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Interactive ozone induces a negative feedback in CO 2 ‐driven climate change simulations
Author(s) -
Dietmüller S.,
Ponater M.,
Sausen R.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd020575
Subject(s) - negative feedback , cloud feedback , climate sensitivity , ozone , positive feedback , sensitivity (control systems) , climate change , environmental science , ozone layer , atmospheric sciences , climate model , nonlinear system , tropospheric ozone , water vapor , climatology , meteorology , physics , geology , engineering , oceanography , quantum mechanics , voltage , electronic engineering , electrical engineering
Interactively coupled climate chemistry models (CCMs) extend the number of feedback mechanisms in climate change simulations by including chemical feedback. In this study the radiative feedback from ozone changes on climate response and climate sensitivity is quantified for a series of simulations driven by CO 2 increases on top of a present‐day reference concentration level. Other possibly relevant feedback via atmospheric chemistry, e.g., via CH 4 and N 2 O, is not fully quantified in the CCM setup as their concentrations are essentially fixed at the surface. In case of a CO 2 ‐doubling simulation, the ozone feedback reduces the climate sensitivity parameter by 3.4%, from 0.70 K/(W m −2 ) without interactive chemistry to 0.68 K/(W m −2 ). In case of a 4*CO 2 simulation, the reduction of the climate sensitivity parameter increases to 8.4%. An analysis of feedback reveals that the negative feedback of stratospheric ozone and the associated negative feedback change in stratospheric water vapor are mainly responsible for this damping. The feedback from tropospheric ozone changes is positive but much smaller. The nonlinearity in the climate sensitivity damping with increased CO 2 concentrations is shown to be due to nonlinear feedback of ozone and stratospheric water vapor.