Why are there different theories about the effects of global warming? a. there is no data to support global warming. b. global climate is complex, so changes in global climate are hard to predict. c. increased levels of carbon dioxide are offset by other changes. d. there has been a decrease of extreme weather.

Option (b) is the correct answer.

Explanation:

When there is increase in number of pollutants like chlorofluorocarbons, carbon dioxide etc in the atmosphere then there occurs increase in temperature of the atmosphere. This increase in temperature is known as global warming.

Since there occurs different changes in different parts of the globe. Therefore, it is very difficult to predict the changes occurring in the globe.

Thus, we can conclude that there are different theories about the effects of global warming because global climate is complex, so changes in global climate are hard to predict.