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Why forests matter for water, energy and climate: what we think we know.


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Presentation by David Ellison of the WeForest Steering Committee at the World Agroforestry COP21 side event on ecological rainfall infrastructure

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Why forests matter for water, energy and climate: what we think we know.

  1. 1. Why Forests Matter for Water, Energy and Climate: What we Think we Know In Support of A WeForest Policy Brief WeForest Steering Committee: David Ellison, Victoria Gutierrez, Cindy Morris, Bruno Locatelli, Jane Cohen, Daniel Murdiyarso, Douglas Sheil
  2. 2. The Nile River Basin (work from Gebrehiwot et al. 2015) §  The Nile Basin provides the water resources to feed some 200 million people. §  The Blue Nile Basin supplies some 85% of the total amount of water that flows to the lower Nile River. §  What is the source of the Blue Nile waters? From a Catchment Basin, Water Balance perspecJve (demand-side approach) §  We would consider the total annual amount of precipitaJon that falls in the Blue Nile Basin §  And we would observe that PrecipitaJon is parJcularly heavy in the Blue Nile Basin area §  But should we go further than this? §  Viste and Sorteberg (2013) suggest a large share of the atmospheric moisture that feeds the precipitaJon in the Blue Nile Basin originates from the West African Rainforests §  There is an increasing amount of deforestaJon in this area §  Some project as much as a 25% reducJon in rainfall in the Ethiopian Highlands with conJnued deforestaJon (Solomon Gebrehiwot, Gebrehiwot et al. 2015)
  3. 3. ROC (Upwind) ETL OE Precipita3on WES ETREC ETOUT WPROD ETIN Catchment Basin RRL _________ (Share of ETREC in P) RRCON __________ (Share of ETIN in P) WCONS Defining the Concept of Hydrologic Space R To Downwind Locations Precipita3on ET?
  4. 4. (Van der Ent et al., 2010) (Bosilovich et al., 2002) The Cross-Continental Transport of Atmospheric Moisture Matters §  Land-atmosphere interac1ons maUer for the distribuJon of water across terrestrial and conJnental surfaces. §  On average, Forests provide more evapotranspira1on (atmospheric moisture) for cross-conJnental transport than other land cover surfaces. §  Land further away from upwind coasts is typically MORE dependent than other lands. Con1nental evapotranspira1on feeds an important share of terrestrial Precipita1on
  5. 5. Atmospheric Moisture Transport Mechanisms Virtuous cycle of increased Precipitation, ET and Forest Growth (Layton and Ellison, under review) How much Forest is enough? (Biotic Pump, Makarieva et al.)
  6. 6. Ice nuclea3on ac3ve microorganisms are implicated in «rainfall feedback» ICE PROPAGATION COLONIZATION ICE NUCLEATION TRANSPORT PRECIPITATION DEPOSITION UPWARD FLUX MULTIPLICATION MICROBIAL STOCK (Cindy Morris, Morris et al. 2014) Forests as Rainfall and Bio-Precipitation Triggers
  7. 7. (Jan Pokorny, Hesslerova et al., 2013) The Cooling Power of Forests (Bounoua et al., 2015) Urban Areas above/below 35% Impervious Surface Area (ISA) §  Forest-water interactions dissipate solar energy §  Transpiration and Evaporation require and use energy §  Surface cooling (lack of warming) is the result.
  8. 8. Canopy cover What Drives Infiltration and Groundwater Recharge? (Bargués Tobella et al.) GroundwaterRecharge TranspirationGroundwater recharge Dominant Paradigm Transpiration Surface runoff Soil evaporation Groundwater rechargeInfiltrationGroundwaterRecharge
  9. 9. Cloud Stripping / Fog Precipitation Location( Elevation((m)( Annual(Rainfall( (mm)( Fog(Precipitation( (mm)( Fog(Precipitation((%( of(total(water(input)( Panama% 500(1270% 1495(6763% 135(2299% 2.3(60.6% Puerto%Rico% 930(1015% 3204(4001% 0(436% 0(26.2% Costa%Rica% 1500% 3191% 886% 21.7% Colombia/Venezuela% 815(3100% 450(1125% 72(796% 3.5(48.3% Guatemala% 2100% 2559% 23% <1% Guatemala% 2550% 2559% 203% 7.4% Hawaii% 981(3397% 300(2449% 134(832% 2.6(61.2% Mexico% 1330(2425% 215(1082% 0(339% 0(50.7% Venezuela% 1750(2150% 828(1009% 354(592% 26(41.7% % (Gazoul and Sheil, 2010) §  What does this mean for the Water Towers of the world? §  How important are Cloud Forests for the Water Balance? §  What is the consequence of deforestation?
  10. 10. The Importance of Spatial Organization §  Where forests are located matters. §  Land conversions impact land-atmosphere interactions and affect the production of atmospheric moisture. §  Up and downwind interactions may matter as much for the Water Balance as up and downstream relationships. §  Upwind sources of atmospheric moisture production affect both Precipitation and the Water Balance and cannot be ignored. §  Likewise, the catchment basin production of atmospheric moisture matters for downwind locations.
  11. 11. Transboundary Relationships and Policy-Making §  Because the supply of atmospheric moisture is transboundary in character, governance structures must consider these larger scale relationships. §  Most water management frameworks, however, are focused on the local level, at much too small a scale. §  And most climate policy frameworks are likewise structured either at the international or the national scale. These governance structures are again inadequate to the task. §  Regional and continental scale governance structures are rare for catchment basin water management. And where they occur, they typically do not consider the supply (or re-export) of atmospheric moisture. §  The international climate policy framework is focused on carbon. Should make positive relationships between forests, water, energy and climate primary.
  12. 12. Trees, Forests, Water, Energy and Climate How we Think they Matter Forest cover plays an important role in the regional and continental hydrologic cycle. More forest cover is, generally speaking, a good thing. It can raise precipitation and water availability in downwind locations. However, increasing forest cover in water poor areas can have negative consequences. (Natural balance matters). In addition to down and upstream considerations, it is also important to think about down and upwind relationships. However, most assessments of the (local) Water Balance fail to do this. Forests represent powerful adaptation tools: In the appropriate surroundings, forests can positively impact atmospheric moisture production, cooling, rainfall, infiltration, groundwater recharge, and other positive features (flood moderation, biodiversity, etc.). Livelihoods depend upon our recognition of the transboundary nature of Hydrologic Space. Water and Energy cycles should be placed at the core of water and land use management and planning strategies. Carbon is secondary. Time for paradigm change. (Blue Nile Basin?)
  13. 13. Thanks for Listening! Comments Welcome (