How much carbon to get to Christchurch?

I need to get down to Christchurch to visit some friends.  It has simply been too long and they are going to forget I exist.  I was already to hop into my trusty rusty old Subaru when Marg caught me up.  “What about your emissions?  How much greenhouse gas are you going to produce?  You know, we all need to do our bit.”

Crikey!  I hadn’t thought about that!  It was time to put pencil to paper and resurrect the maths I learned back in the Pleistocene (i.e., how many woolly mammoths does it take to…).  Let’s see…

The Subaru uses 10 litres petrol per 100 km and a litre of petrol produces 2.4 kg of CO2.  Google Maps tells me that the round trip from Blenheim along Hwy 1 is 614 km.  So, if I drive, I’ll produce 147 kg of CO2.  That is close to twice my weight in greenhouse gas!  Is there a better option?

Air New Zealand calculates your emissions when you book flights, so a quick play on the internet finds that I’ll produce 69 kg CO2 for the 490 km round trip.  That’s better, and the flight is a bit of fun if the weather is clear (and a bit of terror if it is not).  Now it is down to under my weight in CO2, at least. 

But I haven’t taken the train since the tracks were reopened after the earthquake.  How about that?  Kiwirail is a bit cagey about their emissions per passenger-kilometre, so I turn to the trusty Department of Environment, Food and Rural Affairs (DRFRA) tables from the UK.  These are tables that businesses use to calculate their emissions, as required by law in the UK.  Here I find that the round trip would produce about 27 kg CO2.  Better still! About a third my weight in CO2.  And I get to brag about how beautiful the Coastal Pacific trip is to my mates who haven’t ridden it yet. 

I’m all ready to book the ticket when Marg appears again, like the little voice in my conscience, whispering into my ear.  “What about the bus?”   Nuts.  Do I really want to take the bus?  Granted, it would be the cheapest option.  “OK, I’ll check”, I growl.  Out come the DRFRA tables again and it’s only 17 kg CO2 for the round trip! That’s about one-eighth of what it would be if I took the Subaru! 
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Marg smiles.  “So, you’ll be taking the bus, right?  And you can ride your bicycle to the bus station with your backpack!  My handsome eco-warrior.” She has me.  Looks like I’ll be taking the bus.