Here are some references which I am summarizing below: here, here, and here
First off, 10km is about the estimated size of the Chixlub impactor (that killed the dinosaurs) which itself is the third largest known impact crater. So this impact would probably be a top 5 impact for the last billion years. The asteroid hits with an impact of 60 million megatons of TNT (Tsar Bomba was 50 megatons). Its energy release is equivalent to a 12.4 magnitude earthquake (~250 times more powerful than any known earthquake). Chixlub' crater is still 180km across 60 million years later, so it is going to leave a mark.
None! The south pole is on land, and no particularly close to water. No tsunami.
The for that 180km wide impact crator, all the snow and ice is vaporized into steam, which rapidly expands into a blast wave emanating from th south pole. Luckily very few people live near the south pole, but some unlucky folks in places like Tierra del Fuego and the Falklands get flattened and cooked by the blast wave.
The passage of the asteroid literall punches a hole in the atmosphere. Through this hole, molten crust/astroid bits will be thrown up nearly into space. This stuff will then land around the southern hemisphere starting fires. The sky is filled with smoke as the Amazon rainforest burns down.
The heat of the impact fuses nitrogen and oxygen in the atmosphere together into nitrogen dioxide, the precursor for nitric acid. The southern hemisphere is covered in nitric acid rain, dooming any plants not burned by ejecta. Fortunately, the ITCZ provides a weather barrier that limits crossing into the northern hemisphere.
Global smoke reflects sunlight into space and causes massive cooling for several years. After that, the carbon dioxide released by massive world-fires causes massive global warming.
Doesn't sound pleasant! Hope I'm not around.