Wikipedia Step 1

1. Does the Wikipedia article appear to be biased in any way or does it maintain neutrality?

Yes, I believe the article is biased in favor of the idea that global warming is happening, it is an immediate threat to us, and humans are the reason for global warming.  I believe the article is playing on people's emotions by trying to frighten them about imminent dangers.  The article does not examine the possibility that global warming isn't a new thing, that it has cycled and happened in the past, or that we are not in as much danger as they present.

2. What facts has the author omitted?

The author doesn't tell us anything about Earth's temperatures before the 20th century.  Most of the data cited is fairly recent.

3. What additional information is necessary?

Earth's temperatures throughout history going further back than the 20th century.  They need to examine whether this is something that has occurred in the past.

4. What words create a negative impression?

-inadequate
-sudden rise in global temperatures
-changes could occur abruptly
-might also be irreversible
-threat
-amplified global warming
-vulnerability of human societies

5. What impression would I have if different words had been used?

I think they used the negative, scary words to cause people to panic.  If they had used more neutral or positive words, I wouldn't feel that panic.

Examples of bias I found in the article:

"These findings are recognized by the national science academies of all major industrialized nations."

The bias is in the word "all."  I highly doubt that every single group has the same opinion.

"The probability that these changes could have occurred by chance is virtually zero."

The bias is in the word "virtually zero."  I don't trust this statistic; I don't believe it is possible that the chance is zero.

Source
NewsandEventsGuy. (2013, March 17). Global Warming. Retrieved from http://en.wikipedia.org/wiki/Global_warming