You can help minimise the impact of your flying by offsetting your carbon emissions. The total carbon emissions from your itinerary are 1.660 tonnes and the cost of offsetting your emissions is 1458.0 RUB.

Your money will go towards UN certified emission reduction projects.

* Please be aware that once your carbon offset contribution is paid, it cannot be refunded.

* More information on carbon offsetting

The total cost to offset these emissions is

1458.0 RUB *

Вот такая вот информация сообщается мне от British Airways
А внутри картинка, поясняющая, что это значит.