The prime minister’s announcement that she will work with the opposition to try to reach a compromise on Brexit is very welcome. Both sides need to be flexible. And when MPs get to vote again, they must show a greater willingness to compromise.

Brexit means Brexit, but we still do not know what Brexit means. If we are to find out, MPs must stop asking themselves, ‘what is the best outcome from my point of view?’ and ask instead, ‘what outcomes can I live with?’ Look down the list of how MPs voted on Monday and you will see some of the brightest and best from all parties, including some who care deeply about the environment, who made the best the enemy of the not-wholly-unacceptable. And the not-wholly-unacceptable is probably the best most of us can hope for now, given the pickle we are in.

Brexit is about many things, above all the big question of what sort of country we want to be. It is about culture, identity, nationhood, sovereignty, democracy, migration, citizenship and citizens’ rights, the economy, labour standards, food and product safety, trade, fishing, farming and much more. But it is also about the environment. What follows is a brief canter, from an environmental perspective, through the main options MPs will be talking about in the coming days. These are my personal views, drawing on analysis by Greener UK.

No to no deal

First, no deal must be avoided. It carries significant risks for farming, upland farming in particular; landscape and air quality, as lorries queue for miles around our major ports (“Kent, sir — everybody knows Kent — apples, cherries, hops,” …and a huge car park); chemical safety; environmental governance; clean energy; and much else. In the longer term, as Siemens UK’s chief executive Juergen Maier has pointed out, the loss of faith in the UK as a functional polity threatens our ability to forge a low carbon, high tech economic future. One of the many depressing things about Brexit is the insouciance with which some sensible and well-meaning people (as well as some who are rather less sensible) downplay the dangers of no deal.

The prime minister’s deal has promising language on the environment. The backstop section of the Withdrawal Agreement includes a mutual commitment to non-regression in most areas of environmental law. The accompanying Political Declaration says the future relationship will build on the Withdrawal Agreement. This is positive but, as a whole, the declaration is too vague. It needs to be underpinned by much stronger domestic enforcement. The UK government’s proposals on environmental enforcement in England (which could apply to Northern Ireland) fall short of the requirements set out in the Withdrawal Agreement. The Scottish and Welsh governments’ proposals lack detail.

What the deal choices mean for the environment

Greener UK has set out how the Political Declaration can be improved. Not least, it needs to say explicitly that one of the key purposes of the future relationship is to ensure a high level of environmental protection. If Theresa May and Jeremy Corbyn take a version of the current deal back to the Commons, changes along these lines are essential. We also want the government to commit to report on changes to EU environmental law and give parliament the right, at the very least, to keep pace with them.

But it is unlikely that the prime minister will be around to lead the next stage of negotiations and some of her would be successors have made clear that they would adopt a radically different set of negotiating priorities. Boris Johnson, for instance, wants a Canada (or Korea or Mongolia) style free trade agreement with the EU; the UK would diverge from EU standards and potentially pivot towards US standards as the price of reaching a US-UK trade deal. So small improvements to the Political Declaration now cannot guarantee a future government’s commitments to high standards.

A customs union or ‘Norway-plus’ (‘Common Market 2.0’) relationship have both been proposed as ways to a softer Brexit, with fewer risks of divergence from high EU standards. A customs union would enable goods in the low carbon supply chain to travel freely within the EU, making decarbonisation more cost effective.

A Norway-plus agreement would be a closer form of UK-EU co-operation, requiring continued alignment with EU standards and enabling participation in EU agencies and programmes such as REACH, the Emissions Trading System and Natura 2000. The UK would be able to develop independent agriculture and fisheries policies, and we could decide to abide by the Birds and Habitats Directives. However, the UK would become a ‘rule taker’ from the EU, with a significant impact on citizens’ rights to participate in environmental decision-making.

The upsides and downsides of staying

Requiring a confirmatory public vote on any outcome gives the option of remaining in the EU. For many environmentalists, this seems obviously desirable. In fact, there are downsides, not least a loss of the energy that has come with having to decide our own environmental policies, rather than leaving them to protracted negotiations with 27 other countries. We would also remain in the Common Agricultural Policy (CAP) and Commons Fisheries Policy, though it is worth noting that the CAP is being reformed to allow member states more scope to develop their own policies.

More positively, within the EU, the UK would benefit from strong environmental governance and would participate in EU agencies and programmes with full voting rights. We would be able to influence trade negotiations and global discussions on issues such as climate change.

MPs get little sympathy, but most are having a rotten time at present. Brexit is messy. There are few wholly good outcomes available. Compromise is the order of the day, often with a side order of eating one’s words or reneging on manifesto commitments. But as well as asking themselves what is best for business or trade or workers’ rights, I hope MPs will also consider what is best (or least bad) for the environment. A soft Brexit or no Brexit look like the least risky options, followed by the prime minister’s deal. A Canada-style trade arrangement carries great risks. But worst of all would be no deal