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-a positive feedback cycle in which heating caused by the greenhouse effect causes more greenhouse gases to enter the atmosphere, which further enhances the greenhouse effect
-a few billion years ago high levels of CO2 (96.5%) trapped enough heat that lead to further heating, causing extreme changes in the temperature (872 F) of the surface and the composition of the atmosphere
-a few billion years ago high levels of CO2 (96.5%) trapped enough heat that lead to further heating, causing extreme changes in the temperature (872 F) of the surface and the composition of the atmosphere
how does surface heating cause uplift?1. Air molecules expand when warmed becoming less dense (rises)
2. Air molecules contract when cooled becoming more dense (falls)Atmospheric circulation cells and climatic zones in regular latitudinal patterns1. Same Circulation cells in the Northern and Southern Hemisphere
2. Subsidence vs Uplift zones
3. Circulation cells greatly influence patterns of:
a. Precipitation
b. Prevailing windsocean currents1. Surface winds drive ocean currents within first 100m
2. Affects global marine environments and biomes landUpwellingthe upward movement of ocean water toward the surface as a result of diverging currentsUpwelling brings nutrients from the depths of the ocean to the surfaceProvides food for zooplankton and their consumers; these areas are the most productive in the open oceans.true or false: ocean currents influence regional climatetruegreat ocean conveyer belt1. Thermohaline circulation: driven not by winds but temperature and salt.
2. Links all oceans & redistributes heat from the tropics to the poles!
3. Deep-ocean currents are driven by differences in the water's density, which is controlled by temperature (thermo) and salinity (haline).rain shadow effect1. When air masses meet mountain ranges, they are forced upward, cooling and releasing precipitation.
2. North-south trending mountain ranges create a rain shadow effect: The windward slope facing the prevailing winds has high precipitation and lush vegetation; the leeward slope gets little precipitation.global precipitation is influenced by(1) Atmospheric circulation cells,
(2) Ocean currents,
(3) Topography (rain shadow)global precipitation is influenced by(1) Solar Radiation,
(2) Greenhouse gases,
(3) Ocean currents (surface & deep),
(4) Topography (lapse rates)true or false: Seasonal and long-term climate variation are associated with changes in Earth's position relative to the sun.truemisconceptionA view or opinion (conclusion) that is incorrect because it is based on incorrect facts, faulty thinking or understanding.Climate Change Misconception 1The climate has always changed, recent change is no different than the past
truth: The climate has always changed, but recent change IS different from the pas
1. Patterns of ice core temperature reconstruction - pattern ranges per 100k year periods
2. Changes in eccentricity - elliptical path becomes more elongated/changes amount of radiation Earth can absorb by ~5%. every 100,000 years or so, orbital paths around the sun changeWhat are the drivers for changes in eccentricity and ice core temperature reconstruction?1. Changes in Obliquity (tilt)
a. Greater the tilt, warmer the summers and colder the winters.
b. tilt varies between 22.1-24.5 degrees relative to the sun. 41,000 year cycles from one extreme to the other.
2. Axial precession (wobble)
a. Impacts when seasons occur in orbit, influences climate extremes (26,000 yr cycles)
b. Seasonal climate variation due to Earth's wobble
Polaris = warmer summers, colder winters
Vega = colder summers, warmer wintersMilankovitch cycles and long-term climatic variation1. Orbital shape (100k)
2. Axis tilt (41k)
3. Orientation angle relative to stars, wobble (22k)anthropogenic emissions of greenhouse gases cause?warming of the earthThe Hockey StickClimate has been pretty steady until 1800-1850 where temperature increases a significant amountClimate change misconception 2"Increases solar radiation is responsible for warming"
truth:
-Solar radiation and temperature are independent of each other.
-The Sun hasn't changed much since 1850.Climate change misconception 3:"Volcanoes Emit More CO2 than Humans"
truth:
-0.25GT annually, less than 1% of that of humans
-~13% for a super volcano Indonesia 74k years ago
-Actually cool climate. Volcanoes actually cool the Earth for a year or two when they eruptClimate change misconception 4"Aerosols capture heat and responsible for warming"
truth:
-Aerosols change the amount of energy that reaches the surface.
a. Most scatter solar radiation back to space.
b. Small fraction absorb (e.g., black carbon)
-It's not aerosols ... these tiny particles from human activities reduce warming, as they reflect more of the sun's energy back to spaceClimate change misconception 6"Humans emit a tiny fraction of CO2"
truth:
1. The atmosphere has been in balance 260-280 ppm ~10K years (prior to human activities)
2. Atmospheric CO2 concentration
a. Why is the CO2 concentration increasing during Nov-May and decreasing during June-Oct?
