In decades of public debate about global warming, one assumption has been accepted by virtually all factions: that tackling it would necessarily be costly. But a new report casts doubt on that idea, declaring that the necessary fixes could wind up being effectively free. A global commission will announce its finding on Tuesday that an ambitious series of measures to limit emissions would cost $4 trillion or so over the next 15 years, an increase of roughly 5 percent over the amount that would likely be spent anyway on new power plants, transit systems and other infrastructure. When the secondary benefits of greener policies — like lower fuel costs, fewer premature deaths from air pollution and reduced medical bills — are taken into account, the changes might wind up saving money, according to the findings of the group, the Global Commission on the Economy and Climate . “We are […]