"Peak warming" refers to the point at which global temperatures reach their highest level due to climate change. It is the maximum amount of warming that occurs before temperatures stabilize or start to decrease. Full definition
The relationship between peak warming and cumulative CO2 emissions, and its use to quantify vulnerabilities in the carbon — climate — human system. (shapingtomorrowsworld.org)
Their «natural models» grossly underestimated the 40s peak warming by ~ 0.8 ° C (blue line) and when CO2 and sulfates were added the warming event was cooled further (red line). (landscapesandcycles.net)