1. compare the average global temperatures from the early 1900’s and the early 2000’s. how has the
average global temperature changed over the last century?
2. complete the chart using information found during your research.

3. explain the relationship between the amount of greenhouse gases present in our atmosphere and the
change in temperatures over the last century.
4. describe at least two things people can do today to protect earth and reduce levels of co2.
5. briefly explain how greenhouse gases, carbon dioxide in particular, can absorb and radiate heat inside
earth’s atmosphere and thereby contribute to the greenhouse effect.
6. read "what triggers ice ages? " briefly describe what you think the world would be like if the amount of
greenhouse gases in the atmosphere were reduced to levels like those during the ice age.

1.The average global temperatures from the 2000’s early are higher than those from the early 1900’s. We can see from the diagram that the average global temperature in the 1900s was about 57 degrees Fahrenheit (13.8 o C). In the 2000s the temperature raised to more than 58 F (about 14.5 o C). The world temperature is increasing due to human activity or natural variability. Some of the causes of this global warming are:  burning of fossil fuels, agriculture , deforestation all leading to greenhouse effect.

2.Carbon dioxide (CO2) is naturally present in the atmosphere as part of the carbon cycle, but its amount is raised due to human activities. This gas is produced by the process of burning fossil fuels (coal, natural gas, and oil), solid waste, trees and wood products..CO2 is removed from the air by the absorption of the plants or it dissolves into the ocean over a period of 20–200 years.

Methane is produced during the production and transport of coal, natural gas, and oil. It is removed from the atmosphere by chemical reaction, persisting for about 12 years.

Nitrous Oxide (N2O) is formed during agricultural and industrial activities or during the burning of fossil fuels and solid waste.N2O is destroyed in the stratosphere persisting for around 114 years.

Fluorinated gases such as hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are formed in different industrial processes. Those gases have long atmospheric lifetimes sometimes thousands of years.

3.Greenhouse gases such as CO2, N2O, fluorinated gases, methane are gases that trap the heat in the atmosphere, causing the warmer climate. The amount of a particular greenhouse gas in the atmosphere can be measured. Higher emissions of those gases lead to higher concentrations in the atmosphere. Because of the Industrial Revolution , atmospheric greenhouse gas amount is raised for the last century and that increased the global average temperature.

4.There are many ways for reducing the amount of CO2. Some of them are:

•Reduce Vehicle Emissions, since the use of vehicle for transport is one of the largest sources of this greenhouse gas. Drive a bike, get a gas-efficient vehicle or a hybrid car.

•Reduce Home Energy Carbon Emissions by insulating and sealing your home, turning off lights, add solar panels to the roof of your home etc.

5.Solar energy that travels to the Earth is absorbed by the its surface and converted into heat, which is released into the atmosphere. The greenhouse gases such as carbon dioxide (CO2) absorb that heat and send it back to the Earth's surface. This process is known as the greenhouse effect and it leads to temperature increase. This happens because the increase in greenhouse gases in the atmosphere trap too much heat.  

6.Since the greenhouse gases trap the heat, if there were less of those gases, much of the infrared radiation (solar  energy) that is converted to heat today would not be trapped in the Earth's atmosphere. The  temperature of the Earth would cool down, and a conditions of the Ice Age would occur. These conditions would be very unfavorable for plants and animals, oceans would freeze, and weather patterns would change.

the answer is b.) hydrogen bonds between bases.