A dozen countries have called for an EU climate target for 2030 to be drawn up “as soon as possible”, if the bloc is to galvanise the rest of the world before vital UN talks in Glasgow later this year.

In a letter to the EU’s top official on climate action, Frans Timmermans, the dozen EU member states say “the EU can lead by example and contribute to creating the international momentum needed for all parties to scale up their ambition” by adopting a 2030 EU greenhouse gas emissions reduction target “as soon as possible and by June 2020 at the latest”.

This year’s UN talks in Glasgow are crucial, as the world is far adrift of goals set at the landmark 2015 Paris conference, including the aspiration to limit global heating to 1.5C above pre-industrial levels. Even half a degree higher will significantly increase the risks of drought, floods, extreme heat and poverty for millions of people.

The letter piles pressure on Timmermans, who is due to unveil the EU’s long-awaited climate law on Wednesday. A leaked draft of the law shows Timmermans’ plans to propose an EU-wide 2030 target by September. The target would probably be an emissions reduction of 50-55% compared with 1990 levels, which green activists say is not enough to guarantee meeting the EU’s goal of net-zero emissions by 2050.

EU officials think a couple of months’ difference in proposing the target makes little difference, but would allow them to bring onboard more reluctant countries, including Poland, which has not yet signed up to the EU-wide goal of net zero emissions by mid-century.

The climate and environment ministers argue timing is crucial, as they want the EU to have a 2030 target, before an EU-China summit in September and well ahead of Glasgow climate talks in November. “No other major economy is prepared to take the lead to ensure an ambitious implementation of the Paris agreement,” they write.

Wendel Trio, the director of the Climate Action Network Europe, said: “By proposing a 2030 target increase only in September, the commission will give member states no time to reach an agreement by Cop26 in November, the international deadline by which all countries must commit to new, ambitious climate pledges for 2030. The EU needs to have its own house in order, and quickly to push other countries to make substantial contributions well before the deadline.”

The letter, organised by Denmark, was also signed by France, Italy, Spain and the Netherlands. Only two signatories – Slovenia and Latvia – are central and eastern countries that joined the EU after 2004. Germany is conspicuous by its absence.

The EU climate law is the centrepiece of the European Green Deal, which aims to transform Europe’s economy to confront the climate emergency. The law could set Brussels on a collision course with populist governments in Poland, Hungary and the Czech Republic, which have been the slowest moving on the climate emergency. Putting the 2050 net zero target into law means Poland could be outvoted if it continued to refuse to sign up.

Q&A What is the European Green Deal? Show The European Green Deal is the EU’s answer to what the European commission’s new president, Ursula von der Leyen, called the “existential issue” of the climate emergency. Most EU countries have signed up to goal of a climate neutral EU by 2050, a goal demanding dramatic change in energy use, farming, housing, transport, trade and diplomacy. As well as the long-trailed goal of enshrining in law a climate-neutral Europe by 2050, the plan will propose cutting greenhouse gas emissions by at least 50% by 2030 (compared with 1990 levels). The current target is 40%

Making trade deals only with countries that stick to their climate targets under the Paris agreement

Energy efficiency and renewable energy laws will be tightened up to reflect the more demanding climate targets

To avoid penalising European steelmakers and other industry who are cleaning up their act, non-EU competitors importing energy-intensive goods could face a tax, known as “a carbon border adjustment mechanism”

Using EU funds to develop a zero carbon steel industry by 2030.

Car and truck makers will have to do more to curb emissions, while the EU will seek to boost funding for electric vehicle charge points. Container and cruise ships, currently a gaping hole in efforts to tackle the climate emergency, will be brought into Europe’s emissions trading system, meaning maritime companies will probably have to buy pollution permits

A new strategy to protect European nature, as well as plans to plant and restore forests. Also proposed are plans to improve air and water quality, as well as a review that could lead to tightening of industrial pollution laws

Targets to cut pesticides, chemical fertilisers and increase the area of land devoted to organic farming will be part of an overhaul of the EU’s €59bn a year common agricultural policy

A plan to raise a €100bn “just transition fund” from public and private sources to help EU member states move beyond fossil fuels The European Green Deal is only the start of the journey: laws will have to be drafted and agreed by EU ministers and MEPs; money will have to be raised; plans will have to be implemented. It is a route map, rather than a destination, and time is running out.

Under the law, Brussels would also be able to take a government lagging behind on its climate target to the European court of justice, which can issue daily fines for failure to uphold EU law.

Poland, which generates 80% of its electricity from coal, is seeking EU funds to help wean its economy from fossil fuels. The European commission has proposed a €100m (£87m) “just transition” fund to help countries with coal mining jobs adjust to a green economy, but Warsaw has yet to come onboard.

Climate activists have accused the commission of lacking ambition, as the climate law gives scant detail on how the EU will meet the 2050 net zero target, either by phasing out fossil fuel subsidies, reforming the EU’s common agricultural policy or regulating industry.

“With no 2030 climate target and no measures to end subsidies for fossil fuels, industrial farming and other destructive industries, the commission has left a big hole in what’s meant to be the flagship of the European Green Deal,” said Sebastian Mang, a climate and energy policy adviser at Greenpeace.

The Swedish climate activist Greta Thunberg is likely to give her verdict on the EU climate plans when she meets MEPs on Wednesday. She will also lead a “European strike” in Brussels on Friday with Belgian campaigners.