A new modeling study has shown that increasing urban greenery by 30% would have prevented > 12,300 heat-related mortality between 2000 and 2019 globally. Research over the last two decades, from 2000-2019, shows a very significant and illuminating trend. It estimates that if cities around the world had been more verdant, up to 1.16 million lives could have been saved. This research looked at over 11,000 metropolitan areas. It illustrated what an immense difference nature makes for our public health, especially in counteracting the impacts of extreme heat.
These results suggest that over one-third of all heat-related deaths could have been avoided by increasing urban vegetation. This new reality underscores the urgent need for cities to focus on greening initiatives. When they do, they increase equity, improve public health, and make people more resilient to climate impacts.
Study Overview and Methodology
Led by Professor Guo and a team of international researchers, the study used data from 830 sites in 53 nations. In particular, it aimed to directly estimate the potential prevention of heat-related mortality by increasing urban greenness in warm season months. To assess vegetation levels in urban areas, the researchers quantified greenspace and land cover using the Enhanced Vegetation Index (EVI). This metric is based on observations from NASA’s Terra satellite.
The study’s findings demonstrate a profound effect of urban vegetation. Had we raised it by just 30%, we could have avoided an estimated 0.86 million to 1.16 million excess heat-related deaths, representing up to 36.66% of all deaths in the studied period. Here’s hoping that smart and comprehensive assessment, like the one done by Professor Guo, provides the critical insight needed. This highlights that urban greening can be a more effective pathway to reduce heat-related mortality.
Regional Impacts of Increased Urban Vegetation
The study points to stark regional disparities in the potential lives that could be saved by making our cities greener. In Europe alone, we would have saved an estimated 396,955 lives. North America would have experienced a similar 69,306 death prevention. Latin America and the Caribbean could have avoided 123,085 deaths. Simultaneously, Africa would have benefited from a decrease of 35,853 deaths.
Like in the last measure, Asia tops the region’s with the most projected savings—527,989 lives. Even for Oceania and Australia/New Zealand the effects would have been small—maximum reductions of just 2,733 and 2,759 lives. These figures make clear the vulnerability of southern and southwestern regions to increased mortality associated with extreme heat. They urge that greening efforts be targeted towards high-risk areas.
Future Projections and Implications
Moving forward, projections suggest that the number of heat-related deaths could multiply rapidly in the future, particularly under extreme global warming scenarios. Just as importantly, projections seem to understate heat related mortality at around 2.5% in Northern Europe. Southeast Asia can expect rates to reach 16.7% as early as 2090-99. With these scary predictions, the need for greening our cities is greater than ever.
The emerging evidence finds that more vegetation reliably cools cities. Second, it can change heat-related mortality risk through a variety of indirect mechanisms. These include improved mental health, enhanced social engagement, increased physical activity, and better air quality—all factors that contribute to overall well-being.