There will have to be a lot of future movements of the earth's giant plates before the ocean's circulatory patterns are sufficiently changed to permit substantial warming of the northern latitudes. We are only in a short-term interglacial period similar to a preceding, major one that lasted from about 130,000 to 120,000 years ago. Rockfalls generally occur in winter and early spring, as water works its way behind large flakes, freezes and expands, and thereby pries the flakes loose. While all flakes are initially formed through unloading, they can be pried loose by processes other than freezing water. A sufficient tonnage of rocks fell from Liberty Cap to temporarily dam the Merced River just above the brink of Nevada Fall.
Lightning can be another cause of rockfalls.
Finally, from the 1930s, especially during the '60s and '70s, climbers drove countless pitons into thousands of cracks, briefly accelerating the natural rate of exfoliation. Major rockfalls occur every few years in Yosemite Valley. The largest one identified is the prehistoric fall that dammed Tenaya Creek to create Mirror Lake, estimated to be about 15,000,000 cubic yards. The 1987 Middle Brother rockfall, perhaps the largest historic one, pales in comparison at about 800,000 cubic yards. Fresh rockfall sites on cliffs are easy to identify, since they expose fresh rock.