US President Barack Obama arrived in Anchorage, Alaska, on Monday for a three-day visit aimed at underscoring the need to take urgent action to arrest climate change.

Obama is expected to focus on the threats facing America's 49^th state to convince Americans on the need to reduce fossil fuel use and boost renewable energy production.

Authorities say Alaska's melting permafrost and eroding coastlines serve as a preview of bigger disasters that will come sooner if global efforts fail to ease carbon emissions, seen as the biggest contributor to global warming.

Obama thus became the first American leader to visit the Alaska Arctic. He is expected to see first-hand how Alaska has changed over the past decades primarily due to global warming.

Alaska's yearly average temperature has risen 3.3 degrees since 1959. Last year, the state registered its highest temperature, and it will not be surprising if this will be surpassed this year.

Because of this rise in temperature, Alaska's landscape has changed drastically since 1959, when it first became a state. Alaska's glaciers have severely melted over the past half century, producing more than 3.5 trillion tons of water which, experts say, is enough to fill more than 1 billion Olympic-sized pools.

The sea ice that has been protecting Alaskan villages from storms is also dwindling at an alarming rate. In fact, the Army Corps of Engineers warned that 26 villages have become vulnerable because of erosion linked to sea ice loss.

The sea ice also disappears faster and faster each year. Some studies have found out that the sea ice is now absent each year a month longer than it was in the 1970s.

"The state is changing and changing rapidly," said Fran Ulmer, chairwoman of the US Arctic Research Commission and Alaska's former lieutenant governor.

In addition to these, permafrost in Alaska is also thawing much faster as the ground warms, thereby threatening to weaken houses, roads and pipelines. Because of this, some residents have left their homes because the foundations may tilt and shift.

Not only these: The thawing of the permafrost in Alaska is feared to release trapped greenhouse gases, thus speeding up global warming.

Aside from the effect on ice and glaciers, global warming is also triggering massive wildfires in Alaska. Some 5.1 million acres in the state have already been razed this year.

Aboard Air Force One on his way to Alaska, Obama told journalists what he expects to see in America's Arctic territory. "They described for me villages that are slipping into the sea," Obama said. "It's urgent for them today, but that is the future for all of us if we don't take care."

He spent part of his seven-hour flight to Alaska talking with Governor Bill Walker, who said he thanked Obama for a recent decision to allow Royal Dutch Shell to drill in the Chukchi Sea.

On Tuesday and Wednesday, Obama is scheduled to walk to the receding Exit Glacier in Seward, visit the salmon fishing centre of Dillingham and then fly north of the Arctic Circle to the small town of Kotzebue.