Abstract: A system and method may determine or display the carbon emissions impact for transactions, by for example receiving from transaction data sources data items describing transactions, each transaction associated with a user, a merchant, and an amount; for each transaction receiving or creating carbon emissions impact data for the merchant associated with the transaction; and deriving from the amount associated with the transaction and the carbon emissions impact data for the merchant associated with the transaction a carbon emission value associated with the transaction. Each data item may include a transaction amount and a merchant identifier, and/or other information. Calculating carbon emissions for the transaction may include multiplying the currency amount associated with the transaction and the carbon emissions impact data for the merchant associated with the transaction and dividing the result by the annual revenue for the merchant. The carbon emissions value may be displayed to a user.