| Summary: | Since Chaneys report, the range of global warming projections in response to a doubling of CO2from 1.5C to 4.5C or greaterremains largely unscathed by the onslaught of new scientific insights. Conventional thinking regards inter-model differences in climate feedbacks as the sole cause of the warming projection spread (WPS). Our findings shed new light on this issue indicating that climate feedbacks inherit diversity from the model control climate. Regulated by the control climate sea ice coverage via its melt potential, models with greater (lesser) sea ice coverage generally possess a colder (warmer) and drier (moister) climate, exhibit a stronger (weaker) ice-albedo feedback, and experience greater (weaker) warming. The water vapor feedback also inherits diversity from the control climate but in an opposite way: a colder (warmer) climate generally possesses a weaker (stronger) water vapor feedback, yielding a weaker (stronger) warming. These inherited traits compete to influence the warming response obscuring the correlation between the WPS and control climate diversity. We envision this new insight and enhanced control climate lens allow us to refocus an old yet underexplored line of inquiry contributing to the ultimate crack in the WPS armor and convergence of the warming projections.
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