Lecture 3; MrL

1

Outline

Gaia hypothesisUrban world, urbanization and urban growthEnvironmental Values and Knowledge and

resourcesPollution and pollutants

Gaia hypothesis2

The hypothesis states that life manipulates the environment for the maintenance of life.

For example, some scientists believe that algae floating near the surface of the ocean influence rainfall at sea and the carbon dioxide content of the atmosphere, thereby significantly affecting the global climate.

It follows, then, that the planet Earth is capable of physiological self-regulation

Lecture 3; MrL

3

The Gaia hypothesis is really a series of hypotheses:

1. Life, since its inception, has greatly affected the planetary environment. Few scientists would disagree.

2. Life has altered Earth’s environment in ways that have allowed life to persist. Certainly, there is some evidence that life has had such an effect on Earth’s climate.

3. Life deliberately (consciously) controls the global environment. Few scientists accept this idea.

The future status of the human environment may depend in part on actions we take now and in coming years.

James Lovelock first proposed the Gaia hypothesis

Lecture 3; MrL

Urban world, urbanization and urban growth4

We are becoming an urban species because of rapid growth of human population and changes in technology

Our effects on the environment are more and more the effects of urban life

EFFECTS OF URBANIZATION

Urban growth overtakes agricultural land, floodplains, coastal wetlands, which are important habitats for many rare and endangered species.

As urban areas expand, wetlands are filled in, forests cut down, and soils covered over with pavement and buildings.

Lecture 3; MrL

POPULATION IN URBAN AREAS5

% of population live in urban areas

Developed countries: 75% Developing countries: 40%

By 2008: more than 50% people lived in urban areas

By 2025: 67% will live in urban areas

Lecture 3; MrL

Megacities by 20156

Explain the figure.

•Megacities with at least 10 millioninhabitants—increased from 2 in 1950 to 22 in 2005

•Most megacitiesare in the developing world•By 2015 most megacities will be in Asia.

Lecture 3; MrL

Environmental Values and Knowledge7

Deciding what to do about an environmental problem involves both science and values.

Science/knowledge in environment: But to make this choice, we must first know what is possible. That requires knowing the scientific data and understanding its implications.

Value of environment: utilitarian (materialistic), ecological, aesthetic, recreational, inspirational, creative, moral, and cultural.

Lecture 3; MrL

Placing a Value on the Environment(includes environmental resource)

8

Utilitarian (materialistic) justificationSome aspect of the environment is valuable

because it benefits individuals economically or is directly necessary to human survival.

Example, conserving lions in Africa as part of tourism provides a livelihood for local people.

Lecture 3; MrL

9

Ecological justification an ecosystem is necessary for the survival of some

species of interest to us Or the system itself provides some benefit.

For example, a mangrove swamp provides habitat for fish, and although we do not eat mangrove trees, we may eat the fish that depend on them. Also, the mangroves are habitat for many noncommercial species, some endangered. Therefore, conservation of the mangrove is important ecologically.

Placing a Value on the Environment(includes environmental resource)

Lecture 3; MrL

10

Aesthetic and recreational justifications our appreciation of the beauty of nature and

our desire to enjoy it.

For example, many people find wilderness scenery beautiful and would rather live in a world with wilderness than without it.

Placing a Value on the Environment(includes environmental resource)

Lecture 3; MrL

Placing a Value on the Environment

11

Moral justification Various aspects of the environment have a

right to exist and it is our moral obligation to help them,

or at least allow them, to persist.

Example: dog park

Lecture 3; MrL

12

Cultural justificationDifferent cultures have many of the same values

but also some different values with respect to the environment.

All cultures may value nature, but, depending on their religious beliefs, may value it in different degrees of intensity. For example, Buddhist monks when preparing ground for a building may pick up and move disturbed earthworms.

Placing a Value on the Environment(includes environmental resource)

Lecture 3; MrL

Taking decision on environmental issue based on knowledge and value

13

Example: Rampal coal power plant vs Moheshkhali

coal power plant: why two different views by the environmentalist?

Lecture 3; MrL

Pollution and pollutants(details will be discussed in other classes)

14

Pollution An unwanted change in the environment caused by the

introduction of harmful materials or the production of harmful conditions (heat, cold, sound).

Categories Infectious Agents: microorganisms, H1N1 flu pandemicEnvironmentally Transmitted Infectious Disease:

Salmonella, malaria Toxic Heavy Metals: Arsenic (As), Lead (Pb), Mercury

(Hg)Organic Compounds: pesticidesPersistent Organic Pollutants: DDT, Aldrin etcLecture 3; MrL

15

References for today’s lecture

BOTKIN, D. B. & KELLER, E.A. 2011. ENVIRONMENTAL SCIENCE: EARTH AS A LIVING PLANET. JOHN WILEY & SONS, INC.

If you don’t find in this book read directly from the class note.

Lecture 3; MrL

Lecture 3; MrL

16

Any question?