Environment News Service: European leaders today agreed to hold fast to their plan to battle climate change through growth in renewable energy sources and 20 percent cuts in greenhouse gas emissions by 2020, and on ways to share the costs. The plan includes concessions to heavy industry and to countries in Eastern Europe concerned that the cost of curbing greenhouse gas emissions would also curb their economic growth. “This is really historic,” French President Nicolas Sarkozy, holder of the EU’s …