1Oct. 31--Happy Halloween!Global change Atmosphere, climate, biosphereSystems, positive and negative feedbacksAlternate ecosystem states--Pleistocene steppe-->tundra--Hudson Bay marsh-->mudflatSustainability, Resilience2Antarctic ice corearchives climate andatmosphericcomposition over past740,000 yearsThis ice is about491,0000 yearsold3The concentration of CO2 inair today is higher than ithas been in the last 650,000years, and probably since ithas been in the last 50 my. CO2 (ppm)Before 1850 2741958 (Keeling) 3162005 3702075 (est.) 54041995-2004 vs 1940-19805Evidence of global warming•Glacier shrinkage onmountains around the globe•Permafrost melting in Arctic•Acceleration of Greenlanddeglaciation due to moulins•Warming of upper layers ofthe ocean•Melt of Arctic sea ice--opening of the NorthwestPassage6Melting permafrost, ‘drunken trees’7Chapin, Zimov8Thermokarst lakesWater will be more heterogeneously distributed in Arctic landscape9The area burned in western North America has doubled inthe last 40 years10System: group of entities unitedby interaction or interdependenceto form or act as an entire unitFeedback Loops can enhance orbuffer changes that occur in asystem.Positive feedback: change(increase or decrease) in somevariable results in the same type ofchange (increase or decrease) in asecond variable, Enhancing oramplify changes; destabilizing asystem by moving a it away fromequilibrium.Negative feedback: changeproduces a change in the oppositedirection, which dampens orbuffers changes, holding a systemnear some equilibrium state, makingit more stable11fireGreenhouse warmingDrying of uplandsMore CO2Fewer trees++++++Positive Feedbacks12???!Where is the system now and how will it change…?!(Scheffer et al. 2000)LIDAR data from W. E. DietrichAlternative (stable?) states?13 Positive fdbks destabilizing Earth’s response to global warming: * “The clathrate surprise”: Methane clathrates on the oceanfloor release more methane (the clathrate gun hypothesis). * Oxidation of ancient carbon stored in arctic ecosystems withmelt of permafrost terrestrial ecosystems, leading to an increaseof atmospheric CO2 levels * Higher albedo of sea ice and seasonal snow cover. Darkerearth and sea surfaces absorb more sunlight, leading to furtherwarming. *Moulins, deep holes in continental glaciers, allow melt water tolubricate base, accelerating slippage of ice shelfs off continents(e.g. Greenland) into the ocean. *Acidification of the ocean--elevating CO2 concentration willlower ocean pH, interfering with the ability of ocean biota toproduce calcium carbonate. E. Colbert, New Yorker Nov. 202006, pp. 67-76.14“Beyond Color Mapping”Schmitz et al. 2003WolvesMooseSpruce“Climate envelopes” based on FundamentalNiches won’t predict ecosystemconsequences of interactions15Snow geese numbersexploding due to drop inhunting, and agriculturalsubsidies in goosewintering grounds in theU.S.16Hudson BayBlue-waterGreen-marsh vegetationRed—had vegetation in 1973,mudflat in 1993)CanadianArctic–goose switchfrom grazing togrubbing convertsmarsh to mudflat,evaporation causesmud to becomehypersaline, killingvegetation….Gooseexclosure17Sergei Zimov and woolly rhinocerosbone in Siberia18Zimov, Chapin’s—Pleistocene Park12 ky bp, vegetation changedacross all of Beringia fromsteppe grass to mossy tundra.Assumed this due to climatechange, but no record of this inocean sediment or ice cores.Zimov et al. hypothesize overkill of megafauna byPleistocene hunters.19•Pleistocene overkill hypothesis extinctions ofmegafauna coincided with arrival of H. sapiens20Siberian poniespastured downslopefrom grass refugeson hills extendsteppe grasses overtundra…tramplingand grazing killsmoss.Moss tundra is a good insulator, so permafrost shallow,soils waterlogged and hypoxic. Grasses dry up soils,support more productivity and floral diversity, and mightchange (decrease?) runoff to the Arctic Ocean.21Alternative (stable?) States…tipping point – hunting?22http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/home.rxmlSea temperatureswarmer than 26.5 C(red, orange, yellow)will sustain hurricanes,warmer temperaturesustain more intensestormsHurricanes--instabilities drivenin part by Corioliseffects…23Bayou, Mangroves,Ecosystem Services4 miles forested wetlandsremoves 80 feet of storm surge….24Could species impacts change global climate?change in continental scale burning, or freshwater runoff from Beringia?25Land cover change in Glacier National Park26Charles CochraneTrees and water(Todd Dawson, IB)27Keck Hydrowatch, BerkeleyInez FungTodd DawsonBillDietrich28Lee, Oliveira, Dawson and Fung (2005). Root functioning modifiesseasonal climate. Proc. Natl. Acad. Sci. USA 102, 17576-17581NightDayHydraulic Lift by deep rooted trees29How much forest do we need to maintain stablestream flow, to keep regions of (California) moist?How many deep-rooted trees will it take to get Californiathrough the coming droughts?30Ecosystem services• NY City’s water comes from Catskill Mt. Re-forested watershed cost $ 1-1.5B. Now it savesNYC construction costs of $8B and operating(yearly) costs of $300M for water filtration andpurification.Wetlands restoration, levee and channelreconstruction, and barrier island protectionfor Gulf Coast estimated at $14B, cost ofrebuilding New Orleans estimated at $200B(?).31Ball in a basin metaphor for systemstability and resiliency(Resiliency Alliance, Walker and Salt 2006)32“Resiliency thinking is aboutunderstanding and engagingwith a changing world. Byunderstanding how and whythe system as a whole ischanging, we are betterplaced to build a capacity towork with change, asopposed to being a victim ofit.”(Walker and Salt 2006, p. 14)33Everything changes. Everything is connected. Pay attention.(Jane
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