Urban green space is important for alleviating high temperatures, pollution, and flooding in cities. Furthermore, it is becoming increasingly clear that urban green space is important for the mental and physical health of humans residing in cities and that urban green space may harbor unique biodiversity. Understanding the extent and drivers of urban green space is thus important. While urban green space has been mapped and studied at local to national scales, the global patterns and drivers of urban green space remain unknown, potentially hampering effective planning and allocation of resources toward reaching sustainable development goals. Here, we quantified the effect of environmental and socio-economic drivers (temperature, precipitation, human development, and population density) on urban green space globally by focusing on national capital cities. We used satellite imagery to map urban green space using two measures: the Normalized Difference Vegetation Index (NDVI), and the fractional cover of “green” land cover classes. NDVI is useful as it includes all vegetated surfaces, also small ones like gardens. However, land cover classes allow the exclusion of certain classes such as sports fields or cropland. We used boosted regression trees to show that climatic variables accounted for 75 % of the relative influence in urban green space, with a positive effect of precipitation and a negative effect of temperature. Importantly, socioeconomic variables accounted for 25 % of the influence on global urban green space, with a positive effect of human development index (HDI) and a negative effect of population density. HDI in relation to urban green space has not previously been tested globally, and our study shows that significantly affects urban greenspace. The results demonstrate that cities where development status is low and population densities are high, typically in the Global South, have less urban green space than the climate would predict. The results therefore suggest that human wellbeing does not only benefit directly from increasing human development and decreasing population densities in urban areas, but that these effects may be compounded by also improving nature’s contribution to people.

城市绿地对于缓解城市的高温、污染和洪水非常重要。此外，越来越明显的是，城市绿地对居住在城市的人类的身心健康很重要，城市绿地可能蕴藏着独特的生物多样性。因此，了解城市绿地的范围和驱动因素非常重要。虽然城市绿地已经在地方和国家范围内进行了绘制和研究，但城市绿地的全球模式和驱动因素仍然未知，这可能会阻碍有效规划和资源分配以实现可持续发展目标。在这里，我们量化了环境和社会经济驱动因素（温度、降水、人类发展、和人口密度）通过关注国家首都城市对全球城市绿地的影响。我们使用卫星图像绘制城市绿地，使用两种测量方法：归一化差异植被指数 (NDVI) 和“绿色”土地覆盖类别的部分覆盖。NDVI 很有用，因为它包括所有植被表面，也包括花园等小型表面。但是，土地覆盖类别允许排除某些类别，例如运动场或农田。我们使用增强回归树表明，气候变量占城市绿地相对影响的 75%，降水量为正效应，温度为负效应。重要的是，社会经济变量占全球城市绿地影响的 25%，对人类发展指数 (HDI) 有积极影响，对人口密度有消极影响。与城市绿地相关的 HDI 以前没有在全球范围内进行过测试，我们的研究表明这对城市绿地有显着影响。结果表明，发展状况低下且人口密度高的城市（通常位于全球南方）的城市绿地少于气候预测的城市绿地。因此，研究结果表明，人类福祉不仅直接受益于人类发展的增加和城市地区人口密度的降低，而且这些影响还可能因自然对人类贡献的改善而加剧。结果表明，发展状况低下且人口密度高的城市（通常位于全球南方）的城市绿地少于气候预测的城市绿地。因此，研究结果表明，人类福祉不仅直接受益于人类发展的增加和城市地区人口密度的降低，而且这些影响还可能因自然对人类贡献的改善而加剧。结果表明，发展状况低下且人口密度高的城市（通常位于全球南方）的城市绿地少于气候预测的城市绿地。因此，研究结果表明，人类福祉不仅直接受益于人类发展的增加和城市地区人口密度的降低，而且这些影响还可能因自然对人类贡献的改善而加剧。