Can I get into Columbia with bad grades?
Sure! Since it's a pretty competitive University, you should focus as much as you can on your extracurricular involvement, because that's a huge part of the application process. Don't try to be a member of 100 different clubs, though. It's better to just be president of two or three different organizations that actually do a lot of really interesting work. Also, it's a good idea to have some sort of reason for why your grades aren't really great — there's an additional information section in the application where you can explain you had a family obligation, a learning disability or maybe something else was going on in your life.