European Union leaders have reached a landmark deal to cut greenhouse gas emissions by 40 percent by 2030 compared with 1990 levels, calling it a new global standard in the fight against climate change. The binding decision followed heated discussions at a summit in Brussels, where some members had sought to protect their various interests. Poland, for example, is heavily dependent on coal and had expressed concern that costs of decarbonizing its economy would slow business growth. The bloc also agreed to boost the use of renewable energy to 27 percent in the total energy mix and to increase energy efficiency to at leat 27 percent. EU top officials said poorer countries would get help in reaching the agreed targets.