Zhao Gang, Merder Julian, Ballard Tristan C, Michalak Anna M
Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305.
Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Proc Natl Acad Sci U S A. 2023 Aug 15;120(33):e2220616120. doi: 10.1073/pnas.2220616120. Epub 2023 Aug 7.
Climate change, especially in the form of precipitation and temperature changes, can alter the transformation and delivery of nitrogen on the land surface and to aquatic systems, impacting the trophic states of downstream water bodies. While the expected impacts of changes in precipitation have been explored, a quantitative understanding of the impact of temperature on nitrogen loading is lacking at landscape scales. Here, using several decades of nitrogen loading observations, we quantify how individual and combined future changes in precipitation and temperature will affect riverine nitrogen loading. We find that, contrary to recent decades, rising temperatures are likely to offset or even reverse previously reported impacts of future increases in total and extreme precipitation on nitrogen runoff across the majority of the contiguous United States. These findings highlight the multifaceted impacts of climate change on the global nitrogen cycle.
气候变化，尤其是降水和温度变化的形式，会改变陆地表面和水生系统中氮的转化与输送，影响下游水体的营养状态。虽然已经探讨了降水变化的预期影响，但在景观尺度上，对温度对氮负荷影响的定量理解仍然缺乏。在此，我们利用几十年的氮负荷观测数据，量化未来降水和温度的单独及综合变化将如何影响河流氮负荷。我们发现，与近几十年相反，气温上升可能会抵消甚至逆转之前报道的未来总降水量和极端降水量增加对美国大部分毗连地区氮径流的影响。这些发现凸显了气候变化对全球氮循环的多方面影响。
