State dependence of CO<sub>2</sub> forcing and its implications for climate sensitivity.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38033059.
- Also identified by DOI 10.1126/science.abq6872.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
When evaluating the effect of carbon dioxide (CO<sub>2</sub>) changes on Earth's climate, it is widely assumed that instantaneous radiative forcing from a doubling of a given CO<sub>2</sub> concentration (IRF<sub>2×CO2</sub>) is constant and that variances in climate sensitivity arise from differences in radiative feedbacks or dependence of these feedbacks on the climatological base state. Here, we show that the IRF<sub>2×CO2</sub> is not constant, but rather depends on the climatological base state, increasing by about 25% for every doubling of CO<sub>2</sub>, and has increased by about 10% since the preindustrial era primarily due to the cooling within the upper stratosphere, implying a proportionate increase in climate sensitivity. This base-state dependence also explains about half of the intermodel spread in IRF<sub>2×CO2</sub>, a problem that has persisted among climate models for nearly three decades.