Land Use and Climate Land Use and Climate Change Change Stephanie J Houser Stephanie J Houser Earth Climate Systems Earth Climate Systems www.dcnr.state.pa.us www.gnb.ca www.injuryupdate.com .au
Land Use and Climate Land Use and Climate ChangeChange
Stephanie J HouserStephanie J Houser
Earth Climate SystemsEarth Climate Systems
www.dcnr.state.pa.us
www.gnb.ca
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OutlineOutline Why be concerned with land Why be concerned with land
cover/land use changecover/land use change How do different land cover/land use How do different land cover/land use
changes affect climatechanges affect climate Climate model studiesClimate model studies
DOE-PCM A2 & B1 IPCC SRES (Feddema DOE-PCM A2 & B1 IPCC SRES (Feddema et al., 2005)et al., 2005)
CLM3 coupled model (Gibbard et al., CLM3 coupled model (Gibbard et al., 2005)2005)
Summary of findingsSummary of findings
Why?Why?
Changes in land Changes in land cover/use are major but cover/use are major but poorly recognized poorly recognized drivers of long-term drivers of long-term global climate patternsglobal climate patterns
May be as important as May be as important as changes in climate and changes in climate and weather associated with weather associated with greenhouse gasesgreenhouse gases
Changes often Changes often permanentpermanent
IPCC has yet to include IPCC has yet to include effect in assessmentseffect in assessments
Pielke 2005
How do land cover/land use How do land cover/land use changes affect climate?changes affect climate?
Impacts on global climate divided into Impacts on global climate divided into two major categoriestwo major categories
Biogeochemical and BiogeophysicalBiogeochemical and Biogeophysical BiogeochemicalBiogeochemical
Chemical composition of the atmosphereChemical composition of the atmosphere BiogeophysicalBiogeophysical
Directly affect physical parameters that Directly affect physical parameters that determine absorption/distribution of energy determine absorption/distribution of energy at the earth’s sfcat the earth’s sfc
AlbedoAlbedo
How do these changes affect How do these changes affect climate?climate?
DeforestationDeforestation Warming due to Warming due to
decreased decreased evapotranspirationevapotranspiration
Modification of surface Modification of surface fluxes of heat and water fluxes of heat and water vaporvapor
ReforestationReforestation lowering of sfc albedo lowering of sfc albedo
leads to a net warmingleads to a net warming Increase sfc fluxes of Increase sfc fluxes of
water vaporwater vapor Cooling with vegetation Cooling with vegetation
at lower latitudes due to at lower latitudes due to evapotranspirationevapotranspiration
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Climate model studiesClimate model studies Fully coupled Department of Energy Fully coupled Department of Energy
Parallel Climate Model (DOE-PCM) Parallel Climate Model (DOE-PCM) Combined land-cover and atmospheric Combined land-cover and atmospheric
forcings for A2 and B1 IPCC SRES scenariosforcings for A2 and B1 IPCC SRES scenarios Land cover change – Integrated Model to Land cover change – Integrated Model to
Assess the Global Environment (IMAGE) Assess the Global Environment (IMAGE) IPCC SRES land-cover projections and DOE-IPCC SRES land-cover projections and DOE-PCM natural vegetation dataPCM natural vegetation data
For each SRES scenario, ran model fromFor each SRES scenario, ran model from 2000 to 2033 with present day land cover2000 to 2033 with present day land cover 2033 to 2066 with 2050 land cover2033 to 2066 with 2050 land cover 2066 to 2100 with 2100 land cover2066 to 2100 with 2100 land cover
(Feddema et al, 2005)(Feddema et al, 2005)
Feddema et al, 2005
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•Tropical regions with same land cover forcings have different responses
•Amazon – warming due to change from broadleaf forest to agriculture
•Net radiation changes in atm forcing scenarios offset by increases in latent heat fluxes when forests are present
•Land-cover and atm forcing simulations, reduced latent heat flux, increased incident radiation
Indonesia - lack of response attributed to Asian Monsoon circulation which override feebacks from local land-cover change
Feddema et al, 2005
•Temperature change
•All forcing scenario minus atmospheric forcing with constant land cover
•Most significant regional climate effects are associated with changes in mid-latitude and tropical regions
Diurnal Temperature Range
•More significant impact
•Decreases significantly in southern Asia
•(A2) Midlatitide regions experience decrease in DTR
•In the Amazon, significant increase in daily minimum temperatures (nighttime)
Feddema et al, 2005
Climate model studiesClimate model studies Not reproducing observed patterns of land Not reproducing observed patterns of land
cover change, nor realistically simulating cover change, nor realistically simulating possible future scenariospossible future scenarios
CAM3 (Community Atmosphere Model)CAM3 (Community Atmosphere Model) Coupled with the CLM land model and slab Coupled with the CLM land model and slab
ocean and thermo sea ice modelocean and thermo sea ice model Control runs with both current vegetation Control runs with both current vegetation
and bare soiland bare soil Two vegetated experiments, one with trees, and Two vegetated experiments, one with trees, and
one with grass/shrubs.one with grass/shrubs.
(Gibbard et al., 2005)(Gibbard et al., 2005)
a. Temperature difference between the tree simulation and bare soil simulation
- Heating effects of forest in upper latitudes
- Albedo-change dominates over evapotranspiration
b. Vegetation from 20-50N replaced by forest, rest of vegetation current
- Direct effect of trees is warming (more than with bare ground)
c. Albedo change (bare vs. tree)
- Snow-albedo feedback effect responsible for 25% of change in sfc albedo between bare and tree
simulations
- Max albedo change in North where snowfall has decreased due to
increased temperatures
SummarySummary Changes in Land cover and Land use induce Changes in Land cover and Land use induce
changes in climate on regional and global scaleschanges in climate on regional and global scales Albedo-change and evapotranspiration effects Albedo-change and evapotranspiration effects
dominate cooling/warming of climatedominate cooling/warming of climate Overall warming due to reforestation (higher Overall warming due to reforestation (higher
latitudes)latitudes) Forestation causes cooling in Amazon, whereas Forestation causes cooling in Amazon, whereas
deforestation seems to cause warmingdeforestation seems to cause warming Evapotranspiration effects dominate at lower latsEvapotranspiration effects dominate at lower lats
Future research is needed to determine exact Future research is needed to determine exact nature of responses due to land use and land cover nature of responses due to land use and land cover change (Feddema et al., 2005)change (Feddema et al., 2005)
In order for IPCC to more accurately predict future In order for IPCC to more accurately predict future climates the effects of Land cover change and land climates the effects of Land cover change and land use change must be included in future assessmentsuse change must be included in future assessments
Questions?Questions?