So now we have a climate emergency. Are we really going to do this thing? If we are, a lot of the changes have to be about cars. Transport accounts for 20 per cent of New Zealand's greenhouse gas emissions. In Auckland it's 40 per cent.
Our Paris commitments require that we halve emissions by 2030. But it won't happen evenly. Agriculture is required to make only a 10 per cent cut, so other sectors will have to do more.
Surprisingly, transport can do that. And it won't be nearly as painful as you might expect.
Analyst Paul Winton, a financial consultant who has applied his formidable number-crunching skills to transport, says this sector is the low-hanging fruit.
Mind you, he adds, "It's still giraffe height".
Winton started with the goal of a 70 per cent cut in emissions and asked, "What would that look like?" The answers were unexpected.
Some of the most expensive projects in the transport plan will not affect emissions much at all. Some very cheap options could be enormously effective.
Winton set up the 1point5 Project (the level of global warming we need to stay under) and took himself to the leading transport consultancy MRCagney, to show them his PowerPoint.
"To be honest," the company's general manager Jenson Varghese told me later, "we didn't believe him. So we recreated his work ourselves, with a slightly different approach. We realised he was right."
MRCagney then developed an interactive dashboard for the data, showing the impact of each option for reducing emissions. It's publicly available and our graph is based on a part of it.
In 2018, Auckland's transport operations produced 2813 kt CO2-e. That's kilotonnes of carbon dioxide equivalent: mostly it's carbon but there are some other greenhouse gas emissions too. Nearly all of it came from private petrol and diesel vehicles. (See the black bar on the graph.)
By 2030, assuming population growth and no change to current transport behaviour, emissions will rise to 3580 kt CO2-e (the red bar).
It's 28 per cent growth in just 12 years? Why so big? More cars. There were 1.26 million of them on the road in 2018; by 2030, unless something changes, there will be 1.6 million.
So, can we reduce Auckland's transport emissions by 50 per cent by 2030 (the black line)? What about 70 per cent (the green line)? Could we do even more? The answers are yes, yes and yes. Here's how the options stack up.
• Major new public transport projects
Projects that should be completed by 2030 include the City Rail Link, rapid busways from Panmure to Botany and Botany to the airport, and light rail lines from downtown to Mangere and the northwest.
We already know this will cost at least $20 billion; quite probably more.
With the bus fleet converting to electric and public transport becoming twice as popular (a big ask), emissions would reduce by about 300 kt CO2-e.
That's the first surprise. In the scale of things, this is not a big number.
Public transport remains an important part of the package, but it will not solve our emissions problem, or congestion.
Mayor Phil Goff has proposed that all new buses be electric from 2022. But the biggest public transport gains would come from the two light rail projects.
• Copenhagen-level cycling
Cycling costs almost nothing compared to trains and buses, despite the occasional complainant thinking otherwise, but Auckland still doesn't have much cycling infrastructure and progress is painfully slow.
Could cycling become as popular here as it is in Copenhagen? They have 1.3 million people and a third of trips in the city area on a bike. Being like the Danish capital would save 375 kt CO2-e of emissions.
This is the second surprise: cycling could have a bigger impact on emissions than public transport.
To achieve it would require enormous new commitments from politicians and transport officials: much bigger cycling networks, more arterial routes, more dedicated lanes in and around town centres and schools and substantial subsidies for e-bikes.
But Auckland Transport isn't interested. It's spending only $600 million on cycling over 10 years and there's almost no sign of any official enthusiasm anywhere to step that up.
• Higher vehicle occupancy
The New Zealand average is 1.58 people per car. Raising that to two would save close to 750 kt CO2-e.
It would require ride-sharing to be normalised, which we now know can be enabled by smartphone apps. Also, lots more T2 and T3 lanes: repurposing the roadways to prioritise cars with passengers. It wouldn't cost much.
• Less travel by car
Now we're talking. What if there were fewer cars on the road at any one time, because people just didn't travel so much? Work a day a week at home. Share a supermarket visit with your neighbour. Car pool to the kids' sport. Let them walk or ride a bike to school.
In the school holidays, traffic lightens by 6-10 per cent. Could we build on that? A 30 per cent reduction would save 1052 kt CO2-e.
Congestion charges and more difficult and expensive car parking would help, to disincentivise all those trips you don't really need to make. But is raising the cost of driving the best way to build public support? We need to have that debate.
We would also need very good alternatives to driving: this option makes better public transport and cycling support essential.
• Convert to EVs
If half the country's vehicle fleet was electric by 2030, we'd reduce emissions by 1588 kt.
The Government announced this week it will require full conversion of all its own vehicles. Excellent. But why won't it announce an end date for all petrol and diesel imports? Britain has: 2030. Why don't double-cab utes attract fringe benefit tax, and why is there no financial incentive to buy EVs instead?
These things would be easy to introduce, cost taxpayers nothing, and make a big difference.
• Cleaner vehicles
Even without EVs, what about emissions standards? Environment Minister David Parker told a conference last month: "New Zealand is one of the only OECD countries without a clean fuel standard. I'm going to fix that."
If he requires cars to be 50 per cent cleaner than now, on average, that will save 1752 kt.
• Do it all
None of those things on its own will bring our emissions down by 50 per cent, let alone 70 per cent.
But combined, they would be devastatingly effective. Do them all, and our transport could be emitting only around 500 kt CO2-e a year. That's an 80 per cent reduction.
Even if we did only half as well on each measure, we'd be down to 1000 kt CO2-e. That's still very good. It's close to 70 per cent.
It's so doable. It won't ruin lives. It won't impose financial hardship on ordinary commuters, tradies and everyone else who has to get around.
Ten years is not too short a timespan to change transport in this city forever. If we commit to it.
And guess what else happens? If we do all this, Winton and MRCagney estimate the number of cars on the road would drop to 700,000. About half what it is now.
It doesn't mean you won't own a car. You just won't use it as much. Road congestion? Problem solved.
And we'd get better health outcomes. And much more appealing town centres, far fewer road deaths and serious injuries, stronger communities.
What does it really need? Political will. And what does that mean? They have to know we want it.