There are schools out there that will let you pair GH with another concentration (UIC and Emory come to mind). While experience is definitely important in PH, excellent marks, a great SOP, and excellent rec's can make up some ground. If you are set on Columbia contact an admissions rep there and speak to them about your concerns. I also would suggest visiting schools before putting this off for 2 years. While a program may seem like your dream program on paper, reality is sometimes different (experienced this myself this past application cycle).