What happens if the Earth reverses pole? What consequences does this have for nature?

Answer

We’ve never experienced it, a polarity reversal. The last polarity reversal happened 700,000 years ago. So we really don’t know. We can simulate it with computers (see attached link). In the short term (several thousand years) the poles will shift across the earth’s surface to the other side of the world. The magnetic field does not disappear.
From the fossil record it seems that a polarity reversal does not have much effect on the plants or animals. There is nothing in the fossil record to show that changes are occurring. We certainly don’t know for humans, because “homo sapiens” our species have only been around on Earth for 200,000 years and have therefore never experienced a polarity reversal.