Detroit Free Press: On the big picture, Barack Obama and John McCain agree — with a shared sense of urgency — that the United States can’t keep pumping global-warming gases into the atmosphere unchecked, because their accumulation threatens to bring rising seas, mass extinction of plants and animals and more hunger, disease and natural disasters. Scientists say the next president must take action on climate change. McCain and Obama both say that the country will need to respond with a system to limit …