Dafeng Hui Room: Harned Hall 320 Phone: 963-5777 BIOL 4120: Principles of Ecology Lecture 21: Human Ecology (Ch. 29, Global Climate Change) Dafeng Hui Room: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu Some slides in this lecture are borrowed from David Tissue’s seminar

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

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 Diagram Courtesy of Windows to the Universe, http://www.windows.ucar.edu Tilt of the Earth’s axis relative to the Sun is 23.5o, giving rise to 4 seasons. The tilt of Earth’s axis varies from 22.5 to 24o. Affects energy received by different part of the globe. 41,000 yrs. elliptical 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, http://www.windows.ucar.edu

29.1 Greenhouse gases and greenhouse effect Now we enter a new era in history of life on earth. One single species –humans- may have the ability to alter earth’s climate We will exam how human activities are che 30oC lower than without greenhouse gases Role not same for all these gases Water Vapor – most important GH gas makes the planet habitable

Troposphere, stratosphere, mesosphere, thermsphere?, exopshere?

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)

Human Industrialization Changes Climate

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

Annual input of CO2 to the atmosphere from burning of fossil fuels since 1860 US 24%, per capita 6 tons C Figure 29.3 Accumulative, three big countries contributed more than half Top three, more than half Top 20, more than 80%

CO2 Uptake and Release are not in Balance 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 Why do we say it’s human’s problem How do we know CO2 is increasing? CO2 Released by Burning of Fossil Fuels Over Hundreds Of Years

Rising Atmospheric CO2 Charles David keeling We measure it directly

29.3 Tracking the fate of CO2 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 Figure 29.5

Global Carbon Emissions by land use change Land use change (deforstration: clearing and burning of forest) Figure 29.4

Carbon Sink: Convergence of Estimates for Continental U. S 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

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

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 Photosynthesis and respiration: 2 Gt y-1, sink Another way is to react with CO2,

Ocean Water Currents are Determined by Salinity and Temperature Two layers Thin warm layer 18oC Deep cold layer 3oC Therocline, limited the water transfer at the surface below, thus, limiting the abosroption ability. Long-term mixing takes hundreds of years. 70-200meter, total depth 2000 m Not mixed well. Global conveyor belt takes hundred of years 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

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 Another possible sink is Plant and soil. CO2 on photosynthesis, transpiration CO2 fertilization effect:

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

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.

Open-top chamber

FACE (Free air CO2 enrichment) Figure 29.9

Duke, coniferous forest Aspen FACE, WI, deciduous forest Duke, coniferous forest Oak Ridge, deciduous forest Nevada, desert shrub

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

Poison ivy at Duke Face ring.

Poison ivy plants grow faster at elevated CO2 10 350 ul/l 9 550 ul/l 8 7 6 5 4 3 2 1 Mohan et al. 2006 PNAS 1999 2000 2001 2002 2003 2004

Plants respond to increased atmospheric CO2 BER (biomass enhancement ratio) Hendrik Poorter et al. Meta-data, 600 experimental studies 59% of percentage of species shows enhancement

Ecosystem response to CO2 Luo et al. 2006 Ecology

Ecosystem responses to CO2

29.6 Greenhouse gases are changing the global climate Ch4 is 21 times more effective than CO2 N2O, 310 times Methane CH4 and nitrous oxide N2O show similar trends as CO2 CH4 is much more effective at trapping heat than CO2

How to study greenhouse gases effects on global climate change? http://www.ipcc-data.org/ddc_gcm_guide.html

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. http://www.ipcc-data.org/ddc_gcm_guide.html

