Because technically there is no such thing as cold all that exists is heat this is because heat is the rapid movement of particles, made by friction (to understand why you must delve into physics and some chemistry) so, when you feel cold, it's really the absence of heat so instead of "keeping the cold out", which makes no sense at all scientifically, insulation keeps the heat in.
as a side note the feeling of cold is produced when you come in contact with an object (yes, air counts) that has less heat, or energy, than you do, You feel cold because heat (energy) from your body is being transferred to the environment. This ABSENCE OF HEAT in your body is why you feel cold
Human activity can affect the amount of carbon in the atmosphere. When fossil fuels like oil, coal, and natural gas are burned, carbon dioxide is released into the atmosphere as waste.
