Poland, Czech Republic, Hungary, and Estonia prevented the EU from adopting a clear long-term climate neutrality goal at the summit in Brussels on Thursday evening (20 June).

The central and eastern European leaders could not get behind a draft text which said the EU should take measures "to ensure a transition to a climate-neutral EU by 2050" - a date too specific for them.

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Poland was leading the opposition, with support from the Czech Republic and Hungary.

A clear commitment for the 2050 date was also missing from Estonia, an EU source said on condition of anonymity.

Another EU source said "three and a half states" were against - in an illustration of the non-committal stance of Estonia.

"There was lots of back and forth and 'how can we persuade you'," added the source.

But in the end, the leaders decided to scrap the 2050 commitment.

The final text now says the EU aspires to climate neutrality "in line with the Paris agreement", and the mention of the year 2050 was moved to a footnote.

"For a large majority of member states, climate neutrality must be achieved by 2050," that footnote said.

Ironically, in the text published on the European Council website on Thursday evening, the footnote initially was not included.

Climate neutrality refers to an economy in which the emission of greenhouse gases caused by human activity is mostly prevented, and any remaining emissions are compensated through for example planting additional trees or capturing emissions and storing them.

The reference of climate neutrality "in line with the Paris agreement" is open to interpretation.

The global climate agreement, clinched in 2015 in the French capital, said that the entire world should reach climate neutrality "in the second half of this century".

However, the Paris deal also said that efforts must be made to limit global warming to an average temperature rise of 1.5C, compared to pre-industrial levels.

The failure to reach a consensus on 2050 will be a disappointment to many who saw positive signs in recent weeks.

That 2050 target seemed to gain momentum recently after the EU's largest state, Germany, decided to support it.

Also earlier this month, the United Kingdom, although leaving the EU, committed to a domestic zero-emissions target by 2050, while Italy also came on board.

But at the EU summit in Brussels it proved to be impossible to convince the last quartet of sceptics.

Consensus is needed for leaders to adopt official conclusions.

One diplomatic source said the reluctance of some coal-dependent member states was "expected".

"It's easier for Scandinavian countries to commit to climate neutrality," he said.

"These are known differences [between the member states]", he added.

Poland's permanent representation in Brussels said in a tweet that prime minister Mateusz Morawiecki "defends [Poland]'s interests in discussion about climate policy".

"Fair distribution of climate protection costs means taking into account the specificities of [member states]. Climate goals are important in the same way as their implementation, taking into account citizens & economy," it said.

'Blew it'

But non-governmental organisations were frustrated with the outcome.

Greenpeace said that Europe's governments "had a chance to lead from the front and put Europe on a rapid path to full decarbonisation".

"They blew it," the environmental lobby group added.

Friends of the Earth meanwhile called the vetoes "criminal behaviour".

"The reference to being in line with the Paris agreement in such a flimsy text makes a mockery of that agreement, and should not be allowed to stand," said WWF.

The diplomatic source stressed, however, that the EU was "still ambitious" and that he never expected the final target year to be agreed at this summit.

"The climate debate is not finished. It will come back, certainly, in December," he said.

Meanwhile at the summit, the leaders did agree in the text to submit a long-term climate strategy to the UN climate body in "early 2020", and adopted a Strategic Agenda which identified climate action as one of the EU's priorities.

The Strategic Agenda, covering the 2019-2024 period, said the EU's policies should be "consistent with the Paris agreement" - but also did not contain a specific year for carbon neutrality.

"As the effects of climate change become more visible and pervasive, we urgently need to step up our action to manage this existential threat. The EU can and must lead the way, by engaging in an in-depth transformation of its own economy and society to achieve climate neutrality," it said.

Another new impetus for the climate debate will be on 1 July when Finland takes over the helm for six months as EU president.

Earlier this month Finland said it wanted to be climate neutral by 2035.

In the early hours of Friday, European Council president Donald Tusk told press "reaching unanimity was not possible today".

"However, we have good reason to believe that this may change, as no country ruled out the possibility of a positive decision in the coming months," said Tusk.

This article was updated on Friday 21 June, 9:30, to include quotes from Donald Tusk