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GGR348H5 (1)
Lecture

Lecture October 17.docx

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Department
Geography
Course
GGR348H5
Professor
Harvey Shear
Semester
Fall

Description
Atmospheric and Water Quantity Issues Average of global temperature 16 degrees, because of water vapor (should be a lot colder) The earth has been cooling for 4 billion years, and water vapor has cooled Carbon Dioxide (another green house gas) Primary contributors to the natural greenhouse effect Methane is produced by wetlands and cows Global trends in fossil fuel co2 emissions 1750 industrial revolution Where is the growth coming from Developed countries are pretty flat (lower economic activity and growth and more effective control over carbon dioxide) Developing countries , India, China…. So on. Kyoto Target We are supposed to be at 558 Canada has withdrawn from the Kyoto Target (progress has been done at municipal level) Because of central heating , driving (carbon based fuels) 10 to 20 percent precipitation, given the temperature rise it will be rain Projected precipitation change between Winter temperature… temperature Arctic (15-20) Once the sea ice melts, heats up No snow cover, land absorbs the heat (that is one of the theories of why the arctic is getting warmer) More periods of snow cover, the warmer its going to be It is not uniform (Labrador is going to be colder?) Great lakes, summer temperature is going to be warmer Precipitation going to be 10% increase in precipitation during winter (through rain) Not much during winter, so we might have flooding problems Projected changes in the level of the GL Implication of lowering water level… shipping, wetland vegetation change, less habitat available for aquatic species Major lowering of water levels St. Clair river, was suggested for shipping, but couldn’t account for shipping? (warmer summers less ice cover) Regional and Canadian temperature trends The long term average has been up (0.7 degrees) Nationally, higher (1.3) What does it mean; its been a bit lower because water regulates the climate Warmer winters, springs, less for summer Increased frequency of heavy rainfall events in the great lakes region Consequence; short, localized, Intense summer storms, causing flooding Frequency of events (increasing since 2000) Short temr events are increasing and going up even more (longer, 2-3 days increases) Patterns are changing Assessment of accuracy; look at the past and compare Evaporation Avapotranspiration Evapotranspiration is the loss of water through evaporation and transpiration of plant leaves Evapotranspiration increases with temperature Two ways in which water leaves the surface of earth These two are consequences of rising global temperature (from surface of lake and plants) Models predict that etr significantly increases in climate change scenarios Higher etr offsets higher precipitation resulting in a net loss of water from lakes This is why water levels are predicted to be low (loss more than input) Trends in lakes for centuries Things can change very quickly Natural… but… Lake superior; 1920, suddenly increased precipitation (stepwise increase, may not be gradual, shift could to another level “phase-shift”) Complexity, sudden change…. Are predicted for precipitation e.g. Ice age; the melting was a very quick process so what? runoff run off runoff is that portion of precip that does not evaporate but drains through surface and stream channels to the Lakes stream flows are highest in spring, lowest in late summer low flows now appear to be occurring later in the year, high flows earlier in the year (floods are usually in the spring) By late summer, streams are low, ice has already melted, the only water flow is baseflow from ground water Timing is changing… biological communities have evolved to these water patterns…. Nesting; food source not there when they hatch etc, timing is very critical The timeg of runoffis important for wetlands and for reservoir filling Potential changes to runoff Increased runoff because more fain less snow Less precipitation stored in snow pack Decreased spring runoff because of less snow cover (because early snow melt) Only water is groundwater for baseflow If there is not snow, then there is bare surface, and soil run off etc Bad for communities that rely of snow melt and spring runoff Earlier spring runoff because of earlier spring warming Summer and fall low flows become even lower because of higher etr Low flow periods last longer Increased number of severe flow events floods Temperature as well, spring of low flow, the water will warm up very fast and dry up faster, groundwater is feeding ,but not enough for baseflow? We have taken off vegetation so pare These events will put a lot of sediment in streams Clog up streams and flushing pollutants in, sewers flowing into creeks Finer
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