Climate Impacts of Historical Australian Climate Impacts of Historical Australian Land Cover ChangesLand Cover Changes

Slide 1 – Introduction

Peter LawrencePeter Lawrence11, Jozef Syktus, Jozef Syktus22, Clive McAlpine, Clive McAlpine33 and and Steve CrimpSteve Crimp22

  

11Department of Geography, University of Colorado, Boulder, USADepartment of Geography, University of Colorado, Boulder, USA

22Department of Natural Resources, Mines and Energy, Brisbane, Department of Natural Resources, Mines and Energy, Brisbane, AustraliaAustralia

33Department of Geographical Sciences & Planning, The University Department of Geographical Sciences & Planning, The University of Queensland, Brisbaneof Queensland, Brisbane, , AustraliaAustralia

Motivation for this talk

Relevance to stage 3 of C20C

Need for a significant effort/progress to increase realism of simulated vegetation/hydrology & climate interactions for climate change and seasonal prediction work

Not a simple task to change/update land cover characteristics in GCM and still produce good climatology

Slide 2 – Talk Outline

Description of the problems associated with update of land Description of the problems associated with update of land surface parameters in AGCMsurface parameters in AGCM

Representing Representing historical Australian land cover changehistorical Australian land cover changes in the s in the GCMGCM

Overview of land cover change experiments with CSIRO Overview of land cover change experiments with CSIRO GCMGCM

Results Results fromfrom climate modelling experiments climate modelling experiments Implications of the climate impacts of Australian Land Cover Implications of the climate impacts of Australian Land Cover

ChangeChange

Acknowledgement of financial assistance from Meat & Livestock Australia & Australian Research Council. Results from Ph.D. thesis completed by Peter Lawrence

Talk OutlineTalk Outline

Slide 4 – Need for Climate Models

• Given the complexity of the climate system there are Given the complexity of the climate system there are many interacting phenomena effecting climatemany interacting phenomena effecting climate

• Historical climate records have many other sources of Historical climate records have many other sources of climate variability and change that interact with land climate variability and change that interact with land cover effectscover effects

• Climate modelling allows the climate effects of land cover Climate modelling allows the climate effects of land cover change be isolated and examined independently of these change be isolated and examined independently of these other sourcesother sources

Why are climate models needed for climate and Why are climate models needed for climate and land cover?land cover?

Slide 6 – Land Cover Climate Impacts

Land Cover and Climate Interactions and FeedbacksLand Cover and Climate Interactions and Feedbacks

Slide 10 – Current Land cover representation

• Model vegetation types (Simple Biosphere) derived for Model vegetation types (Simple Biosphere) derived for Australia from AUSLIG mapping of current day Australia from AUSLIG mapping of current day vegetation and Globally from International Geosphere vegetation and Globally from International Geosphere Biosphere Program (IGBP) MappingBiosphere Program (IGBP) Mapping

• Mean monthly Surface Reflectivity (Albedo) derived Mean monthly Surface Reflectivity (Albedo) derived from MODerate resolution Imaging Spectroradiometer from MODerate resolution Imaging Spectroradiometer (MODIS) satellite imagery.(MODIS) satellite imagery.

• Mean monthly Leaf Area Index (LAI) derived from Mean monthly Leaf Area Index (LAI) derived from Pathfinder AVHRRPathfinder AVHRR

• All three are used to generate land surface parameters All three are used to generate land surface parameters that describe monthly dynamics of: Solar radiation; that describe monthly dynamics of: Solar radiation; Deep rooted transpiration; and Surface roughnessDeep rooted transpiration; and Surface roughness

New land surface conditions described by New land surface conditions described by vegetation mapping and satellite imageryvegetation mapping and satellite imagery

Slide 11 – Global Land Cover Mapping

Slide 12 – Global Albedo Mapping

Slide 13 – Global LAI Mapping

Slide 14 – Incorporating Land cover data in CSIRO GCM

• The spatial scale of the land cover data (1 - 8 km) was much finer The spatial scale of the land cover data (1 - 8 km) was much finer than the land surface parameters of the CSIRO GCM (~180 km)than the land surface parameters of the CSIRO GCM (~180 km)

• The land cover changes in radiation budgets, transpiration rates The land cover changes in radiation budgets, transpiration rates and surface roughness needed to be calculated as GCM land and surface roughness needed to be calculated as GCM land surface parameters surface parameters

• New land surface parameter generation techniques produced New land surface parameter generation techniques produced relatively fine scale vegetation, monthly albedo, and monthly LAI relatively fine scale vegetation, monthly albedo, and monthly LAI data and differences between current and pre-clearing land coverdata and differences between current and pre-clearing land cover

• Aggregation rules used to take generate GCM parameters from Aggregation rules used to take generate GCM parameters from fine scale parameters fine scale parameters

Representing Land Cover Data in the CSIRO GCMRepresenting Land Cover Data in the CSIRO GCM

Slide 9 – GCM Vegetation Density

Slide 15 – Land Surface Parameter Methods

Incorporating Fine Scale Land Surface Data in GCM ParametersIncorporating Fine Scale Land Surface Data in GCM Parameters

Control simulations with old and new modern land surface characteristics were compared in term of seasonal mean skill for various fields.

