Does Human Activity Cause Global Warming?

The issue of global warming cuts across science, economics, public planning, and politics. If global warming is a real trend, and if the direct projections for the future hold true, your grandchildren may inhabit a very different world than the one we live in now. But if models of human impact on global warming are overestimated, attempts to turn back global warming could negatively effect our economy with little or no tangible benefit.

Imagine that you are a policy advisor to the government on the issue of global warming. What course of action would you recommend? To help you formulate a policy, you will examine some of the data on the phenomenon of global warming and the role that humans play. You will investigate questions such as:

• Is the world getting warmer? (referred to Meteorologists Earth Surface temperature records)

--According to the National Aeronautics and Space Administration (NASA), 1995 was the hottest year on record. The average temperature around the world was approximately 59.8° Fahrenheit, which is .8° higher than the average temperature for the years 1950 to 1980. And since the 1880s, the world's eight warmest years have all taken place since 1979.

• Is such warming a short- or long-term trend? (hit the standard average temp was from 1961 to

1990)

--The Earth's global average surface temperature from 1970 to 2009 can be modeled as a random walk with a warming trend. Despite the overall warming trend, short time periods can show cooling.

• Is global warming caused by greenhouse gas emissions?

--Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F).The major greenhouse gases are water vapor, which causes about 36–70 percent of the greenhouse effect; carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which causes 4–9 percent; and ozone (O3), which causes 3–7 percent. Clouds also affect the radiation balance, but they are composed of liquid water or ice and so have different...