Chapter 1 Our Changing Environment

Chapter 1Our Changing Environment Bethany Lavins 7th period An example of a building using green architecture, integrating wind turbines, photovoltaic panels and solar hot water generation.

Objective 1 Define environmental science and explain why environmental sustainability is an important concern of environmental science.

Environmental Science – The interdisciplinary study of humanity’s relationship with other organisms and the nonliving physical environment.

Environmental Sustainability – the ability of the environment to function indefinitely without going into a decline from the stresses imposed by human society on natural systems (soil, water, air) that maintain life.

Humans are currently: Using non-renewable resources as renewable, using renewable resources faster than they can be replenished naturally, polluting the environment, and experiencing uncontrollable population growth.

Unwise use of our planet can threaten the ability of the Earth to support life as we know it.

Objective 2 Summarize human population issues, including population size and level of consumption.

Thousands of years to reach 1 billion, 130 years to reach 2 billion, 15 years to reach 4 billion, 12 years to reach 5 billion, and 12 years to reach 6 billion.

Highly developed nations consume many more resources per person than developing nations.1.3 billion people are now living in extreme poverty and an estimated 800 million do not receive recommended daily levels of food, mostly in developing nations.

As human population and consumption increase worldwide, so does humanity’s impact on Earth.

Objective 3 Briefly describe some of the data that suggest that many chemicals used by humans also function as endocrine disrupters in animals, including humans.

Endocrine Disrupters include hundreds of widely used chemicals such as PCB’s and dioxins, heavy metals, lead, mercury, DDT, kepone, dieldrin, and even plastics and plastic additives.

Endocrine disrupters can mimic hormones, such as the female hormone estrogen, and send false signals to the body that interfere with normal functions. When Lake Apopka was contaminated by a spill in 1980 with DDT, the mortality for alligator rate increased, and male alligators suffered from low levels of testosterone and feminized or small reproductive organs.

The National Academy of Science published a report in 1999 that concluded there was strong evidence that endocrine disrupting chemicals can disrupt a human body’s natural functioning. They cited examples of some human health problems similar to those noted in wildlife, but did not directly link human problems, such as sperm declines, to endocrine disrupters.

Objective 4 Provide an overview of how human activities have affected the following: Georges Bank fishery, tropical migrant birds, wolf populations in Yellowstone National Park, and exotic species such as comb jellies and zebra mussels.

In 1994 The U.S. Commerce Dept. closed the Georges Bank fishery where over fishing had caused the haddock population to drop by 75%, and caused Cod and other important fish to become commercially extinct.

Tropical Migrant birds are loosing habitat in both their winter and summer homes, and are suffering population declines due to loss of habitat, and nest parasitism due to forest fragmentation.

Wolves were reintroduced to Yellowstone in 1995 in an effort to reestablish gray wolves, an animal that trapped, hunted, poisoned and snared to extinction in the area. Many are hopeful that it will help control the elk population that has grown out of control in the absence of a serious predator.

Zebra mussels, brought to the Great Lakes in 1985 from the Caspian sea, have spread through the U.S., threatening native fish, mussels and clams, and causing over $5 billion in damage. Likewise, when the Comb Jelly was brought to the Black Sea from the U.S., it had no natural predators and quickly multiplied, depriving other native species of their food supply, and eliminating almost all commercially important fish in the Black Sea.

Objective 5 Characterize human impacts on the global atmosphere, including stratospheric ozone depletion and climate warming.

Chlorofluorocarbons (CFC’s) played a large role in the thinning of the stratospheric ozone layer over the Arctic until public awareness and international laws restricting the use of CFC’s caused the hole to begin to shrink. Still, complete recovery could take until the year 2050.

Human burning of fossil fuels such as coal, oil and gas, and the destruction and burning of the world’s forests has added to the increased amounts of CO2 in the atmosphere.

Earth’s temperature has also been on a rise, and scientists estimate that is trends are not changed, Earths average temp. could rise from 1.5-4.5° by the middle on the century, causing changing weather patterns,melting of ice sheets, and rising ocean levels.

Objective 6 Describe some of the consequences of tropical rainforest destruction.

Many developing countries clear as many as 2 million heartares of rainforest a year to meet the demand for timber and firewood. This contributes to a worldwide decrease in biodiversity due to loss of hundreds of plants, animals and microorganisms.

Clearing of the forest through clear cutting and slash and burn practices decreases soil fertility, and increasing erosion, which in turn affects the water quality as the sediment clogs the streams and harms the animals that live in them.

Clearing of the rainforest also contributes to global climate warming and increased levels of CO2 which trees remove from the atmosphere, and can store for hundreds of years.

Objective 7 Summarize the progress made in solving environmental problems since the 1992 Earth Summit.

Although many of the goals set have not been met, Earth Summit still represents the largest international meeting to discuss environmental problems. That in itself has proven a success by making millions of people worldwide aware of the problems facing the globe.

Many countries, as a result of the conference, have enacted more stringent air pollution laws, and phased out leaded gasoline.

Much progress has also been made at the state, local and national levels, and many corporations have joined to form the World Business Council for Sustainable Development, promoting environmentally responsible business practices.

Essay QuestionDescribe several ways in which humans have impacted the environment, and what the consequences of those changes are.

Essay Answer: Humans have impacted the natural environment in which we live in many ways. Several key impacts, however, are clearly displayed through increased population, production and use of pesticides and chemicals such as DDT, CFC’s and PCB’s, and destruction of tropical rainforests. Over the last few years, earth’s population has been expanding at an unprecedented, exponential rate. While it took the earth thousands of years to reach the 1 billion mark, earth’s population increased from 5 to 6 billion in just 12 years (in 1999). This staggering population increase has produced many negative consequences, some of which we are only beginning to realize. 1.3 billion people live in poverty, and over 800 million don’t receive the proper daily nutrition. In an attempt to feed and house this burgeoning population, we are using up our natural resources, over farming land, burning fossil fuels, and depleting animal populations, as in the Georges Fishery. Humans have also produced many synthetic pesticides and chemicals to control insects and run machines and companies. The production and use of these agents, however, has caused drastic environmental damage. Not only has the use of pesticides led to the destruction of beneficial as well as harmful species, it has also caused major impacts on other larger animals as well. The pesticide, DDT, for example, acts as a hormone disrupter, and has led to reproductive problems in many animals. Such as in the case of the alligators of Lake Apopka, male alligators experienced feminization and shrinking of their reproductive organs, and mortality rate for young alligators increased drastically. The production of CFC’c, , another chemical, has also led to a decrease in the stratospheric ozone level, although some of the consequences of this have been eliminated as CFC levels have been reduced. Finally, humans have also led to the destruction of vast amounts of tropical rainforests. In an attempt to fulfill the worldwide demand for timber, some developing nations are harvesting as much as 2 million heartarcs a year of their forests. As a result, tropical migrant birds are on a decline because of shrinking habitat. The earth is experiencing a worldwide loss of biodiversity as millions of animals and species, many not even discovered yet, perish with the destruction of the rainforest. Rainforest destruction also contributes to the increase in global carbon dioxide levels, and as the trees are removed, the soil washes away, decreasing soil fertility and clogging waterways. Overall human have had many negative impacts on the environment through our increased population, production of pesticides, and destruction of tropical rainforests. Only by realizing these problem can we hope to reverse and change some of the negative impacts we have had on the earth.

Chapter 1 Our Changing Environment