1. Presented by: Audrey Eggenberger Geography: ASCS major Amazon Deforestation and Climate Change (1990) By: J. Shukla et. all Combined Climate and Carbon-Cycle Effects of Large-Scale Deforestation (2007) By: G. Bala et. all

2. Profile of the Amazon  Incredible biodiversity  Important ozone sink  Important role in global tropospheric chemistry  Experiencing alarming rates of deforestation  If nothing is changed, Amazon will disappear in 50- 100 years

3. What do plants do?  Absorb and store CO 2  Act as H 2 O reservoir and heat reservoir  Transpiration  Reflect incoming solar radiation (SWdn)  Albedo —fraction of SWdn reflected

4. Focus: Forests Tropical Boreal Temperate Boreal Temperate

5. Vegetation and Climate  Traditionally vegetation type was thought to be a RESULT of local climate  Complex experiments have shown, however, that the type of vegetation can influence regional climate  Current climate and vegetation coexist in a dynamic equilibrium

6. Effects of Deforestation  Releases CO 2 stored in the living plants to atmosphere and eliminates future storage  Alters physical properties of Earth’s surface  Root system  Water and heat storage  Albedo

7. Climatological Implications  Warming influence from:  Addition of CO2 greenhouse gas  Decreased evapotranspiration (short run)  Cooling influence from:  Increased surface albedo  Decreased evapotranspiration (long run) Greenhouse Effect Albedo Effect

8. It’s Complicated…  Dynamic equilibrium  Complex interactions  Teleconnection and Feedback problem  Models are unable to solve this problem in foreseeable future  There are local variations too  Subgrid-Scale Problem

9. Amazon Deforestation and Climate Change Shukla et. all  Investigates the effects of deforestation on the local physical climate system  Uses a coupled numerical model of global atmosphere and biosphere  Control Case: forest intact  Deforestation Case: forest cover is replaced by degraded pasture Area of interest

10. Experiment  Coupled model was integrated for 1 year for both the Control and Deforestation cases  Only change from Control to Deforestation case was the replacement of forest with pasture (grass)  Integrations were carried out for 12.5 months, starting from December 15 th

11. Results  Surface/soil temp (T s ) warmer  Consistent with reduction in evapotranspiration (E)  More Lwup (Ln)  Higher albedo (a), leads to reduction of absorbed SWdn  Reduced moisture and heat storage capacity Recall: B=SH/LH

12. Results cont.  Reduction in evapotrans- piration by 49.6 cm annually  Reduction in precipitation by 64.2 cm annually Deforestation case Control case

13. Bottom Line…  Rise in surface temperature locally  Significant decrease in precipitation  Precip decrease is larger than the reduction in evapotranspiration  Moisture flux decreases as a whole  Longer dry season  Makes reclamation by rainforest highly unlikely  Valuable ecosystem disrupted, if not devastated

14. Combined Climate and Carbon-Cycle Effects of Large- Scale Deforestation Bala et. all  Investigates global effects of deforestation on climate  Uses 3-D coupled global carbon-cycle and climate model  Lawrence Livermore National Lab Integrated Climate and Carbon (INCCA) Model  Vegetation, land, ocean

15. Experiment  6 different model runs (from year 2000-2150): 1. Control—no CO2 or deforestation 2. Standard—no deforestation 3. Tropical—deforestation in tropics only 4. Temperate—deforestation in mid-latitudes 5. Boreal—deforestation in boreal zones 6. Global—deforestation EVERYWHERE

16. Results  In Global Case (compared to Standard):  Atmospheric CO 2 content higher  More ocean uptake of CO 2  Annual mean temperature COOLER  Annual mean temperature COOLER (by ~0.3K)

17. Cooling? Wait…what?!  It’s all thanks to our good friend, albedo  Albedo increases for all forest domains  More SWdn reflected globally  Decrease in evapotranspiration also helps  Smaller Heat reservoir

18. A Closer Look: Tropics (Includes SH mid-latitudes)  Raised albedo = more reflected SWdn  Less moisture= fewer clouds, greater sunlight penetration  Raised CO 2 levels = warming  RESULT: Slight cooling(~0.3K) Simulated spatial temperature difference relative to Standard case centered on year 2100 for tropical deforestation.

19. Temperate Zone  Raised albedo = more reflected SWdn  Raised CO 2 levels = warming  Clouds are not important factor  RESULT: Cooling (~1.6K) Simulated spatial temperature difference relative to Standard case centered on year 2100 for temperate zone deforestation.

20. Boreal Zone  Large albedo increase + already high albedo (snow) = MUCH more reflected SWdn  Raised CO 2 levels and sensitivity = warming  Clouds are not important factor  RESULT: Cooling (~2.1K, some places exceed 6K) Simulated spatial temperature difference relative to Standard case centered on year 2100 for boreal zone deforestation.

21. Global Case  Adding the three zones together is equivalent to the Global Case  As stated earlier, net result globally is COOLING by about ~0.3K Simulated spatial temperature difference relative to Standard case centered on year 2100 for global deforestation.

22. In Summary…  Although removal of forests causes global warming through Carbon-Cycle effects, this warming is overwhelmed by the local and global cooling effects of increased albedo and decreased evapotranspiration, most strongly in the boreal regions.

23. Conclusions/Opinions  Afforestation in tropics = beneficial  Afforestation in temperate and boreal zones = counter productive  Complex atmosphere-biosphere dynamic  Teleconnection and Feedback Problem  Results vary by location  Subgrid-Scale Problem  Problems with INCCA Model  Comparable studies with other models needed  Goal should still be preservation of ecosystems

24. Any Questions??