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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 Email: [email protected]. What Controls Climate?. Solar radiation input from the Sun - PowerPoint PPT Presentation
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BIOL 4120: Principles of EcologyBIOL 4120: Principles of Ecology
Lecture 21: Human Ecology Lecture 21: Human Ecology(Ch. 29, Global Climate (Ch. 29, Global Climate
Change)Change)
Dafeng HuiDafeng Hui
Room: Harned Hall 320Room: Harned Hall 320
Phone: 963-5777Phone: 963-5777
Email: [email protected]: [email protected]
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
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
elliptical
29.1 Greenhouse gases and greenhouse effect
Water Vapor – most important GH gas makes the planet habitable
29.2 Natural Climate Variability - Atmospheric CO2
Very High CO2 about600 Million Years Ago(6000 ppm)
CO2 was reducedabout 400 MYA as LandPlants Used CO2 in Photosynthesis
CO2 Has FluctuatedThrough Time but hasRemained stable forThousands of YearsUntil Industrial Revolution (280 ppm)
Human Industrialization Changes Climate
Global Fossil Carbon Emissions
Fossil fuel use has increasedtremendously in 50 years
Annual input of CO2 to the atmosphere from burning of fossil fuels since 1860
US 24%, per capita 6 tons C
Issue of Time ScaleCO2 Uptake and Release are not in Balance
CO2 Taken Up Over Hundreds of Millions of Years by PlantsAnd Stored in Soil as Fossil Fuel
CO2 Released by Burning ofFossil Fuels Over Hundreds
Of Years
Rising Atmospheric CO2
Charles David keeling
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
Land use change (deforstration: clearing and burning of forest)
Global Carbon Emissions by land use change
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
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
Ocean Water Currents are Determined by Salinity and TemperatureCold and High Saline Water Sinks and Warm Water RisesRising and Sinking of Water Generates Ocean Currents
Ocean Currents Have Huge Impacts on Temperature & Rainfall on LandThis 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
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
Growth chamber
Potted plants can be grown in this growth chamber
Greenhouses at a Mars Base: 2025+Greenhouses at a Mars Base: 2025+
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
Open-top chamber
FACE (Free air CO2 enrichment)
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
1999 2000 2001 2002 2003 20040
1
2
3
4
5
6
7
8
9
10350 ul/l
550 ul/l
Mohan et al. 2006 PNAS
Plants respond to increased atmospheric CO2
BER (biomass enhancement ratio)
Hendrik Poorter et al.
Meta-data, 600 experimental studies
Ecosystem response to CO2
Luo et al. 2006 Ecology
Ecosystem responses to CO2
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
How to study greenhouse gases effects on global climate change?
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.
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 5.8oC 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).
IPCC, 2007.Global temperature has increased dramatically during past 100 years
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
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
Species richness declines in southeastern US under climate change conditions predicted by GFDL
Distribution of Eastern phoebe along current -4oC average minimum January T isotherm as well as
predicted isotherm under a changed climate
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.
Global warming research
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
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, 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.
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
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%.
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)
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 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 & SnowHeat from Sun Determines Ice Melt and Water Runoff
Change in Ocean Temperature Determines Ocean Circulation
Natural Climate Variability - Temperature
Billion Years
Thousand Years
Alternating WarmAnd
Cool Periods
Earth GraduallyCooled Over Time(160o F to 58o F)
Natural Climate Events Can Not Completely ExplainRecent Global Warming
Increased Solar Activity and Decreased Volcanic Activity CanExplain up to 40% of Climate Warming
Natural Climate Events Can Not Completely ExplainRecent Global Warming
Increased Solar Activity and Decreased Volcanic Activity CanExplain up to 40% of Climate Warming
Carbon balance in China (Piao et al. 2009, Nature)
PgC/yr
Each line represents an experiment using different tree species