Cosmic Shoreline for planets—not limited to transiting rocky planets—around M dwarfs for bolometric instellation (left panel) and cumulative XUV instellation (right panel). All planets for which the presence of a thick (≥1 bar CO₂-bearing atmosphere has been ruled out from thermal emission observations are shown as diamonds, while all planets that are likely to be volatile-rich based on density measurements (≤0.6ρ_⊙) are shown as circles. The markers are scaled by the inverse of their densities. The size of the markers in the legend correspond to Earth (diamond) and Jupiter densities (circle). The yellow line in each panel is the same as Figure 1 and passes through TRAPPIST-1 c for the bolometric and above Mars for the cumulative XUV Cosmic Shorelines, respectively, and its width shows a representative uncertainty range in each instellation. The gray line is drawn by eye to suggest a loose separation within the observed planets, and its width represents the overlap between the two populations.