CHRIS KAHNNEW YORK (AP) ¿ Industry, economic and environmental groups are making a final push to influence a climate bill that may go before the Senate within weeks. Investors managing more than $13 trillion in assets called for new global emissions laws Wednesday, illustrating how the issue has divided even groups that traditionally have opposed new curbs. Speaking at the International Investor Forum on Climate Change, Lord Nicholas Stern, among Britain's most influential economists, said the global debate over curbing greenhouse gases has reached a critical point. If the U.S. does not pass substantial climate legislation, few believe other nations, particularly developing countries, will cut emissions on their own. "We have to act now," said Stern, chair of the Grantham Research Institute on Climate Change and the Environment at the London School of Economics. "Some things you can postpone. This is not one of them." Stern three years ago issued an influential report on the global costs of climate change. Greenhouse gases from burning coal and other fossil fuels are blamed for global warming.