Global warming pollution in Maine increased by 24 percent between 1990 and 2004, according to an analysis of state fossil fuel consumption data released today by the Environment Maine Research & Policy Center.

The state’s output of carbon dioxide from the use of fossil fuels leveled off in 2003 and dropped slightly in 2004, however. Maine contributed about 18.4 million tons of carbon dioxide in 1990, rising to 23 million tons in 2003 and dropping to 22.8 million tons in 2004, according to the report.

Nationally, emissions rose 18 percent during the same 15-year time period, the report said.

Transportation is the leading contributor of carbon dioxide in Maine and vehicle miles traveled in the state increased by 26 percent between 1990 and 2004, the report said. Residential heating and electricity generation are also major contributors.

The 15-year increase in emissions is largely tied to Maine’s expanded use of natural gas to make electricity and replace the power generated by the Maine Yankee nuclear plant in Wiscasset.

The leveling off of emissions in 2003 and 2004 is not explained in the report, though discharges are affected by such factors as economic growth and how much homeowners need to heat their homes in a given winter.

The report is based on data compiled by the U.S. Department of Energy, and 2004 represents the most recent state-by-state data available.