A rising body of research is trying to quantify the impact of personal climate actions. The results show the most powerful impacts may come from some surprising places.

It's hard to get clear-cut evidence on what impact the personal actions we take in our lives can have on climate change.

While there has long been a focus on how to reduce the carbon footprint of what we buy, do and eat, it's harder to pin down the impact of many other measures people take, from community engagement and how we choose to vote, to where we save our money and the impact we can have in our workplaces.

But a growing body of research is revealing just how effective such other actions can be. In short, it seems, they can change a lot more than we might think.

Now a project named Shift (Super High-Impact Initiative for Fixing Tomorrow) has created a questionnaire to help guide people towards their most impactful climate actions, tailored to each person's individual circumstances and based on scientific research.

Kimberly Nicholas, professor at Lund University Centre for Sustainability Studies in Sweden, launched the guide alongside Project Drawdown, a US non-profit which focuses on science-based solutions to climate change. The BBC spoke to Nicholas to find out which personal actions really tend to make the most difference for the climate, according to the evidence.

What is the Shift guide and how did it come about?

For the last 10 years, I've been working on identifying and communicating effective climate action. I started thinking a lot about how consumer actions are really important, but they're not enough, and we need to focus more broadly on a set of "climate superpowers", as I call them. I and other researchers identified those five roles in a paper published in 2021, and they were also taken up by the IPCC [Intergovernmental Panel on Climate Change], the UN climate panel in its 2022 report.

The consumer is one of them, but it's also how people engage as citizens, investors, professionals and role models. We wanted to help people recognise the power they already have to make a really big difference for climate and essentially direct people towards what we know works, what we have evidence that moves the needle. I see it as connecting personal and systemic change.

Research by Felix Creutzig and others has shown it's possible to reduce greenhouse gas emissions 40-80% with changes that involve behaviour change or demand-side change. They're complimentary to and connected with changes in infrastructure and norms and policies, but they do involve people making changes in their everyday life.

I have a philosophy with Shift: I want to eliminate the noise, just focus on the few really big actions that we have strong evidence make a big difference, and try to break those into small, doable steps that people can take. I've used as much literature as exists to rank actions in the order of effectiveness. So you know, it's eat the frog first – put the big stuff up front and start with the thing that can make the biggest difference.

Your questionnaire starts by asking three main questions: is your income over $38,000 (£28,000), do you live in a liberal democracy and do you have a college degree. Why did you choose these three things?

Essentially, it's to focus on the most effective superpowers. This is living in a democracy for citizen actions, earning over the income threshold for consumer and investor actions, and having a college degree for professional actions. And then role model actions applied to everyone, because everyone is part of different communities and circles, neighbourhoods, groups, families, where they can inspire and influence and learn from and help create conversations with others.

Income is the most clear: we know about half of climate pollution from households comes from a group that makes over $38,000 (£28,000) a year, and the majority of climate pollution comes from household consumption, so 60-72%. So we're not going to cut emissions in half and eventually get to zero without addressing high-polluting households.

The investor role is also connected to income: many people probably have a bank, even if they don't have huge investment money.

Then the professional actions were connected to education. This is maybe the most tenuous, but assuming that if you have a higher degree – so a university college degree, or vocational school, some kind of tertiary education – you're more likely to have a professional position that gives you an opportunity to use your powers at work in a really effective way.

The group that will say yes to those three questions will have all five superpowers. It's less than 10% of people on Earth who actually belong to that group. Globally, they are among the most powerful people who have ever lived. If people can realise that and start using that power effectively, I really believe that it can make a transformation happen for climate action.

If you answer yes to all three questions, the top 'climate superpower' given is your role as a citizen. How much impact can people really have as citizens?

There's really good evidence that citizen actions are important for changing climate policy. The best study comes from

© BBC