It took a lot of effort to get climatology close to that of original model!

Slide 8 – Historical Australian LCC

• Studies by Studies by Graetz, Graetz, et al. 1995 and Barson, et al. 2000 used the et al. 1995 and Barson, et al. 2000 used the Australian Australian pre European pre European Vegetation mapping of AUSLIG with Vegetation mapping of AUSLIG with Landsat MSS and TM Landsat MSS and TM satellite imagerysatellite imagery

• Australian land cover change in both studies were divided into the Australian land cover change in both studies were divided into the Intensive Landuse Zone and the Extensive Landuse ZoneIntensive Landuse Zone and the Extensive Landuse Zone

• Changes in the Intensive Landuse Zone were principally structural Changes in the Intensive Landuse Zone were principally structural changes in vegetation from clearing forests and woodlands changes in vegetation from clearing forests and woodlands to to replacereplace with crops, pastures and urban areas with crops, pastures and urban areas

• For the study land cover changes restricted to vegetation changes For the study land cover changes restricted to vegetation changes in the Intensive Landuse Zone since European settlementin the Intensive Landuse Zone since European settlement

Historical Australian Land Cover ChangeHistorical Australian Land Cover Change in CSIRO GCM in CSIRO GCM

How How areare the changes in the changes in Australian land coverAustralian land cover since European since European settlement settlement described described ??

Slide 9 – Land cover change maps

Australian Historical and Recent Australian Historical and Recent Land Cover ChangeLand Cover Change

• AUSLIG Structural Changes in AUSLIG Structural Changes in Australian Vegetation 1788 – 1990Australian Vegetation 1788 – 1990

• Barson, et al. 2000 Recent Barson, et al. 2000 Recent Australian Land Cover Change Australian Land Cover Change from Landsatfrom Landsat TM TM satellite imagery satellite imagery 1990 – 19951990 – 1995

Slide 16 – Extrapolating Pre-Clearing Land cover

• Model vegetation types (Simple Biosphere) derived from AUSLIG Model vegetation types (Simple Biosphere) derived from AUSLIG mapping of pre European vegetationmapping of pre European vegetation

• Mean monthly LAI extrapolated from current monthly LAI of Mean monthly LAI extrapolated from current monthly LAI of remnant natural vegetation in the immediate neighbourhoodremnant natural vegetation in the immediate neighbourhood

• Mean monthly Albedo extrapolated from current monthly Albedo Mean monthly Albedo extrapolated from current monthly Albedo of remnant natural vegetation in the immediate neighbourhoodof remnant natural vegetation in the immediate neighbourhood

• Again all three are used to generate land surface parameters that Again all three are used to generate land surface parameters that describe monthly dynamics of: Solar radiation; Deep rooted describe monthly dynamics of: Solar radiation; Deep rooted transpiration; and Surface roughnesstranspiration; and Surface roughness

Pre European land surface conditions extrapolated from Pre European land surface conditions extrapolated from current day land surface with historical vegetation mappingcurrent day land surface with historical vegetation mapping

Slide 17 – Land Cover Mapping

Australian Historical Land Cover Australian Historical Land Cover MappingMapping

• AUSLIG Current (1990) AUSLIG Current (1990) Vegetation mapped in Land Cover Vegetation mapped in Land Cover ClassesClasses

• AUSLIG Pre-European (1788) AUSLIG Pre-European (1788) Vegetation mapped in Land Cover Vegetation mapped in Land Cover ClassesClasses

Slide 18 – SiB Land Cover Mapping

Australian Historical Land Cover Australian Historical Land Cover Change MappingChange Mapping

• AUSLIG Current (1990) AUSLIG Current (1990) Vegetation mapped in the Simple Vegetation mapped in the Simple Biosphere Classes of ModelBiosphere Classes of Model

• AUSLIG Pre-European (1788) AUSLIG Pre-European (1788) Vegetation mapped in Simple Vegetation mapped in Simple Biosphere ClassesBiosphere Classes

