The world’s populations could face between three and six concurrent climate hazards by 2100 if greenhouse gas emissions are not aggressively reduced, suggests a Review published online this week in Nature Climate Change.
The impacts of climate hazards on humans are multi-faceted, but have been largely studied in isolation. Narrow analyses that focus on single hazards may not reflect the true, simultaneous and integrated effect of climate change on humans.
To better understand the broad threat of climate change to humans, Camilo Mora and colleagues systematically reviewed 3,280 papers, cataloguing 467 interactions between ten climate hazards (such as warming, floods, droughts, heat waves and fires) and six aspects of human systems (such as health, food and water). Although the authors find a few instances of positive or neutral effects, the overwhelming majority of climate impacts are detrimental to human systems.
The authors then mapped the projected changes in global climate hazard exposure under different emissions scenarios, and evaluated the extent to which populations will be confronted with climate hazards by the end of the century. They find that if greenhouse gas emissions are aggressively reduced, the world’s populations could be exposed to at least one hazard at a time. If emissions continue unabated, however, the authors suggest that populations could face at least three climate hazards concurrently - and up to six in some coastal regions.
The authors conclude that the number of climate hazards that could simultaneously impact future societies emphasizes the urgency with which we must reduce greenhouse gas emissions, and that we must develop diverse approaches to adapt.