Effects of Documented Land Use Change on Climate in Hungary

1. Effects of Documented Land Use Change on Climate in Hungary Áron DrüszlerUniversity of West Hungary, Institute of Environmental and Earth Sciences Workshop in Landscape History, Sopron, Hungary, 22 April 2010

2. 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

3. 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

4. (IPCC, 2007) Workshop in Landscape History, Sopron, Hungary, 22 April 2010

5. 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

6. 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

7. 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

8. Direct Effects of Land Use Change • 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.) (Latent heat) (Sensible heat)

9. The Net Climatic Effects of Afforestation • 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?

10. 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 OSU Land-Surface Model Workshop in Landscape History, Sopron, Hungary, 22 April 2010

11. Investigation the Climatic Effects of Land Use Change with MM5 • 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 Workshop in Landscape History, Sopron, Hungary, 22 April 2010

12. Land Use Change in Hungary • 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 %) Workshop in Landscape History, Sopron, Hungary, 22 April 2010

13. 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 2007but 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

14. Effects of Land Use Change on the Regional Climate Temperature Dewpoint Precipitation + 0.14 °C - 0.03 °C + 0.06 mm Workshop in Landscape History, Sopron, Hungary, 22 April 2010

15. GyMS county: Temperature Dewpoint Precipitation + 0.1 °C - 0.02 °C - 0.07 mm Pest county: Temperature Dewpoint Precipitation + 0.32 °C - 0.12 °C + 0.31 mm Workshop in Landscape History, Sopron, Hungary, 22 April 2010

16. 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