The atmospheric circulation controls how global climate change will be expressed regionally. Substantial circulation changes are expected under global warming, including a narrowing of the intertropical convergence zone1, 2, a slow down and poleward expansion of the tropical circulation3, 4, and a poleward shift of mid-latitude stormtracks and jets5, 6. Yet, climate model projections of the circulation response to climate change remain uncertain7. Here we present simulations with two different aquaplanet climate models and analyse these simulations using the cloud and water-vapour locking method. We find that radiative changes of clouds and water vapour are key to the regional response of precipitation and circulation to global warming. Model disagreement in the response of key characteristics of the atmospheric circulation—the intertropical convergence zone, the strength of the Hadley circulation, and the trade winds—arises from disagreement between the models in radiative changes of tropical ice clouds and their coupling to the circulation. We find that cloud changes amplify a poleward shift of the extratropical jet, whereas water vapour changes oppose such a shift, but the degree of compensation is model-dependent. We conclude that radiative changes of clouds and water vapour are not only integral to the magnitude of future global-mean warming but also determine patterns of regional climate change.
At a glance
- Tropical drought regions in global warming and El Niño teleconnections. Geophys. Res. Lett. 30, 2275 (2003). , &
- Patterns of the seasonal response of tropical rainfall to global warming. Nature Geosci. 6, 357–361 (2013). , , , &
- Robust responses of the hydrological cycle to global warming. J. Clim. 19, 5686–5699 (2006). &
- Expansion of the Hadley cell under global warming. Geophys. Res. Lett. 34, L06805 (2007). , &
- A consistent poleward shift of the storm tracks in simulations of 21st century climate. Geophys. Res. Lett. 32, L18701 (2005).
- Response of the midlatitude jets and of their variability to increased greenhouse gases in CMIP5 models. J. Clim. 26, 7117–7135 (2013). &
- 1029–1136 (Cambridge Univ. Press, 2013). et al. in IPCC Climate Change 2013: The Physical Science Basis (eds Stocker, T. et al.) Ch. 12,
- Robustness and uncertainties in the new CMIP5 climate model projections. Nature Clim. Change 3, 369–373 (2013). &
- What are climate models missing? Science 340, 1053–1054 (2013). &
- Using aquaplanets to understand the robust responses of comprehensive climate models to forcing. Clim. Dynam. 1–21 (2014). , &
- A standard test for AGCMs including their physical parametrizations: I: The proposal. Atmos. Sci. Lett. 1, 101–107 (2000). &
- The Aqua-Planet Experiment (APE): Control SST simulation. J. Meteorol. Res. Jpn 91A, 17–56 (2013). et al.
- An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc. 93, 485–498 (2012). , &
- Atmospheric component of the MPI-M Earth System Model: ECHAM6. J. Adv. Model. Earth Syst. 5, 146–172 (2013). et al.
- Climate change projections using the IPSL-CM5 Earth System Model: From CMIP3 to CMIP5. Clim. Dynam. 40, 2123–2165 (2013). et al.
- Mechanisms of global warming impacts on regional tropical precipitation. J. Clim. 17, 2688–2701 (2004). &
- Robust direct effect of carbon dioxide on tropical circulation and regional precipitation. Nature Geosci. 6, 447–451 (2013). et al.
- An important constraint on tropical cloud–climate feedback. Geophys. Res. Lett. 29, 1951 (2002). &
- The general circulation of the atmosphere. Annu. Rev. Earth Planet. Sci. 34, 655–688 (2006).
- http://gfd.whoi.edu/proceedings/2000/PDFvol2000.html Woods Hole Oceanographic Institute Geophysical Fluid Dynamics Program (Woods Hole Oceanogr. Institute, 2000);
- Width of the Hadley cell in simple and comprehensive general circulation models. Geophys. Res. Lett. 34, L18804 (2007). , &
- Water vapor feedback and global warming. Annu. Rev. Energy Environ. 25, 441–475 (2000). &
- Marine boundary layer clouds at the heart of tropical cloud feedback uncertainties in climate models. Geophys. Res. Lett. 32, L20806 (2005). &
- Radiative impact of clouds on the shift of the Intertropical Convergence Zone. Geophys. Res. Lett. 41, 4308–4315 (2014). , , &
- Southern Hemisphere cloud-dynamics biases in CMIP5 models and their implications for climate projections. J. Clim. 27, 6074–6092 (2014). &
- Weakening and strengthening structures in the Hadley Circulation change under global warming and implications for cloud response and climate sensitivity. J. Geophys. Res. 119, 5787–5805 (2014). et al.
- Cloud feedback processes in a general circulation model. J. Atmos. Sci. 1397–1416 (1988). &
- Climate feedback efficiency and synergy. Clim. Dynam. 41, 2539–2554 (2013). et al.
- The response of the ITCZ to extratropical thermal forcing: Idealized slab-ocean experiments with a GCM. J. Clim. 21, 3521–3532 (2008). , , &
- Compensation of hemispheric albedo asymmetries by shifts of the ITCZ and tropical clouds. J. Clim. 27, 1029–1045 (2014). , , &
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