Record low Arctic/Record high Antarctic sea ice is not a contradiction
That's the problem you run into when you only examine something at a superficial level. In science common sense doesn't always work.
Regarding sea ice first you need to understand the fundamental difference between the Arctic and the Antarctic. That is the Arctic region is an ocean surrounded by land and the Antarctic is land surrounded by ocean. That difference has profound effects on the sea ice.
For instance as long as we have been observing it the sea ice surrounding Antarctica melts nearly completely every summer then reforms the next winter. In the Arctic the observation has been that the sea ice melts a bit around the periphery but the core of ice in the middle of the Arctic Ocean remained. (That is less true with the record melting in the past few years of course.)
Why Antarctic sea ice is expanding somewhat is really kind of fascinating. It mainly has partly to do with the ozone hole over the Antarctic and partly to do with global warming.
Ozone is also a greenhouse gas and the ozone hole over Antarctica in winter results in stronger cooling over the continent. This results in stronger winds around the continent which blows the existing sea ice around more opening up more polynyas, exposing more open water to the atmosphere which subsequently freezes over to create more sea ice area.
The global warming aspect is that warming results in more precipitation. This freshens the surface water making it easier to freeze and reducing its density which stratifies the water layers more strongly reducing the ability of warmer water to rise from below and break up/melt the surface sea ice.
Neither of those aspects could be arrived at just by superficial common sense which says "More ice must mean it's colder".
