In the tropics, the absorbed solar energy is greater than the emitted thermal radiation lost to space. The reverse is true at the poles. What stops the tropics getting hotter and hotter and the poles getting colder and colder?

Cyclones and ocean currents transport heat towards the poles

Explanation:

The reason why the tropics is not getting hotter and the poles not getting colder is due to the activities of cyclones and ocean currents which transport heats towards the poles thus enabling the temperatures at the tropics and the poles to remain fairly constant.