WASHINGTON - California, New York City, three other states and a coalition of environmental groups will file notice Thursday that they'll sue the Environmental Protection Agency to push it to regulate pollution from ocean ships and aircraft that's causing global warming.

Under the Clean Air Act, a U.S. district court can compel the EPA to take action to protect the public's welfare if the agency delays doing so for an unreasonably long time. The law requires that a notice of intent to sue be filed 180 days in advance, the step that the groups are taking now.

The timing means that any suit would be filed after President Bush leaves office. The groups concluded that they couldn't guess what the next administration would do and should be ready to sue if necessary, said Jackie Savitz of Oceana, a group that's devoted to protecting the world's oceans.

"It's basically what we have to do to maintain our progress going forward to get ships and aircraft regulated," she said.

The environmental legal-rights group Earthjustice, acting on behalf of Oceana, Friends of the Earth and the Center for Biological Diversity, planned to send the notice as a letter to the EPA. California, Connecticut, New Jersey, Oregon, New York City, the South Coast Air Quality Management District, the California Air Resources Board and the Pennsylvania Department of Environmental Protection planned to file similar notices.

Aircraft and ships are a large and growing source of carbon dioxide, the main heat-trapping gas that's causing the Earth's average temperature to increase.

The environmental groups filed petitions late last year asking the EPA to determine whether greenhouse gases from aircraft and ships endanger public health and welfare, and if they do, to regulate them as federal law requires.

The EPA issued a notice this month about future rule-making calling for a comment period. Bush opposes mandatory controls on emissions.

EPA spokesman Jonathan Shradar said the agency plans no further steps. "EPA has been responsive to these petitions with our advanced notice of proposed rulemaking and we will continue down that path," he said.

"When we filed the petition, the EPA didn't respond. . . . (Then) they came out with a 500-page document that does everything but make a rule," Savitz said. The comment period, she said, "basically guarantees they won't have to do anything in their lifetime."

The environmental groups reported that aircraft produce 12 percent of the carbon dioxide emitted by all forms of American transportation. They also emit nitrogen oxides, which add to ozone - another greenhouse gas - and water vapor, which forms contrails - which are associated with increased cirrus cloud cover, another warming factor.

Oceana, in a new report about shipping and global warming, says the world's ocean-going vessels release nearly 3 percent of global carbon dioxide.

Oceana reported that ships could reduce those emissions by 23 percent by traveling 10 percent more slowly. The slower speed would mean a 23 percent fuel savings as well, it said.

Oceana's report "Shipping Impacts on Climate: A Source With Solutions": www.oceana.org/climate/shipping-impacts

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