human impact on the environment

last therese assesment!

Earth has a ___ supply of resources

__finite__

***RENEWABLE RESOURCES***

**can be replaced by a natural process**

**ex) food, wood, wind and solar energy, water***

***NON-RENEWABLE RESOURCES***

these cannot be replaced once they are used

\*\*\*Overuse will cause their depletion

ex) fossil fuels, metals, water\*

Maintenance of atmosphere

through respiration and photosynthesis, the levels of CO2 and O2 are kept in a range suitable for life

Soil Formation: 

soil forms when weathering breaks down rock and organic materials from decaying plant and animals accumulate

\-  soil holds root systems of plants & provides a habitat for decomposers

Water cycle:

 maintains a fresh water supply for ecosystems

Waste Removal and Recycling of Nutrients

carried out by decomposers

Humans have ___ the environment and

humans may ___ from that damage just like any other species

__damaged, suffer__

**Human population growth**

**Many serious environmental problems are related to human population growth**

**The more people there are, the more resources they use** ***and*** **the more wastes produced**

**A population remains stable if the birth rate and death rate are equal**

**Improvements in technology, food production, sanitation and health care have caused the human death rate to decline sharply**

**Humans may reach a point at which the environment cannot support them any longer**

Carrying capacity

**the most individuals of a population that can be supported by the environment**

Limiting factor

**a factor that halts any further growth in a population** 

**ex) food and clean water are limiting factors for humans**

Biodiversity

a measure of the variety of species that exist within an ecosystem

**The ___ the biodiversity, the more ___ an ecosystem**

greater, stable

**Removing species from an environment can cause _ due to loss of organisms fulfilling critical _**

instability, niches

The destruction or removal of a species from their habitat is called __**___**__

direct harvesting

__**Habitat Destruction**__

People take over land for their own use

Whole ecosystems can be damaged and entire species may become extinct

Deforestation

destruction of forests

Today, some habitats are protected by law

**Imported (Alien) species**

These are organisms that are moved from one environment into another

The species may not have natural predators in the new environment so their population cannot be controlled

Alien species can crowd out, feed on or out-compete native species

**Biological Controls**

the use of a natural predator, natural chemical scent (pheromone) to trap pests or a pathogen (virus, bacteria) to control the population

May be a better alternative than using chemical pesticides which can harm other organisms

**The Impact of Technology & Industrialization** 

Contributes to air and water pollution and increases demand for energy, water and fuel

**Water pollution**

* People dispose of wastes, including sewage, in rivers, lakes and oceans


* Sewage and animal wastes can act as fertilizer, increasing the growth of plants, algae and bacteria


* Plants and algae use O2 all day and night, but only produce O2 during the day


* O2 levels drop, and some organisms can die
* Pesticides and other chemicals used on land can run off into water (biological magnification)
* Some industrial wastes contain metals like mercury and lead that are poisonous to humans and other animals


* Thermal pollution occurs when water is used by power plants and industry to cool off equipment and dumped back into the lake or river


* Increased temperature causes a decrease in amount of dissolved O2 gas


* The warmer water does not hold enough oxygen for many marine species to live

**Air pollution**

Burning of fossil fuels like gasoline, oil and coal produces air pollution

**Acid Rain**

* SO2 (sulfur dioxide) is produced by the burning of coal and oil


* SO2 reacts in the atmosphere to produce sulfuric acid (H2SO4)
* Sulfuric acid in rainwater is a major component of acid rain
* Acid rain can gradually destroy stone buildings and monuments


* Sulfuric Acid (H2SO4)can change the pH of lakes and ponds killing many of the organisms they contain

**Ozone Depletion**

* Ozone in the upper atmosphere protects us from damaging ultraviolet radiation


* CFCs (chlorofluorocarbons) released into the atmosphere have damaged the ozone layer


* CFCs have been used as coolants in refrigerators & air conditioners, and as propellants in aerosol cans
* A “hole”, or thinning, of the ozone layer increases the amount of ultraviolet light that reaches the earth
* This could cause an increase in the incidence of skin cancer
* Thinning ozone layer over the Antarctic
* Use of CFCs have been banned in many countries
* Alternatives have been developed

**Greenhouse Effect**

* Sunlight passes through the gases in the atmosphere to reach Earth


* Greenhouse gases trap & absorbs infrared radiation that bounces off the Earth


* Without the greenhouse effect, Earth’s temperatures would be too cold to allow for life
* The burning of fossil fuel and deforestation lead to higher carbon dioxide concentrations in the atmosphere 
* More heat is trapped at the Earth’s surface

Global warming

**the increase in the average temperature of the Earth's** __**near-surface air**__ **and** __**oceans**__ **in recent decades**

**Global Warming Is Causing Climate Change**

* Sea levels are rising due to thermal expansion of the ocean, in addition to melting of land ice


* Amounts and patterns of precipitation are changing
* Changes in temperature and precipitation patterns increase the frequency, duration, and intensity of other extreme weather events, such as floods, droughts, heat waves, hurricanes and tornadoes
* Diseases like malaria are returning into areas where they have been extinguished earlier. 
* Some species of birds are laying eggs earlier than usual, some plants are flowering earlier and mammals are breaking hibernation sooner
* numerous species have shifted poleward or moved to a higher elevation -- indicating that some plants and animals are occupying areas that were previously too cold for survival
* could disrupt the connectedness among species and possibly lead to numerous extinctions

**Climate Change (reducing carbon footprint)**

* Reduce emissions:  hybrid cars, public transportation
* Find “cleaner fuels”:  solar, wind, water, nuclear, biofuels
* Use energy efficient appliances, use them less
* Reduce, Recycle, Reuse
* Question everything you do!