Today parliament is scheduled to vote on a new runway for Heathrow Airport. It could and should, be very close. Shadow chancellor John McDonnell is loudly proclaiming on Twitter his opposition to the plan, while the government, on its own, doesn’t have the numbers to get it through.

Some Tory MPs, mostly those with constituents under the flight path, are going to be abstaining. Boris Johnson, yes the MP who swore he’d lie down in front of the bulldozers to stop Heathrow, is conveniently on a plane somewhere – not offering his vote of opposition, not putting his body on the line, but which still means that there’s one less vote for the Heathrow plan.

The SNP support is at least uncertain – although that it should be considering it at all is certainly telling when it makes claims to green credentials. But odds are that the vote will be for Heathrow to go ahead. For Labour is not whipping its MPs to vote in opposition.

It’s not wholeheartedly opposing a development that blows a great hole in Britain’s promises to cut carbon emissions. It’s not wholeheartedly opposing a development that will greatly worsen air pollution in a city where thousands die every year as a result of it. And it’s not acknowledging at all that this is an outdated white elephant, built on a model of development now entirely discredited – neoliberal globalisation. If it did those things, it would be imposing the strongest possible whip on its MPs to vote against the runway.

I can see the Twitter troll coming at me now: the Greens don’t whip, so why are you demanding that Labour do it for this vote?

Well, first, that is the way the Labour Party works – their choice – and to not do it in this case is an expression of the lack of seriousness, the lack of focus, on this crucial vote. But more than that, the Green Party doesn’t whip, on this and other votes, because we don’t need to.

Green political philosophy is built on the understanding that you can’t have infinite growth on a finite planet. We know that having to live within the physical limits of our fragile, massively abused home, isn’t ultimately a matter of politics, but physics. It isn’t a choice, but the only option for a future that offers security for us all. We have to live, as Kate Raworth puts it, within the doughnut. No Green would vote for an expansion of Heathrow. And I’d suggest there’s a lesson in that.

If you want a realistic government, one that understands the economy is entirely a subset of the environment, that the ecosystems we entirely depend on for life are under massive strain, there’s only one government to have, a Green one. Others might put on layers of “greenwash”, make promises or the right noises, some of the time. But they won’t be committed, be prepared to stand up for what they’ve said – or stand with the people who are.

In pictures: 70 years of Heathrow Show all 22 1 /22 In pictures: 70 years of Heathrow In pictures: 70 years of Heathrow Inside one of the terminal tents in 1946 The year the airport opened. Comfortable armchairs and flowers try to distract from the conditions Graham Bridges collection In pictures: 70 years of Heathrow An aerial view of the airport in 1949 Construction of the runway layout and Central Area are under way In pictures: 70 years of Heathrow A Pan Am crew checks out the Boeing Stratocruiser N1029V Clipper Golden Eagle in 1954 During the early 1950s, Pan Am and American Overseas Airlines operated Statocruisers into London Airport in direct competition on the North Atlantic route operated by BOAC In pictures: 70 years of Heathrow One of the first official London Airport guidebooks C.1953, priced 1s In pictures: 70 years of Heathrow In 1950 a permanent concrete terminal building was built This replaced the tents previously used at London Airport North and is seen still in use for charter and cargo flights in this 1959 view via Graham Bridges In pictures: 70 years of Heathrow BOAC check-in desk in 1954 Inside the new London Airport North terminal building, just before the move to the Central Area Graham Bridges collection In pictures: 70 years of Heathrow Air traffic control tower in the 1960s Inside the visual control room CAA Archives via Pete Bish In pictures: 70 years of Heathrow Rear cover of the 1956 guidebook Showing a plan of the airport at the time, with entrance prices to the spectators’ viewing terraces and for airport coach tours In pictures: 70 years of Heathrow Spectators in 1958 How close can you get? As soon as the Central Area was open, spectators were afforded unprecedented views of the airliners In pictures: 70 years of Heathrow Terminal 3 was opened as the Oceanic Terminal on 13 November 1961 It was built to handle flight departures for long-haul routes. Renamed Terminal 3 in 1968, it was expanded in 1970 with the addition of an arrivals building In pictures: 70 years of Heathrow Inside Terminal 3 in 1969 Check-in desks for BOAC and QANTAS airlines In pictures: 70 years of Heathrow Plane spotting on Heathrow’s viewing terraces in the 1960s Wrap up warm, take your spotting logbooks, pen and binoculars and get your mum to pack your sandwiches In pictures: 70 years of Heathrow No 1 Passenger Building Also called the Europa Building. In this photo, taken on 22 June 1963, flags of the many airlines it serves are flown Lee Holden In pictures: 70 years of Heathrow Luggage-trailer-towing Routemaster buses When BEA and BOAC merged to form BA on 1 April 1974, both fleets had to be repainted in the new livery, but so did all the ground support equipment In pictures: 70 years of Heathrow The entrance to the traffic tunnel in 1974 A Lufthansa Boeing 737 is seen on the runway In pictures: 70 years of Heathrow A 40 per cent scale model of Concorde In September 1990 it was erected on the roundabout at the entrance to the tunnel that passes under the northern runway at Heathrow Airport. It was built in four main parts, with an 80ft-long central fuselage section, to which the wings and tail fin were attached. The completed model was placed on the roundabout in September 1990 and was monitored by CCTV and surrounded by an infrared perimeter alarm that was connected to the local Heathrow police station to ensure it was not vandalised In pictures: 70 years of Heathrow Heathrow Airport's 50th anniversary On 2 June 1996, Heathrow marked its anniversary with a flypast of representative airliner types that have served the airport over the years. This culminated in a formation flypast by Concorde with Hawks of the RAF Red Arrows aerobatic team In pictures: 70 years of Heathrow The roof of Terminal 3’s car park One of the last bastions for plane spotters and spectators was here. This is the unfriendly notice that greets anyone who attempts this today Richard Vandervord In pictures: 70 years of Heathrow On 24 October 2003 BA withdrew its Concordes from service The final scheduled commercial flight was BA002 from JFK operated by G-BOAG. Here we see three of the Concordes parked together outside the BA hangar on 8 November 2003 following withdrawal John Hughes In pictures: 70 years of Heathrow The new control tower Costing £50 million to construct, it gives controllers an excellent 360-degree panoramic view NATS photograph In pictures: 70 years of Heathrow The new Terminal 2 The Queen’s Terminal In pictures: 70 years of Heathrow Looking due west down Runway 27L

There’s a good chance the new Heathrow runway will never get started – the economic case doesn’t stack up – but if the bulldozers do arrive, the people already thinking about the campaign to stop them know the Greens will be with them, just as the anti-fracking protection camps and campaigns around the country know that it is the Green leadership, the massed Green members, who’ll be standing with them in front of the frackers’ lorries.

On my recent visit to Preston New Road in Lancashire, where Ineos has been forced to resort to the expensive courts after having been rejected by the people, campaigners were again asking me “where’s Jeremy Corbyn?” Luckily I’d told them a year ago, when they asked the same question, not to hold their breath.