Lecture15_2011r

Lecture15_2011r - Examine Climatic events Younger Dryas...

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Unformatted text preview: Examine Climatic events: Younger Dryas Medieval Warm Period The Little Ice Age El nino Weather vs Climate ------------------------------------------------------------------There is an important distinction between weather and climate. Weather pertains to occurrences from hour to hour, or day to day, in a specific location. Climate pertains to average weather over an extended period of time, in a specific region or on a larger scale. Climate can correspond to averages over a season, year, or century and over a county, state, country, or the globe. What does δO18 tell us about climate? 1. Reservoir 2. Temperature When an oxygen-bearing mineral precipitates chemically from an aqueous solution (from seawater, for example), oxygen gets fractionated. Some oxygen atoms go into the newly-formed solid mineral, and many remain in the solution. The heavier oxygen atoms (the 18Os) vibrate more slowly and move more sluggishly, and so they are preferentially included in the mineral (where atoms are trapped and can't move as freely). The extent of the preferential inclusion of 18O in minerals is dependent on temperature. The colder it is, the more 18O is preferentially included in the mineral that is forming. Thus, if two samples formed from the same water (e.g., seawater), the one with a higher δ18O formed at a lower temperature. That's a relative statement; in fact, a transfer function exists to calculate an absolute temperature of mineral formation if one knows the mineral's isotopic composition and the isotopic composition of the water from which it precipitated. How has the climate changed in the past? Evidence for the Younger Dryas cooling event (~10,500 13,000 calendar years ago) is found in a variety of climatic proxies, such as variations in pollen records, composition of ice cores, grain size in loess deposits, chemistry of ocean sediments, and the presence of glacial moraines. Records from Ice, vegetation, and oceans = Tight coupling of the Ocean/ Atmosphere system Keigwin and Lehman, 1992, Nature Younger Dryas Estimated Temperatures for the Medieval Warm Period and the Little Ice Age MWP LIA δ18O suggests T˚ difference between MWP and the LIA as well as Tree Rings Thorland left Norway because of exile Son Eric the Red left Iceland due to exile During the MWP there was a high number of sunspots referred to as the Medieval Maximum, while during the LIA there were two periods of very low sunspot numbers called the Spörer Minimum and Maunder Minimum. Large eruptions at low latitudes can cause the greatest global climate change. Weaker eruptions only send their eruptive materials into the troposphere where weather processes quickly remove them and high latitude eruptions only send their materials into one hemisphere. The explosion of Mt. Tambora in 1815 led to the year 1816 being called "the year without a summer”. The eruption of Mt. Pinatubo in 1991 provided a good example of how a large low latitude eruption can quickly influence global climate. Pristine vs. Urban California Water Landscapes (Above)The unmodified lagoon shorward of the La Jolla Submarine Canyon as it appeared in 1930. Photo: F. Shepard Collection. So we may be entering a phase of significantly reduced rainfall in southern California. How will this affect us now vs. how it might have affected us 50 years ago? The landscape has natural ways of coping with draughts/floods. What have we done to change that? How else have humans impacted the hydrologic cycle? Photo from Kuhn, Gerald G., and Francis P. Shepard Sea Cliffs, Beaches, and Coastal Valleys of San Diego County: Some Amazing Histories and Some Horrifying Implications. Berkeley: University of California Press, c1984. http:// ark.cdlib.org/ark:/13030/ft0h4nb01z/ California’s Pristine Waterscape Note free-flowing rivers, Salton sink, Owens Lake, wetlands/marshes Almost no San Joaquin river water makes it to the bay--diverted for irrigation. ~60 mi of channel are dry. Of 4 million acres of marsh/riparian forest in Central Valley -- now only 350,000 acres of marshes and 1/10 of riparian forest left. These areas once soaked up spring flood waters, slowly releasing back into rivers. (Riparian forest = forested area next to stream/river/marsh/shoreline) San Francisco Urbanization Coastal estuaries/salt marshes extremely productive--nutrient rich. Nurseries for many commercially harvested oceanic fish and shellfish. Natural place for floodwaters to spread. Control erosion and clean water by trapping and filtering sediments. Freshwater holds back saltwater intrusion. Freshwater input to the bay holds back saltwater intrusion. Diversion of so many rivers has resulted in a more saline bay. Coastal estuaries/salt marshes extremely productive--nutrient rich. Nurseries for many commercially harvested oceanic fish and shellfish. Natural place for floodwaters to spread. Control erosion and clean water by trapping and filtering sediments. SD Bay and Tijuana estuary are a couple of the rare places left where coastal marshes have not been destroyed. Extra Credit 2 page report on a specific topic that illustrates that you read the book and relate it to a subject cover in class or is of interest to you. Full credit 10 points! Not if………..When? Fred Pearce Urban hardscapes changes the ratio between runoff and infiltration Decrease infiltration, increases runoff. Plus now lots of pollutants in runoff that now go directly into streams/rivers through storm drains. Non-”urban” impacts Runoff vs. Raw Sewage Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Compliance with federal regulations to reduce pollutants discharged from municipal storm sewers. Cooperation among many municipalities. Cross-border effects… Peak discharge in undeveloped vs developed conditions. Note that here “developed” is not necessarily “urban” Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) Surfing after storms-Pollutant-laden storm water runoff plumes are common coastal ocean features throughout the Southern California Bight following winter storms. In Santa Monica Bay, these plumes have been associated with high toxicity and water-borne pathogens. This ERS-1 synthetic aperture radar (SAR) image illustrates the spatial extent of one of these plumes in the bay. Wind direction and speed are indicated by the black arrow, `MDR' denotes Marina del Rey, and `LAX' denotes the airport. (From DiGiacomo, Paul M. Benjamin Holt, and Libe Washburn, Pollution Hazards off the Southern California Coast: Satellite and In-Situ Observations of Naturally Occurring Oil Seepage and Storm Water Runoff Plumes, AGU Ocean Sciences Meeting, Honolulu, Hawaii, February 2002. ) mitigate pollutants in runoff What can we do about it? Public awareness Asphalt designed to increase infiltration Asphalt designed to increase infiltration ...
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