"I support this European green deal, I think it goes in a good direction, but it is very ambitious and it will not be easy to translate it into concrete results", said Barroso on the sidelines of a meeting of the Council of the Portuguese Diaspora in Cascais.

The measures "could generate conflicts" with "workers in the industrial sector, or even agriculture ... so from so-called traditional sectors” resisting them, he warned. “If [the policies] are not well explained... and there are no follow-up measures, they will revolt against these measures."

He cited as an example the "yellow vest" protests in France against the government’s decision to increase fuel prices, which he said showed there was a need to develop other alternatives. The policy was in principle correct and environmentally fair but people, especially in the provinces, who need to drive more often and greater distances, with petrol- or diesel-driven cars or tractors, felt discriminated against.

"The social component in the energy transition is very important,” Barroso stressed. "We can have a big problem here if we can't manage it prudently.

"Unfortunately, other great partners [in the world] are not necessarily aligned with us" on environmental policy, he added. While within the EU only Poland has broken ranks, without a commitment from other major polluting countries outside Europe, companies will face competitiveness problems.

"If European companies will have to implement these policies (EU) in view of these targets and others do not, then we may have a competition problem," he said. "The so-called carbon tax is provided for in the European Green Deal, that is taxing imports into the European Union originating in countries that do not apply comparable measures. Except this is going to be very difficult, if not impossible, to apply.”

The US and China are the world's largest polluters today, he noted, but India is on the same trajectory, while Europe is responsible for a relatively small volume of greenhouse gases.

"Even if Europe achieves all its goals, even if it had zero emissions today, it would not solve the problem of climate change," he stressed.