The invention relates to a method for extracting carbon dioxide from the atmosphere, said method comprising the thermochemical conversion of biomasses as a natural intermediate vector for storing carbon dioxide, the carbon dioxide being trapped by a thermochemical cycle (3) that comprises a combustion reactor (8) and an oxidation chamber (9) connected together, and in which flow metal oxides which are alternately oxidised and reduced and which ensure the oxygen supply for the combustion, wherein said thermochemical conversion is achieved using a pyrolysis reactor (2) and said thermochemical cycle (3). According to the invention, the biomasses are dried (1) by air-lean fumes (13) exiting from the oxidation chamber (9) of said thermochemical cycle before said pyrolysis.