title: On the causal structure between CO2 and global temperature.
abstract: We use a newly developed technique that is based on the information flow concept to investigate the causal structure between the global radiative forcing and the annual global mean surface temperature anomalies (GMTA) since 1850. Our study unambiguously shows one-way causality between the total Greenhouse Gases and GMTA. Specifically, it is confirmed that the former, especially CO2, are the main causal drivers of the recent warming. A significant but smaller information flow comes from aerosol direct and indirect forcing, and on short time periods, volcanic forcings. In contrast the causality contribution from natural forcings (solar irradiance and volcanic forcing) to the long term trend is not significant. The spatial explicit analysis reveals that the anthropogenic forcing fingerprint is significantly regionally varying in both hemispheres. On paleoclimate time scales, however, the cause-effect direction is reversed: temperature changes cause subsequent CO2/CH4 changes.
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Research Unit, Via E. Fermi 2749, Ispra 21027, Italy.
authors.forename: Adolf
authors.initials: A
authors.lastname: Stips
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Research Unit, Via E. Fermi 2749, Ispra 21027, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Macias
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Research Unit, Via E. Fermi 2749, Ispra 21027, Italy.
authors.forename: Clare
authors.initials: C
authors.lastname: Coughlan
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Research Unit, Via E. Fermi 2749, Ispra 21027, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Garcia-Gorriz
authors.affiliation: School of Marine Sciences, Nanjing Institute of Meteorology, 219 Ningliu Blvd, Nanjing 210044, China.
authors.forename: X San
authors.initials: XS
authors.lastname: Liang