Read the passage and find if the passage agrees, disagrees, or has a neutral stance on whether Global warming is caused by human activities. Answer only with keyword (a) agrees - if passage agrees with the target (b) disagrees - if passage disagrees with the target (c) neutral - if the given passage neither agrees nor disagrees with the target. You don't need to use external knowledge in this task, and you have to answer based on the given passage.

Q: The U.S. going back to the stone age will not do anything to stop global warming.

A: neutral
****
Q: Global trade merely outsourced U.S. emissions.

A: neutral
****
Q: There could be as little as 30 years of burning fossil fuels before the threshold is reached.

A:
neutral
****