One billion people across all regions will be at risk of extreme heat stress once the world’s temperature reaches 2°C, according to new figures and a map from the UK’s National meteorological service.
The UK MET office warned that the number of people affected by extreme heat stress could increase nearly 15 fold if the world’s temperature reaches 2°C. It also cautioned that a 4.0°C rise of temperature could see nearly half of the global population potentially affected.
WET BULB GLOBE
The indicator used for this assessment of a wet-bulb globe temperature above 32.0°C is part of the international standard for measuring heat stress in working environments. Climate Impacts Lead at the Met Office Andy Hartley said that people are defined as being at extreme risk above this level. He pointed out that vulnerable population and those with physical outdoor jobs are at greater risk of adverse health effects. “Currently, the metric is met in several locations, such as parts of India, but our analysis shows that with a rise of 4.0°C, extreme heat risk could affect people in large swathes of most of the world’s continents,” he said.
The maps of drought, flood and heat-stress risks are from research by a large international team in the EU-funded project HELIX (High End Climate Impacts and eXtremes) https://helixclimate.eu/ led by the University of Exeter. The Met Office team did further analysis to assess where the most severe projected impacts overlap with each other and with the regions currently most vulnerable to food insecurity.
URGENCY TO LIMIT TEMPERATURE
Prof Richard Betts MBE of the University of Exeter, who led the HELIX project, stated that the new analysis showed the urgency of limiting global warming well below 2.0 °C. “The higher the level of warming, the more severe and widespread the risks to people’s lives, but it is still possible to avoid these higher risks if we act now,” the professor said. Earth System and Mitigation Science head Dr Andy Wiltshire noted that any one of the climate impacts presented a scary vision of the future. Severe climate change will drive many impacts, and our maps show that some regions will be affected by multiple factors, Witshire added.
The researcher said that parts of the tropics are most affected with countries like Brazil and Ethiopia potentially facing impacts from four of the hazards. Human heat stress risk depends on both temperature and humidity and is indicated using wet bulb globe temperature (WBGT). WBGT above 32.0°C is defined as “extreme risk”. At this level, vulnerable members of the population, and those with physical outdoor jobs are at greater risk of adverse health effects.