[coldbrewed]

The impacts of climate change are nonlinear. For example 100 year storms become 10 year storms, weather anomalies like polar vortices become much more common, and in general climactic extremes become both more extreme and more common. More concerningly, tipping points are reached (in order to rebuild the polar ice caps we won't need to go back -1.5C, but -4C), and tipping point events cause cascades that lock in climate change.

Worse yet, we're exiting the stable climactic conditions that civilization assumes is present. Assumptions regarding maximum temperatures, precipitation, ground water are baked into our reservoirs, power transmission lines, asphalt roads, train tracks, et cetera. Increased extreme weather compromises our ability to maintain society; look no further than the heat domes in the Pacific Northwest or the cold snaps in Texas to see how those assumptions compromise basic societal functions.

0.5C doesn't imply slightly worse weather, it means the additions of staggering amounts of heat to our land, water, and seas -- and the resulting amplifications of storms.