Some scientists have linked the little ice age that spanned much of the early modern period to the

The correct answer for this question is this one: "current era." Some scientists have linked the little ice age that spanned much of the early modern period to the current era. The Little Ice Age is a period between about 1300 and 1870 during which Europe and North America were subjected to much colder winters than during the 20th century. 

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Maybe haha

Carbon dioxide is the correct answer