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BIOL 4120: Principles of Ecology Lecture 21: Human Ecology

BIOL 4120: Principles of Ecology Lecture 21: Human Ecology. Dafeng Hui Room: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu. What Controls Climate?. Solar radiation input from the Sun Distribution of that energy input in the atmosphere, oceans and land.

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BIOL 4120: Principles of Ecology Lecture 21: Human Ecology

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  1. BIOL 4120: Principles of Ecology Lecture 21: Human Ecology Dafeng Hui Room: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu

  2. What Controls Climate? • Solar radiation input from the Sun • Distribution of that energy input in the atmosphere, oceans and land

  3. Relationship between Sun and Earth Major Impact on Solar Radiation • The pacemaker of the ice ages has been driven by regular changes in the Earth’s orbit and the tilt of its axis Approximate primary periods: Eccentricity 100,000 years Precession 23,000/18,000 years Tilt 41,000 years Hence a rich pattern of changing seasonality at different latitudes over time, which affects the growth and retreat of the great ice sheets. Diagram Courtesy of Windows to the Universe, http://www.windows.ucar.edu

  4. 29.1 Greenhouse gases and greenhouse effect Water Vapor – most important GH gas makes the planet habitable

  5. 29.2 Natural Climate Variability - Atmospheric CO2 Very High CO2 about 600 Million Years Ago (6000 ppm) CO2 was reduced about 400 MYA as Land Plants Used CO2 in Photosynthesis CO2 Has Fluctuated Through Time but has Remained stable for Thousands of Years Until Industrial Revolution (280 ppm)

  6. Human Industrialization Changes Climate

  7. Global Fossil Carbon Emissions Land use changes such as deforestation reduce CO2 uptake and increase CO2 loss Fossil fuel use has increased tremendously in 50 years

  8. Issue of Time Scale CO2 Uptake and Release are not in Balance CO2 Taken Up Over Hundreds of Millions of Years by Plants And Stored in Soil as Fossil Fuel CO2 Released by Burning of Fossil Fuels Over Hundreds Of Years

  9. Rising Atmospheric CO2

  10. Annual input of CO2 to the atmosphere from burning of fossil fuels since 1860 US 24%, per capita 6 tons C

  11. Land use change (deforstration: clearing and burning of forest)

  12. 29.3 Tracking the fate of CO2 emissions Emissions From fossil fuel: 6.3Gt Land-use change:2.2Gt Sequestrations: Oceanic uptake: 2.4Gt Atmosph. accu.: 3.2Gt Terrestrial Ecos.: 0.7Gt Missing C: 2.2 Gt

  13. 29.4 Global Climate – Impact of Ocean Currents Ocean Water Currents are Determined by Salinity and Temperature Cold and High Saline Water Sinks and Warm Water Rises Rising and Sinking of Water Generates Ocean Currents Ocean Currents Have Huge Impacts on Temperature & Rainfall on Land

  14. 29.5 Plants respond to increased atmospheric CO2 • CO2 experiments • Treatment levels: Ambient CO2, elevated CO2 • Facilities: growth chamber, Open-top-chamber, FACE • Some results at leaf and plant levels • Ecosystem results

  15. Growth chamber

  16. EcoCELLs DRI, Reno, NV Air temperature and humidity, trace gas concentrations, and incoming air flow rate are strictly controlled as well as being accurately and precisely measured.

  17. Open-top chamber

  18. Rhinelander, deciduous forest Duke, coniferous forest Oak Ridge, deciduous forest Nevada, desert shrub

  19. CO2 effects on plants Enhance photosynthesis Produce fewer stomata on the leaf surface Reduce water use (stomata closure) Increase more biomass (NPP) in normal and dry year, but not in wet year (Owensby et al. grassland) Initial increase in productivity, but primary productivity returned to original levels after 3 yrs exposure (Oechel et al. Arctic) Down-regulation: photosynthesis measured at high CO2 growth condition similar to that measured at lower CO2 concentration. – mostly observed in pot experiments, less in field studies More carbon allocated to root than shoot

  20. Poison ivy at Duke Face ring.

  21. Poison ivy plants grow faster at elevated CO2

  22. Plants respond to increased atmospheric CO2 CO2 fertilization effect: Enhanced photosynthesis at high CO2. BER (biomass enhancement ratio) Meta-data, 600 experimental studies

  23. Each line represents an experiment using different tree species

  24. Ecosystem response to CO2 Luo et al. 2006 Ecology

  25. Ecosystem responses to CO2

  26. Historic trends in greenhouse gas emissions Methane CH4 and nitrous oxide N2O show similar trends as CO2

  27. 29.6 Greenhouse gases are changing the global climate • How to study greenhouse gases effects on global climate change?

