ENVS 202 1st Edition Lecture 15 Outline of Last Lecture I. Antarctic HistoryII. Antarctic PoliticsIII. ManagementOutline of Current LectureI. Sea LevelII. Sea Level Rise AttributionsIII. PredictionsCurrent LectureI. Sea LevelSea level is the height of the sea relative to some benchmarkNOAA uses a nineteen year average of the sea levelSea level varies on many time and space scalesTidesWavesStorms (atmospheric effects)Regional ocean circulation (upwelling)Interannual variability (El Nino) Glacial reboundClimate changeThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Human induced effectsSea level is measured by tide gaugesRepresents longest observational record of sea levelQuality and quantity vary over time and spaceGood data must have a long term average, correct for land movement, and high accuracyThere are more and better tide gauges over timeSea level is also measured by satellite altimetersThis is a space borne tide gage that measures the distance to the sea surfaceII. Sea Level Rise AttributionsClimate Change: thermal expansion and increased mass to oceansThermal expansion of sea waterAnalogous to air expanding when warmerThe ocean is warming, so water density is decreasingThis contributes ~30% of sea level rise from 1993-2003Increased mass of oceansAdding freshwater to oceans from ice sheets and mountain glaciers raises the sea levelImplies that ice sheets are not steady state, they are losing more than they’re gainingThis contributed ~15% from 1993-2003, but has been contributing ~60% since 2003Human induced: damming, reservoirs, groundwater useMassive dam building in middle of the 20th century led to sea level decline of about -0.5 mm per yearThis decrease is compensated for in many regions by increased groundwater use, which causes sea level rise since the ground is moving downGlacial ReboundDue to being in a deglaciation age, ice melts and the land liftsWhy do we even care about ice?Albedo keeps temperatures stableFresh waterSea level riseRecreational glaciersGlaciers and spiritualityGlacial disasterGlaciers as laboratoriesGlaciers and conservationIII. PredictionsSLR increase: thermal expansion, mass loss from ice, land subsidenceSLR decrease: dam building, glacial reboundHalf of the world lives in coastal zones – major effectsRisksFlooding, increased storm surgeIncreased erosionLoss of habitatsThere is uncertainty in predictions because of unsure measurements in the