Reuters: The European Union and green groups piled pressure on the United States on Monday to agree to a target to halve global greenhouse gas emissions by mid-century and back the need for rich countries to set 2020 goals as well. Climate change is high on the agenda for the G8 nations meeting at a luxury hotel on the northern Japanese island of Hokkaido from Monday to Wednesday. But green groups fear the summit will end in failure by not committing to a pledge to slash emissions by 2050. …