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This summer, the world is experiencing record hot temperatures: June continued a 2020 streak, ranking among the warmest months in history. A weather station in Death Valley, California, clocked a scorching 53.3°C /128°F in July, one of the hottest temperatures ever observed on Earth. Officials from Dehli to Tokyo to Lagos, cities where past heat waves have claimed hundreds of lives, are bracing for dangerously hot periods. Simultaneously, the coronavirus pandemic’s devastating mortality impact and economic fallout are demanding society prioritize public health like never before.
How much is temperature to blame when hospital visits surge during heat waves and cold spells? What role might adaptations like indoor heating and cooling systems play in blunting those effects? And, at what cost? A new study from the Climate Impact Lab, published today by the National Bureau of Economic Research, takes on these questions and finds that in a world with continued high fossil-fuel emissions, warmer temperatures will rank among the world’s most significant public health threats by the end of the century.
Specifically, the study projects that climate change’s effect on temperatures could raise global mortality rates by 73 deaths per 100,000 people in 2100 under a continued high emissions scenario, compared to a world with no warming. That level is roughly equal to the current death rate for all infectious diseases—including tuberculosis, HIV/AIDS, malaria, dengue, yellow fever, and diseases transmitted by ticks, mosquitos, and parasites—combined (approximately 74 deaths per 100,000 globally).
In the worst-hit countries, including Ghana, Bangladesh, Pakistan and Sudan, climate change could be responsible for an additional 200 or more deaths per 100,000 by the end of the century. Lab researchers reveal the role of higher incomes in reducing heat’s health threat and the significant costs of adapting to rising temperatures, clearing a major hurdle that to-date has stymied researchers in this field. Under a scenario of continued high emissions, the researchers estimate that climate change’s impact on mortality will cost the world roughly 3.2% of global economic output in 2100.
The results, which quantify mortality risk, provide a partial Social Cost of Carbon. This tool can be used by decision-makers to weigh the benefits of reducing emissions: emitting one additional ton of CO2 today costs ourselves and future generations a total of $36.6 under a continued high emissions scenario and $17.1 under a moderate emissions scenario.
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