While religion, politics, economy, culture, and ethnicity can contribute to or be used to fan global conflicts, the latter can also be caused by global environmental issues.

1. Problems that cause global warming and greenhouse effects.

Green house effect: global warming created by both emission of gas and the decrease of forests.  

Developing countries, for lack of fuel, often chop down trees to use as daily fuel supply.  Population density and the low agricultural yield because of poor soil and lack of adequate fertilizer and advanced technology also lead to search of new farmland, often the cultivation of pastureland or burning down of forests to clear new land. 

One consequence of decreasing world forests is the decrease in the forests' function to regulate the atmosphere, especially their ability to absorb carbon dioxide.  Carbon dioxide, together with Nitrogen oxides expelled in the emissions from car exhausts, aircraft, and factories, and freons that have widely been used in aerosols and refrigerator coolants, together contribute to the Green house effect: like a blanket they wrap around the earth, preventing the earth to cool down by letting hot air escape.  

Nitrogen oxides and freons also contribute to the destruction of the ozone, a layer of oxygen about 15-50km above the earth's surface.  By absorbing most of the solar ultraviolet radiation the ozone layer protects living organisms on earth.  The fact that the ozone layer is thinnest at the equator is believed to account for the high equatorial incidence of skin cancer as a result of exposure to unabsorbed solar ultraviolet radiation.  In the 1980s it was found that depletion of the ozone layer was occurring over both the poles, creating ozone holes. 

The extensive use of energy in the developed countries, such as in cars (e.g. p.394), heating, cooling, and in many other areas also contribute to global warming.

•    The article on Tokyo's climate going up.
• Global warming and the burning of the Amazon rain forest.

Greenhouse effect and change of rain distribution, as well as effect on agriculture.

•   Article on forecast of deluge and drought.
• Weather change and disease.
• The flooded world.

2. Unequal distribution of food and the environment.

Besides global warming and its consequences, the second point McKibben makes is the limitations of land on earth and the expanding area each person in the developed world needs to provide their daily food (beef, other meats, grains, vegetables and fruits, such as that unnutritious lettuce, p.389). Regarding beef production, a steer needs the equivalent of sixteen pounds of grain to produce one pound of edible meat, and a third of the world's grain supplies, two-thirds of the oilseeds, half the fishmeal and a third of the milk products are fed to livestock. In 1972-1974, 43 per cent of the world's cereal production was used as feed for livestock (largely for Western consumption), versus 88 percent in the US, and 71 percent for Europe. Opulence in the developed countries contrasts with starvation in many of the developing countries. Malnutrition make infectious diseases more likely. Chief killers in developing countries (44% of deaths, and 3/4 deaths among Latin American children) are infectious, parasitic, and respiratory diseases, helped along by malnutrition. In contrast, chief killers in the U.S., such as certain cancers and heart disease, are often the result of eating too well (too many calories, too much cholesterol).

In the 1970s, third world poverty was reduced by the Green Revolution, when new crops and new technologies, as well as better irrigation, were introduced to countries such as Indonesia and India, leading to lessened starvation and longer life spans, as well as lower infant mortality rate. All this has contributed to population growth, and the possible doubling of population in the world (from 6 billion to 12 billion), which could lead to greater problems on the ecosystem. Population growth in different places also means different things: in developing countries where per capita energy consumption is low, it can simply mean there are more people than food; in developed countries, it could mean greater damage to the environment. (p.400)

3. Another eco-crisis: the explosion of third world cities.

1. The rural-urban divide in developing countries.

Unlike in the U.S. where the divide is small, many developing countries face a tremendous gap in the two regions:

• Differences in income, schooling, electricity, and every other facility.
• Result of colonial rule: with an overemphasis on urban development.

2. Internal migrations in developing countries and overcrowdedness in cities.

Because of all the facilities and higher income of the cities, internal migration to cities becomes commonplace in developing countries, leading to overcrowded cities, such as Mexico City, Shanghai, etc. Such overcrowdedness leads to many problems, such as rapid spread of disease (e.g. SARS in Hong Kong in 2002), and pollution (e.g. by cars, and other energy burning sources).

In China for a long time under Communism, the rural (90 percent of China's population) were confined to the countryside through a household registration system that would leave them with no food or clothes to buy in the cities, thereby controlling urban population. After 1978, a market economy weakened the household registration system, leading to massive exodus of rural migrants from their hometowns to the cities for better jobs, where they often work and live under substandard conditions, leading to multiple problems.

3. Solutions to problems of urban overcrowdedness?

Linden believes solutions lie in 1. good leadership, such as in the Brazilian city of Curitiba and the Indian city of Bangalore (India's cilicon valley), and 2. international investment.