As climate change accelerates, positive feedback loops could establish between atmospheric warming and increasing greenhouse gas (GHG) emissions from natural ecosystems. Of particular interest are high‐latitude environments, many of which contain large stores of organic carbon and have experienced decades of accelerated warming. Freshwater ecosystems situated in carbon‐rich Arctic landscapes are predicted to respond to warming with higher respiration rates relative to primary production rates, increasing their carbon dioxide partial pressure (pCO₂) and thus CO₂ emissions to the atmosphere. However, large areas of shallow soil/bedrock occur in Arctic and sub‐Arctic regions and could respond differently due to the lower availability of stored carbon. Here, we used pH and alkalinity to calculate 23 years (1994–2017) of summertime (July and August) pCO₂ and CO₂ fluxes for 19 sub‐Arctic tundra lakes located on the shallow‐bedrock granitic Canadian Shield in Nunavut, Canada, and found a significant decline in CO₂ emissions. Regional precipitation did not change over this period, yet dramatic increases in pH, conductivity, and total alkalinity indicated that longer ice‐free periods and changes in primary production, both functions of accelerated climate warming at higher latitudes, may be suppressing lacustrine CO₂ emissions. Northern lakes overlying differing geological landscapes may thus be responding in contrasting ways in terms of pCO₂ and CO₂ fluxes, with potential major implications for regional carbon budgets and predicted climate change feedbacks.

中文翻译：

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花岗岩景观中苔原湖夏季pCO2含量下降

随着气候变化的加速，可以在大气变暖与自然生态系统温室气体排放量之间建立正反馈回路。特别令人感兴趣的是高纬度环境，其中许多环境包含大量有机碳，并且经历了数十年的加速变暖。相对于初级生产力，位于富碳北极景观中的淡水生态系统预计将以更高的呼吸速率响应变暖，从而增加其二氧化碳分压（p CO ₂），从而增加CO _2。排放到大气中。然而，在北极和亚北极地区，大面积的浅层土壤/基岩发生，并且由于储存的碳的可利用性较低，因此可能会有不同的反应。在这里，我们使用pH和碱度来计算位于加拿大努纳武特的浅基岩花岗岩加拿大盾构中19个亚北极苔原湖的23年（1994-2017）夏季（7月和8月）的p CO ₂和CO ₂通量。 ，并发现CO ₂显着下降排放。在此期间，区域降水量没有变化，但是pH，电导率和总碱度的急剧增加表明更长的无冰期和初级生产的变化，这两者都是高纬度地区气候变暖的加速作用，可能会抑制湖泊中的CO ₂排放。 。因此，覆盖不同地质景观的北部湖泊可能在p CO ₂和CO ₂通量方面以相反的方式做出反应，这可能会对区域碳预算和预测的气候变化反馈产生重大影响。