The average carbon dioxide emissions of cars sold in the UK rose for the third year in a row during 2019 as falling diesel sales and the rising popularity of SUVs dealt a blow to Britain’s hopes of reaching climate targets.

Average CO₂ emissions rose for the third year in a row, up 2.7% year on year to 127.9g of CO₂ per kilometre, according to data from the car industry body. This is far above the newly introduced EU target of 95g per kilometre carmakers need to achieve over this year and next for all new cars. Cars account for just over 18% of UK emissions, according to government figures. Transport emissions as a whole account for a third of the UK total, with the sector viewed as vital contributor if the country is to achieve goals of cutting emissions to 51% of 1990 levels by 2025 and to reach net zero by 2050.

All manufacturers selling in the EU are rushing to meet emissions regulations that came into force on 1 January. The regulations were introduced in response to the climate crisis, with road transport a major contributor to global CO₂ emissions.

Overall UK car sales fell by 2.4% year on year to about 2.3m, according to the Society of Motor Manufacturers and Traders, with the industry body blaming Brexit uncertainty and the slump in diesel sales as the main factors.

This indicates the worst year for the UK market since 2013, when sales were 2.26m. They reached a peak of 2.7m in 2016 but have declined steadily since.

A quarter of the CO₂ increase was caused by the 21.8% drop in diesel sales over the year. Newer diesels on average have lower CO₂ emissions than petrol cars, despite a backlash prompted by air quality concerns. Another quarter was caused by increased sales of SUVs, which are often heavier and have much worse aerodynamic profiles than smaller cars. Increased fuel use by SUVs was the second largest contributor to the increase in global CO₂ emissions from 2010 to 2018, according to the International Energy Agency.

The other half of the headline CO₂ increase was caused by a change to testing standards.

Mike Hawes, the SMMT chief executive, acknowledged the CO₂ figures showed the challenge facing the industry. He said: “The step change that is required is significant.”

Under the EU regulations, carmakers face fines potentially running into billions of euros across the UK and the rest of Europe if they surpass individual limits designed to ensure that average fleet emissions hit the 95g target.

One bright spot in an otherwise declining market was the rapid increase in sales of battery electric vehicles, which have zero CO₂ tailpipe emissions, and hybrid vehicles, which combine an internal combustion engine with a battery-powered motor. Annual sales of alternatively fuelled vehicles rose by 20.6% to a record market share of 7.4%. That was driven by the surge in battery electric sales, which were up by 144%.

However, sales of battery electric vehicles would need to rise from the 1.6% market share for 2019 to 27% to hit the 95g target alone, according to the SMMT’s calculations.

Hawes repeated his industry’s plea for a post-Brexit trade deal that preserves frictionless trade between the EU and the UK, and that prevents the imposition of tariffs. He added that Brexit uncertainty remained his number one fear for the industry.

“Undoubtedly consumer confidence around our big-ticket items is weak,” said Hawes, speaking at a briefing in London before the publication of the final figures.