Identified as recently as 10 years ago, the phylum Thaumarchaeota (Ta) remains poorly known, especially with regard to the very large number of environments where these Archaea can be found and their key role in the nitrogen cycle. The full physiological and genomic diversity of these Ammonia-Oxidizing Archaea (AOA) has not been discovered yet, mainly because of the lack of cultured representatives. Because of their widespread distribution in terrestrial and aquatic environments, Ta represent a major source of archaeal lipids in sediments and soils. In order to regulate the functionality and fluidity of their cell membranes, Ta are able to respond to changing temperatures by altering their membrane lipid composition (i.e. the relative abundance of isoprenoid glycerol dialkyl glycerol tetrathers, socalled iGDGTs). In aquatic environments, the relative abundance of the different iGDGTs produced by Ta was correlated with the water surface temperature, leading to the development of a temperature proxy, the TEX86 (Schouten et al., 2002), largely applied to marine and lacustrine paleorecords (e.g. Castañeda et al., 2010; Berke et al., 2012). In contrast, the relationship between temperature and GDGTs from Ta is not well understood in soils, where the applicability of the TEX86 is questioned. More information on soil Ta, especially their response to temperature changes, is crucially needed.