Evidence for higher Earth-system sensitivity from long-term carbon-cycle observations
T. E. Wong, Y. Cui, D. L. Royer, and K. Keller
arXiv [physics.geo-ph] (26 October 2019)
URL: http://arxiv.org/abs/1910.11987
Projections of future temperature are critical for developing sound strategies to address climate risks, but depend on deeply uncertain Earth system properties, including the Earth-system sensitivity (ESS). The ESS is the long-term (e.g., millennial-scale and longer) global warming resulting from a doubling of atmospheric carbon dioxide (CO2) levels, relative to pre-industrial conditions. Long-term carbon cycle models provide a common approach to estimate ESS, but previous efforts either lack a formal data assimilation framework, or focus on paleo periods with the most available data. Here, we improve on ESS estimates by using a Bayesian approach to fuse deep-time paleoclimate data with a long-term carbon cycle model. Our updated ESS estimate of 5.1 Celcius (3.8-6.6 Celcius; 5-95