You Have a Friend Who Is Wary of Environmentalists' Claims

You have a friend who is wary of environmentalists' claims that global warming could lead to major biological change on Earth. Which of the following statements can you truthfully make in response to your friend's suspicions?

A) We know that atmospheric carbon dioxide has increased in the last 150 years.
B) Through measurements and observations, we know that carbon dioxide levels and temperature fluctuations were directly correlated even in prehistoric times.
C) Global warming could have significant effects on United States agriculture.
D) Sea levels will likely rise, displacing as much as 50% of the world's human population.
E) A, B, C, and D are all correct