Both English "are" and Danish "er" come from Old Norse "eru."
Source: tatoeba (12147448)
Eru
Synonyms for "eru"
Ranked by relevance and common usage.
Sample sentences
2 total sentences available.
Three principal types of emission credits may also be traded under this regime: (a) the “emission reduction unit” (ERU); (b) the “certified emission reduction” (CER); and (c) the “removal unit” (RMU). Each ERU, CER, and RMU is an entitlement to emit the equivalent of one metric ton of carbon dioxide into the atmosphere. […] ERUs stem from “joint implementation” measures undertaken pursuant to Article 6 of the Kyoto Protocol.¹²
Source: wiktionary