-Total amount of land area available for photosynthesis
1. Northern hemisphere has more land area → more carbon uptake happening → CO2 concentrations drop
2. When Northern hemisphere is in winter → more respiration and less photosynthesis → CO2 concentrations rise
-We have unbalanced the system
3. Yes, its greenhouse gases
a. Rising concentrations of greenhouse gases, as the result of human activity, are by far the biggest causeClimate change misconception 5"Depletion of the stratospheric ozone layer is causing warming"
truth:
1. Ozone functions:
a. High in the stratosphere, it absorbs ultraviolet light from the sun (protects us and the earth).
b. Near the ground, it is a pollutant and contributor to smog with GHG characteristics.Climate change misconception 7"We are too far gone"
truth:
1. How much warming should we anticipate
a. linked to our carbon emissions
b. climate change scenarios: shared socioeconomic pathways (SSPs)
-Simulated scenarios of what will happen whether or not we take action to combat emissions
-SSP5- 8.5 is what we can reach if we do nothing & SSP1-1.9 is ideal situation if we have zero emissions
2. current emissions: 42.2/GtCO2 per year
a. Carbon clock shows time left to reach that 1.5-2.0 degree thresholds
3. What are acceptable impacts?
a. 5 to 6 degrees is still possible this century!
b. Would take 300,000 years to reabsorb all of the CO2 from the atmosphere.what are acceptable impacts?positive feedback mechanismstrue or false: Energy in ecosystems originates with primary production by autotrophs.true
-All energy used by living organisms traces back to the sun (or thermal vents!)Primary ProductionChemical energy generated by autotrophs during photosynthesis and chemosynthesis.Plant RespirationPlants use respiration to convert the energy stored in the form of carbohydrates into usable chemical energyphotosynthesisbiomass production (carbohydrates)plant respirationenergy production (plant growth + maintenance)net primary productivity (NPP)Photosynthesis - Plant Respirationtrue or false: Net primary production is constrained by both physical and biotic environmental factors.trueprimary production can be considered at many ___scales
-Spatial scales involved ... photosynthesis & gross, net primary production.
-span about 14 orders of magnitudegross primary production (GPP)total amount of carbon fixed by autotrophs.
GPP is controlled by...
•Climate (temp/precip) through its influence on photosynthetic rate.
•Leaf area index (LAI)—leaf area per unit of ground area.net primary production (NPP)—total amount of energy fixed by autotrophs that results in an increase in living plant matter.
-NPP = GPP - plant respiration
-NPP is the plant material (i.e., energy) left over for consumption by detritivores and herbivores.NPP allocation to RootsPlants allocate the most NPP to tissues that limit their growth.how is NPP measured?-The difference between maximum and minimum biomass during the year can be used as an estimate of net primary production in grassland ecosystems
-In forests, dendrometer bands are used to measure changes in the diameter of tree stems.
-Then an allometric equation between diameter and biomass is used to estimate total tree biomass, and NPP.Remote sensing-Remote sensing can be used to estimate NPP over large areas and time in order to understand: deforestation, desertification, atmospheric pollution, and other phenomena.
-Spectral reflectance, vegetation indices
-Can evaluate patterns of NPP using space-borne sensors MODIS
1. Can evaluate if the distribution of NPP changes over time (histograms)
2. Can evaluate if spatial patterns of NPP increase, decrease, and/or stay the same over time (scatter plots)Net Ecosystem Exchange (NEE)total amount of energy fixed by autotrophs that results in an increase in living plant matter, minus heterotrophic respiration.
NEE = NPP - (microbe+animal R)
NEE = GPP - (plant+microbe+animal R)true or false: Global patterns of net primary production reflect climate constraints and biome types.trueHow does terrestrial NPP vary globally?• NPP varies with Biome Distribution
• Biome varies with Climate (see Climate lecture)Global patterns of terrestrial NPP are correlated with climate.Plant size and age control NPP, whereas climate is a covariate with size and agePhotosynthesis and light...-at the compensation point, photosynthesis balances respiration.
