What is fuel consumption of an A330 during climb and descent? I want to know how to calculate or estimate an aircraft's fuel consumption when climbing from sea level to 15,000 ft, followed by a descent to 10,000 ft.

I would like to see an example for an Airbus A330-300 with CF6-80E1A4 engines.
Descent tables

Climb tables

These tables are for the A330-200 and A330-300: in the footer of the page you can see for which engine these are. What you missed to indicate is the thrust setting, atmospheric conditions and weight to be able to give a realistic answer.