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Pollution of Lakes and Rivers Chapter 14: Greenhouse gas emissions and a chnaging atmosphere: tracking the effects of climatic change on water resources Copyright © 2008 by DBS Contents • • • • • Climate change, pollution, and paleolimnology The need for paleoclimatic data Human-influenced climatic change: our greatest environmental problem Paleolimnological methods to track climate change Climate change and pollution Greenhouse Gas Emissions Climatic Change, Pollution, and Paleolimnology • Climate changes have myriad effects on water quality Greenhouse Gas Emissions The Need for Paleoclimatic Data • • • Only 200 yrs of direct temperature measurements Variable observational standards Most from major Western European cities – ‘urban heat island effect’ • Longer term measurements needed to answer the following questions: – What are the types and ranges of natural variability at different time-scales? – How have human influences affected climate? – Has the frequency and intensity of extreme climate events increased? • Also useful for modeling future changes Greenhouse Gas Emissions Human-Influenced Climatic Change NATURAL: Younger Dryas (12,800 yr BP): Earth returned very quickly into near glacial conditions Ended extremely abruptly (after 1,200 yrs), temperature increased by as much as 10°C in 10 years Glacial termination: 15,000 years ago, the Earth started warming after ~ 100,000 of "ice age" Greenhouse Gas Emissions Human-Influenced Climatic Change • Natural forcing mechanisms: – Earth’s orbit (eccentricity, obliquity, precession) – Solar activity – Ocean circulation patterns – Volcanic activity • How do we know climate has changed? – Landscape features – Dinosaur bones – Plant and animal remains Greenhouse Gas Emissions Human-Influenced Climatic Change • Man-made influences: burning fossil fuels, deforestation Greenhouse Gas Emissions Human-Influenced Climatic Change • Keeling Curve What could be responsible for this seasonal up-down fluctuation? Since 1958 atmospheric carbon dioxide has risen by more than 15% http://www.cmdl.noaa.gov/ccgg/index.html Greenhouse Gas Emissions Human-Influenced Climatic Change Animation http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm Greenhouse Gas Emissions Paleolimnological Methods to Track Climate Change: Biological • Direct inferences – Early work by palnologists and entomologists – Paleolimnology since 1990s – species distributions, transfer functions – Chironomids - Walker et al (1991) – Diatoms - Pienitz et al (1995) – Cladocera - Lotter et al (1997) – Ostracods - Curry & Delorme (2003) From Walker et al. (1991) Greenhouse Gas Emissions Paleolimnological Methods to Track Climate Change: Biological • Indirect inferences – Tracking past lake and pond ice cover – Tracking past river discharge – Trees, water chemistry, and shifting ecosystem boundaries – Links between lake water pH and climate – Shifts in precipitation-evaporation (P/E) ratios Greenhouse Gas Emissions Paleolimnological Methods to Track Climate Change • f Greenhouse Gas Emissions Paleolimnological Methods to Track Climate Change • f Greenhouse Gas Emissions Paleolimnological Methods: Isotopes • • • • Stable isotopes (McCrea, 1950; Ito, 2001; Talbot, 2001; Leng and Marshall, 2001; Leng et al, 2006) Fractionation of oxygen-16 and oxygen-18 isotopes (16O/18O ratio) 16O more easily evaporated, water is enriched with 18O Signatures from lipids (Huang et al 2004), ostracod shells (Donovan et al, 2002) or diatom frustules (Jones et al, 2004; Rosqvist et al, 2004) Greenhouse Gas Emissions Paleolimnological Methods: Geological Techniques • • • • • Chivas & Holmes (2002) Francus et al (2002) Lamoureux et al (2006) Last and Ginn (2005) Smith et al (2004) Greenhouse Gas Emissions Climate Change and Pollution • Climate influences every water-quality issue addressed so far: Higher temperatures: • speed up chemical and biological reactions e.g. P loading (Blenckner et al, 2006) • Stronger and more prolonged thermal stratification • Enhanced periods of deepwater anoxia • Concentration of pollutants through evaporation of water (Schindler and Donahue, 2006) • Changes in biodiversity Greenhouse Gas Emissions Climate Change and Pollution Alteration of atmospheric transport patterns: • Transport of acidic deposition • Grasshopper effect of cycling POPs • Melting of mountain glaciers (Blais et al, 2001) mobilizes local pollution • Cumulative and synergestic effects of higher loads in aquatic ecosystems (Wrona et al, 2006) Wind and precipitation: • Erosion changes (Kelley et al, 2006) Drought: • Decline in pH, DOC and increased UV penetration (Yan et al, 1996) Greenhouse Gas Emissions Summary • • Reconstructing climate is not simple Several proxy methods are available References • • • • • • • • • • • • • • • • • • • Alverson et al (1999) Battarbee (2000) Blais et al (2001) Blenckner et al (2006) Bradley (1999) Brooks (2006) Chivas and Holmes (2003) Cohen (2003) Curry and Delorme (2003) DeDekker et al (1988) Donovan et al (2002) Flannery, T. (2005) Goose et al (2005) Goose et al (2006) Huang et al (2004) Ito (2001) Jones et al (2004) Kelley et al (2006) Leng et al (2006)