Climate model projections using offline aridity and/or drought indices predict substantial terrestrial drying over the twenty-first century1,2,3,4,5,6,7,8,9,10,11. However, these same models also predict an increased runoff12,13,14,15. This contradiction has been linked to an absence of vegetation responses to an elevated atmospheric CO2 concentration [CO2] in offline impact models12,14,16,17. Here we report a close and consistent relationship between changes in surface resistance (rs) and [CO2] across 16 CMIP5 models. Attributing evapotranspiration changes under non-water-limited conditions shows that an increase in evapotranspiration caused by a warming-induced vapour pressure deficit increase18 is almost entirely offset by a decrease in evapotranspiration caused by increased rs driven by rising [CO2]. This indicates that climate models do not actually project increased vegetation water use under an elevated [CO2], which counters the perception that ‘warming leads to drying’ in many previous studies1,2,3,4,5,6,7,8,9,10,11. Moreover, we show that the hydrologic information in CMIP5 models can be satisfactorily recovered using an offline hydrologic model that incorporates the [CO2] effect on rs in calculating potential evapotranspiration (EP). This offers an effective, physically-based yet relatively simple way to account for the vegetation response to elevated [CO2] in offline impact models.
Subscribe to Journal
Get full journal access for 1 year
only $17.75 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The CMIP5 model outputs are available from the CMIP5 archive (http://cmip-pcmdi.llnl.gov/cmip5/).
Cook, B. I., Smerdon, J. E., Seager, R. & Coats, S. Global warming and 21st century drying. Clim. Dynam. 43, 2607–2627 (2014).
Dai, A. Increasing drought under global warming in observations and models. Nat. Clim. Change 3, 52–58 (2012).
Feng, S. & Fu, Q. Expansion of global drylands under a warming climate. Atmos. Chem. Phys. 13, 10081–10094 (2013).
Fu, Q. & Feng, S. Responses of terrestrial aridity to global warming. J. Geophys. Res. Atmos. 119, 7863–7875 (2014).
Huang, J., Yu, H., Guan, X., Wang, G. & Guo, R. Accelerated dryland expansion under climate change. Nat. Clim. Change 6, 166–171 (2015).
Lin, L., Gettelman, A., Feng, S. & Fu, Q. Simulated climatology and evolution of aridity in the 21st century. J. Geophys. Res. Atmos. 120, 5795–5815 (2015).
Park, C.-E. et al. Keeping global warming within 1.5 °C constrains emergence of aridification. Nat. Clim. Change 8, 70–74 (2018).
Sherwood, S. & Fu, Q. A drier future? Science 343, 737–739 (2014).
Trenberth, K. E. et al. Global warming and changes in drought. Nat. Clim. Change 4, 17–22 (2013).
Scheff, J. & Frierson, D. M. W. Terrestrial aridity and its response to greenhouse warming across CMIP5 climate models. J. Clim. 28, 5583–5600 (2015).
Naumann, G. et al. Global changes in drought conditions under different levels of warming. Geophys. Res. Lett. 45, 3285–3296 (2018).
Milly, P. C. D. & Dunne, K. A. Potential evapotranspiration and continental drying. Nat. Clim. Change 6, 946–949 (2016).
Greve, P., Roderick, M. L. & Seneviratne, S. I. Simulated changes in aridity from the last glacial maximum to 4xCO2. Environ. Res. Lett. 12, 114021 (2017).
Roderick, M. L., Greve, P. & Farquhar, G. D. On the assessment of aridity with changes in atmospheric CO2. Water Resour. Res. 51, 5450–5463 (2015).
Scheff, J., Seager, R., Liu, H. & Coats, S. Are glacials dry? Consequences for paleoclimatology and for greenhouse warming. J. Clim. 30, 6593–6609 (2017).
Milly, P. C. D. & Dunne, K. A. A hydrologic drying bias in water‐resource impact analyses of anthropogenic climate change. J. Am. Water Resour. Assoc. 53, 822–838 (2017).
Swann, A. L. S., Hoffman, F. M., Koven, C. D. & Randerson, J. T. Plant responses to increasing CO2 reduce estimates of climate impacts on drought severity. Proc. Natl Acad. Sci. USA 113, 10019–10024 (2016).
Scheff, J. & Frierson, D. M. W. Scaling potential evapotranspiration with greenhouse warming. J. Clim. 27, 1539–1558 (2014).
Roderick, M. L., Sun, F., Lim, W. H. & Farquhar, G. D. A general framework for understanding the response of the water cycle to global warming over land and ocean. Hydrol. Earth Syst. Sci. 18, 1575–1589 (2014).
Samaniego, L. et al. Anthropogenic warming exacerbates European soil moisture droughts. Nat. Clim. Change 8, 421–426 (2018).
Shuttleworth, W. J. in Handbook of Hydrology (ed. Maidment, D. R.) Ch. 4 (McGraw-Hill Education, New York, 1993).
Allen, R. G., Pereira, L. S., Raes, D. & Smith, M. Crop Evapotranspiration—Guidelines for Computing Crop Water Requirements FAO Irrigation and Drainage Paper No. 56 (FAO, 1998).
Sheffield, J., Wood, E. F. & Roderick, M. L. Little change in global drought over the past 60 years. Nature 491, 435–438 (2012).
Field, C. B., Jackson, R. B. & Mooney, H. A. Stomatal responses to increased CO2: implications from the plant to the global scale. Plant Cell Environ. 18, 1214–1225 (1995).
Novick, K. A. et al. The increasing importance of atmospheric demand for ecosystem water and carbon fluxes. Nat. Clim. Change 6, 1023–1027 (2016).
Westra, S. et al. Future changes to the intensity and frequency of short-duration extreme rainfall. Rev. Geophys. 52, 522–555 (2014).
Chou, C. et al. Increase in the range between wet and dry season precipitation. Nat. Geosci. 6, 263–267 (2016).
Ainsworth, A. E. & Rogers, A. The response of photosynthesis and stomatal conductance to rising [CO2]: mechanisms and environmental interactions. Plant Cell Environ. 30, 258–270 (2007).
Jasechko, S. et al. Terrestrial water fluxes dominated by transpiration. Nature 496, 347–350 (2013).
Zhang, Y. et al. Multi-decadal trends in global terrestrial evapotranspiration and its components. Sci. Rep. 6, 19124 (2016).
Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc. 93, 485–498 (2012).
Jones, P. W. First- and second-order conservative remapping schemes for grids in spherical coordinates. Mon. Weather Rev. 127, 2204–2210 (1999).
Choudhury, B. Evaluation of an empirical equation for annual evaporation using field observations and results from a biophysical model. J. Hydrol. 216, 99–110 (1999).
Y.Y. and M.R. acknowledge the support of the Australian Research Council (CE1101028, CE170100023). T.M. and R.D. acknowledge the support from CSIRO Land and Water.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Yang, Y., Roderick, M.L., Zhang, S. et al. Hydrologic implications of vegetation response to elevated CO2 in climate projections. Nature Clim Change 9, 44–48 (2019). https://doi.org/10.1038/s41558-018-0361-0
The response of reference evapotranspiration to climate change in Xinjiang, China: Historical changes, driving forces, and future projections
International Journal of Climatology (2020)
Journal of Hydrology (2020)
Nature Climate Change (2019)
Exploring the stationarity of Australian temperature, precipitation and pan evaporation records over the last century
Environmental Research Letters (2019)
A Framework for Global Multicategory and Multiscalar Drought Characterization Accounting for Snow Processes
Water Resources Research (2019)