Will deforesting Canada cool the...
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Will deforesting Canada cool the climate? Alvaro Montenegro CMOS, May 2012
Transcript of Will deforesting Canada cool the...
Will deforesting Canada cool the climate?
Alvaro Montenegro
CMOS, May 2012
Authors Patrick Longobardi Climate and Atmospheric Sciences Institute (CASI), StFX Hugo Beltrami CASI, StFX Gurpreet Matharoo CASI, StFX Michael Eby UVic Quiazhen Mu U. of Montana
Outline How deforestation impacts climate
High-latitude deforestation impacts from observations
High-latitude deforestation impacts from global climate models
Deforestation
Carbon emissions to the atmosphere
Deforestation
Increase in surface albedo
Deforestation
Increase in surface albedo
Deforestation
Decrease in evapotranspiration (ET) Reduction in latent heat flux
Decrease roughness length (RL) Reduction in sensible and latent heat flux
Deforestation
Changes in cloud cover
Deforestation
Probably only important for large scale change
Impact of deforestation from global climate models
Impact of deforestation from global climate models
Warming
Cooling ???
???
Impact of deforestation from global climate models
Global or whole latitude band land cover change
Most experiments based on:
Historical land use change
Impact of deforestation from global climate models
Are these results the same when smaller area fractions of the land surface are deforested?
Deforestation with the UVic Earth System Climate Model
Simulations:
Duration: 2010 to 2200
Forcing: A2 emissions to 2100 then constant
Control - no deforestation
Deforestation – Trees substituted by crops/grasslands in single step at start of 2010
Longobardi et al. submitted
Deforestation with the UVic Earth System Model
Progressive deforestation fractions from 5% to 100%
Results UVic – High Latitudes Surface Air Temperature Anomaly
global deforested areas
2100 – 100%
Impact of deforestation from global climate models
Not all global modelling experiments show cooling for high latitude deforestation
Historical ALCC with the ECHAM5 ESM
Pongratz et al., GRL, 2011
Net radiative forcing (albedo + CO2)
Deforestation effects from afforestation simulations
Estimated by inverting effects of afforestation
-1
=
Arora and Montenegro, 2011
Afforestation with the Canadian Earth System Model
No statistically significant change in surface air temperature due to afforestation at NH high- and mid-latitudes
Arora and Montenegro, 2011
Impact of deforestation from observations
cooling from drawdown Total Drawdown - warming from darkening Equivalent Emissions
net cooling Net Drawdown
Afforestation effects from satellite observations
Methods
Montenegro et al., 2009
Afforestation effects from satellite observations
11
3
Mean Net Drawdown
kg/m2
Results
Afforestation effects from satellite observations
-1.5
Results
Minimum Net Drawdown 2.5
kg/m2
Deforestation effects from observations in Québec
Bernier et al, Agric. For. Meteorol., 2011
Albedo and CO2 forcing resulting from forest to lichen woodland conversion
Deforestation effects from observations in Québec
Bernier et al, Agric. For. Meteorol., 2011
Albedo and CO2 forcing resulting from forest to lichen woodland conversion
CO2
Albedo
Net
40-60% - 0-10%
Forested non-forested differences from MODIS
Not the effects of deforestation, just present day differences between forested and non-forested areas.
Resolution – 5 km x 5 km Spatial Coverage – Global Temporal Coverage – 2003-2007 average Parameters – Surface temperature (skin temperature)
Forested non-forested differences from MODIS Non-forested – Forested Surface Temperature
North America
Citizen Alvaro
NO!
Scientist Alvaro
Depending on location and magnitude of deforestation
probably yes …
Will deforesting Canada cool the climate?
Modelled widespread high-latitude deforestation Global air temperature response: Cooling
Local air temperature response: Cooling
Conversion of forest to lichen woodlands
Observed net radiative balance indicates cooling
Deforestation near present agricultural land* Models and observations:
Heterogeneous response
Mean best guess: neutral to small warming
* Deforestation and afforestation studies
Albedo effects MUST be considered in estimates of the temperature mitigation potential of afforestation.
A plea:
Results UVic – High Latitudes
Atmospheric CO2 Anomaly
Deforestation
Atmospheric carbon emissions Soil carbon
Deforestation effects
Biogeochemical CO2 emissions – warming*
Biogeophysical Albedo Increase – cooling
ET decrease – surface warming
Cloud cover change*
* scale dependent
RL decrease – surface warming
* Potential offset by Soil C?
Results UVic – High Latitudes
Carbon Budget Anomalies
25% 45%
Global increase in soil carbon after high-latitude deforestation described for the ECHAM5 earth systems model (Bathiany et al., Biogeosciences, 2010).
Results UVic – High Latitude deforested areas
Soil temperature anomaly P-E anomaly
And higher NPP over many deforested areas.
Historical ALCC with the ECHAM5 ESM
Radiative forcing from:
Albedo change
CO2 emissions
Net (albedo + CO2)
Pongratz et al., GRL, 2011
Afforestation effects from observations
Big advantage: spatial resolution closer to scale of LCC
Yah, and they are observations…
X
Afforestation effects from observations
Disadvantages: Missing parameters Spatial/temporal representativeness No climate feedback
Yah, and they are observations…
Afforestation effects from satellite observations
Methods
Potential Vegetation 0.08o x 0.08o
Present day vegetation 0.05o x 0.05o
Forests
Crops
Realizable afforestation
Deforestation effects on local T from observations
Bonan, J. of Climate, 2001
Higher Daily Max T Lower Daily Max T
Large scale forest to cropland conversion *
Regional air temperature response: Cooling
* mid-latidudes really…
Forested non-forested differences from MODIS
Non-forested – Forested Surface Temperature
Forested non-forested differences from MODIS
latitude
Non-forested – Forested Surface Temperature K
Forested non-forested differences from UVic
Non-forested – Forested Surface Temperature
Forested non-forested differences from MODIS Non-forested – Forested Surface Temperature
North America
MM5 domain
MODIS x MM5
latitude
Non-forested – Forested Surface Temperature North America
X MODIS O MM5
All data
Lat. mean
Forested non-forested diff. from MODIS Large variability. On average non-forested warmer up to ~ 50˚ N
Forested and non-forested temperature differences
Forest Non-forest*
Land Cover
Other
* Grassland and crops
Forest T Non-forest T Other T
Temperature Temp. difference Non-forest T – Forest T
T Diff
Forest H Non-forest T Other H
Elevation
Lapse rate adjustment
~35 km*
~55 km*
* at 50˚N
Forested non-forested diff. from MODIS Large variability. On average non-forested warmer up to ~ 50˚ N
