It is not a matter of consequences but of obligation to act.

Decisions made in the European Court of Human Rights influence law across its 46 member states. Estelle Dehon KC, a barrister at Cornerstone Barristers in the UK, said “the judgement […] comprehensively dismisses the argument that courts cannot rule on climate legal obligations because climate change is a global phenomenon or because action by one state is just a ‘drop in the ocean’,” she told BBC News. Governments globally have signed up to drastically reduce their greenhouse gas emissions.

Basically, EU governments are now legally bound to follow through their obligations.