According to the majority of scientists, which of the following occurrences is most responsible for recent increases in global temperatures? A. Volcanic and earthquake activity
b. an increase in sun radiation
c. changes in the earths orbit
d. an increase in greenhouse gasses within the atmosphere

Match your vocabulary word to its definition. 1. emigration 2. immigration 3. migration 4. overpopulation 5. sustainable development 6. under population 7. unsustainable development 8. urbanization the movement from one place to another the number of people exceeds the available natural resources in an area leaving one's homeland to settle in a new place the increase in the population of a city the movement of people to a new country the ability to meet current needs without reducing the ability to meet future needs resources being used up at a faster rate than they can be replenished birth rate insufficient to replace the existing population

What was apartheid and how did it restrict the rights of non-whites?

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed