Impact of Human Population on the Environment

Objective 5.03: Assess human population and its impact on local ecosystems and global environments

Ozone, O3, is a naturally

occurring gas that collects in the

stratosphere and shields the Earth

from harmful ultraviolet

radiation released from the Sun.

Hole in the Ozone Layer

Hole in the Ozone LayerCertain synthetic chemicals, especially

chlorofluorocarbons, CFCs, rise into the stratosphere and act as catalysts that break

down ozone faster than its formed.

One CFC can destroy 100,000 ozone

molecules

Hole in the Ozone LayerCFCs are commonly used as coolants in air

conditioners, cars, and refrigerators. CFCs are also used in aerosol spray cans and to make

Styrofoam products.

Hole in the Ozone LayerSince the 1980’s,

atmospheric measurements have

shown a periodic hole in the ozone layer over Antarctica. As a result,

the amount of skin cancer and cataracts

have increased worldwide.

Hole in the Ozone LayerInternational effort began to reduce the use of

CFCs by using substitutes and to only allow licensed mechanics to change Freon in car air

conditioners.

The ozone hole is decreasing yearly

and can be expected to be fully repaired

by 2050

Increased CO2 LevelsSince the industrial revolution that began in the

1850’s, the levels of carbon dioxide in the atmosphere has increased by over 30%

Increased CO2 LevelsReasons for the increase in CO2 levels

are mainly due to increase in burning of fossil fuels for energy or combustion

Increased CO2 LevelsCO2 is released from coal power plants; combustion engines; and from burning

wood especially forests.

Slash and burn practice of clearing tropical rainforests to make room for more farmland

Increased CO2 Levels

Increased CO2 LevelsNot only does the burning of a forest release

CO2 into the atmosphere, it also reduces trees that are able to remove and store a lot of CO2 from the atmosphere during photosynthesis

Carbon dioxide is one of the greenhouse gases. Other greenhouse gases include: water vapor, methane, CFCs, Ozone, and

nitrous oxide.

Increased CO2 Levels

Methane is the second largest contributor to

increase in greenhouse gases

Greenhouse EffectMethane is released by cows, every time they breathe. However, methane is also released from mining practices, landfills,

and during the production of gas products.

A Greenhouse, made of glass, allows light radiation in that heats the ground. Heated

objects emit infrared radiation, heat, that cannot pass through glass and becomes trapped.

Greenhouse Effect

Greenhouse EffectIn the atmosphere, greenhouse gasses

allow light radiation to pass through but trap infrared radiation, thus

keeping the Earth warm.

95% of the atmosphere on Venus is 95% CO2 – Temperatures on Venus reach 900F

Global Climate ChangeMeasurements from ice cores in Antarctica,

the temperature has varied periodically through time. Changes in CO2 levels

coincide with the changes in temperature.

Global Climate ChangeCooling

Decrease in Temperature Glacial Formation

Glacial Formation Higher reflection of sunlight

Higher reflection of sunlight Lower light intensity

Lower light intensity Shorter Growing Seasons

Shorter growing season Less photosynthesis

Less photosynthesis Increase in atmospheric CO2

Decrease in atmospheric CO2 Decrease in Temperature

Global Climate ChangeWarming

Increase in atmospheric CO2 Increase in temperature

Increase in temperature Melting of glaciers

Melting of glaciers Decrease of light reflection

Decrease of light reflection Increase in light intensity

Increase in light intensity Increase in Photosynthesis

Increase in photosynthesis Decrease in atmospheric CO2

Decrease in atmospheric CO2 Decrease in Temperature

Global Climate ChangeSince the 1900’s, global levels of atmospheric CO2 have increased

dramatically.

The increase with CO2 levels do coincide with

the advent of the industrial revolution.

Global Climate ChangeSince the 1900’s, there

has also been an increase in global

temperature.

Although there has been periodically

cooler years, the overall trend is still increasing.

Global Climate ChangeScientists use carbon isotopes to

determine if atmospheric CO2 was derived from the burning of fossil fuels

or natural earth’s processes

Climate Model – Both natural CO2 and that from the burning of fossil fuels

Global Climate ChangeEvidence shows that atmospheric levels CO2 from natural Earth’s processes has not increased over the past 100 years.

Climate Model – Just atmospheric CO2 from natural earth’s processes

Global Climate ChangeIf the warming trend continues, it could lead to a change in our global climate where there

is a significant change in the “average” temperature

Global Climate ChangePossible changes if the global climate

changes could include:Melting of Polar Ice Caps

Rise in Sea LevelDisappearance of Many IslandsFlooding of Major Coastal Cities

Global Climate ChangePossible changes if the global climate

changes could include:More Extreme Weather Patterns(Hot and Cold)

Change in Agricultural regionsDestruction of Coral Reefs

Acid RainAcid rain is created when sulfur oxides and

nitrogen oxides from the burning of fossil fuels combine with rain to make it more acidic

Acid RainAcid rain washes minerals such as calcium and

magnesium from the soil that plants need to grow

Smog refers to a mixture of smoke and fog in the air. Smog traditionally arose from smoke released from coal burning plants. However, since the 1950’s, the

largest contribution to smog has been from automobile exhaust.

Smog

SmogSmog is created when nitrogen oxides (NOx) and volatile organic compounds (VOC’s) react under

sunlight to form ozone.

While ozone in the upper stratosphere

blocks harmful ultraviolet radiation,

it is harmful upon exposure, in the

lower troposphere

SmogSmog or ozone is particularly harmful to older and very young people, as well as people with

existing respiratory issues.

SmogThe EPA now monitors ozone levels on a daily basis

and issues ozone warning when levels reach dangerous levels, especially in the summer time.

The End