(V) Biosphere and Humans

Past and Present

Humans, in exercising a unique and powerful influence on the physical and living world, have modified their environment.

1. Negative Aspects

Examples of Negative Aspects:

Human Population Growth

Human Activities

Overhunting Importation of Organism Exploitation Poor Land Use Management Deforestation Technological Oversight

As we discuss these issues, please keep in mind the 2 terms: renewable natural resources and non-renewable natural resources. Make sure you understand the difference.

a ) Human Population Growth

The total population of humans has risen at a rapid rate, partly because of the removal of natural checks on the population, such as disease.

The unavailability of food, water, and space act as a limiting factor for every population and halts any further growth.

The size of a population that can be supported by the environment is called the carrying capacity of the environment.

At some point in the future, human population growth must stop because the earth will reach its carrying capacity and will not be able to support any more humans

Limiting Factors Limiting Factors

Determines the types of organisms that may exist in that environment.

Examples are:

1. A low temperature common to northern latitudes determines in part what species of plants can exist in that area.

2. The amount of oxygen dissolved in a body of water will help determine which species of fish will exist there.

3. The amount of food in a given area.

HOW MIGHT EACH OF THESE FACTORS INCREASE THE DEATH RATE IN A POPULATION?

The French use a riddle to teach schoolchildren the nature of exponential growth. A lily pond, so the riddle goes, contains a single leaf. Each day the number of leaves doubles – two leaves the second, four the third, eight the fourth, and so on. “If the pond is full on the thirtieth day,: the question goes, “at what point is it half full?”

Answer: “On the twenty-ninth day.” 

When this was written in 1978, some felt that (at 4 billion people) the earth

was ½ full. We are now at

http://www.worldometers.info/

https://www.youtube.com/watch?v=s-57ui-r6Qw

Population growth places strains on the environment –• Population growth places strains on the environment –•Deforestation and species extinction

•Global warming

•Alteration of the ozone

The natural situation in which heat is retained by this layer of greenhouse gases is called the greenhouse effect

Carbon dioxide, water vapor, and several other gases in the atmosphere allow solar radiation to enter the biosphere but slow down the loss of heat to space. These greenhouse gases cause the greenhouse effect, which helps maintain Earth’s temperature range.

http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/

Any change in Earth’s climate can have a profound effect on the biosphere There is evidence of an increase in the temperature of Earth’s atmosphere and oceans

The term used to describe this increase in the average temperature of the biosphere is global warming.

2. What kinds of changes are taking place in the Arctic now?Average temperatures in the Arctic region are

http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/

What is the cause of global warming?

human activities

Adding carbon dioxide and other greenhouse gases such as methane to the

atmosphere. As a result, the global atmospheric greenhouse is retaining more heat

The burning of fossil fuels, combined with the cutting down and burning of forests, has been adding carbon dioxide to the

atmosphere faster than the carbon cycle can remove it

Weeds, insects, and rodents will flourish in a wide range of conditions and reproduce and spread relatively quickly.

Other species might be unable to survive. There may be increases in diseases, such as the mosquitoes that

transmit malaria.

Visit: http://www.stopglobalwarming.org/sgw_classroom.asp

to see what YOU can do to help.

http://www.nrdc.org/globalwarming/polaraction.pdf

Ozone Depletion

Naturally occurring ozone layer serves an important function- It absorbs harmful ultraviolet, or UV, radiation from sunlight before it reaches Earth’s surface

There is a “hole” in the ozone layer over Antarctica during winter.

A similar ozone hole has also appeared over the Arctic

This problem is caused by compounds called chlorofluorocarbons (klawr-oh-flawr-uh-kar-bunz), or CFCs. CFCs were once widely used as propellants in aerosol cans, in the production of plastic foams, and as coolants in refrigerators, freezers, and air conditioners.

http://www.airinfonow.org/html/makingozone/o3play.htm

Human Activities Some human activities have led to the extinction or endangerment of numerous species of plants and animals as well as producing less favorable living conditions for many species, including humans.

The following represents a list of human activities that negatively affect our environment.

1. Overhunting

Uncontrolled hunting, trapping, and fishing still occur in many parts of the world .

