Your article (Revealed: the 20 firms behind a third of all global carbon emissions, 10 October) highlights the biggest polluters and contributors to the climate crisis over the last half-century – the “uncooperative crusties” of capitalism. It is these companies that are standing in the way of progress. But we shouldn’t just look at the carbon they have pumped into the atmosphere, but also the money – our money, in banks and pension funds – that they have invested and the power that huge amount of capital gives them. They can choose to either transform their businesses into something positive for the planet or to extend the shelf life of a carbon-based business model well past its best-before date.

This week, the Treasury select committee asked me, ShareAction and the UK Sustainable Investment and Finance Association what investors can do about the oil and gas industry. My answer was that we need to use more than just persuasion. Our money can shape the strategies of these companies directly. Savvy investors should back those that respond to change, not the ones who deny the urgency.

At this week’s Extinction Rebellion protests I spoke at the event called The Future is Here. It was inspiring to meet so many people thinking about how they can use their resources to deliver net zero. The future is now for the large energy companies, and it is time to make our money matter in the fight against a climate emergency.

Bruce Davis

Founder and joint managing director, Abundance Investment

• It is right that the world’s oil firms have been called out (Secretive assets: Most reserves are held by state-owned firms, 10 October). Environmental groups and activists have been pointing this out for more than 20 years, and the response from governments has usually been a shrug. Now that, thankfully, climate activism has become mainstream and the big polluters have been outed, we must welcome them into the fold and make it politically easier for them to adjust their activities. It could be a time of exciting cooperation and inventiveness.

And let us not forget that each one of us must take responsibility for our use of fossil fuels; put flying at the back of the queue as the transport of last resort. Train travel within Europe is fast and comfortable. People will soon adjust. We just have to.

Val Mainwood

Wivenhoe, Colchester

• George Monbiot places primary responsibility for global warming with petrochem firms, and classes the middle classes of the west as gullible victims of the machinations of the oil producers (Polluters drove the climate crisis, yet it’s us they blame, Journal, 10 October).

Walmart could be held responsible for more CO 2 emissions than any of the petrochem firms cited. Think global supply chains, packaging, and billions of short car trips to the supermarket – not to mention the fuel pumps at the car park exit. It’s just that crunching the numbers is complicated and contestable. It’s easier to do the numbers on oil firms.

In the nasty cocaine trade, who is really at fault? The Colombian farmer who produces it (“petrochem”), the cartel which manages the whole chain (“Walmart”), or the westerner who snorts it (“gullible victim”)?

To me, listing the top petrochem firms as the primary drivers of global warming looks like listing the 20 biggest farmers in the foothills as the primary drivers of the drug trade.

Of course the parallel is not perfect, but the logic holds. If every middle-class westerner with a weekend habit makes do with a cup of tea instead, the cocaine trade stops. So, ditch your car; scrap your boiler; cut off the power. Yeah, right.

Peter Anderson

Barwick-in-Elmet, West Yorkshire

• Your articles covering the top 20 global polluters were excellent. As well as exposing the massive contribution the 20 make to the destruction of our planet, they also highlight the absurd levels of income of their CEOs. The income of half of them is undisclosed, but the other half are paid a total about $130m a year. So let’s be clear: these companies are not just helping bring about extinction, they’re also fuelling gross inequality. The rebellion against them must be on both fronts.

Jol Miskin

Sheffield

• I broadly agree with George Monbiot. Consumerism, encouraged by the present economic system, and especially by the fossil fuel companies, has led humanity to face the “first great extinction”. But while I also agree that “In such a system, individual choices are lost in the noise”, this should not allow individuals to think that their actions make no difference. There are numerous ways in which each of us can, and do, contribute to the battle against climate change. Don’t invest in fossil fuel companies. Don’t drive. Don’t fly. Reduce, re-use, refurbish, recycle everything. March, lobby, demonstrate, talk to people.

Rose Harvie

Dumbarton

• It’s all very well outing the top 20 firms behind the world’s carbon emissions, but are the Extinction Rebellion people prepared to go without their central heating, gas stoves and electric lights? When do they suggest we switch it all off?

Angela Singer

Cambridge

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