What is a GCM? Numerical models (General Circulation Models or GCMs), representing physical processes in the atmosphere, ocean, cryosphere and land surface, are the most advanced tools currently available for simulating the response of the global climate system to increasing greenhouse gas concentrations (criterion 1). While simpler models have also been used to provide globally- or regionally-averaged estimates of the climate response, only GCMs, possibly in conjunction with nested regional models, have the potential to provide geographically and physically consistent estimates of regional climate change which are required in impact analysis, thus fulfilling criterion 2. GCMs depict the climate using a three dimensional grid over the globe (see below), typically having a horizontal resolution of between 250 and 600 km, 10 to 20 vertical layers in the atmosphere and sometimes as many as 30 layers in the oceans. Their resolution is thus quite coarse relative to the scale of exposure units in most impact assessments, hence only partially fulfilling criterion 3. Moreover, many physical processes, such as those related to clouds, also occur at smaller scales and cannot be properly modelled. Instead, their known properties must be averaged over the larger scale in a technique known as parameterization. This is one source of uncertainty in GCM-based simulations of future climate. Others relate to the simulation of various feedback mechanisms in models concerning, for example, water vapour and warming, clouds and radiation, ocean circulation and ice and snow albedo. For this reason, GCMs may simulate quite different responses to the same forcing, simply because of the way certain processes and feedbacks are modelled.

GCMs prediction of global temperature and precipitation change Simulate climate change: Simulation of past, better Prediction, large difference 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 2100.

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). Figure 29.12

Global temperature has increased dramatically during past 100 years This slide from IPCC reports shows global and continental temperature change. X is time in year from 1900 to 2000, Y is temperature anormaly, relative change of temperture. Black solid line is measured surface T. Blue shade band represents modeled temperature range without considering human influence. Red shade band show modeled T considering both nature and anthoropogenic forcing. It is quite clear that T has increased dramatically during the last century. It is predicted that T will continue to rise by 1.8 to 4.0 at the end of this century. FIGURE SPM-4. Comparison of observed continental- and global-scale changes in surface temperature with results simulated by climate models using natural and anthropogenic forcings. Decadal averages of observations are shown for the period 1906–2005 (black line) plotted against the centre of the decade and relative to the corresponding average for 1901–1950. Lines are dashed where spatial coverage is less than 50%. Blue shaded bands show the 5–95% range for 19 simulations from 5 climate models using only the natural forcings due to solar activity and volcanoes. Red shaded bands show the 5–95% range for 58 simulations from 14 climate models using both natural and anthropogenic forcings. {FAQ 9.2, Figure 1} Global temperature has increased dramatically during past 100 years IPCC, 2007.

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. 9-12) Relative competitive abilities of species (ch.13) Community structure (Ch. 16-18) Biogeographical ecology (biome distribution, extinction, migration) (Ch. 23) Productivity and nutrient cycling (Ch. 20,21)

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 Figure 29.14

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 A double CO2

Species richness declines in southeastern US under climate change conditions predicted by GFDL Figure 29.17

Distribution of Eastern phoebe along current -4oC average minimum January T isotherm as well as predicted isotherm under a changed climate Figure 29.16

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. Figure 29.18

Global warming research

Figure 29.19 Passive warming (OTC) at International Tundra Experiment (ITEX) site at Atqasuk, Alaska

Warming and CO2 experiment in ORNL, TN

Global warming experiment at Norman, Oklahoma

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

Global warming experiment in Inner Mongolia, China

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

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 Shrink caused by drying induced by high T Some place by both increased T and decreased PPT Other places, PPT increase, but the increase is not sufficient to meet the demand increase

Figure 29.21a

Figure 29.21b

Sea level has risen at a rate of 1.8 mm per year 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 Figure 29.21

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. Bangladesh: due to global warming and land subsidence (a result of land collapsing in response to removal of groundwater). Below 3m level, 25% of the population; 1m level: 6 million.

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 1oC increase in growing season would shift the corn belt significantly to the north. Japan The shifts in agri zones imply significant changes in regional land-use patterns, with associated economic and social costs.

Reduce production of cereal crops by up to 5%. 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) Developing countries will be influenced more by climate change. Drought and flooding: Why north decrease and south increased? Reduce production of cereal crops by up to 5%.

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.

Nearly 15,000 people died in the European hot wave in 2003 More hot days (>35oC) HI: heat index. For example, nearly 15,000 people died in the European hot wave in 2003 and Hurricane Katrina 2006? caused billions of dollars of property damage. Nearly 15,000 people died in the European hot wave in 2003

Average annual excess weather-related mortality for 1993, 2020, and 2050 (Kalkstan and Green 1997 Figure 29.26

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

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

The end

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

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

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

Figure 29.13

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

Map of Per captial emission of C

Halocarbon: C+F, Cl, I etc. CO2 is very important

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

Each line represents an experiment using different tree species Figure 29.8