If hypothyroidism goes untreated, there is an associated risk of due to high levels of low-density lipoproteins (ldl or bad cholesterol).

This can lead to heart disease. High levels of LDL cholesterol can lead to a buildup in the arteries and veins, leading to atherosclerosis. The blood vessels will thicken and make it difficult for blood to pass through because of the presence of white blood cells and plaque along the cell walls.

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun