The five largest pension funds in Poland may lose 4.2 percent of their assets if the European Union moves quickly toward clean energy sources and a “carbon bubble” of overvalued fossil fuel investments bursts. The loss would amount to 2.3 billion euros ($2.5 billion) on 53.7 billion euros assets by funds owned by ING Groep NV, Aviva Plc, PZU SA, MetLife Inc. and AXA SA, according to a study commissioned by the Greens group in the European Parliament. That compares with an average weighted loss of 2.5 percent pension funds across the region, under the same shock scenario, the Amsterdam-based Profundo consultancy said in the research paper. Poland, which depends on coal for more than 80 percent of its electricity, sees the most-polluting fossil fuel as the cornerstone of its energy security and is fighting for concessions in EU negotiations on climate laws for the next decade. The government’s strategy faces increasing criticism from environmental lobbies after almost 200 nations agreed in Paris last December on a landmark deal to rein in the greenhouse gases.