 It is generally assumed that humans will be able to adapt to global climate change. But just as there are environmental thresholds beyond which ice sheets will melt and rainforests will collapse, there is a temperature threshold beyond which the human body will overheat and shut down. In other words, there is a limit on human adaptation to climate change, a limit that could be reached by the end of this century. In this study, researchers projected different climate scenarios in and around the Persian or Arabian Gulf using a high-resolution regional climate model, demonstrating that the current pace of greenhouse gas emission is likely to produce temperatures that will severely affect human habitability. The upper temperature limit of the human body is expressed in terms of something called the wet bulb temperature. The wet bulb temperature is the lowest temperature air can be cooled to by evaporating water into it until it can't hold any more water vapor. The wet bulb temperature therefore provides a measure of how well the body can cool itself by sweating. Sweating helps us maintain a skin temperature equal to the wet bulb temperature, ideally below our core body temperature of about 37 degrees Celsius. Exposure to wet bulb temperatures above 35 degrees Celsius for more than 6 hours is therefore enough to cause even the fittest human body to overheat and begin to fail. Around the globe, wet bulb temperatures rarely exceed 31 degrees Celsius. But over the Persian Gulf and Red Sea, persistently clear skies, strong absorption of sunlight, and high evaporation rates combine to maximize the flow of heat over these regions, producing wet bulb temperatures that have historically exceeded 31 degrees Celsius. To predict how future climate change would affect wet bulb temperatures in this area, and thus the ability of residents to adapt, a regional climate model was run under two different scenarios, one in which the emission of greenhouse gases is mitigated in the near future, and one in which the current pace of emission is maintained. In the second scenario, the area characterized by maximum wet bulb temperatures exceeding 31 degrees Celsius grows to include most of the southwest Asian regions next to the Persian Gulf, Red Sea, and Arabian Sea. By the end of the century, the annual maximum wet bulb temperature would exceed the 35 degrees Celsius threshold several times over 30 years in cities such as Abu Dhabi, Dubai, Doha, Dharan, and Bandar Abbas. And days currently among the hottest 5% of summer days would become roughly normal summer days. With a rapidly increasing population in southwest Asia, the scientists highlight the benefits that global mitigation efforts could provide in fostering a habitable environment for the future, the most important being that the maximum wet bulb temperature would not exceed the 35 degrees Celsius threshold in any location examined in their study. The scientists stress that even under the business as usual emissions scenario, wet bulb temperatures are not projected to top 35 degrees Celsius more than once every decade or every few decades by the end of the century. But under this scenario, the uncommonly high wet bulb temperatures that today occur in the Gulf about once every 20 days will characterize the normal summer day of tomorrow.