Weather Variability Induced Uncertainty of Contrail Radiative Forcing

Persistent contrails and contrail cirrus are estimated to have a larger impact on climate than all CO2 emissions from global aviation since the introduction of jet engines. However, measure for this impact, effective radiative forcing (ERF) or (RF), suffers uncertainties that much those CO2. Despite ongoing research, so called level scientific understanding has not improved 1999 IPCC Special Report Aviation Global Atmosphere. In paper, role weather variability as major component uncertainty range RF is examined. Using 10 years MOZAIC flights ERA-5 reanalysis data, we show natural causes large variations in instantaneous (iRF) persistent contrails, which source uncertainty. Most (about 80%) small positive iRF up 20 W m?2. IRF exceeds m?2 about 10% cases but these disproportionally remaining negative iRF. The distribution values heavily skewed towards an exponential decay. Monte Carlo experiments reveal difficulty determining precise long-term mean measurement campaign data alone. Depending chosen sample size, calculated means scatter considerably, caused exclusively by variability. Considering many additional sources variation been deliberately neglected present examination, results suggest there fundamental limit precision with ERF can be determined. our opinion, does imply low understanding; rather grown considerably over recent decades. Only determination annual still difficult will probably coming decades, if forever. little knowledge is, therefore, no argument postpone actions mitigate contrail’s warming impact.