The extinction of the dodo bird and the passenger pigeon resulted from such activities.

Pygmy Hippopotamus Although hippos once ranged through Europe and Asia, they are now found only in the African interior and on game reserves.

The major threats to this species are deforestation and hunting. 

Tiger - Formerly abundant in several Asian countries, tigers are now severely threatened. The Bengal tiger population of India has fallen to an estimated 4000, and it is listed as an endangered species. The destruction of the tiger's forest habitat, trophy hunting, commercial hunting, and killing in order to protect  domestic livestock have all been contributing factors in the decline of these magnificent animals. 

2. Importation of Organisms (invasive species)

Humans have accidentally and/or intentionally imported organisms to areas where they have no natural enemies leading to the disruption of existing ecosystems. Examples include the Japanese beetle

Gypsy moth

ECOLOGICAL THREATPurple loosestrife adapts readily to natural and disturbed wetlands. As it establishes and expands, it outcompetes and replaces native grasses, sedges, and other flowering plants that provide a higher quality source of nutrition for wildlife. The highly invasive nature of purple loosestrife allows it to form dense, homogeneous stands that restrict native wetland plant species, including some federally endangered orchids, and reduce habitat for waterfowl.

Differentiate between “invasive” and “non-native” species.

3. Exploitation

The exploitation of wildlife for their products and pet trade has led to threatened populations and ecosystem disruptions.

Examples include: the African elephant—ivory; the Colombian parrot—pet trade; Tropical rain forest—plywood.

4. Poor Land Use Management

•The rapid growth of cities and suburban areas around cities has reduced the land available for agriculture, modifies watersheds (which replenishes water supplies), disrupts natural habitats (including wetlands), and threatens the existence of wildlife species.

• Poor land management practices have led to overcropping, overgrazing, and failure to use cover crops. This has resulted in the loss of valuable soil nutrients and topsoil. • Covercrops - are crops planted to cover a whole field and that have fibrous roots that form a dense mat in the soil. This mat prevents soil erosion.

5. Deforestation Ex: The extensive cutting down of the tropical rain forests have led to habitat loss of wildlife and erosion of topsoil.

Dust Storm Disaster(Also known as The Great Dust Storm)Words and Music by Woody Guthrie

On the 14th day of April of 1935,There struck the worst of dust storms that ever filled the sky.You could see that dust storm comin', the cloud looked deathlike black,And through our mighty nation, it left a dreadful track. From Oklahoma City to the Arizona line,Dakota and Nebraska to the lazy Rio Grande,It fell across our city like a curtain of black rolled down,We thought it was our judgement, we thought it was our doom. The radio reported, we listened with alarm,The wild and windy actions of this great mysterious storm;From Albuquerque and Clovis, and all New Mexico,They said it was the blackest that ever they had saw. From old Dodge City, Kansas, the dust had rung their knell,And a few more comrades sleeping on top of old Boot Hill.From Denver, Colorado, they said it blew so strong,They thought that they could hold out, but they didn't know how long. Our relatives were huddled into their oil boom shacks,And the children they was cryin' as it whistled through the cracks.And the family it was crowded into their little room,They thought the world had ended, and they thought it was their doom. The storm took place at sundown, it lasted through the night,When we looked out next morning, we saw a terrible sight.We saw outside our window where wheat fields they had grownWas now a rippling ocean of dust the wind had blown. It covered up our fences, it covered up our barns,It covered up our tractors in this wild and dusty storm.We loaded our jalopies and piled our families in,We rattled down that highway to never come back again.

http://The Great Dust Storm

6. Technological Oversight

Have led to unplanned consequences, which have contributed to the pollution of the water, air, and land.

Examples are: a) Water Pollution c) Biocide Use b) Air Pollution d) Disposal Problems * All of these have led to negative environmental changes like acid rain and the greenhouse effect.

Water Pollution

Major water pollutants include: heat, sewage, and chemicals such as phosphates, heavy metals, and PCB’s. Ex: The dredging of the Hudson River

Air Pollution

Major air pollutants include: carbon monoxide, hydrocarbons, and particulates

The burning of fossil fuels (petroleum, coal, natural gas) produces harmful air pollutants such as smoke, ash, soot, nitrogen oxides, sulfur, and hydrocarbons. These pollutants combine with water vapor forming acid rain which kills plants and lowers the pH of lakes and ponds, thereby Harming And Killing Aquatic Wildlife.

