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