The report quantifies climate sensitivity as between 2.5 and 4 C for each doubling of carbon dioxide in the atmosphere.[1] Geopolitics has been included in climate models for the first time, as five Shared Socioeconomic Pathways,[12] with SSP1-1.9 being a new pathway to model how people could keep warming below 1.5 C.[11] The report narrows the range of probable temperature rise to between 1.5 C and 5 C,[12] with 1.5 C likely to be reached before 2040.[11] The threats from compound impacts are rated higher than in previous IPCC reports.[11] The famous hockey stick graph has been extended.[11] Extreme weather is expected to increase in line with temperature and compound each other, making extreme weather events more impactful on society.[11]