Tree planting is not as straightforward as it seems! A recent article published in Nature Geoscience points out that in high-latitude regions, tree planting might actually accelerate global warming. The Arctic and its surrounding areas are perpetually covered with ice and snow, and this snow-white land, known as tundra, acts like a mirror, reflecting the sunlight back into the sky and effectively preventing local heat accumulation. If trees are planted in tundra regions, the dark foliage of the trees will cover the bright white land. When the sun shines, the forest will absorb more heat instead. Tree planting in these areas also speeds up the rate of carbon decomposition by soil microorganisms, disrupting the originally established carbon cycle in the region and releasing more carbon. In addition, with the increasing frequency of extreme disasters such as wildfires and droughts in the Arctic and its surroundings, the survival of trees is at risk. When trees die, the carbon they have fixed will be released into the atmosphere, exacerbating global warming. Moreover, not only the geographical location but also the diversity of tree planting matters. Previous researchers have found that the more diverse the planted trees are, the better the carbon sequestration effect. The tropical rainforest is a prime example – different trees have different “preferences” for environmental resources, they each take what they need, which reduces competition while making full use of resources and is more conducive to growth and carbon sequestration.