The O'Malley administration's aggressive new plan to fight climate change calls for Maryland residents to further cut their energy use or face higher monthly utility bills.

The plan, to be released Thursday by Gov. Martin O'Malley, also requires that more of the state's electricity come from renewable sources by 2020.

Maryland's goals for reducing greenhouse gases are among the most ambitious in the nation. The plan requires stricter measures than previously proposed to meet the requirement set by the General Assembly in 2009 to cut carbon emissions that scientists say drive climate change.

"Although it might seem high, it's really the first step, the first down payment that we need to make in order to avoid a real climate catastrophe in the world," said Donald Boesch, president of the University of Maryland Center for Environmental Science.

A business policy group criticized the proposal, pointing out that efforts in such a small state won't alter the course of climate change but will directly affect people's expenses.

"It's a laudable goal, but there's a countervailing issue that the consumers are getting hit directly with the costs to do it," said Kim Burns, president of Maryland Business for Responsive Government. "If it's going to take money out of people's pocketbooks and it's not going to have a measurable impact, why do it?"

The two pieces expected to cut the most carbon emissions already cost residential customers about $2.60 per month unless they use a state program to curb energy use. State officials expect the new plan to make that cost slightly higher.

State officials say the plan will create significant economic benefits, bringing 37,000 jobs and netting more than $1 billion for Maryland's economy.

Mike Tidwell, executive director of the Chesapeake Climate Action Network called it a "credible and very effective plan" that would "trigger market changes in fuel consumption."

"Maryland, as a state, cannot single-handedly solve global warming," Tidwell said. But given its 4,000 miles of shoreline and vulnerability to rising sea levels, he said, "Maryland should lead by example."

Maryland is one of eight states whose laws require a cut in greenhouse gases. Maryland's goal to reduce emissions to 25 percent below its 2006 levels is the second-most aggressive plan in the country behind California's.

Maryland's 2009 Greenhouse Gas Reduction Act, which passed with bipartisan support, requires the governor to develop a plan that meets that goal without causing economic harm. State lawmakers are required to vote in 2015 whether to continue with the plan O'Malley will present Thursday or send him back to the drawing board.

Part of the new plan calls for increasing Maryland's reliance on renewable energy sources such as wind and solar to 25 percent of electricity generation in the state by 2020. The previous goal was 20 percent by 2022.

"These are tough things to achieve," said state Secretary of the Environment Robert M. Summers. "It would have been done by now if it were easy."

Electricity rates are expected to rise as the state uses more renewable sources, but state officials said higher electric bills could be offset by using less electricity through energy-efficient appliances, switching off lights in empty rooms, setting the thermostat a little higher in the summer, plugging air leaks in homes or upgrading insulation, among other techniques.

Much of Maryland's plan involves programs, agreements and federal laws that are already in place. The state participates in a regional cap-and-trade system that calls for reducing emissions from its coal-burning power plants. Already, Maryland requires new cars and trucks to have the country's highest fuel efficiency.

Other pieces of the plan include creating newer, greener building codes and more public transit, putting less trash in landfills, and planting or replanting 43,030 acres of forest.

ecox@baltsun.com