Warming-Induced\nVegetation Greening May Aggravate\nSoil Mercury Levels Worldwide

Mercury,\na neurotoxic substance, circulates globally,\nsignificantly\nstored in soils through atmospheric deposition and plant decay. Despite\nbeing deposited, mercury can be remobilized and released into the\natmosphere and water, enhancing its global cycle. Recent research\nsuggests that climate warming may amplify the remobilization of soil\nmercury, facilitating its incorporation into food webs that humans\nexploit. However, the potential geospatial feedback of soil mercury\nlevels in response to warming remains unclear. By leveraging up-to-date\nsoil measurements and observation-driven models, we determined the\namount of mercury stored in global 0–100 cm soils to be 4.3\nTg (interquartile range: 2.5–6.3 Tg). Furthermore, our analysis\nindicates that warming likely aggravates global soil mercury levels,\nparticularly in many temperate areas in East Asia, North Europe, and\nNorth America (>20 ng g<sup>–1</sup> increase by 2100) due\nto warming-induced vegetation greening. Critically, observation-driven\nmodels raise the possibility that implementing ambitious mercury-emission-control\nschemes alone may be insufficient to counterbalance the positive feedback\nof soil mercury concentration, while process-based biogeochemical\nmodeling demonstrates consistent patterns that reinforce this concern.\nThese findings hold broad implications; for example, such feedback\nmay catalyze mercury remobilization in land-ocean continuums and exacerbate\nhuman risks, stressing the necessity for continued reductions in greenhouse\ngas and mercury emissions.