BIOL 4120 Principles of Ecology Lecture 21 Human

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

What Controls Climate? v v 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 n 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 elliptical 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 20 k to 18 k BP). Diagram Courtesy of Windows to the Universe, http: //www. windows. ucar. edu

29. 1 Greenhouse gases and greenhouse effect Water Vapor – most important GH gas makes the planet habitable

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)

Human Industrialization Changes Climate

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

Annual input of CO 2 to the atmosphere from burning of fossil fuels since 1860 US 24%, per capita 6 tons C

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

Rising Atmospheric CO 2 Charles David keeling

29. 3 Tracking the fate of CO 2 emissions Emissions From fossil fuel: 6. 3 Gt Land-use change: 2. 2 Gt Sequestrations: Oceanic uptake: 2. 4 Gt Atmosph. accu. : 3. 2 Gt Terrestrial Ecos. : 0. 7 Gt Missing C: 2. 2 Gt

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

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

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

29. 4 Absorption of CO 2 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 CO 2 equally into the entire volume of water

Two layers Thin warm layer 18 o. C Deep cold layer 3 o. C 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 Have Huge Impacts on Temperature & Rainfall on Land This process occurs over hundreds of years Amount of CO 2 absorbed by oceans in Short-term is limited

29. 5 Plants respond to increased atmospheric CO 2 experiments • Treatment levels: Ambient CO 2, elevated CO 2 • Facilities: growth chamber, Open-topchamber, FACE Some results at leaf and plant levels Ecosystem results

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

Eco. CELLs 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 CO 2 enrichment)

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

CO 2 effects on plants n n n Enhance photosynthesis (CO 2 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 CO 2 10 350 ul/l 9 550 ul/l 8 7 6 5 4 3 2 1 Mohan et al. 2006 PNAS 0 1999 2000 2001 2002 2003 2004

Plants respond to increased atmospheric CO 2 BER (biomass enhancement ratio) Hendrik Poorter et al. Meta-data, 600 experimental studies

Ecosystem response to CO 2 Luo et al. 2006 Ecology

Ecosystem responses to CO 2

29. 6 Greenhouse gases are changing the global climate Methane CH 4 and nitrous oxide N 2 O show similar trends as CO 2 CH 4 is much more effective at trapping heat than CO 2

How to study greenhouse gases effects on global climate change?

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.

What is a GCM?

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. 8 o. C by the year 2100.

Changes in annual temperature and precipitation for a double CO 2 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).

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 n Physiological and behavioral response of organisms (ch. 6 -8) n Birth, death and growth of population (ch. 912) n Relative competitive abilities of species (ch. 13) n Community structure (Ch. 16 -18) n Biogeographical ecology (biome distribution, extinction, migration) (Ch. 23) n 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

Anantha Prasad and Louis Iverson, US Forest Service Used FIA data, tree species distribution model and GCM model (GFDL) predicted climate changes with double [CO 2] Predicted distribution of 80 tree species in eastern US Here shows three species Red maple, Virginia pine, and White oak

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

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

David Currie (University of Ottawa) Use relationship between climate (mean 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.

Global warming research

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

Warming and CO 2 experiment in ORNL, TN

Global warming experiment at Norman, Oklahoma

Multiple factor experiment (CO 2, T, PPT, N) at Jasper Ridge Biological Reserve, CA

Global warming experiment in Inner Mongolia, China

Global warming experiments n Facility • • Passive warming (open-top chamber) Active warming (warm air) Electronic heater Buried heating cables n Changes in species composition (Shrub increases in heated plots, grass decreases) Decomposition proceeds faster under warmer wetter conditions Soil respiration increases under global warming n more CO 2 will released back to atmosphere n n

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

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

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, 2 m by 2100 China east coast, 0. 5 m influence 30 million people India: 1 m 7. 1 million people, 5. 8 million ha of land loss. Mumbai, economic impact is estimated to go as high as US $48 billion.

29. 10 Climate change will affect agricultural production Complex: CO 2, area, and other factors Crops will benefit from a rise in CO 2 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

Changes in regional crop production by year 2060 for US under a climate change as predicted by GCM (assuming 3 o. C increase in T, 7% increase in PPT, 530 ppm: Adams et al. 1995) Reduce production of cereal crops by up to 5%.

29. 11 Climate change will both directly and indirectly affect human health n Direct effects • Increased heat stress, asthma, and other cardiovascular and respiratory diseases n Indirect effects • Increased incidence of communicable disease n Insects, virus, bacteria as vector • Increased mortality and injury due to increased natural disasters n Floods, hurricanes, fires • Changes in diet and nutrition due to change in agricultural production.

More hot days (>35 o. C) 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

29. 12 Understanding global change requires the study of ecology at a global scale n n n 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 CO 2 increase and global warming, we need to act now!

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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 (160 o F to 58 o 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

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

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

Each line represents an experiment using different tree species