Efforts to cut carbon dioxide (CO2) emissions in Leeds have been hampered by increased transport over five years.
The latest data from the Department for Business, Energy and Industrial Strategy has revealed that CO2 emissions from freight and passenger transport rose by 5.2% between 2011 and 2016.
That means traffic was responsible for 40.6% of the total amount carbon dioxide released in the area in 2016.
Overall, emissions from transport, both private and for business purposes, increased by 3.5% in the UK over the period.
The heatwave that has hit the UK over the summer has raised awareness about the growing risks of climate change.
Scientists believe that future heatwaves will be more frequent and hotter due to carbon dioxide emissions.
Total CO2 emissions fell by 15.2% over the five years in Leeds. The area was responsible for releasing 4 million tonnes of CO2 in 2016 - down from 4.72 million tonnes five years earlier.
Gareth Redmond-King, head of climate change at the World Wildlife Fund UK, put the increase in emissions from transport down to the greater number of large cars on British roads.
He said: "We’re aping the American market and more drivers are switching to unnecessarily large vehicles with greater carbon emissions. Bigger vehicles tend to be less efficient on fuel use.
Jason Torrance, a transport expert at UK100, a network of local governments committed to promoting clean energy, called on the Government to take urgent action to tackle transport emissions.
He said: "It is expected that the Government will want to give local authorities more powers to tackle air pollution in the environment legislation next year. But without significant shifts on things like electrification of railway lines, cleaner buses and taxis, plus a shift away from car dependency by designing our cities better, this trend will only get worse.
"There is Â£78.5 billion of planned government spend on transport infrastructure in England to essentially increase road capacity. That will worsen the problem rather than decarbonising or tackling air pollution."
In Leeds, industrial and commercial activities accounted for 30.1% of CO2 emissions.
In 2016, households produced 29.3% of the carbon dioxide in the area, lower than five years earlier.
The department put the decreased emissions from the domestic sector down to lower coal consumption.
Phil MacDonald, analyst for the climate change policy think tank Sandbag, said the UK has made some progress on energy efficiency, particularly through the quick uptake of LED lightning.
There is still work to do, he added: "Compared to the continent, our housing stock is coming from a low base. There's a lot more to be done in reducing domestic emissions, and much of it, like loft insulation or cavity wall insulation, pays back in reduced energy bills almost immediately."
Overall, the UK reduced its carbon emissions by 15.4% between 2011 and 2016 and there were are only three areas in the country where emissions rose.
Top of the list is Flintshire, in the North of Wales, where carbon dioxide increased by 14.8%. The area where emissions went down the most was Northumberland, falling by 78.6% in five years.