A significant portion of the global population could face life-threatening extreme heat and humidity due to climate change. Low and middle-income countries in the tropics, who contribute the least to the crisis, will suffer the most. In 1992, countries agreed on the UNFCCC to stabilize greenhouse gas concentrations and limit global temperature increase to below 2 degrees Celsius. Many countries use 1990 as a reference year to develop plans for achieving these goals, including the UK.