-beyond the saturation point, photosynthesis no longer increases with increasing light intensityNPP is limited by nitrogen• Nitrogen is the most common limiting element, followed by Phosphorus. • Aquatic systems often nutrient limited.Abiotic Limits on Primary Productivity-NPP changes according to the effects of the environment on photosynthesis and respiration:
• Photosynthesis is often limited by light, nutrients, temperature, and precipitation...
• Respiration is often limited by temperature and substrate availability from photosynthesisPersistent Organic Pollutants (POPs) in Inuit Women-POPs linked to cancer, infertility, miscarriage, and diabetes
-Caused by events related to industrialization
-These toxins get to the Arctic and in Inuit women, even though they are not partaking in industrialization
-they eat animals with high levels of toxinsTrophic dynamics determine how the energy and nutrients move through an ecosystem, by determining...what an organism eats and what eats themtrue or false: Trophic levels describe the feeding positions of groups of organisms in ecosystems.trueArctic Marine Food Chain-Some organisms don't fit conveniently into trophic levels e.g. omnivores
-All organisms are either consumed by other organisms or enter the pool of dead organic matter (detritus).Little NPP is consumed by herbivores, most NPP ends up as detritusOn average, about 13% of terrestrial NPP is consumed; in aquatic ecosystems, an average of 35% NPP is consumed.The amount of energy transferred from one trophic level to the next depends on...n food quality, consumer abundance, and physiologyFood chains represent energy relationshipsThe 2nd law of thermodynamics states that during any transfer of energy, some is dispersed and becomes unusable. Thus, available energy will decrease with each trophic level.trophic energy pyramidApproximately 90% of the energy consumed at one trophic level is lost as heat in the transfer to the next level.terrestrial trophic pyramidEnergy and biomass pyramids are similar because biomass is closely associated with energy production.marine trophic pyramid-In aquatic ecosystems, the biomass pyramid may be inverted.
-life span increases as you move up the trophic level therefore in any given moment in time biomass pyramid will appear inverted.What limits the length of the food chain?Factors that determine how much energy flows from one trophic level to the next:
1. Amount of NPP at base of food web
2. Proportion of each trophic level consumed by the one above it
3. Nutritional content of autotrophs, detritus, and prey 4. Efficiency of energy transferstrophic efficiency-Amount of energy at one trophic level divided by amount of energy at the trophic level immediately below it.
-replaces the "10% law" - an average; not fixed
-Trophic efficiency = (NPPlevel n / NPPlevel n-1)what are the three components of trophic efficiency?• Proportion of available energy that is ingested consumption efficiency)
• Proportion of ingested food that is assimilated (assimilation efficiency)
• Proportion of assimilated food that goes into new consumer biomass (production efficiency)food webs are...conceptual models of the trophic interactions of organisms in an ecosystem.Bioaccumulation (linearly)Some chemicals aren't metabolized or excreted, and become more concentrated in tissues over a single organism's lifetimeBiomagnification (non-linearly)Concentration increases in animals at higher trophic levels, as they consume prey with higher concentrations.Concentrations of ToxinsA single organism can become more concentrated with toxins over its lifetime (bioaccumulation) or animals at higher trophic levels will consume prey with higher concentrations (biomagnification). Hence, larger organisms will have the highest concentrations of toxinswhich animal would likely have the highest concentrations of toxins?Humans have highest concentrations because they are eating the whales, which have very high concentrations of toxinsWhy are Nutrients Important?-They are the key building blocks of all life; all living organisms need nutrients for metabolism, growth, etc. and they are in limited supply in natural systems.
-They are the key building blocks of all life; all living organisms need nutrients for metabolism, growth, etc. and they are in limited supply in natural systems.Elements are released from rock minerals by weathering.-Mechanical weathering: Physical breakdown of rocks (freeze/thaw, plant roots, physical disturbance). Ex. potholes
-chemical weathering: Chemical reactions release soluble forms of the mineral elements. Ex. Cleopatra's fixture in NYCClimate strongly influences Weathering-For each 10 degrees C increase in temperature, the chemical reaction doubles
-More water more chemical reactions and mechanical weatheringsoil= mineral particles + organic matter + water + organismsnutrient cycle (nitrogen)-Nutrients may be cycled within an ecosystem, repeatedly passing through organisms and the soil or water.
