The mayors of Paris, Madrid, Athens and Mexico City have said they have committed to ridding their cities of diesel engines by 2025 to improve air quality.
The announcement comes as a large group of mayors of major cities meets in Mexico to discuss climate change.
Paris Mayor Anne Hidalgo told the gathering the world's big cities will need $375bn of investment to curb climate change.
"It is a lot, but there is no other option. Together we will seek that money," Ms Hidalgo, the new president of the C40 network of big cities, said.
If that amount is made available "humanity will have a chance of surviving," she said.
The mayors were meeting to plot strategy in the face of climate change scepticism from US President-elect Donald Trump.
They said they planned to make commitments to reduce harmful emissions by promoting cycling in cities and renewable energy, among other measures.
As leaders of busy, polluted cities that are home to millions of people, the mayors gathered in Mexico City want countries to push on with adopting the so-called Paris Agreement to limit harmful emissions.
Mr Trump has cast doubt on the accord, which aims to limit global warming to two degrees Celsius above pre-industrial levels.
The Republican billionaire has in the past vowed to tear up international climate agreements, though he said in an interview last week that he has an "open mind" about supporting them.
He had previously said global warming was a "hoax" invented by the Chinese and not scientifically proven.
The C40 group's 85 cities include London, New York, Vancouver, Hong Kong and Seoul.
Los Angeles Mayor Eric Garcetti told the gathering that 38 US cities had sent a letter to Mr Trump to tell him they would push ahead with their efforts against climate change.
C40 executive director Mark Watts said in an analysis unveiled this morning that the world's big cities must collectively cut their carbon footprint by nearly half within a decade if the 196-nation Paris Agreement is to be met.
With only one degree Celsius of warming so far, the world has already seen an upsurge in extreme weather, including droughts, superstorms, heat waves and coastal flooding boosted by rising seas. This mover
Donal Byrne looks at the implications of this diesel ban for Ireland and diesel car owners:
It may be a political move but the science exists to prove that this move spells the end of diesel. Ironically, it has been our preferred choice for our cars since 2008 and even earlier. A reduction in tax in 2008 to reduce CO2 emissions from cars and other vehicles meant there was a rush to diesel to avail of the tax reduction and about 70 per cent of the cars we have bought since have been diesel.
What has not been taken into account since then is the extremely harmful effects of nitrous oxide and particulates, which diesel cars spew out and are a major source of air pollution.
The Toyota C-HR is one of the few hybrids on sale in Ireland.
At the moment only Toyota, Kia and Hyundai offer hybrid alternatives on the Irish market. Others offer limited electric alternatives, with the best being the Nissan Leaf, but all manufacturers will now have to rush headlong into alternative energy sources for cars. This ban is only the beginning and more and more cities will embrace it
Most car companies lie about their diesel emissions and figures from Emissions Analytics (testing above) show this.
Click here for an earlier analysis by Donal Byrne of the health effects of diesel cars:
