Northern Forests Face Serious Challenges to Carbon Cycling

A study published in the Swedish journal *Nature* has confirmed, based on nearly 60 years of data, that rising atmospheric CO₂ concentrations are the primary cause of nitrogen deficiency in northern forests. High CO₂ levels accelerate the growth of trees such as pine and spruce, causing them to consume large amounts of soil nitrogen. This leads forests to gradually enter a nitrogen-limited state, which in turn significantly weakens their carbon sink function, having far-reaching implications for the global carbon cycle and climate regulation.