futureforests and treesforlondon

My flight to Sydney and back via Kuala Lumpur was an estimated 34368 Km and produced 3.78 tonnes of CO2. According to futureforests.com I need to plant 5 trees to make my flight CarbonNeutral or supply 5 energy saving lightbulbs to a small community in the developing world. So that’s an additional ?42.50 to think about before I buy my next trip over. I think to be fair they should just add another tax.
I’ve gone for the trees option as I’ve already been sponsoring trees with treesforlondon.co.uk