://topics.nytimes.com/topics/reference/timestopics/subjects/w/water_pollution/index.html

Satisfaction of our energy needs through the combustion of fossil fuels (coal, oil, natural gas, wood, etc.) is the basic cause of acid rain. Emissions from motor vehicles, power plants and industries all contribute to acid rain. Emissions of SO2 and NOx from the heavily industrialized Midwest have been identified as significant contributors to New York State's deteriorating air quality as well. Fish populations are damaged in a number of ways. Acidic water disrupts their reproductive cycle. It also leaches aluminum from the soil into the water, clogging the fish's gills and altering their blood chemistry. Forests are damaged because acid precipitation drains nutrients from the soil. High concentrations of fine-particulate sulfate and nitrate can enter the cardiovascular and respiratory systems, resulting in disease or even death.Metals such as mercury and cadmium from soil deposits in lakes, streams, and reservoirs can accumulate in the tissues of fish, making them toxic to humans.

The Formation of Acid Rain

http://www.youtube.com/watch?v=HE6Y0iEuXMQ

Biocide Use

•The use of some biocides (such as pesticides) without a complete assessment of their environmental impact has contaminated the soil, atmosphere, water supply, and has disrupted food webs.

Ex: DDT – disruption of food webs and has led to near extinction of organisms like bald eagles and peregrine falcons.

Add this to your notes:As the chemical made it’s way up the food chain, the DDT became more and more concentration. This is known as BIOLOGICAL MAGNIFICATION 

•Compounds used in aerosol sprays have weakened the Earth’s ozone layer, allowing more UV radiation to penetrate the atmosphere, causing harm to both plants and animals.

Disposal Problems

The lifestyle of humans currently requires increasing supplies of products and energy, the production of which produces considerable wastes: solid, chemical, and nuclear. Solid wastes are biodegradable or nonbiodegradable

2. Positive Aspects

Through increased awareness of ecological interactions, humans have attempted to prevent continued disruptions of the environment and to counteract the results of many of our negative practices. Examples of Positive Aspects

Population Control

Conservation of Resources

Pollution Control

Species Preservation

Biological Control

Reforestation

Laws

Population Control

•Methods of controlling the human reproductive rate have been, and continue to be developed.

Conservation of Resources

•Cover plantings (reforestation and covercropping) serve as erosion controls.

•Water and energy conserving measures are currently being implemented.

•The economic significance of recycling is now being realized

•Other efforts that are being made to conserve our natural resources include building watersheds to control the wasteful runoff of rainwater.

Pollution Control

•Attempts are being made to control air and water pollution by laws and by the development of new techniques of sanitation.

Species Preservation

•Animals, which were once endangered, are now successfully reproducing and increasing their numbers.

•Some efforts to sustain endangered species have included habitat protection (wildlife refuges and national parks) and wildlife management (game laws and fisheries).

Examples of endangered animals that are responding to conservation efforts and beginning to make a comeback are the bald eagle and the peregrine falcon.

Biological Control

Biological control of insect pests continues to be encouraged.

This method is less likely to affect those species which are beneficial to humans, disrupt food webs, and contaminate the land.

Examples include the use of sex hormones (called pheromones, are used to attract pests in order to lure them into traps) and natural predators of pests.

Ex: the release of sterilized male insects into wild pest populations causing females to produce infertile eggs.

Laws

There are laws that regulate and guide the use of natural habitats.

Example:

• Freshwater Wetlands Act

• Air Pollution Control Laws

• Returnable Container Laws

• Endangered Species Act

Reforestation

Replanting of trees in cut areas.

http://www.dec.ny.gov/docs/wildlife_pdf/wetart24a.pdf

Air Pollution Control - Origins of Modern Air Pollution Regulations | Air Pollution Control Orientation Course | Air & Radiation | US EPA

Summary of ESA | Laws & Regulations | US EPA

http://www.youtube.com/watch?v=wtoeZ9Nkeqk

Things you can do:http://www.dec.ny.gov/26.html