Historical sensible-heat-flux variations key to predicting future hydrologic sensitivity

• Published in: NPJ climate and atmospheric science 2024-06, Vol.7 (1), p.128-10
• Main Authors: Norris, Jesse, Thackeray, Chad W., Hall, Alex, Madakumbura, Gavin D.
• Format: Article
• Language: English
• Subjects: 704/106/35/823; 704/106/694/2786; Anthropogenic factors; Atmosphere; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate change; Climate Change/Climate Change Impacts; Climate models; Climate variability; Climatology; Confidence intervals; Cooling; Earth and Environmental Science; Earth Sciences; Energy; Energy budget; Enthalpy; ENVIRONMENTAL SCIENCES; GEOSCIENCES; Global climate; Global climate models; Heat; Heat exchange; Heat flux; Hydrologic cycle; Hydrology; Precipitation; Radiation; Sensible heat; Sensitivity; Standard deviation; Uncertainty
• ISSN: 2397-3722; 2397-3722
• DOI: 10.1038/s41612-024-00676-4

Under anthropogenic climate change (CC), the global hydrological cycle intensifies at a rate known as hydrologic sensitivity (HS). Global climate models (GCMs) exhibit substantial uncertainty in HS. Past work suggests that another form of HS, derived from internal climate variability (IV), is useful for constraining this uncertainty. However, these two forms of HS are weakly related. Here we show that decomposing HS under both CC and IV, based on the global energy budget, provides insight into the likely range of future HS. We find that sensible heat exchange between the atmosphere and ocean is not accounted for in the atmospheric energy budget under IV, masking the connection between HS under IV and CC. Removing this term, a closer relationship emerges. We use observations in conjunction with this relationship to suggest an upward shift in the likely range of future HS (66% confidence interval: 2.00–2.36 W m −2  K −1 ).