The emergence of heat and humidity too severe for human tolerance View ORCID ProfileColin Raymond1,2,*, Tom Matthews3 and Radley M. Horton2,41Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, USA.2Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA.3Department of Geography and Environment, Loughborough University, Loughborough, UK.4Lamon