put
https://api.climateclick.com/flights/co2emissiefactoren/order
If a flight has a connection, each individual flight must be specified in a single API call (e.g. for a trip between Amsterdam(AMS) and Chicago(ORD) with a stop in New York(JFK), there will be 1 API call containing flights AMS-JFK and JFK-ORD)
If a flight is a return flight, 2 API calls must be made, one for each direction. Using the example above, there will be 1 API request containing AMS-JFK, JFK-ORD and 1 API request containing ORD-JFK, JFK-AMS.