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Anthropogenic Effects onAtmosphere & Ecosystems
VALU 191The Environment &
Society
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Impact of Man
After reading articles 1 and 2 inyour text you should have a goodidea about how man impacts the
environment.
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Issues
Some of the environmental issuesor problems that the authors havebrought up include:
Global warming
Ozone hole
Smog
Pollution Overfishing
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Closer Look
Lets take a closer look at one ofthe issues that has been addressed Global warming
What is it? Global warming is a term used to
describe a gradual increase in the earthsaverage ground and atmospherictemperatures across the whole planet.
(source for all statistics on effects ofglobal warming U. S. EnvironmentalProtection Agency)
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Terminology: Climate Change
or Global Warming?
The term climate change is often usedinterchangeably with the term globalwarming, but according to the NationalAcademy of Sciences, "the phrase
'climate change' is growing in preferreduse to 'global warming' because it helpsconvey that there are [other] changes inaddition to rising temperatures."
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What is climate change?
Climate change refers to anysignificant change in measures ofclimate (such as temperature,
precipitation, or wind) lasting for anextended period (decades orlonger)
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What is climate change?
Climate change may occur as a resultfrom: natural factors, such as changes in the sun's
intensity or slow changes in the Earth's orbit
around the sun natural processes within the climate system
(e.g. changes in ocean circulation)
human activities that change the
atmosphere's composition (e.g. throughburning fossil fuels) & the land surface (e.g.deforestation, reforestation, urbanization,desertification, etc.)
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Whats happened
Measurements indicate that theglobal temperature has increasedby about 1 degree Fahrenheit in the
past century. It was determined that human
activities were beginning toincrease the carbon dioxide (CO2)and other greenhouse gases in theatmosphere.
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No question
There are certain facts we know fromdata that has been collected:
Atmospheric temperatures have increased~1F over the last 100 years
The amount of certain gases (i.e. carbondioxide) in the atmosphere have increased.
The greenhouse effect is a documented &
tested scientific phenomena.
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Future Problems?
Most scientists believe that anuncontrolled rise in carbon dioxideemissions will lead to further climate
change Uncertainties remain about the timing
and severity of resulting climatic change.
Most scientists believe there is enough
evidence to warrant a sensible approachtoward minimizing the potentialconsequences of global warming.
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Environmental Issues
Another environmental issue that ismentioned in unit 1 is depletion ofthe ozone layer.
Ozone is a molecule that contains 3oxygen atoms bonded together.
It is a strong oxidizer & has somecommercial & practical applicationssuch as disinfecting drinking water.
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What is the Ozone Hole?
Ozone depletion refers to the thinning ofthe ozone layer in the stratosphere,which extends ~9-31 miles above theEarths surface.
A diminished or absent ozone layerallows more harmful radiation to reachthe Earths surface.
The ozone layer in the atmosphereshields the Earths surface from muchof the harmful UV radiation from the sun
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What caused the ozone-hole?
Stratospheric ozone depletion (or theozone hole) was caused primarily by thepresence of certain chemicals in theatmosphere (CFCs
chlorofluorocarbonds). These chemicals reacted with the ozone in
the outer atmosphere which reduced theconcentration of ozone present.
Therefore, mans use of a lab generatedchemical caused a large scale globalenvironmental problem
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Ozone: good or bad or both
Ozone in the outer atmosphere orstratosphere is a good thing.
It blocks out harmful radiation from the sun.
Ozone in the troposphere (ground levelor at the Earths surface) is a bad thing.
It causes smog and many respiratoryproblems for people.
Air with high concentrations of ozone isunhealthy to breathe.
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The Greenhouse Effect, Climate
Change, and Global Warming
Scientists are certain about thegreenhouse effect.
They know that greenhouse gases makethe Earth warmer by trapping heat in theatmosphere.
The atmosphere has an effect on theEarths climate.
Climate is the long-term average of aregions weather events lumpedtogether.
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The Greenhouse Effect, Climate
Change, and Global Warming
Climate change represents a change in long-term weather patterns.
Climates can become warmer or colder; annualamounts of rainfall or snowfall can increase ordecrease.
Global warming refers to an average increasein the earths temperature, which in turn causeschanges in climate.
Global warming doesnt mean that the wholeplanet will become hotter.
The warmer atmosphere will impact existingweather patterns which may cause a variety ofproblems.
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The Greenhouse Effect, Climate
Change, and Global Warming
A warmer Earth may lead tochanges in rainfall patterns, a rise insea level, and a wide range of
impacts on plants, wildlife, andhumans.
When scientists talk about the issue
of climate change, one of theirconcerns is about rapid globalwarming caused by human activities.
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Climate Change Impacts
Human health, natural ecologicalsystems, and socioeconomicsystems are all sensitive to both the
magnitude and the rate of climatechange
Many physical and ecological
systems will be simultaneouslyaffected.
