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BIOL 4120: Principles of Ecology Lecture 21: Human Ecology (Ch. 29, Global Climate Change) Dafeng Hui Room: Harned Hall 320 Phone: 963-5777

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Presentation on theme: "BIOL 4120: Principles of Ecology Lecture 21: Human Ecology (Ch. 29, Global Climate Change) Dafeng Hui Room: Harned Hall 320 Phone: 963-5777"— Presentation transcript:

1 BIOL 4120: Principles of Ecology Lecture 21: Human Ecology (Ch. 29, Global Climate Change) Dafeng Hui Room: Harned Hall 320 Phone:

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 (latest 20k to 18k BP). Diagram Courtesy of Windows to the Universe, elliptical

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

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6 29.2 Natural Climate Variability - Atmospheric CO 2 Very High CO 2 about 600 Million Years Ago (6000 ppm) CO 2 was reduced about 400 MYA as Land Plants Used CO 2 in Photosynthesis CO 2 Has Fluctuated Through Time but has Remained stable for Thousands of Years Until Industrial Revolution (280 ppm)

7 Human Industrialization Changes Climate

8 Global Fossil Carbon Emissions Fossil fuel use has increased tremendously in 50 years

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

10 Issue of Time Scale CO 2 Uptake and Release are not in Balance CO 2 Taken Up Over Hundreds of Millions of Years by Plants And Stored in Soil as Fossil Fuel CO 2 Released by Burning of Fossil Fuels Over Hundreds Of Years

11 Rising Atmospheric CO 2 Charles David keeling

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 Land use change (deforstration: clearing and burning of forest) Global Carbon Emissions by land use change

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15 Carbon Sink: Convergence of Estimates for Continental U.S. from Land and Atmospheric Measurements (From Pacala et al. 2001, Science) Land estimates based on USDA inventories and carbon models PgC/yr

16 Tree carbon per hectare by U.S. county Carbon Stocks and Stock Changes Estimated from Forest Inventory Data

17 29.4 Absorption of CO2 by ocean is limited by slow movement of ocean Currents Given the volume, oceans have the potential to absorb most of the carbon that is being transferred to the atmosphere by fossil fuel combustion and land clearing This is not realized because the oceans do not act as a homogeneous sponge, absorbing CO2 equally into the entire volume of water

18 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 This process occurs over hundreds of years Amount of CO2 absorbed by oceans in Short-term is limited Two layers Thin warm layer 18oC Deep cold layer 3oC

19 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

20 Growth chamber Potted plants can be grown in this growth chamber Greenhouses at a Mars Base: 2025+

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

22 Open-top chamber

23 FACE (Free air CO2 enrichment)

24 Aspen FACE, WI, deciduous forestDuke, coniferous forest Oak Ridge, deciduous forestNevada, desert shrub

25 CO2 effects on plants Enhance photosynthesis (CO2 fertilization effect) Produce fewer stomata on the leaf surface Reduce water use (stomata closure) and increase water use efficiency 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) More carbon allocated to root than shoot

26 Poison ivy at Duke Face ring.

27 Poison ivy plants grow faster at elevated CO ul/l 550 ul/l Mohan et al PNAS

28 Plants respond to increased atmospheric CO2 BER (biomass enhancement ratio) Hendrik Poorter et al. Meta-data, 600 experimental studies

29 Ecosystem response to CO2 Luo et al Ecology

30 Ecosystem responses to CO2

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32 29.6 Greenhouse gases are changing the global climate Methane CH4 and nitrous oxide N2O show similar trends as CO2 CH4 is much more effective at trapping heat than CO2

33 How to study greenhouse gases effects on global climate change?

34 General circulation models General circulation models (GCMs): Computer models of Earth’s climate system 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. Can be used to predict how increasing of greenhouse gases influence large scale patterns of climate change.

