Which change would occur over the longest amount of time?

A.

tide rising

B.

high pressure system forming

C.

wind direction changing

D.

polar ice caps melting

D. Polar ice caps melting. Polar ice caps melt due to major temperature increase. That would be a result of global warming

Option (D)

Explanation:

The polar ice cap melting is an event that takes place at a longer duration, and is usually measured by the end of every decade. This melting of ice caps in the polar region is caused due to the increasing amount of the earth's surface temperature. One of the main reasons is the increasing amount of carbon in the atmosphere for the last few decades.

On, the other hand, there occurs certain changes which take place in a very short time, in terms of hours or days. Some of its examples include the rise in the sea level due to the tidal effect, changing of wind direction and changing of the pressure system from low to high and vice versa.

Thus, the correct answer is option (D).