Which of the following facts can prove that the surface temperature of the earth has increasedgreatly according to the text?
选项：

A: During the summer days, the temperature on land surface areas is recorded much higher thanthat of the ocean.
B: The hot days are becoming so much more than the cool days
C: The continental glaciers over the world are getting smaller than before
D: It's easier for the ocean surface than for land surface to increase in temperature in the summer.