  28. General circulation models General circulation models (GCMs): Computer models of Earth’s climate system Can be used to predict how increasing of greenhouse gases influence large scale patterns of climate change. Many GCMs, based on same basic physical descriptions of climate processes, but differ in spatial resolution and in how they describe certain features of Earth’s surface and atmosphere.

  29. GCMs prediction of global temperature and precipitation change Changes are relative to average value for period from 1961 to 1990. Despite differences, all models predict increase in T and PPT. T will increase by 1.4 to 5.8oC by the year 2001.

  30. Changes in annual temperature and precipitation for a double CO2 concentration Temperature and PPT changes are not evenly distributed over Earth’s surface For T, increase in all places For PPT, increase in east coastal areas, decrease in midwest region (<1). 1 means no change to current. Another issue is increased variability (extreme events).

  31. 29.7 Changes in climate will affect ecosystems at many levels Climate influences all aspects of ecosystem • Physiological and behavioral response of organisms • Birth, death and growth of population • Relative competitive abilities of species • Community structure • Productivity and nutrient cycling

  32. Example of climate changes on relative abundance of three widely distributed tree species Distribution (biomass) of tree species as a function of mean annual temperature (T) and precipitation (P) Distribution and abundance will change as T and P change

  33. Anantha Prasad and Louis Iverson, US Forest Service Used FIA data and GCM model (GFDL) predicted climate changes Predicted distribution of 80 tree species in eastern US Here shows three species

  34. Species richness declines in southeastern US under climate change conditions predicted by GFDL

  35. Distribution of Eastern phoebe along current -4oC average minimum January T isotherm as well as predicted isotherm under a changed climate

  36. David Currie (University of Ottawa) Predict a northward shift in the regions of highest diversity, with species richness declining in the southern US while increasing in New England, the Pacific Northwest, and in the Rocky Mountains and the Sierra Nevada.

  37. Global warming experiments • Electric heater • Passive warming (open-top chamber) • Buried heating cables • Shrub increased in heated plots (grass decreased) • Decomposition proceeds faster under warmer wetter conditions • Soil respiration increased under global warming •  more CO2 will released back to atmosphere

  38. 29.8 Changing climate will shift the global distribution of ecosystems Model prediction of distribution of ecosystems changes in the tropical zone A: current B: predicted

  39. 29.9 Global warming would raise sea level and affect coast environments During last glacial maximum (~18,000 years ago), sea level was 100 m lower than today. Sea level has risen at a rate of 1.8 mm per year

  40. Large portion of human population lives in coastal areas 13 of world 20 largest cities are located on coasts. Bangladesh, 120 million inhabitants 1 m by 2050, 2m by 2100 China east coast, 0.5m influence 30 million people

  41. 29.10 Climate change will affect agricultural production Complex: CO2, area, and other factors

  42. Changes in regional crop production by year 2060 for US under a climate change as predicted by GCM (assuming 3oC increase in T, 7% increase in PPT, 530 ppm) Reduce production of cereal crops by up to 5%.

  43. 29.11 Climate change will both directly and indirectly affect human health • Direct effects • Increased heat stress, asthma, and other cardiovascular and respiratory ailments • Indirect effects • Increased incidence of communicable disease • Increased mortality and injury due to increased natural disasters • Changes in diet and nutrition

  44. Average annual excess weather-related mortality for 1993, 2020, and 2050

  45. 29.12 Understanding global change requires the study of ecology at a global scale • Global scale question, require global scale study • Link atmosphere, hydrosphere, biosphere and lithosphere (soil) • Feedback from population, community, ecosystem, regional scale (tropical forest, Arctic) • Global network of study • Modeling is an important approach

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