How planting more trees in towns, cities could slash heat-related deaths

By Mark Waghorn via SWNS

Planting more trees in towns and cities will slash heat-related deaths by a third, according to new research.

Life-threatening highs - like Britain's record 40.3°C (104°F) last summer - are set to become the norm over the coming decades.

Trees provide shade - combating the "urban heat island" effect. Pavements absorb the sun's energy when they are left exposed.

A study of 93 European cities found increasing cover by up to 30 percent would lower temperatures by an average of 0.4 degrees and prevent heat-related deaths.

Of 6,700 premature annual deaths attributed to warm weather, one in three (2,644) would have been prevented. Average city tree coverage in Europe currently stands at 14.9 percent.

Lead author Dr. Tamara Iungman, of the Barcelona Institute for Global Health, said: "We already know high temperatures in urban environments are associated with negative health outcomes, such as cardiorespiratory failure, hospital admission, and premature death.

"This study is the largest of its kind, and the first to specifically look at premature mortality caused by higher temperatures in cities and the number of deaths that could be prevented by increasing tree cover."

She added: "Predictions based on current emissions reveal that heat-related illness and death will become a bigger burden to our health services over the next decades."

Towns and cities record higher temperatures than the surrounding countryside.

Human modification of landscapes by replacing vegetation with asphalt and buildings traps more heat.

With CO2 emissions continuing to exacerbate global warming, there is an urgent need for adaptations that protect public health.

Iungman said: "Our ultimate goal is to inform local policy and decision makers about the benefits of strategically integrating green infrastructure into urban planning in order to promote more sustainable, resilient and healthy urban environments and contribute to climate change adaptation and mitigation.

"This is becoming increasingly urgent as Europe experiences more extreme temperature fluctuations caused by climate change.

"Despite cold conditions currently causing more deaths in Europe, predictions based on current emissions reveal that heat-related illness and death will present a bigger burden to our health services over the next decade."

The international team estimated mortality rates of residents aged over 20 between June and August 2015 - accounting for 57 million inhabitants.

Data was compared with daily average city temperatures with and without urban heat islands. A second model simulated temperature reduction as a consequence of increasing tree cover.

At the time cities were an average 1.5°C warmer than the surrounding countryside - rising to 4.1°C in Cluj-Napoca, Romania.

Across all cities, three quarters of the total population lived in areas with an average summer city temperature difference greater than one degree, and a fifth more than two than two.

Heat related deaths accounted for 4.3 and 1.8 percent of summer and year round mortality - and 1.8 percent of year-round mortality.

Worst hit cities were in Southern and Eastern Europe.

The findings published in The Lancet support the idea planting trees in urban areas provides substantial public health and environmental benefits.

It should be combined with other interventions such as replacing asphalt with other materials.

Meeting the target of 30% tree coverage can be very challenging for some cities due to urban design, with city average tree cover in Europe currently at 14.9%.

Co-author Professor Mark Nieuwenhuijsen, director of Urban Planning, Environment and Health at the Barcelona Institute for Global Health, said: "Our results suggest large impacts on mortality due to hotter temperatures in cities, and that these impacts could be partially reduced by increasing the tree coverage to help cool urban environments.

"We encourage city planners and decision-makers to incorporate the urban green infrastructure adapted to each local setting whilst combining with other interventions to maximize the health benefits while promoting more sustainable and resilient cities, especially as we already know that green spaces can have additional health benefits such as reducing cardiovascular disease, dementia and poor mental health, improving cognitive functioning of children and the elderly, and improving the health of babies."

More than 2,800 more people aged 65 and over died in England during last summer's heatwaves than would have otherwise, government figures have shown.

It marked the highest excess death toll caused by heat in at least two decades.

Epidemiologist Professor Kristie Ebi, of the University of Washington, Seattle, who was not involved in the study, said: "Essentially all heatwave-related deaths are preventable; no one needs to die from the heat.

"With climate change projected to increase the frequency, intensity, and duration of extreme heat events, communities need to understand the most effective interventions, particularly developing and deploying heatwave early warning and response systems.

"Equally important are Heat Action Plans that explicitly incorporate the consequences of a changing climate into longer-term urban planning.

"Heat Action Plans detail how to modify urban form and infrastructure to increase the resilience and sustainability of our communities as we face an even warmer future.

"Encouraging and enabling decision-makers and local communities to develop and implement Heat Action Plan is an effective way to promote climate resilience as soaring temperatures continue to be felt globally.

"The tools and guidelines are available; the gaps are in human and financial resources for implementation. The time to start is now."