The writer is an author and environmentalist

Pity the poor banking chief executive, or large-scale asset manager, beset by whiny activists going on and on about record fires and record floods and record temperatures. perhaps his 16-year-old daughter has a poster of greta thunberg on the wall, and is asking increasingly difficult questions about, you know, the future. what is he to do?

So far, the preferred answer is to make some noises about net zero this or carbon-free that, and pointedly to pick distant 2050 as a moment when all this should happen. in the uk, barclays has announced that it aims to become a net zero bank by 2050 and to align our entire financing portfolio to the goals of the paris agreement. barclays uk peer natwest has also committed to do what is necessary to achieve alignment with paris.

In the us, morgan stanley just announced it plans to reach net-zero financed emissions by 2050 and the shareholders of jpmorgan chase this spring barely defeated a measure requiring the bank to explain how it was going to align with paris. by next spring, surely such a measure will succeed: after all, california has just seen what may be the highest temperature ever reliably recorded on the planet, and now the west coast is thoroughly ablaze. climate concern isnt going away, and the next big un round of climate negotiations set for glasgow in late 2021 is supposed to focus on getting commitments from financial institutions.

These are only beginnings. for them to mean anything, we need some guidance on what paris alignment would actually look like for financial institutions. such guidance has now been provided by a consortium of 60 environmental and rights groups headed by rainforest action network.

These principles are fairly simple. they draw on the scientific consensus set out in a 2018 report from the un intergovernmental panel on climate change. it reckoned that to have just a 50 per cent chance of reaching the paris targets keeping the global temperature rise to only 1.5c wed need to cut emissions roughly in half by 2030 and zero them out by 2050.

The most important number in that previous sentence is 2030, which is now about nine years, or 37 financial quarters, away. its possible that a current bank chief executive might still be in the job then or, at least, not in the grave.

So what would these principles mean in practice? a critical line in the sand is that banks or other financiers cannot support any project that explores for new fossil fuels or expands fossil fuel infrastructure. weve already got way too much of that: to meet those ipcc targets, this decade has to be about conversion away from fossil fuels and toward renewables.

That means no money, insurance or advisory services for new pipelines or liquefied natural gas ports, or many other things weve taken as normal. and its not just project financing that must stop. it is all finance of any kind for any company that is expanding fossil extraction or infrastructure, or exploring for new reserves.

The principles also call on financial institutions to require their clients to publish plans by the 2021 glasgow meeting to wind down fossil fuel operations on a timeline that meshes with the ipcc goals. the same goes for financing companies that degrade peatlands, cut down tropical forests or violate the rights of indigenous people.

Signing up obviously would require big changes. banks, insurers, private equity companies and others would have to drop clients including coal, oil, and gas majors, unless those companies see fit to change dramatically. bps announcement that it will cut oil and gas production by 40 per cent this decade is a start, but it is not clear precisely what that means or that others will follow.

Culling those clients might sting but it would open up new opportunities to work with the renewable energy and other emerging clean economy industries. they also need capital and are far less risky on these fronts.

This choice should not be impossible for financiers. their core skill is maths. and climate change, at this point, is just a maths problem. scientists have told us how much more carbon we can burn, and it is far, far less than the fossil fuel industry wants to combust. there is no way to make the sums work, even if we believe that we will someday get help from conjectural carbon-sucking technologies that do not exist now. we have to do the right thing, or the planet burns.

I dont know how many banks and asset managers and insurance companies will actually decide to be responsible. but at least now they have these principles to act as a road map, and they can no longer claim to not know what paris alignment would mean.