A group of environmentalists wants Massachusetts to be the first state to adopt a so-called carbon tax.
The Committee for a Green Economy tells the Boston Globe that it's launching a campaign to get the signatures needed to put the issue on the 2014 ballot.
The tax would impose new levies on gasoline and other fossils fuels, based on how much carbon dioxide they produce when burned. The aim is to fight climate change by reducing the use of fossil fuels. The committee says the tax could generate $2.5 billion in revenue annually.