Slide 19 – Summary of Parameter Changes

• CurrentCurrent Australian albedo was marginally higher, with south west Australian albedo was marginally higher, with south west Western Australia consistently higher, and eastern Australia Western Australia consistently higher, and eastern Australia higher in summer but with mixed differences in winterhigher in summer but with mixed differences in winter

• Current Australian LAI was significantly lower, with south west Current Australian LAI was significantly lower, with south west Western Australia significantly lower in summer and marginally Western Australia significantly lower in summer and marginally higher in spring, and eastern Australia consistently lower, with higher in spring, and eastern Australia consistently lower, with marginally closer values in southern areas in springmarginally closer values in southern areas in spring

• Current Australian stomatal resistance was marginally higher, with Current Australian stomatal resistance was marginally higher, with south west Western Australia significantly lower, south eastern south west Western Australia significantly lower, south eastern Queensland marginally higher and eastern New South Wales Queensland marginally higher and eastern New South Wales marginally lowermarginally lower

• Current Australian surface roughness was significantly lowerCurrent Australian surface roughness was significantly lower

Summary of Australian Historical Land Cover Change Summary of Australian Historical Land Cover Change Impacts on GCM Surface ParametersImpacts on GCM Surface Parameters

Slide 7 – Land Cover Sensitivity

• Experiment 1 – Use CSIRO GCM to model climate for 1969 – Experiment 1 – Use CSIRO GCM to model climate for 1969 – 2000 with current land surface conditions2000 with current land surface conditions

• Experiment 2Experiment 2 – – Use Use CSIRO GCM CSIRO GCM to to model the climate for the model the climate for the same same periodperiod with with p pre European land coverre European land cover

• Remove otherRemove other sources of of climate variability by prescribing the sources of of climate variability by prescribing the same observed sea surface temperatures and sea ice distribution same observed sea surface temperatures and sea ice distribution from in both experiments for modelling periodfrom in both experiments for modelling period

• Compare climate between tCompare climate between the two he two experimentexperimentss

• Attribute differences in climate with changes in Attribute differences in climate with changes in land surfaceland surface processes that have resulted from land cover changesprocesses that have resulted from land cover changes

Land Cover Change and Climate modelling experimentsLand Cover Change and Climate modelling experiments

CSIRO Mk3 AGCM Model• Atmosphere

Grid: T63 (1.88o x 1.88o) 18 levels - hybrid ,p

Semi-Lagrangian moisture transport

UKMO convection (Gregory & Rowntree)

Liquid water clouds (Rotstayn)

• Land surface

Soil model - 6 levels

Temperature, water, ice

9 soil types

13 land surface and/or vegetation types

Snow-cover model - 3 layers

Parameters required for the vegetation description

rs - min stomatal resistance

LAI – leaf area index

z0 – roughness length

α – canopy albedo

ε – canopy emissivity

δ – fraction of canopy

Parameters required

saturated moisture content wilting moisture content field capacity moisture content matrix potential hydraulic conductivity z0 – roughness length α – soil albedo soil density specific heat

Soil Model6-layers for moisture and temperature

Slide 20 – Jan GCM Land Surface Parameters

Slide 22 – Conclusion of Parameter Changes

Australian land cover change modified the Australian continental Australian land cover change modified the Australian continental and regional land surface properties of surface albedo, leaf area and regional land surface properties of surface albedo, leaf area index, surface roughness, and stomatal resistance index, surface roughness, and stomatal resistance

These changes impacted on: surface radiation budgets; canopy These changes impacted on: surface radiation budgets; canopy resistance to transpiration; canopy moisture storage capacity; resistance to transpiration; canopy moisture storage capacity; canopy interception rate for precipitation and dew; and boundary canopy interception rate for precipitation and dew; and boundary layer turbulencelayer turbulence

The differences in CSIRO GCM land surface parameters between The differences in CSIRO GCM land surface parameters between pre-clearing and current Australia, however, were smaller in pre-clearing and current Australia, however, were smaller in magnitude than the differences between the original CSIRO GCM magnitude than the differences between the original CSIRO GCM parameters and the new satellite derived land surface parametersparameters and the new satellite derived land surface parameters

Conclusions on Australian Historical Land Cover Change Conclusions on Australian Historical Land Cover Change Impacts on GCM Surface ParametersImpacts on GCM Surface Parameters

Slide 24 – Australian Air Temp Difference

Slide 25 – Australian Precipitation Difference

Slide 23 – Climate Impact Results

• Statistical analysis was performed to assess the performed to assess the Australian continental and regional modelled climate impact of historical modelled climate impact of historical Australian land cover changeAustralian land cover change.

