Climate Effects of Land Use Change in CESM

Dr. Peter Lawrence

Project Scientist

Terrestrial Science SectionClimate and Global Dynamics Division

(With thanks to the TSS group for their many contributions)

Slide 1 - Title

Understanding the Land Surface in the Climate System: Investigations with an Earth System Model (NCAR CESM)

The land is a critical interface through which:

1. Climate and climate change impactshumans and ecosystems

and

2. Humans and ecosystems can force global environmental and climate change

Gridcell

Glacier Wetland Lake

Landunit

Columns

PFTs

UrbanVegetated

Soil Type 1

Community Land Model (CLM) subgrid tiling structure

Slide 4 – Land Cover Change

Land Cover Change Cropping and Forests in CLM4

1. Direct Biogeophysical Impacts:- Albedo – Radiation (Snow Interactions)- Surface Hydrology (Irrigation)- Surface Roughness

2. Direct Biogeochemical Impacts:- Vegetation and Soil Carbon Fluxesfrom Conversion Natural -> Human systems

- Harvesting from Forestry and Agriculture

3. Indirect Impacts:- Increased Photosynthesis through higherCO2, Nitrogen, Phosphorus and Potassium

- Atmospheric Responses in Temperature, Cloud,Precipitation and Larger Scale Circulation

- Fire, Methane, Dust, Volatile Organics, AerosolsLawrence et al., [2011], Lawrence and Chase, [2010], Feddema, et al., [2005], Findell, et al., [2007], IPCC, [2007], Bonan, [2008], and Canadell, et al., [2007]

Slide 4 – Land Cover Change

Human Land Cover Change

AgricultureAfforestation

Growth Growth

Urban

Forestry

1. Direct Biogeophysical Impacts:- Albedo – Radiation (Snow Interactions)- Surface Hydrology (Irrigation)- Surface Roughness

2. Direct Biogeochemical Impacts:- Vegetation and Soil Carbon Fluxesfrom Conversion Natural -> Human systems

- Harvesting from Forestry and Agriculture

3. Indirect Impacts:- Increased Photosynthesis through higherCO2, Nitrogen, Phosphorus and Potassium

- Atmospheric Responses in Temperature, Cloud,Precipitation and Larger Scale Circulation

- Fire, Methane, Dust, Volatile Organics, AerosolsLawrence et al., [2011], Lawrence and Chase, [2010], Feddema, et al., [2005], Findell, et al., [2007], IPCC, [2007], Bonan, [2008], and Canadell, et al., [2007]

Slide 4 – Land Cover Change

Human Land Cover Change

AgricultureAfforestation

Growth Growth

Urban

Forestry

1. Direct Biogeophysical Impacts:- Albedo – Radiation (Snow Interactions)- Surface Hydrology (Irrigation)- Surface Roughness

2. Direct Biogeochemical Impacts:- Vegetation and Soil Carbon Fluxesfrom Conversion Natural -> Human systems

- Harvesting from Forestry and Agriculture

3. Indirect Impacts:- Increased Photosynthesis through higherCO2, Nitrogen, Phosphorus and Potassium

- Atmospheric Responses in Temperature, Cloud,Precipitation and Larger Scale Circulation

- Fire, Methane, Dust, Volatile Organics, AerosolsLawrence et al., [2011], Lawrence and Chase, [2010], Feddema, et al., [2005], Findell, et al., [2007], IPCC, [2007], Bonan, [2008], and Canadell, et al., [2007]

Slide 4 – Land Cover Change

Human Land Cover Change

AgricultureAfforestation

Growth Growth

Urban

Forestry

1. The biogeophysical climate impacts of changing land cover from precleared vegetation to current day vegetation were investigated with the CCSM 3.0 model in Lawrence and Chase (2010)

2. The investigation compared six ensemble members of 30 years of current day equilibrium climate simulated in the fully coupled CCSM 3.0 model with Precleared Vegetation land surface parameters, against the same climate simulated with Current Day land surface parameters

3. The Land Surface Hydrology representation in CLM 3.0 was modified as described in Lawrence and Chase (2009) to address modeling biases.

