Polar amplification refers to the observation that any change in the net radiation balance (for example greenhouse intensification) tends to produce a larger change in temperature near the poles than the planetary average. On a planet with an atmosphere that can restrict longwave radiation to space (a greenhouse effect), surface temperatures will be warmer than a simple planetary equilibrium temperature calculation would predict. Where the atmosphere or an extensive ocean is able to convect heat polewards, the poles will be warmer and equatorial regions cooler than their local net radiation balances would predict.