Elevated ground-level ozone, a result of human activity, is known to reduce plant productivity, but its influence on tropical forests remains unclear. Here we estimate how increased ozone exposure has affected tropical-forest productivity and the global carbon cycle. We experimentally measure the ozone susceptibility of various tropical tree species, and then incorporate these data into a dynamic global vegetation model. We find that current anthropogenic-derived ozone results in a substantial decline in annual net primary productivity (NPP) across all tropical forests, with some areas being particularly impacted. For example, Asia sees losses of 10.9% (7.2–19.7%) NPP. We calculate that this productivity decline has resulted in a cumulative loss in carbon drawdown of 0.29 PgC per year since 2000, equating to ~17% of the tropical contemporary annual land carbon sink in the twenty-first century. We also find that areas of current and future forest restoration are disproportionately affected by elevated ozone. Future socioeconomic pathways that reduce ozone formation in the tropics will incur benefits to the global carbon budget by relieving the current ozone impacts seen across both intact forest and areas of forest restoration, which are critical terrestrial regions for mitigation of rising atmospheric carbon dioxide.

众所周知，人类活动造成的地面臭氧升高会降低植物生产力，但其对热带森林的影响仍不清楚。在这里，我们估计臭氧暴露增加如何影响热带森林生产力和全球碳循环。我们通过实验测量各种热带树种的臭氧敏感性，然后将这些数据纳入动态的全球植被模型中。我们发现，目前人为产生的臭氧导致所有热带森林的年净初级生产力（NPP）大幅下降，其中一些地区受到的影响尤其严重。例如，亚洲的 NPP 损失为 10.9% (7.2–19.7%)。我们计算出，自 2000 年以来，生产力下降导致每年碳减少累计损失 0.29 PgC，相当于 21 世纪热带当代年度陆地碳汇的 17% 左右。我们还发现，当前和未来的森林恢复地区受到臭氧浓度升高的影响尤为严重。未来减少热带地区臭氧形成的社会经济途径将通过减轻目前对完整森林和森林恢复地区的臭氧影响而为全球碳预算带来好处，这些地区是缓解大气二氧化碳上升的关键陆地区域。