-All nutrients are ultimately derived from abiotic sources: minerals in rocks and gases in the atmosphere.
-Plants and microorganisms take up nutrients in simple, soluble forms from the environment.N2 is?not bioavailable!!!. plants can solve this problem through nitrogen fixation.nitrogen fixation-is the process of converting N2 into a biologically useful form
-Biological N fixation uses the enzyme nitrogenase, which only occurs in certain bacteria
-Some N-fixing bacteria are free-living; others are symbionts. Legumes make nodules for symbiotic N2 fixing bacteria
-high energy is able to break covalent bonds in N2, creating nitrate (lightning)nitrogen resorption-Nitrogen cycling so plants don't lose the Nitrogen they worked hard to obtain.
-As leaves turn red, carotenoids and anthocyanins make up leaf chemistry, rather than chlorophyl
-The greater the change in leaf colors, the greater the Nitrogen resorptionAnnual budget of N within an ecosystem-Internal ecosystem balance (equilibrium) is maintained if annually: N requirement = N uptake + N resorption
-N is required to:
1. grow leaves
2. grow wood
3. replace N lost by leaching from canopy by rain.
-Nitrogen uptake by roots, Nitrogen reabsorbed from leaves in the fall.Elemental Composition of Organisms-All organisms have similar nutrient requirements, but amounts and specific nutrients needed vary.
-C - structural compounds; N - enzymes
-C:N ratios are key:
• Animals/microbes have lower C:N ratios than plants.
• Herbivores must consume more food than carnivores to get enough nutrients, such as N.nutrient regeneration:decomposition = fragmentation + mineralizationDetritusdead plants, animals, and microorganisms, as well as waste productsDecompositiondetritivores breaking down detritus to obtain energy and nutrients.
-releases nutrients as simple, soluble organic and inorganic compounds that can be taken up by other organisms.Fragmentationincreases surface area, which facilitates chemical breakdown.Mineralizationchemical conversion of organic matter into inorganic nutrientsClimate controls the activity of decomposers-Decomposition requires a lot of energy.
-So, soil microbial respiration ≈ decomposition rate
-Q10: Reaction rates double with an increase in 10 degrees C.true or false: faster decomposition means higher productivitytruethe lower the C:N in materialsthe higher the heterotrophic respiration and vice-versaLandscape EcologyFocuses on questions related to the composition, structure, and function of landscapes over space and time...Spatial patterns:Why are certain ecological features found in some places but not others?Change in Spatial patterns:How does change in these ecological features alter ecological processes (carbon exchange, nutrient cycling, surface energy balance)?Landscape Ecological Questions•What Biome/Region? i.e. spatial pattern/extent
•What phenomenon (response variable) in the landscape is changing (forcing mechanism (and how?))?
•What time horizon? i.e. temporal extent
examples:
1. How might NPP in the grasslands of the Tibet Plateau change with projected warming?
2. How might wildfire severity influence rates of forest succession along a precipitation gradient in the Sierra Nevada Mountains?What tools and techniques do landscape ecologists use?• Traditional field ecology
• Geographic Information Systems (GIS)
• Spatial Statistics/Geostatistics
• Remote sensing analysis
• Process-based modeling
• Machine/Deep learning modelingWhat are some "New" Ecological-Geographical Tools?•Aerial photography gave ecologists the first way to look at "the big picture."
•Remote sensing satellites provide images of Earth that expand our view of large-scale ecological patterns.Moores Lawcomputing power tends to double every two yearsGeographical Information Systems (GIS)-Computer-based systems allow storage, display, and analysis of spatial data.
Uses:
•Landscape planning
•Urban development •Conservation
•Scientific applications!Conservation Application Using GIS-Using a computer to produce data layers
-Combines satellite for gathering imaging data, aerial photography, and data gathered on the ground
-Example: Lark bunting distribution. Use GIS to compare predicted distributions versus conservation lands and protected areastrue or false: Landscape ecology examines spatial patterns and their relationship to ecological processes.trueLandscapeAn interacting heterogeneous mosaic of elements (veg, soil, water) or ecosystems.types of landscape mosaics• Plant communities
• Habitat
• Topography
• Hydrology
• Landformslandscape mosaic (landform)composite of heterogeneous elementsLandscape heterogeneity...may involve different types of landscape elements, and how they are arrangedLandscape composition:Types of elements and how much of each type
-Composition is quantified by the number of different elements or the proportion of mapped area covered by each kind of element.Landscape structure-physical configuration of the landscape elements.
