The Japanese unit of the US burger giant Tuesday offered a Big Mac for 150 yen (1.3 dollars), about half the normal price, to anyone demonstrating a commitment to preventing climate change. People were asked to check up to 39 boxes on a form they could download from the environment ministry's website, each listing a way of reducing carbon dioxide emissions blamed for global warming.

"We started seeing a rise in access yesterday and it surged this morning. We are now trying to restore the system," said Kenji Someno, who heads the ministry's Lifestyle Policy Office. It was the ministry's first system crash following a corporate offer related to environmental efforts. "McDonald's is such a familiar name with people and they eat there often. The Big Mac discount gives them the strong impression that it's a bargain," Someno said.

McDonald's is one of more than 80 companies offering goods or other prizes to help the government's drive to reduce greenhouse gases. Despite being the home of the Kyoto Protocol, Japan is far behind in its requirement under the landmark treaty for cutting emissions by six percent by 2012 from 1990 levels amid a steady economic recovery. The 39 measures range from cutting air conditioning use to reducing shower time by one minute to simply wiping water off the bottom of a kettle to save energy when heating it on a stove.

Customers can print the forms or show them on their cell phones. The McDonald's campaign lasts for three weeks starting Friday. The ministry official said most hits on the website were just after 9:00am, indicating many people were thinking about Big Macs as they started work.