Large Dutch firms which are part of the European emissions trading system produced 2.9% more greenhouse gases last year than in 2023, ending seven years of successive reductions, Trouw reported on Monday.

In Europe as a whole, however, emissions were down 5%.

The ETS requires big polluters, such as chemicals companies, to buy “rights” for every tonne of greenhouse gases they emit. The aim is to encourage firms to reduce their emissions so that by 2038 the market dries up altogether.

The Emissions Authority said one reason for the Dutch increase was the restart of a Tata Steel blast furnace, which had been closed for renovations for six years. The chemicals industry, which is energy-intensive, is also recovering, the authority said.

In addition, the aviation sector continued to grow in the wake of the coronavirus pandemic, and that led to 17% more greenhouse gases being emitted. While efforts to reduce emissions per passenger, such as using more biofuel, were paying off, it was not enough to offset the increase in flights.

The European system does not have individual country targets.