IS GLOBAL TEMPERATURE INCREASING?

1. Is global temperature increasing?

2. Is this temperature increase caused by natural factors or as a result of human impact on the environment?

3. What sources might you use to find the best data to answer these questions? On what data can your conclusion be based? What measurements could be used to obtain the answers?

 1. Is Global Temperature Increasing?

The United Nations Intergovernmental Panel on Climate Change (IPCC) has concluded that global temperature has increased .6 degrees Celsius in the past 50 years (IPCC, 2001; Patz, 2002). One third of this change occurred in the period from 1990 to 2000 (IPCC, 2001). The 24 warmest years since 1900 have all occurred since 1973. Prior to 1990, the 1980s was the warmest decade on record. The ten warmest years have all occurred since 1990 with 1998 being the hottest year on record until recently (Blatt, 2005; Nordell, 2003; Liu, 2005; Patz, 2002). The year 2005 currently holds the record as the hottest year on record (Leahy, 2006). The average temperature in Antarctica has increased 5oF since 1945 (Blatt, 2005).

GLOBAL TEMPERATURE

--after Kemp, 2004

This temperature increase is observed throughout the world and it is significant compared to historical values. The following graphs depict data gathered from a variety of natural sources on the temperature of North America since the year 1000 A.D. and South America since 1600.

heat increase in North America

--after Jones, 2001

heat increase in south america

--after Jones, 2001

2) Is the Temperature Increase Caused by Human or Natural Factors?

There are natural factors which affect global temperature. When these are taken into account, models can be made based on what global temperature would be predicted to be if these natural factors were the only factors which determined the global temperature. Does a model based on natural factors only (the green line in the following graph) match the increased temperature in the right hand portion of the graph?

heat increase graph

adapted from IPCC, 2001

Human activity can affect global temperature. When human activity is taken into account, models can be made based on what global temperature would be predicted to be if human factors were the only factors which determined the global temperature. Does a model based on human impact only (the purple line in the following graph) match the increased temperature in the right hand portion of the graph?

heat increase graph

adapted from IPCC, 2001

1.If you had a question as to whether carbon dioxide levels were causing increased global temperatures, which of the following sources would you recommend to find the answer?

a) a climate scientist who measures carbon dioxide levels or global temperature

b) someone who has no training in climate sciences, who has not published research on the climate, and who has not even read the climate research published by experts

c) someone affiliated with the industries which would be most neagatively effected by carbon dioxide level controls

d) a politicians who receives contribution from industries which would be most negatively effected by carbon dioxide level controls

2. Why do you think a person might make a conclusion on this issue without consulting the data obtained through climate research?
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