If you think about climate change, it can really only change the reference elevation of the world by increasing the sea level which we use for a definition of zero ( mean sea level ). Mean sea level has been rising for
about the last 12,000 years, and it hs risen about 400 feet, or 120 meters
in that time period. It will continue to rise as ice melts, and the oceans warm, and expand. This is no real big deal unless you live on an island in the Pacific where all of the land is less than 2 meters above mean sea level, and all of your fresh water is from rainfall.
In a general context, what you may want to read (if you have not done yet so) is the classic paper of Peter Molnar and Philip England (1990): Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg? (doi:10.1038/346029a0) and the subsequent debate what can be summarized as glaciation induced relief enhancement.
Concerning the slope distributions the paper of Robl et al. (2015) is one of the best contributions to read (doi:10.1016/j.gloplacha.2015.01.008).