전치사 to ..

... ...
“global agriculture must produce more food to feed a growing population,” they write. “yet scientific assessments point to climate change as a growing threat to agricultural yields and food security.”

밑줄 친 부분의 to는 전치사인 것 같은데.. 왜 전치사인 to를 썼는지 알고싶어요..
친절한 답변 부탁드려요 ~~ ㅜㅠ