Humid heat exceeds human tolerance limits and causes mass mortality

The hottest boreal summer on record has driven widespread humid heat mortality across every continent of the Northern Hemisphere. With critical physiological limits to human heat tolerance

drawing ever closer, this Comment highlights the urgent need to limit further climate warming and emphasizes the adaptation challenge ahead. Access through your institution Buy or subscribe

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ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support REFERENCES * Ebi, K. L. et al. _Lancet_ 398, 698–708 (2021). Article  Google

Scholar  * Sherwood, S. C. & Huber, M. _Proc. Natl Acad. Sci. USA_ 107, 9552–9555 (2010). Article  CAS  Google Scholar  * Wolf, S. T., Cottle, R. M., Vecellio, D. J. & Kenney, W. L.

_J. Appl. Physiol._ 132, 327–333 (2022). * Wolf, T. S., Cottle, R. M., Fisher, K. G., Vecellio, D. J. & Kenney, W. L. _Commun. Earth Environ._ 4, 486 (2023). * Vanos, J. et al. _Nat.

Commun._ 14, 7653 (2023). Article  CAS  Google Scholar  * Powis, C. M. et al. _Sci. Adv._ 9, eadg9297 (2023). Article  Google Scholar  * Vecellio, D. J., Kong, Q., Kenney, W. L. & Huber,

M. _Proc. Natl Acad. Sci. USA_ 120, e2305427120 (2023). Article  CAS  Google Scholar  * Kenney, W. L. & Zeman, M. J. _J. Appl. Physiol._ 92, 2256–2263 (2002). * Lu, Y.-C. & Romps,

D. M. _Environ. Res. Lett._ 18, 094021 (2023). Article  Google Scholar  * Jay, O. et al. _Lancet_ 398, 709–724 (2021). Article  Google Scholar  * Ramsay, E. E., Hamel, P., Chown, S. L. &

Duffy, G. A. _One Earth_ 7, 2–5 (2024). Article  Google Scholar  * Harrington, L. J. & Otto, F. E. L. _Nat. Clim. Change_ 10, 796–798 (2020). Article  Google Scholar  * Matthews, T.,

Wilby, R. L. & Murphy, C. _Nat. Clim. Change_ 9, 602–606 (2019). Article  Google Scholar  * Abdelmoety, D. A. et al. _BioMed Res. Int._ 2018, 5629474 (2018). Article  Google Scholar 

Download references ACKNOWLEDGEMENTS The authors are members of the Lethal Humidity Global Council. While the views stated here are the authors’ own, our initiative is additionally supported

by the following members of the Council: S. Dey, Indian Institute of Technology Delhi, India; E. Shuckburgh, Cambridge Zero, Cambridge University, UK; V. Venugopal, Sri Ramachandra

Institute of Higher Education and Research, India; T. Lenton, Exeter University; L. Slater, Oxford University; B. Hare, Murdoch University and Climate Analytics; R. Glasser, Australian

Strategic Policy Institute (ASPI); D. McCauley, University of California Santa Barbara; A. Dutta, Professor of Epidemiology at Public Health Foundation of India (PHFI); K. Mohaddes,

Cambridge Judge Business School. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Geography and Centre for Integrated Research in Risk and Resilience, King’s College London,

London, UK Tom Matthews * Asian School of the Environment, Nanyang Technological University, Singapore, Singapore Emma E. Ramsay * Climate Analytics, Berlin, Germany Fahad Saeed * Climate

Change Research Centre, University of New South Wales, Sydney, New South Wales, Australia Steven Sherwood & Katrin J. Meissner * Heat and Health Research Centre and Thermal Ergonomics

Laboratory, University of Sydney, Sydney, New South Wales, Australia Ollie Jay * Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, Los

Angeles, CA, USA Colin Raymond * ARC Centre of Excellence for the Weather of the 21st Century and Research School of Earth Sciences, Australian National University, Canberra, Australian

Capital Territory, Australia Nerilie Abram & Sarah Perkins-Kirkpatrick * Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine, National University of Singapore,

Singapore, Singapore Jason Kai Wei Lee * University of Western Australia, Perth, Western Australia, Australia Shanta Barley & Andrew Forrest * Fortescue, Perth, Western Australia,

Australia Shanta Barley & Andrew Forrest * Fenner School of Environment and Society, Australian National University, Canberra, Australian Capital Territory, Australia Sarah

Perkins-Kirkpatrick * Weather and Climate Services, Islamabad, Pakistan Mariam Saleh Khan, Atta Ullah & Anwar Sadad * Centre for Ecology and Conservation, Exeter University, Exeter, UK

Callum Roberts * Indian Institute of Public Health, Gandhinagar, India Dileep Mavalankar * Walter and Eliza Hall Institute of Medical Research (WEHI), Parkville, Victoria, Australia Kenneth

G. C. Smith * University of Melbourne, Melbourne, Victoria, Australia Kenneth G. C. Smith * Luskin Center for Innovation, University of California, Los Angeles, Los Angeles, CA, USA Victoria

Turner * Minderoo Foundation, Perth, Western Australia, Australia Andrew Forrest Authors * Tom Matthews View author publications You can also search for this author inPubMed Google Scholar

* Emma E. Ramsay View author publications You can also search for this author inPubMed Google Scholar * Fahad Saeed View author publications You can also search for this author inPubMed 

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this author inPubMed Google Scholar * Jason Kai Wei Lee View author publications You can also search for this author inPubMed Google Scholar * Shanta Barley View author publications You can

also search for this author inPubMed Google Scholar * Sarah Perkins-Kirkpatrick View author publications You can also search for this author inPubMed Google Scholar * Mariam Saleh Khan View

author publications You can also search for this author inPubMed Google Scholar * Katrin J. Meissner View author publications You can also search for this author inPubMed Google Scholar *

Callum Roberts View author publications You can also search for this author inPubMed Google Scholar * Dileep Mavalankar View author publications You can also search for this author inPubMed 

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author inPubMed Google Scholar * Anwar Sadad View author publications You can also search for this author inPubMed Google Scholar * Victoria Turner View author publications You can also

search for this author inPubMed Google Scholar * Andrew Forrest View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS T.M., E.E.R., F.S., S.B.,

S.S., A.F. and O.J. conceptualized the Comment. E.E.R. processed observed data and made the figure. T.M., E.E.R., S.S., O.J. and S.B. drafted the paper. All authors contributed ideas and

edits to the Comment. CORRESPONDING AUTHOR Correspondence to Tom Matthews. ETHICS DECLARATIONS COMPETING INTERESTS All authors are members of the Lethal Humidity Global Council, an assembly

of dedicated leaders and global experts to protect humanity against lethal temperature and humidity combinations, and the risks posed by climate change more generally. RIGHTS AND PERMISSIONS

Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Matthews, T., Ramsay, E.E., Saeed, F. _et al._ Humid heat exceeds human tolerance limits and causes mass mortality. _Nat. Clim.

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