Land-Atmosphere Interaction: Deforestation and Afforestation

1. Land-Atmosphere Interaction: Deforestation and Afforestation Eric Caudill Fourth Year Undergraduate Atmospheric Sciences

2. The Literature • First paper from JagdishShukla, a meteorologist and professor at George Mason University • Focus on the Amazonian Rainforest and the effects of its deforestation on the climate • Second paper from GovindasamyBala and the National Academy of the Sciences • Focus on the effects of a global deforestation, not just a specific region

3. What is Deforestation? • Deforestation is the clearing of a large section of forest for burning of wood or logging • Deforestation is also done for conversion of the land to non-forest uses, such as farms or pastures for cattle, urbanizing the area, even oil drilling

4. Why is Deforestation Problematic? • Contrary to the common belief that ALL deforestation is bad, it actually is not • In temperate climates, clearing of forest is actually called “regeneration harvest”, Bala will touch on this discovery • However, we are not looking at this scenario. • Consequences of deforestation include: • Ridding of carbon sinks and releasing massive amounts of CO2 into the atmosphere • Climate change • Loss of biodiversity; potential extinction • Potential aridity, hindering potential further growth of plants and animals • Soil erosion

5. Focus on Shukla • Much older paper (in hindsight, was this an omen?) • Shukla gives consequences of deforestation based on his own model runs • Believes strongly deforestation in Amazon will extend the dry season • If deforested, Shukla believes it would not be able to revert itself and would degrade into a wasteland • Shukla barely touches on the mid-latitudes and the effects of deforestation on climate change in the region

6. Model Results Compared to the control, the results shown at the right show one-year: (A) increases in surface temperature (in degC), (B) increases in soil temperature (in degC), (C) decreases in precipitation (in mm), and (D) decreases in evapotranspiration (in mm)

7. More Model Results • Increase in albedo • Lower surface roughness length • Lower capacity for soil moisure • Suggests that the atmosphere interaction with the model could even further reduce the amount of moisture in the region, because of the sharp drop in both precipitation and evapotranspiration

8. Deforestation in the Amazon • Trade in Brazil often times fuels the need for deforestation • Dependent upon inflation of their currency called Real • When Real deflates, the price of beef increases dramatically and incentivizes ranchers to clear-cut in order to expand pasture. • China mines in the Eastern Amazon for metals like nickel and copper • In 2012 the Ecuadorian President who was previously known as a Green President even pushed towards having a massive Chinese mining facility for economic reasons

9. Onward, To Bala! • Much more recent literature • Focuses on global deforestation • Generally relevant in many aspects, very solid research and overall coverage of the topic • Builds on the idea of deforestation and afforestation effects being region dependent • Explains that while there is an increase in CO2 ppmcontributing to warming, there are biogeophysical effects that attribute to atmospheric cooling in some latitudes

10. Bala’s Models • Standard control model • Global deforestation model • Tropical, temperate, and boreal models also shown. This is to explain the latitudinal differences in deforestation and afforestation effects.

11. Bala’s Findings • Albedo, evapotranspiration, and cloud cover from deforestation changes will actually contribute to cause a net cooling in comparison to the CO2 being put into the atmosphere, in the Northern Hemisphere mid and high latitudes. • There is actually only a warming by 0.1K in the Southern Hemisphere mid latitudes as well, but it is not as pronounced. • Focuses more on the Global case for findings because the linear sum of the other three cases is very close to the Global case.

14. Proceed With Caution! • Bala himself distinguishes that this is only one model run and that this may not actually be correct, rather a theory. • Could be dependent on other outside factors, like hydrology at the surface and the dynamics of the clouds in the model. • Although he shows his skepticism as all scientists should, he still believes that because the model was consistent with previous studies, but also provided this new information, that it is very good. • Specifically states that this deforestation should not be a mitigation technique for climate change, because we already know that it is in general a contributor to global warming and not a preventor.

15. Solutions Proposed? • Deforestation is known to be a necessary evil • Management of forest and forest resources • Replacement of trees, or the regeneration harvest, in any area where trees are clear-cut • Limiting the amount of area that can be clear-cut

16. Negative Outlooks in Amazon • Increase in temperature, drought, and ENSO event frequency will cause a negative feedback loop that will be very, very bad for the Amazon in conjunction with deforestation! • Less forest is less ability to use resource • Tends to lead to increase in poverty • This will sometimes require human migration into the forest, which is already resource-stressed

17. Short Clip on Clear Cutting • http://www.youtube.com/watch?v=HkD1esxaK8U • Because who doesn’t like YouTube videos, right?

18. Opinions, Opinions • The Shukla paper was quite technical and dense in comparison to the Bala paper, which was well-written and covered many topics in a concise fashion. • Both papers did their job of explaining the research and giving a general understanding of what was found through the modeling process.

19. Questions?