HACKENSACK, N.J. – A plan being considered by nine northeastern states to reduce so-called greenhouse gases that contribute to global warming will not impose undue costs on businesses and governments, according to several new studies.

“We’re talking about pennies or dollars a month, not $100,” Dale Bryk, an attorney with the Natural Resources Defense Council, told The Record of Bergen County for Monday’s newspapers. “The cost that we’re looking at is minuscule and really the cost of the problem we’re looking at is monumental.”

A New Jersey electric customer on average would see increased costs of $3.28 to $40 a year over the next 15 years, according to one study by an economic development consultant. The study found that personal incomes in the region would fall no more than 0.03 percent by 2021.

New Jersey utilities are skeptical about the numbers.

“We can’t imagine that making these kinds of reductions would not have a significant impact on these prices,” said Ellen Raines, a spokeswoman for FirstEnergy Corp., which owns Jersey Central Power & Light Co.

Plans to create the Regional Greenhouse Gas Initiative involve New Jersey, Delaware, New York and the six New England states. In addition, Maryland and Pennsylvania are monitoring its progress, and California, Oregon and Washington are developing their own global warming reduction plans.

The United States produces 25 percent of all the planet’s greenhouse gases.

Massachusetts Gov. Mitt Romney has not endorsed the plan, expressing concerns over its cost to businesses and its failure to account properly for the greenhouse gases produced by automobiles.

The proposal would freeze utility emissions at current levels through 2015, and then require a 10 percent reduction by 2021. It also would create a market for greenhouse gases, allowing those who lower emissions to sell excess “credits” to those who can’t cut quickly enough.

Some critics fear such a plan could drastically increase electricity rates because it would force companies to build new plants, or convert them to use natural gas.

A study by the New Jersey Board of Public Utilities predicted initial costs for the new rules would add $5 to $10 a year to consumers’ bills, said Mike Winka, the board’s clean energy director. He said electricity bills might decrease over time because the regulations would force more energy conservation.