Personally, I think we underestimate these changes, because we tend to project them linearly from known factors. However, physical systems typically go through phase changes at different energy levels. Phase changes tend to happen quickly, and are accelerated by positive feedback mechanisms.
For example, I see it as unlikely that we can currently model the rate of change accurately when sea level has already risen by 1m.
Models aren't perfect, and projecting is hard, so "We find that a global total SLR exceeding 2 m by 2100 lies within the 90% uncertainty bounds for a high emission scenario," therefore we should be more alarmed, and use fewer resources on other priorities and focus on this threat. —PNAS, the journal that brought you himmicanes
Models aren't perfect, and projecting is hard, so "We find that a global total SLR below 20 cm by 2100 lies within the 90% uncertainty bounds for a low emission scenario," therefore we should be less alarmed, and focus resources on other priorities. —Crackpot science deniers
"Changes in population, age, income, technology, relative prices, lifestyle, regulation, governance, and many other aspects of socioeconomic development will have an impact on the supply and demand of economic goods and services that is large relative to the impact of climate change." —Intergovernmental Panel on Climate Change