CCSM Land Cover Change Climate Experiments

Slide 2 - Outline

Current Day – Preclear Vegetation CCSM Climate-Albedo

Slide 5 – CLM Parameters - Sub-Patch PFTSLawrence and Chase (2010)

Current Day – Preclear Vegetation CCSM Climate-Latent

Slide 5 – CLM Parameters - Sub-Patch PFTSLawrence and Chase (2010)

1. High latitude winter cooling due increased albedo from current day crops and grasses which replace natural forests, savannas and shrublands. These changes were amplified by snow interactions

2. Tropical warming and summer higher latitude warming associated with reduced evapo-transpiration which left more of the surface energy budget available for sensible heating – despite higher albedo

Summary of CCSM 3.0 Land Cover Change Experiments

Slide 2 - Outline

CMIP5 Land Cover Change in (CLM4 CN) Biogeochemistry

Land Cover Change Contribution:

Slide 3 – IPCC Land Cover Change b

CMIP5 Transient Land Cover in CLM 4 PFTs

CMIP5 - RCP Land Cover Change PFTs – Trees %area

LCC in CCSM 4 – Coupled Climate & Prescribed CO2

LCC in CCSM 4 – Coupled Climate & Prescribed CO2

CMIP5 CCSM Land Cover Change Emissions and Warming

Slide 2 - Outline

Time Series Landuse PgC CO2 PPM Temp OC

Historical 1850-2005 120.0 30 0.35

RCP 2.6 Image 176.9 44 0.51

RCP 4.5 GCAM 150.0 38 0.44

RCP 6.0 AIM 182.7 46 0.53

RCP 8.5 Message 259.6 65 0.75

LCC in CCSM 4 – Coupled Climate & Prescribed CO2

Slide 6 – PFT Mapping

CESM Land Cover Change – Impacts of Albedo

Jones et al. 2013 (LBNL & UCB)

- Applied very large land cover change in RCP 4.5 - Found strong cooling in

northern latitudes from albedoincreases against afforestation

- These partially offset CO2warming.

Slide 6 – PFT Mapping

CESM Land Cover Change – Albedo and Hydrology

CESM Land Cover Change and Hydrology Experiments:

- Land Cover Change: Current Day to All Grass- Hydrology changes in CLM to address known Evapo-Transpiration issues (New Hydro)

- New Hydro reduces annual temperature cooling over the extra-tropics from going from trees to grasses and increases warming in tropics

22

Urban Areas in a Climate ModelGridcell

Glacier Wetland Lake

Landunits

Columns

Vegetated

(RURAL)

PerviousShaded WallRoof Sunlit Wall Impervious

Canyon Floor

Urban

,sunwall sT ,shdwall sT

,roof sT

imprvrdHprvrdH

shdwallHsunwallH

roofH

, , , ,H E L S τ↑ ↑

Impervious Road “Pervious” Road

,prvrd sT,imprvrd sT

, ,s s sT q u

Canopy Air Space

W

H

Roof

Sunlit Wall

Shaded Wall

,1prvrdT

,10prvrdT

,1imprvrdT

,10imprvrdT

,1roofT

,10roofT

,1sunwlT ,10sunwlT

roofR

imprvrdR prvrdR

,1shdwlT,10shdwlT

Atmospheric Forcing

,atm atmT q

, ,atm atm atmP S Latmu

imprvrdEprvrdE

roofE

min , maxi buildT T T< <

Community Land Model – Urban (CLMU)Oleson et al. 2008a, b, JAMC

wasteH

Present day Urban Heat Island (UHI) simulated by CLM Urban (°C)

Urban Heat Island in CCSM4

Modeled UHI ranges from near-zero up to 4°C with spatial and seasonal variability controlled by urban to rural contrasts in energy balance.

1. Changing Natural Vegetation to Agriculture and Afforestation in CESM results in three competing processes on the climate:

Albedo changes surface energy from Vegetation and Snow Evapo-Transpiration changes surface heating from latent heat Carbon fluxes impact Radiative Warming of Atmosphere

2. The representation of land cover change in CLM4 have different impacts on the surface radiation processes, evapo-transpiration partition, hydrology and the terrestrial carbon cycle which reflect these competing climate impacts.

3. The Land Surface Hydrology and Carbon Cycle representations in CLM 4 have been shown to have significant modeling biases Bonanet al. (2012). These need to be better constrained to determine robust land cover change impacts on climate in CESM.

4. The CLM Urban model has robust Urban Heat Islands with the model continuing to be improved allowing the Urban climate to be further understood in the context urban development and climate change.

CESM Land Cover Change and Climate – Summary

Slide 2 - Outline