English: Peatlands are a type of wetlands among the most valuable ecosystems on Earth: they are critical for preserving global biodiversity, providing safe drinking water, minimising flood risk and helping address climate change because they sequester 0.37 gigatonnes of carbon dioxide (CO2) a year – storing more carbon than all other vegetation types in the world combined. A particular type of peatlands can be found in the Arctic tundra, “frozen” mires in which large quantities of organic deposits remain frozen throughout the years. Their hydrological regime and other characteristics are strongly dependent on the status and health of the permafrost. A recent study of the University of Stockholm found that, if the global warming scenarios are proven right, arctic peatlands will emit more carbon than they can store, because of the thawing of the permafrost, resulting in severe repercussions on the global climate. This image acquired on 31 July by one of the Copernicus Sentinel-2 satellites shows a detail of the Lena Delta, in Siberia, whose landscape is characteristic of Arctic tundra. Copernicus Sentinel-2, with a maximum revisit time of five days, is very useful for monitoring the impact of climate change in such an important and delicate environment as the Arctic Circle.