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Potential Climate Change Impacts
Climate change can add to existingenvironmental stresses
Health Impacts
Weather-related Mortality Infectious Diseases
Air Quality-Respiratory Illnesses
Agriculture Impacts Crop yields
Irrigation demands
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Potential Impacts (continued)
Forest Impacts
Change in forest composition
Shift geographic range of forests
Forest Health and Productivity
Water Resource Impacts
Changes in water supply
Water quality
Increased Competition for water
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Potential Impacts (continued)
Impacts on Coastal Areas
Erosion of beaches
Inundate coastal lands
Costs to defend coastal communities
Species and Natural Areas
Shift in ecological zones
Loss of habitat and species
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Direct weather-related mortality
Climate change is expected to increase thefrequency of very hot days For Chicago, if average July temperatures rise 5.4F,
the probability the heat index will exceed 120Fduring the month increases from one in 20 to one in 4
During heat waves, deaths from cardiovascularand respiratory illnesses also increase
Winter mortality may decrease, but notexpected to offset summer mortality increases
The elderly, particularly those living alone, andchildren are in the greatest danger during heatwaves
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Water Resources
Precipitation changes and increasedevaporation can affect: water supplies
water quality and drinking water
water uses: hydropower, irrigation, fisheries
Floods more likely due to more intense rainfall
Droughts likely to be more severe due toincreased evaporation and drier soils
Climate change will add to stresses in the Great
Basin, California, Missouri, Arkansas, TexasGulf, Rio Grande and Lower Colorado riverbasins
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Impacts on Forests
Suitable habitats for many tree species likely toshift faster than rate at which trees naturallymigrate
Forest dieback due to drought, insects and
disease may increase, especially alongsouthern boundaries and in drier areas
Projected increase in summer droughts wouldincrease risk of forest fires, especially whereforests are already under stress
At risk are commercial timber production,recreational activities, and wildlife habitat
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Impacts on Coastal Areas
Along much of the U.S. coast, sea levels haverisen 10-12 inches in the last century
Sandy beaches would be eroded 100-150 feetwith a 1-foot rise in sea level in 2100
The projected global sea level rise of 20 inches
(6-38 inches) by 2100 could: Inundate 5,000 square miles of dryland Drown 15-60 percent of our coastal wetlands
Some states will experience greater increasesin sea level (e.g., over 4 feet in Louisiana)
Cumulative capital costs of defending against a20 inch rise in sea level are estimated at $30-40billion
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Impacts on Wetlands
Coastal wetlands are vulnerable to sea levelrise and coastal erosion At risk: fish, shellfish, flood and erosion control,
habitat
Inland freshwater marshes (including prairiepotholes) are vulnerable to hotter, drierconditions At risk: migratory bird and other species habitat
Western riparian wetlands are vulnerable to
hotter, drier conditions At risk: fish and wildlife habitat, flood and erosion
control, water quality, grazing
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Impacts on Species
Each 1C of warming will shift temperature zones byabout 100 miles northward (or 500 feet in elevation) Many plant and animal species will be unable to migrate
fast enough to find suitable habitats Natural or man-made barriers may block natural migration
Climate change poses risks to major U.S. national parks
(e.g., Everglades National Park, Glacier National Park) An increase of 3C could threaten 7-11% of North
Americas plant species Northern limits of many birds strongly associated with
climate Loss of cold-water fish habitat of 1.7-2.3 million acres by
2060
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Agriculture
Current modeling is inadequate because it fails to fullyaccount for climate variability, adaptation, and indirecteffects Location specific modeling is needed since temperature,
precipitation, and soil moisture changes and wateravailability varies from place to place
Average climatic changes projected to affect crop yieldsand the geographic distribution of crops Some states will gain, but other states may see substantial
losses Some crops will be more impacted than other crops
Farmers likely to adapt to changing climate conditions
Some agricultural adaptations may be costly Adaptation may alter land-use patterns (e.g., forestsconverted into agricultural land)
Adaptation often depends on questionable availability ofwater
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Predictions
The preceding slides discussedprobable outcomes from a rise inthe ambient temperature as studied
and developed by the U.S. EPA. You can get on EPAs website, theUN Environmental Programwebsite, or a variety of other sites
to read about predictions regardingthe effects of climate change.
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Weather Patterns
What about long-range changes toweather patterns?
Weather patterns are dependent onatmospheric temperature and otherthings such as ocean temperature.
Obviously, the chemical make-up of ouratmosphere also plays a role in ouratmospheric temperature.
Without some CO2 in our atmosphere, itwouldnt be warm enough on Earth tosustain life!
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Weather Patterns
As air heats and cools, it moves in theatmosphere.
The ocean & other large bodies of water
impact the heat exchange in theatmosphere.
The oceans have a large impact onglobal weather.
If oceans gain or lose energy (evident bytemperature changes) it affects ourprecipitation patterns & wind movement.
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Weather Patterns
We are also discovering thatpollutants in our atmosphere canimpact our ambient temperatures.
Some pollution can block orabsorb energy from the sunresulting in a cooling effect ==solar
dimming Some pollutants can trap energy
from the sun therefore warming our
atmosphere ==global warming
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Bottom line
The presence of man & mans
activities can impact ourenvironment.
Some impacts are positive
Some impacts are negative
Well be talking a lot more about
this during the semester.