Transport and climate change

You will remember the news headlines from October 2018: “12 years to limit climate change catastrophe.” This was the media’s interpretation of the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). So what was this all about?

The IPCC produced a report on the impacts of global warming of 1.5°C above pre-industrial levels and how we have to reduce global greenhouse gas (GHG) emissions to stay within this level. Global warming is at 1.0°C above pre-industrial levels. They gave us ways to limit the increase, and to have a 50% chance of staying within 1.5°C above pre-industrial levels, we need to reduce our 2010 emission levels by about 45% by 2030. That was in 12 years’ time hence the headline.

Let us assume that we all pull our weight and each geographic area gets on with this. Let us further assume that each emission sector does meets this reduction target. So where do GHG emissions come from locally? Christchurch City Council has done some work on this and they found that in the city, a whopping 53% come from transport. Wow, that’s a huge contribution. So what do we do about that?

Christchurch greenhouse gas emission sources

Let’s do an analysis based on household travel survey data that the Ministry of Transport collects. Let’s keep this simple and not worry about flying (which make up about 3% of GHG emissions) or goods transport. What we know is that in the Christchurch metro area, we collectively drove 3.35 billion kilometres in our city during 2010. That’s the equivalent to 4357 return trips to the moon. Or 11 times to the sun and back. In just one year.

In 2010, Christchurch drivers made the equivalent to 4357 return trips to the moon

If we want to reduce that by 45% by 2030, we will then be driving 1.85 billion kilometres. That requires a massive change in behaviour; a reduction of 2.25% per year as per the following figure. That’s a big change but seems like something that is manageable.

IPCC target of 45% emission reduction by 2030 (2010 base)

The bad news is that we didn’t start reducing our GHG emissions in 2010, but they have since increased the distance driven in the Christchurch metro area by another 15%. If we still want to achieve our target, we need from now on reduce our distance driven by 4.7% each year. That feels like a lot!

IPCC target of 45% emission reduction by 2030 (2019 base)

The even worse news is that we haven’t even started the discussion whether we want to meet the IPCC targets. Yes, both the city and regional councils have declared climate emergencies, but no corrective actions have been agreed on yet. If we assume that we carry on with business as usual for the next three years and then, in 2022, come to the conclusion that the IPCC 2030 target should be met, what would things look like at that point?

IPCC target of 45% emission reduction by 2030 (2022 base)

As can be seen, even waiting for a relatively short period makes the task of achieving the IPCC target so much harder, with a 6.7% annual reduction in driving necessary from 2022. 

What I take from this is that we need to make it our priority to have this discussion. Should we, in the Christchurch metro area, strive to do our share to meet the IPCC target that gives us a chance to stay within 1.5°C above pre-industrial levels? If so, should each emission source reduce its own part? If so, how do we achieve such massive shift in travel behaviour? Or should we leave this to our children and grandchildren to sort out, while we carry on with business as usual?

If we want to get on top of this then one thing is for certain: people will have to travel and for there to be sustainable options, our public transport services will have to become significantly better (and our policies contain the ideas how to achieve that). Or else people won’t have the chance to change their current behaviour and play their part in creating a stable climate for the future.