US Treasury Secretary Janet Yellen on Friday called on her G20 counterparts meeting in Venice to take urgent action to decarbonise the global economy and tackle climate change.

The Group of 20 richest countries “are responsible for 80 percent of global carbon emissions, so it is our responsibility to take action — and do so immediately,” she told a forum before the formal opening of the talks between finance ministers and central banks.

She also emphasised the importance of increased international cooperation to avoid “friction” between different countries trying to reduce their greenhouse gases.

French Finance Minister Bruno Le Maire, also speaking in Venice, proposed a global minimum for the price of carbon.

“Instead of having a global unique carbon price, which we cannot reach for the time being, we propose to have a global floor for carbon price,” he said.

“I think a global floor could be a very good starting point to have all the G20 member states committed on a carbon price.”

The International Monetary Fund last month issued a report calling for all the world’s top polluters to adapt such a floor.

It said that carbon pricing was now widely accepted as the most important policy tool to achieve the drastic emissions cuts required to limit global warming to two degrees Celsius by 2050.

But four-fifths of emissions currently remain unpriced and the global average carbon price is just $3 a tonne — far below the level needed to incentivise energy efficiency and redirect innovation towards green technologies.