35 What is a GCM?

36 GCMs prediction of global temperature and precipitation change Changes are relative to average value for period from 1961 to Despite differences, all models predict increase in T and PPT. T will increase by 1.4 to 5.8oC by the year 2100.

37 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).

38 IPCC, Global temperature has increased dramatically during past 100 years

39 29.7 Changes in climate will affect ecosystems at many levels Climate influences all aspects of ecosystem Physiological and behavioral response of organisms (ch. 6-8) Birth, death and growth of population (ch ) Relative competitive abilities of species (ch.13) Community structure (Ch ) Biogeographical ecology (biome distribution, extinction, migration) (Ch. 23) Productivity and nutrient cycling (Ch. 20,21)

40 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

41 Anantha Prasad and Louis Iverson, US Forest Service Used FIA data, tree species distribution model and GCM model (GFDL) predicted climate changes with double [CO2] Predicted distribution of 80 tree species in eastern US Here shows three species Red maple, Virginia pine, and White oak

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

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

44 David Currie (University of Ottawa) Use relationship between climate (mean Jan July T and PPT) and species richness 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.

45 Global warming research

46 Passive warming (OTC) at International Tundra Experiment (ITEX) site at Atqasuk, Alaska

47 Warming and CO2 experiment in ORNL, TN

48 Global warming experiment at Norman, Oklahoma

49 Multiple factor experiment (CO2, T, PPT, N) at Jasper Ridge Biological Reserve, CA

50 Global warming experiment in Inner Mongolia, China

51 Global warming experiments Facility Passive warming (open-top chamber) Active warming (warm air) Electronic heater Buried heating cables Changes in species composition (Shrub increases in heated plots, grass decreases) Decomposition proceeds faster under warmer wetter conditions Soil respiration increases under global warming  more CO2 will released back to atmosphere

52 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

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55 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

56 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 India: 1m  7.1 million people, 5.8 million ha of land loss. Mumbai, economic impact is estimated to go as high as US $48 billion.

57 29.10 Climate change will affect agricultural production Complex: CO2, area, and other factors Crops will benefit from a rise in CO2 Temperature will influence the optimal growth range of crops, and associated economic and social costs. a: “corn belt” shifts to north b: shift of irrigated rice in Japan

58 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: Adams et al. 1995) Reduce production of cereal crops by up to 5%.

59 29.11 Climate change will both directly and indirectly affect human health Direct effects Increased heat stress, asthma, and other cardiovascular and respiratory diseases Indirect effects Increased incidence of communicable disease Insects, virus, bacteria as vector Increased mortality and injury due to increased natural disasters Floods, hurricanes, fires Changes in diet and nutrition due to change in agricultural production.

60 Nearly 15,000 people died in the European hot wave in 2003 More hot days (>35oC)

61 Average annual excess weather-related mortality for 1993, 2020, and 2050 (Kalkstan and Green 1997

62 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) together as a single, integrated system Feedback from population, community, ecosystem, regional scale (tropical forest, Arctic) Global network of study Modeling is an important approach

63 To slow down CO2 increase and global warming, we need to act now!

64 The end

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66 Climate Interactions – Water Cycle Heat from Sun Increases Rainfall & Snow Heat from Sun Determines Ice Melt and Water Runoff Change in Ocean Temperature Determines Ocean Circulation

67 Natural Climate Variability - Temperature Billion Years Thousand Years Alternating Warm And Cool Periods Earth Gradually Cooled Over Time (160 o F to 58 o F)

68 Natural Climate Events Can Not Completely Explain Recent Global Warming Increased Solar Activity and Decreased Volcanic Activity Can Explain up to 40% of Climate Warming

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71 Natural Climate Events Can Not Completely Explain Recent Global Warming Increased Solar Activity and Decreased Volcanic Activity Can Explain up to 40% of Climate Warming

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74 Carbon balance in China (Piao et al. 2009, Nature) PgC/yr

75 Each line represents an experiment using different tree species


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