•Size of patches: species diversity
•Whether patches are aggregated or dispersed: isolation by distance •Complexity of patch shape, and degree of fragmentation: dispersal and species diversitytrue or false: Landscape ecology examines spatial patterns and their relationship to ecological processestrueecological processes vary with...scaleWhat are the drivers of Carbon Fluxes (GPP) at differing scales?-Regional to Landscape: Climate, Biome distribution
-Plant to Leaf: Light, LAI, Nutrients
-Landscape to Ecosystem: Soil moisture, Vegetation communityObservations of various scales can be challenging• Every image or photograph you have ever seen is a raster image
• Rasters are made up of many pixels (grains)Scale is very important in Landscape Ecologygrain: size of the smallest homogeneous unit of study (e.g., a pixel in a digital image); determines resolution.
extent:—boundary of the area or time period encompassed by the study (i.e. spatial or temporal).
-scaling up and down is one of the biggest challengesexamples of different resolution pixels and their purpose.Shrub cover change: <=3 m resolution pixels
Forest expansion: <=10m resolution pixels
Agricultural productivity: <=250m resolution pixels
Sea surface temperature: 1,000m resolution pixelsartic burningThe Arctic is burning like never before despite bone-chilling temperatures - "Zombie fires"Why should we care about Arctic ecosystems and why is this change occurring?-High latitude: less direct solar radiation (Climate)
• Very cold: very low decomposition (Nutrient Supply and Cycling)
• Contain 50% of global organic carbon pool, locked in frozen soil (Productivity & N supply)
• Temperatures are rising very fast changes in surface energy balance (sea ice loss and warmer oceans; Climate &Climate Change)
• Temperature is rising- decomposition is increasing (N supply and Cycling); and availability of food (Energy flow & Food webs)
• Wildfires are more frequent compounding this positive feedback to climate (Climate change)Earth System Model ProjectionsHuman Impacts on Global Ecological Dynamics-fire, drought, flood, storm
-Climate change is the largest "experiment" ever initiated, on the largest scale!
-⅓ of all plant and animal species could be extinct in 50 yearscurrent extinction happening-Revisiting ~600 sites over 10 years across the globe.
-Half (~44%) of species had local extinctions if temperatures increased by more than 0.5 degrees C
-Nearly 95% of species had local extinctions if temperatures increased by more than 2.9 degrees C."The Great Dying"-Biggest mass extinction caused by global warming leaving ocean animals gasping for breath
-Wiped out 96% of all life in the oceans, was caused by global warming, which deprived the oceans of oxygen with warming 9-10 degrees C (projected by 2300)Great Barrier Reef, AustraliaCover less than 1% of Earth's surface, but provide a home for over 25% of all marine life.
Coral Bleaching & Death:
1. Never recorded prior to 1997
2. The coral becomes stressed in warmer waters and expel the algae that live inside it.
3. That algae gives coral its color, and also provides it with most of the energy it needs to survive.
4. If temperatures do not recover quickly, the coral starves and dies.
5. The amount of carbon dioxide in water determines the pH of the water. The lower the pH, the lower the calcium carbonate and lower the growth rates.
6. Within 20 years, 70-90% of coral reefs will die... by 2100... extinctionhow many severe bleaching events have there been in the past 5 years?3Sea Level Rise(1) Melting cryosphere (i.e. glaciers, ice sheets, etc.)
(2) Thermal Expansion. heated water has more expansion (particles less condensed)Contributors of sea level risethermal expansion, added water (meltwater), or bothClimate Refugees• As of 2018, the world's number of displaced people has reached 65.6 million
• 1/3: "sudden onset" weather events
• 2/3: "slow onset" environmental change
• Without action 143M people displaced by 2050.
• Poorest will be most vulnerable -hardest hit.sourcewhen the ecosystem is releasing more carbon than taken upsinkwhen the ecosystem is taking up more carbon than releasingmitigateto lessen, or make less severe
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