Why is the southern hemisphere warmer than the northern?

The majority of the southern hemisphere is made up of oceans, which warm up in the summer and hold heat throughout the winter. Water has a high specific heat capacity, meaning that it loses heat slowly.

The continental effect, which causes extremely cold winters in the central parts of the northern continents, illustrates how the northern hemisphere has a much larger land mass that loses heat more quickly.

The Earth's perihelion occurs around January 3rd, and its aphelion occurs around July 3rd. The Earth's average temperature is slightly higher in July, when it is furthest from the Sun, than it is in January, when it is closest, due to heat retention in the oceans of the southern hemisphere.

Because of the Earth's elliptical orbit and axial tilt, the Southern Hemisphere experiences warmer summer temperatures than the Northern Hemisphere.