Although he doesn't show up at the Copenhagen climate talks until next week, U.S. President Barack Obama won't be far from global warming issues when he lands in Oslo Thursday to collect his contentious Nobel Peace Prize.

Greenpeace activists said they had laid out the message "Obama: our climate, your decision" in enormous cloth letters covering an area 500 feet by 170 feet (150 meter by 50 meter) in an empty field next to Oslo's Gardermoen airport.

"This is our message and we want to send it most importantly to the president himself," Greenpeace spokeswoman Bente Myhre Haast said, adding that she hopes it will be visible from Obama's flight path.

On the sidewalks near Oslo's lavish Grand Hotel, where Obama will stay, activists sprayed similar slogans on the pavement _ from "you won it, now earn it" to "change the politics, save the climate."

The Norwegian committee that awards the Nobel Peace Prize said it chose Obama for, among other achievements, bringing the U.S. into the fight against global warming and for supporting multilateral diplomacy.

But Greenpeace and other environmental groups dispute the decision, saying Obama hasn't done enough to combat climate change.

Anti-war activists, meanwhile, contend that Obama's decision to increase troop levels in Afghanistan by 30,000 soldiers made a mockery of awarding the president a prize whose mandate includes honoring those who work for "the abolition or reduction of standing armies."

It's been a decade since a sitting U.S. president visited Norway, and Norwegian anti-war and climate change activists both say they plan to use this rare occasion to make sure the president hears them.

On the anti-war front, Benjamin Endre Larsen _ leader of Norway's Peace Initiative and a protest organizer _ estimated that about 5,000 people will turn out on Thursday to voice their dissent from Obama's strategy in Afghanistan and Iraq.

Demonstrators plan to gather in sight of Obama's hotel room balcony, where he is expected to wave to a torch-lit procession in his honor, and chant slogans playing on Obama's own campaign slogans, foremost among them: "Change: Stop the War in Afghanistan."

With all the attention Obama's visit has generated, about 2,500 police officers from all over the Nordic country have deployed to Oslo. The Norwegian military has also contributed support in the form of helicopters and sharpshooters.

Last week, city maintenance crews welded shut over 400 manholes in downtown Oslo, and police said they will remove all downtown trash cans on Wednesday afternoon to eliminate potential hiding places for bombs.

The Justice Ministry is shelling out 92 million kroner ($16 million) for security.