The Guardian’s analysis is a guide – intended to provoke debate before the next election

Why it's imperative to hold MPs to account on their climate record

The Guardian’s analysis of MPs’ climate records relies on two extensive pieces of research.

Politicians were rated from 0% to 100% based on 16 key parliamentary votes that would affect the UK’s carbon emissions.

The votes were chosen by the Guardian and DeSmog UK with additional consultations with Friends of the Earth, Greenpeace and other sources. A detailed breakdown of the methodology can be found here.

The Guardian also compiled publicly available information about donations, salaries, gifts and other interests registered by MPs that are linked to the fossil fuel industries.

MPs and the oil industry: who gave what to whom? Read more

The analysis has already provoked strong reactions from some MPs, while others – even those with modest scores – recognised it was an important exercise that would stimulate debate between voters and the people who represent them.

The sole criteria in assessing MPs’ scores was whether their votes were likely to increase or reduce emissions.

So, votes for fracking and Heathrow expansion were considered negative because those bills encouraged more carbon-intensive gas production and airline travel.

But votes for onshore wind and subsidies for renewable energy were deemed positive because those bills would have accelerated the shift to a low-carbon economy.

For this analysis, a vote for nuclear power was judged positive in purely climate terms, even though there are many other serious environmental and economic concerns about this form of energy. Motions passed without a recorded vote could not be included in the scores.

In addition, the Guardian looked at information taken from the parliamentary register of MPs’ interests that showed donations, salaries or benefits from fossil fuel companies, aviation firms or individuals and organisations that deny the need for urgent climate action.

The results are not intended as the final word on whether an MP is for or against climate action, and there are limitations to the methodology used.

Q&A What is the polluters project? Show Hide The Guardian has collaborated with leading scientists and NGOs to expose, with exclusive data, investigations and analysis, the fossil fuel companies that are perpetuating the climate crisis – some of which have accelerated their extraction of coal, oil and gas even as the devastating impact on the planet and humanity was becoming clear.

The investigation has involved more than 20 Guardian journalists working across the world for the past six months. The project focuses on what the companies have extracted from the ground, and the subsequent emissions they are responsible for, since 1965. The analysis, undertaken by Richard Heede at the Climate Accountability Institute, calculates how much carbon is emitted throughout the supply chain, from extraction to use by consumers. Heede said: "The fact that consumers combust the fuels to carbon dioxide, water, heat and pollutants does not absolve the fossil fuel companies from responsibility for knowingly perpetuating the carbon era and accelerating the climate crisis toward the existential threat it has now become." One aim of the project is to move the focus of debate from individual responsibilities to power structures – so our reporters also examined the financial and lobbying structures that let fossil fuel firms keep growing, and discovered which elected politicians were voting for change. Another aim of the project is to press governments and corporations to close the gap between ambitious long-term promises and lacklustre short-term action. The UN says the coming decade is crucial if the world is to avoid the most catastrophic consequences of global heating. Reining in our dependence on fossil fuels and dramatically accelerating the transition to renewable energy has never been more urgent.

For example, it is difficult to quantify the work politicians do in committees, mobilising colleagues, spending time on climate issues or speaking out in the House of Commons. Individual MPs’ votes are also heavily influenced by the party whip.

Yet academics and campaigners said they hoped the analysis would spur a debate about why parliament is not doing more to cut the UK’s emissions.

“Every MP will look at this list and say: ‘Why am I there?’ They will have to justify their position,” said Rebecca Willis, a research associate at Lancaster University who has studied parliamentary attitudes on global warming.

The analysis also comes at a critical moment, before a likely general election that could leave the winning party in power until 2025 – halfway through the decade in which scientists warn that humankind must make a decisive shift away from fossil fuels and other sources of carbon emissions.

The current government already claims to be on the right path and political parties across the spectrum express support for radical action.

Yet the the Guardian’s analysis shows Tory MPs have frequently voted down short-term practical measures to reduce emissions, for example through home heating efficiency or renewable energy subsidies, while lending their support to fracking and airport expansion.

The Conservatives have the worst record of any party, with an average score of 17%.

Despite Labour’s relatively high score of 86%, the party’s record was more mixed when it was in power in 2008-10. A year after pushing through the landmark Climate Change Act, Gordon Brown’s government voted against the 10:10 climate campaign and blocked a bill that would have made airport expansion more difficult.

The Conservatives, who were then in opposition, supported both measures because their leader David Cameron wanted to create an image of a greener party. Yet after winning in 2010, his party – then in coalition with the Liberal Democrats – rolled back ambitious climate policies.

The Lib Dems had an average score of 59% – until they accepted a number of ex-Tory MPs. Their inclusion brought the party down to 51%.

The research has thrown up anomalies.

Some relatively green Conservative MPs, such as Peter Bottomley (23%), Sarah Newton (15%), Peter Aldous (23%) and James Heappey (0%), have low scores because they were only eligible for a handful of votes, and in those they stuck to the party line.

Other more climate sceptical MPs – most notably Owen Paterson (42%) – scored relatively highly because he has been in the house long enough to have been part of Cameron’s green Tory rebranding.

Similarly, some Labour MPs have higher scores because they have only voted in opposition, while the stalwart environmental campaigners Kerry McCarthy (86%) and Mary Creagh (78%) fell short of a perfect mark because they stuck to the party line over the 10:10 campaign and airport expansion.

Ed Milliband scored 78% although, as author of the 2008 Climate Change Act, he has arguably achieved as much as any MP in promoting emissions cuts.

MPs who have a strong record on the environment said privately they were glad parliamentarians were being held to account on their climate voting records, though this could never be a perfect measure.