Planes, Trains And Automobiles

I have a few long-ish distance work related trips coming up around Christmas and in the New Year and the question is should i be flying, driving or taking the train?
Unfortunately i am unable to copy 16 year old Greta Thunberg who chose who sailed to a UN climate conference in New York in a zero-emissions yacht so it's planes, trains and automobiles but which?
The BEIS/Defra Greenhouse Gas Conversion Factors has a guide to CO2 emissions from different modes of transport for each kilometre travelled and my three round trips to Wales, Ireland and Birmingham rack up to approximately 2415 km which if i fly is a whopping 321,195 grammes (0.32 tons) of CO2 emissions.
Driving is even worse with a massive 412,965 grammes (0.41 tons) of emissions but a train for all three trips is 99,015 grammes (0.09 tons) so it seems a no brainer to let the train take the strain to Wales and Birmingham and fly to Ireland, a total of 189,180 grammes (0.18 tons) for the trips.
The average annual carbon dioxide emissions per head for Europe is about 10 tons so i still have 9.82 tonnes of CO2 to play with although a tree can absorb 21,772 grammes of carbon dioxide per year so to cancel out my 189,180 grammes i would need to plant 8.6 trees which the local park warden may not be happy about but unless i can borrow a zero emissions yacht i may be hopping over the park fence in the dead of night in the new year.