study.
一项新研究警告说，相比乡间树林里的树，城里的树“长得快但死得早”。
Researchers found that trees in urban areas die faster than ones in the countryside as higher levels of carbon dioxide make it harder for the plant to survive.
研究人员发现，城区树木的寿命比乡间树木短，因为城市二氧化碳浓度更高，让树更难存活。
City-dwelling trees suffer a net loss of carbon storage which means trees produce less energy from the air.
生长在城里的树碳储量是净亏损的，这意味着树用空气转化成的能量更低。
Now researchers say more must be done to tackle the environmental impacts of urbanisation.
研究人员表示，必须做更多工作来应对城市化对环境的影响。
Ian Smith, a PhD student of Boston University in the United States, said: 'Cities are at the forefront of implementing climate mitigation policies including urban greening, to combat rising temperatures and atmospheric CO2 concentrations.
美国波士顿大学的博士生伊恩·史密斯说：“为了对抗气温升高和大气中二氧化碳浓度变高，在推行城市绿化等减缓气候变化的政策时，城市是处于最前线的。”
'We find that tree planting initiatives alone may not be sufficient to maintain urban canopies
