The role of vegetation-climate interaction on Africa under climate change - literature review seminar Minchao Wu Supervisor: Markku Rummukainen, Guy Schurgers.

The role of vegetation-climate interaction on Africa under climate change- literature review seminar

Minchao WuSupervisor: Markku Rummukainen, Guy Schurgers

2015-01-15

Main drivers of climate and climate change

Source. IPCC 2013

The development of Earth System Models (ESMs)

Source. IPCC 2013

Vegetation feedback on climate

A

Source. Bonan et al. 2008

Challenge to quantify due to various sensitivity in different process

Adapted from Zhang et al. 2014

+

Positive or negative depends on process sensitivity (contribution)

Effects of large-scale deforestation

Source. Bala et al. 2007

Borael : Deforst. Albedo (+) shortwave net rad. (-) temp. (-)

Tropics : Deforst. Albedo (+) shortwave net rad. (-) evap. (-) & sensible heat flux (-) temp. (+)

Effects of vegetation carbon-cycle feedback

CO2 (+) Stomata cond. (-) Evap. (-)

Precp. (-)Veg. (-)

Temp. +

Source. Bett et al. 2004

RCMs : essential for policymaking for regional climate change

Coupled Regional climate model – dynamic global vegetation model(coupled RCM-DGVM)

Feedback Variables

Study region

Models(RCM/DGVM)

FindingPapers Comments/outlook

Vegetation structure

Central United States

RAMS/CENTURY(weekly)

Seasonal vegetation phenological variation strongly influences regional climate patterns through its control over land surface water and energy exchange.

(Lu et al., 2001) The inadequate and unrealistic description of vegetation evolution in its current land surface models is considered a major deficiency

Vegetation structure

West Africa

RegCM3/CLM-DGVM(asynchronously, yearly)

Precipitation increase by 23% over the Sahel in summer compared 5% decrease without vegetation feedback

(Alo and Wang, 2010), (Wang and Alo, 2012)

Should use synchronously (fully) coupling approach in future study; Land use should be consider; model consistency: soil moisture;

Vegetation structure, fraction

Europe RCA/LPJ-GUESS,(fully coupled, daily)

Feedback effects are rather modest: feedback contribute 0.2-1 degree C increase for southern Europe and 0.2-0.5 decrease for northern and central Europe.

(Smith et al., 2011, Wramneby et al., 2010)

Smaller than assumed, such as in other studies Betts et al., 2000, Bala et al., 2007; Land use should be consider; model consistency: such as land surface process, stomatal regulation and soil hydrology.

Land use Unite State

WRF3/CLM3.5 Strong soil moisture-precipitation feedback in Midwest irrigated area

(Lu and Kueppers, 2012)

Need to improve LAI simulation, and irrigation scheme.

Crop, Vegetation structure, vegetation fraction

East Asian monsoon area

RegCM3/CERES(fully coupled, daily, land-surface scheme derived from BATS)

Reduced RMSE of the simulated precipitation by 2.2–10.7% over north China

(Chen and Xie, 2012) Uncertainties in modeling how monsoon dynamics responds in RCMs. Uncertainties also lie in the lack of description of natural vegetation growth and develop and the simplification of cropping system over the region.

Vegetation structure

Europe REMO/iMOVE (vegetation part originates from JSBACH)

Dynamics of vegetation cover and density contribute to difference from REMO2009

(Wilhelm et al., 2013) Soil hydrological dynamics is not capture for some regions that influence vegetation growth, e.g. LAI Further development effort should put to multi-layer scheme

Uncertainties in vegetation dynamicsOr coupling approach

RCA-GUESS application (Europe)

Nor

mal

ized

phen

olog

y in

dex

sum

mer

Te

mp.

sum

mer

La

tent

Hea

t flu

x

Change in future Feedback contribution

Wramneby et al., 2010

Northern & central E.: cooler & wetter

Southern E: warmer & drier

RCA-GUESS application (Arctic)

Nor

mal

ized

phen

olog

y in

dex

Change in future Feedback contribution

Zhang et al., 2014

Spring: warmingSummer: cooling

Reflection of previous RCA-GUESS studies

Europe - Small feedback effects: Climate is controlled by general circulation and

effects of the Atlantic sea. Feedback is merely locally significant?

Artic – More processes should be included? SST feedback, Permafrost C feedbacks, land use,

nutrient feedbacks

Attractive research domain - Africa• Carbon stock: 20% of global (NPP)

• Landscape change: Deforestation: ca. 10% of the total forest area of Africa annually

(2000-2010)Greening: 10%-50% increase in NDVI in over Sahel.20% of global land use CO2 emission

• Wildfire: > 68% of the global wildfire,

40% fire emission

Research Questions• General research question: What is the role of regional vegetation-climate feedback for African climate change studies?

Sub-research questions: Can vegetation-climate feedbacks help to better understand

regional climate and vegetation conditions for present-day Africa?

If vegetation feedback is still limited to local or regional effects, it remote effect is possible to identify?

If integrating more processes would help better under vegetation-climate feedback and if so if how to better constrain uncertainty?

Papers plan

Some results for the current project plan

Thanks!