Anthropogenic Effects on Atmosphere & Ecosystems_1

7/28/2019 Anthropogenic Effects on Atmosphere & Ecosystems_1

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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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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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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.

Anthropogenic Effects on Atmosphere & Ecosystems_1

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