Cenozoic climate change. (a) Most recent compilation of category 1 (most trustworthy) atmospheric CO₂ data (Cenozoic CO₂ Proxy Integration Project (CenCO₂PIP) Consortium 2023) as a function of proxy with their fully developed uncertainty estimates (95% confidence intervals). (b) CO₂ radiative forcing $(\text{Δ}{\text{R}}_{\left[{\text{CO}}_2\right]}=5.35\left[\ln \left({\text{CO}}_2\right)-\ln \left({\text{CO}}_{2,0}\right)\right]\text{W\hspace{0.17em}}{\text{m}}^{-2}$, CO_2,0 = 278 ppm) of a 500-kyr running mean through data with median and 50 and 95% credible intervals: dark and light-green shading, respectively (Cenozoic CO₂ Proxy Integration Project (CenCO₂PIP) Consortium 2023). (c) benthic δ¹⁸O recording a mixture of deep ocean temperature and sea level, raw data (points) and 500-kyr running mean (line) (Westerhold et al. 2020). (d) Reconstructed sea level change, raw data (points) and 500-kyr running mean (line) (Miller et al. 2020). Vertical broken lines mark the most likely time window (14.8–12.4 Myr ago, for d_Sun–cloud within 20–30 pc) of the Solar System being located in the dense region of the ISM suggested by this study. (e–h) Zoom in on the time window 20–10 Myr ago.