来源：《新科学家》
原文刊登日期：2023年1月31日
Doubling tree cover in European cities could cut the number of heat-related deaths during summer months by nearly 40 per cent, according to a modelling study.
根据一项模拟研究，欧洲城市的树木覆盖率增加一倍，可以使夏季与高温有关的死亡人数减少近40%。
The average canopy tree coverage in European cities is just under 15 per cent. This is defined as the area covered when viewed from above. Cities such as London and Barcelona are aiming to double this coverage to 30 per cent by 2030 and 2037, respectively.
欧洲城市的平均树冠覆盖率略低于15%。这是指从高处俯瞰时所覆盖的面积。伦敦和巴塞罗那等城市计划分别在2030年和2037年将这一覆盖率提高一倍，达到30%。
To investigate the effect of achieving this, Tamara Iungman and her colleagues at the Barcelona Institute for Global Health, Spain, combined mortality data from 93 cities between June and August 2015 with daily temperature statistics to estimate the number of heat-related deaths over this three-month period.
为了调查实现这一目标的效果，西班牙巴塞罗那全球健康研究所的塔玛拉·伦格曼和她的同事将2015年6月至8月期间93个城市的死亡数据与每日气温统计数据相结合，以估计这三个月期间与高温相关的死亡人数。
The researchers have said they chose to study 2015 data because that is the most recent year for which European-wide statistics are available and its temperatures were typical of the current European climate.
研究人员表示，他们之所以选择研究2015年的数据，是因为这是最近一年欧洲范围内可用的统计数据，而且这一年的气温是当前欧洲气候的典型。
They then modelled the impact on temperatures and mortality if tree cover in the cities increased. “We already know that trees provide cooling,” says Mark Nieuwenhuijsen, a co-author of the study. The team set out to discover how much cooling trees provide and how many deaths they can prevent, he says.
然后，他们模拟了城市树木覆盖率增加对温度和死亡率的影响。“我们已经知道树木可以降温，”该研究的合著者马克·纽文慧森说。他说，研究小组着手研究树木能提供多少降温，以及它们能防止多少死亡。
Between June and August 2015, 6700 premature deaths occurred across the 93 cities due to extreme heat. Yet 2644 of these – nearly 40 per cent – could have been prevented by increasing tree cover to 30 per cent, the results suggest.
2015年6月至8月期间，由于极端高温，93个城市中有6700人过早死亡。然而，研究结果表明，如果将树木覆盖率提高到30%，其中2644起(近40%)是可以避免的。
Trees help tackle a phenomenon known as the “urban heat island effect”, which sees temperatures in cities climb higher than in nearby rural areas. This is because urban surfaces, such as asphalt and concrete, absorb and retain heat. In some areas, the temperature difference between cities and nearby rural areas can be more than 4°C.
树木有助于解决一种被称为“城市热岛效应”的现象，即城市的气温高于附近的农村地区。这是因为城市表面，如沥青和混凝土，吸收和保留热量。在一些地区，城市和附近农村地区的温差可能超过4°C。
As climate change accelerates, cities must brace for increasingly extreme heatwaves, says Nieuwenhuijsen. In 2022, parts of the UK hit 40°C for the first time.
纽文慧森说，随着气候变化的加速，城市必须准备好应对日益严重的极端热浪。2022年，英国部分地区气温首次达到40°C。
“Our city centres are too hot,” says Nieuwenhuijsen. “We can use nature-based solutions like tree planting to reduce the effect of the heat island and related mortality.”
“我们的城市中心太热了，”纽文慧森说。“我们可以使用基于自然的解决方案，如植树，以减少热岛效应和相关的死亡率。”