Alaska is often just a fuel stop for US presidents headed for Asia.

But Barack Obama will spend three days in The Last Frontier next week and become the first sitting US president to visit the Alaskan Arctic, the setting of the most spectacular impacts of climate change.

Just three months ahead of the United Nations climate conference in Paris, the US president wants to shore up public support to tackle what he calls "one of the greatest challenges we face this century."

After landing in Achorage on Monday, Obama's visit to the largest and most sparsely populated US state will include a meeting with fishermen in the town of Dillingham, a tour of the Northwest Arctic city of Kotzebue, a visit to glaciers and the GLACIER international conference on the Arctic in Anchorage.

"In Alaska, glaciers are melting," Obama said in a video posted Thursday.

"The hunting, fishing, upon which generations have depended for their way of life and for their jobs, are being threatened.

"As Alaskan permafrost melts, some homes are even sinking into the ground. The state's God-given natural treasures are at risk."

Obama's lengthy journey -- some 3,500 miles (5,600 kilometers) -- aims to bring "awareness of the profound nature of change and the urgency that goes with that," said Rafe Pomerance, member of the Polar Research Board at the National Academy of Sciences.

"The Arctic is unraveling," added the former deputy assistant US secretary of state for environment and development.

"When you look at the glaciers of Alaska and Greenland, when you look at sea ice, permafrost, spring snow cover in the Northern Hemisphere; all of it is melting and shrinking very rapidly with profound consequences in the rest of the world."

Scientists have routinely warned of those consequences, such as when permafrost, a thick subsurface layer of frozen soil that holds billions of tonnes of greenhouse gases, continues to melt.

That melting slowly releases the carbon dioxide and methane that had been accumulated and neutralized in this frozen environment for millennia.

It is a vicious cycle: as the permafrost melts, it releases greenhouse gases in the atmosphere, which increases the warming of the planet further.

- 'Brazen assault' -

"What happens in the Arctic doesn't stay in the Arctic," said Deputy Special Envoy for Climate Change Karen Florini.

"The Arctic matters hugely for its own sake, particularly for the four million people who live in the Arctic, but it matters to everyone because of its impacts beyond the Arctic."

Obama recently unveiled a plan for drastic cuts to carbon emissions from power plants, expected to cause the closure of several dilapidated coal plants.

And over the past few months, he has toughened his tone on a topic he had prioritized during his first presidential campaign in 2008.

But he will meet a tough audience in Alaska, at a time when many of his Republican foes deny that the planet is warming or that human activity is influencing the phenomenon.

The state's junior senator, Republican Dan Sullivan, accused Obama of trying to turn Alaska into "one big national park."

"As if on command from the most extreme environmentalist elements, this president and his team of DC bureaucrats believe they alone know what's best for Alaska," echoed Congressman Don Young.

"But this brazen assault on our state and our people will do the complete opposite."

- Climate hypocrisy? -

Obama's environmental critics have also accused him of "climate hypocrisy."

He has been criticized for approving Shell Oil drilling operations in the Chukchi Sea while also making his latest push on site against climate change.

Environmental activists say such moves send a counterproductive message ahead of the Paris conference, a crucial meeting aimed at clinching a global accord to slow global warming.

Yet Obama has also received praise for decisions like his move in late December to halt drilling in the Bristol Bay and to protect millions of acres of coastland and wilderness.

The White House stresses that a transition toward green energy will take time, and that its moves are the best solution possible in the interim.

"I would rather us -- with all the safeguards and standards that we have -- be producing our oil and gas, rather than importing it," Obama said in May.

The Alaska Climate Action Network, which includes groups such as Greenpeace, plans its own chilly welcome for Obama in Alaska, where it will stage protests against the president's "deeply hypocritical" positions when he arrives in Anchorage.