sopron, Hungary, 22 April 2010