One argument against electric vehicles (EVs) made by those that wish to cling to the certainties of the internal combustion engine is that we need to decarbonise the power system first otherwise cars are no cleaner than if they use gasoline.

Many observers question whether electric cars really are ‘greener’ once emissions from production and generating their electricity are taken into account.

Leaving aside the instant improvements in local air quality from not having harmful tailpipe emissions pumping into the atmosphere, a new study suggests that EVs help to tackle climate change in all but the most coal-reliant countries.

A new study by the universities of Exeter and Cambridge in the UK and Nijmegen in the Netherlands has concluded that electric cars lead to lower carbon emissions overall, even if electricity generation still relies on fossil fuels. The results are reported in the journal Nature Sustainability.

Under current conditions, driving an electric car is better for the climate than conventional petrol cars in 95% of the world, the study finds.

The only exceptions are countries such as Poland, where the electricity network is still mostly based on coal-fired power generation.

In countries with a heavily decarbonised system such as Sweden and France, which have large amounts of renewable and nuclear generating capacity, the average lifetime emissions from electric cars are up to 70% lower than petrol cars, while in the UK, which is rapidly phasing out coal but still has a reasonable amount of gas-fired power plants, emissions are around 30% lower.

But as power systems around the world become less carbon-intensive, the advantages of EVs will continue to grow and even inefficient electric cars will be less emission-intensive than most new petrol cars in most countries.

The study projects that by 2050, half of cars on the roads could be electric, leading to a reduction in global CO2 emissions of up to 1.5 gigatons per year, which is the same as the total current CO2 emissions of Russia.

It’s not just cars – electric heating options are more climate-friendly, too. The study found that electric household heat pumps also produce lower emissions than fossil-fuel alternatives in 95% of the world. Heat pumps could reduce global CO2 emissions in 2050 by up to 0.8 gigatons per year – roughly equal to Germany’s current annual emissions.

"The idea that electric vehicles or electric heat pumps could increase emissions is essentially a myth," said lead author Dr Florian Knobloch, from the University of Nijmegen. "We’ve seen a lot of discussion about this recently, with lots of disinformation going around. Here is a definitive study that can dispel those myths. We have run the numbers for all around the world, looking at a whole range of cars and heating systems.

"Even in our worst-case scenario, there would be a reduction in emissions in almost all cases. This insight should be very useful for policy-makers."

The study divided the world into 59 regions to account for differences in power generation and technology. In 53 of these regions – including the US, China and most of Europe – the findings show electric cars and heat pumps are already less emission-intensive than fossil fuel alternatives.

These 53 regions represent 95% of global transport and heating demand and, with energy production decarbonising worldwide, senior author Dr Jean-Francois Mercure from the University of Exeter said the "last few debatable cases will soon disappear."

"Understanding the effect of low-carbon innovations on relevant sectors of the economy, such as heating and transport, is crucial for the development of effective policy," said co-author Dr Pablo Salas, from the Cambridge Institute for Sustainability Leadership. "We hope our work can inform the policy process here in the UK and abroad, particularly around discussions of the new carbon targets under the Paris Agreement framework."

The researchers carried out a life-cycle assessment in which calculated greenhouse gas emissions generated when using cars and heating systems, as well as in the production chain and waste processing for those sectors.

"Taking into account emissions from manufacturing and ongoing energy use, it’s clear that we should encourage the switch to electric cars and household heat pumps without any regrets," Knobloch said.