Guardian: 1. Global vision The world has yet to formally agree a goal in the battle against global warming. This could be a maximum temperature rise, such as 2C, or concentration of carbon dioxide in the atmosphere. More likely, it will be a vaguer ‘direction of travel’ such as the G8 pledge to halve global emissions by 2050. 2. Mitigation The key issue – who will cut their carbon by how much and by when. To be meaningful, targets must be short-term, perhaps something like 25-40% …