Reuters: European Union nations on Monday dug in for a battle over the costs of tackling climate change, with few signs of compromise emerging ahead of a summit of EU leaders later this week. Two groups have emerged to demand changes to the plan, threatening the chance of a successful deal to curb greenhouse gas emissions. The margin between success and failure will be narrow, Czech Deputy Prime Minister Alexandr Vondra told Reuters ahead of the two-day summit of EU leaders that starts …