• The only statistically significant changes in average Australian The only statistically significant changes in average Australian climate were for austral summer (DJF), which was warmer climate were for austral summer (DJF), which was warmer (+0.15 C, p = 0.00) and dryer (-0.09 mm/day, p = 0.05)(+0.15 C, p = 0.00) and dryer (-0.09 mm/day, p = 0.05)

• Regional analysis showed statistically significant changes in Regional analysis showed statistically significant changes in average climate for south east Queensland, where summer was average climate for south east Queensland, where summer was warmer (+0.15 C, p = 0.00) and dryer (-0.31 mm/day, p = 0.00), warmer (+0.15 C, p = 0.00) and dryer (-0.31 mm/day, p = 0.00), and spring was cooler (-0.33 C, p = 0.02)and spring was cooler (-0.33 C, p = 0.02)

• Eastern New South Wales, where summer was warmer (+0.4 C, Eastern New South Wales, where summer was warmer (+0.4 C, p = 0.00) p = 0.00)

• and south west Western Australia, where it was overall cooler and south west Western Australia, where it was overall cooler (-0.35 C, p = 0.00), with summer cooler (-0.32 C, p = 0.00), (-0.35 C, p = 0.00), with summer cooler (-0.32 C, p = 0.00), autumn cooler (-0.7 C, p = 0.01), winter wetter (+0.24 mm/day, autumn cooler (-0.7 C, p = 0.01), winter wetter (+0.24 mm/day, p = 0.01), and spring cooler (-0.32 C, p = 0.02).p = 0.01), and spring cooler (-0.32 C, p = 0.02).

Climate Impacts of Australian Land Cover ChangeClimate Impacts of Australian Land Cover Change

Slide 31 – Precip and MSLP changes

Slide 32 – Implications of Results

• Statistically significant DJF warming and drying modelled over Statistically significant DJF warming and drying modelled over south east Queensland, corresponds with strong drying trends south east Queensland, corresponds with strong drying trends over the last 50 yearsover the last 50 years

• This region and the areas to the north and west, continue to be This region and the areas to the north and west, continue to be actively cleared, accounting for the majority of current land actively cleared, accounting for the majority of current land clearing occurring across Australiaclearing occurring across Australia

• Statistically significant increase in JJA precipitation over south Statistically significant increase in JJA precipitation over south west Western Australia was opposite to the observed drying west Western Australia was opposite to the observed drying trends of the last 100 and 50 years. trends of the last 100 and 50 years.

• This showed the increased JJA latent heat fluxes over agricultural This showed the increased JJA latent heat fluxes over agricultural land had the potential to increase precipitation, supporting the land had the potential to increase precipitation, supporting the observations of observations of Ray et al.Ray et al. (2003). (2003).

• This suggested the strong drying trend over south west Western This suggested the strong drying trend over south west Western Australia has been in response to large scale circulation changes, Australia has been in response to large scale circulation changes, rather than historical land cover change.rather than historical land cover change.

Implications of the Climate Impacts of Australian Land Implications of the Climate Impacts of Australian Land Cover ChangeCover Change

Trends in Annual Rainfall

1950 - 1999

Australian Land Cover Change:

Clearing 1990 - 1995

Slide 34 – Conclusions

• Changes in land cover result in regional and seasonal changes in Changes in land cover result in regional and seasonal changes in surface conditions which can only be realistically described with surface conditions which can only be realistically described with current satellite observation and historical extrapolationcurrent satellite observation and historical extrapolation

• The differences in the satellite-derived land surface properties The differences in the satellite-derived land surface properties and the original CSIRO land surface parameters are larger than and the original CSIRO land surface parameters are larger than the differences described for Australian land cover changethe differences described for Australian land cover change

• Changes in surface conditions have strong regional and Changes in surface conditions have strong regional and continental impacts on modelled Australian climatecontinental impacts on modelled Australian climate

• The climate changes result from direct impacts from changes in The climate changes result from direct impacts from changes in surface fluxes, and indirect impacts from changes in atmospheric surface fluxes, and indirect impacts from changes in atmospheric circulation, precipitation induced soil moisture feedbacks, and circulation, precipitation induced soil moisture feedbacks, and cloud induced short wave radiation feedbackscloud induced short wave radiation feedbacks

• The climate impacts of human induced land cover changes need The climate impacts of human induced land cover changes need to be incorporated into Australian climate change assessmentsto be incorporated into Australian climate change assessments

ConclusionsConclusions