It's kind of lucky for everyone that climate is mostly a perfect sliding scale, the more CO2 you avoid putting into the atmosphere the more heat capacity you'd avoid. So every bit helps. Many negative impacts of heat, like changing intense weather, biodiversity loss, and deaths to high heat also correspondingly change linearly with heat. So every bit is a literal victory, there's no major cutoff that we know of until things get really bad (which they might). What's your point?