Every year I listen to the Leaders’ speeches from the UK Party Conference season to analyse their commitment to Sustainability. I’ve long argued that leadership is the difference between the best and the rest in Sustainability whether at a organisational or a national level, so no matter what is discussed lower down the conference agenda, it is what gets through to the leader’s speech that tells the true story.

This year’s conferences were overshadowed not only by Brexit, but by the row over the prorogation of Parliament and the subsequent court case. So those rows dominated all three conferences, but, it has to be said, Sustainability still shone through in the leaders’ speeches.

First up, was the Lib Dem’s new leader Jo Swinson, who made a commitment to net zero by 2045, 5 years earlier than current Government policy, and filled in some of the policies the Lib Dems would implement to achieve this:

A Liberal Democrat Government will plant the trees and retrofit the homes. We will build the wind turbines, the solar panels and the tidal barrages. But Government alone cannot solve this. It will take all of us – government, individuals and business – to build the zero-carbon UK we need to become. That’s why my Liberal Democrat Government will introduce climate risk reporting and create a new Green Investment Bank, to channel investment into green projects and away from fossil fuels. And it’s why I want to engage everyone in the country by establishing a UK Citizens’ Climate Assembly to drive a national debate about how exactly we will reach net-zero by 2045 – and earlier if possible.

We will do it all, not because it will create thousands of good new jobs – although it will; not because it will cut energy bills – although it will; not because it will make our country a cleaner, richer, happier nation – although it will. We will do it because we have to. Because, as the placards say, there is no Planet B.

Labour party leader Jeremy Corbyn’s speech was pulled forward and pruned down due to the striking down of prorogation (which meant I missed seeing it live as I was travelling at the time, so I’m working off the published text). Interestingly, although Labour delegates had earlier endorsed a radical  ‘net zero by 2030’ policy via a ‘green new deal’, neither was explicitly referenced in the speech. Whether this was deliberate or inadvertent is unclear, but some Unions had expressed concern about 2030 which may be why Corbyn hedged his bets.

With a serious industrial strategy and a radical Labour government, the economy can be a tool in our hands rather than the master of our fate. And with a government that’s prepared to intervene we can prioritise the things that matter most.

Which is precisely what our times demand, because nothing matters more than the climate emergency. That means taking on the big polluters and wealth hoarders who profit from the current system. Bringing our emissions down to net zero won’t happen by itself. It will only be possible with massive public investment in renewable energy and green technology.

That’s not a burden. It’s an opportunity to kickstart a Green Industrial Revolution that will create hundreds of thousands of high-skill high-wage unionised jobs as we triple solar power, double onshore wind and bring about a seven-fold increase in offshore wind projects.

And that’s why we announced today that the next Labour will build three new battery plants in South Wales, in Stoke-on-Trent and Swindon.

Last up was new Prime Minister Boris Johnson. His speech has been described by many pundits as more of an after dinner speech than a conference speech and there wasn’t a neat climate paragraph for me to cut and paste in here. In general the speech was more about what great things are happening in the country now rather than the PM’s vision for the future, but this is the closest we got to a vision:

Thanks to British technology there is a place in Oxfordshire that could soon be the hottest place in the solar system –  the tokamak fusion reactor in Culham and if you go there you will learn that this country has a global lead in fusion research and that they are on the verge of creating commercially viable miniature fusion reactors for sale around the world delivering virtually unlimited zero-carbon power. Now I know they have been on the verge for some time – it is a pretty spacious kind of verge, but remember it was only a few years ago when people were saying that solar power would never work in cloudy old Britain and that wind turbines would not pull the skin off a rice pudding. Well there are some days when wind and solar are delivering more than half our energy needs.

We can do it.

We can beat the sceptics.

I’m sure he also made an off the cuff commitment to net zero, but it doesn’t appear in the transcript (the only one I can find). The ‘rice pudding’ reference was a self-deprecating dig as he was the sceptic who said it at the time. Whether you see this as a Damascene conversion to green technology or someone facing the way the wind is blowing probably depends on your overall view of the character of Boris Johnson.

I’m an eternal optimist and I think all three speeches had enough Sustainability commitment despite the domination of the Brexit debate to keep me reasonably cheerful. With a General Election in the offing, the manifesto content will be a good guide to true commitment – what form will the Green New Deal take in the Labour Manifesto and whether the PM’s list of shiny new green technologies will be converted into a climate vision are the key questions left open from the conferences.

Disclosure: I’m a member of the Liberal Democrats.