ANCHORAGE, Alaska — President Barack Obama is painting a doomsday scenario for the Arctic and beyond if climate change isn’t dealt with fast: entire nations submerged underwater, cities abandoned and refugees fleeing in droves as conflict breaks out across the globe.

It’s a harrowing image of a future that Obama insists is inevitable unless the world follows his and America’s lead by making sweeping cuts to greenhouse gases. Lest his sense of urgency get lost, Obama was to drive the message home today by hiking a melting glacier in Alaska.

Obama is counting on Alaska’s exquisite but deteriorating landscape to elicit a sense of urgency that his previous calls to action on climate change have not. He opened his three-day trip to the nation’s largest state on Monday with a speech to an Arctic climate summit, calling global warming an escalating crisis already disturbing Alaskans’ way of life.

“We will condemn our children to a planet beyond their capacity to repair,” Obama said. Alluding ironically to the threat of rising seas, he castigated leaders who deny climate change as “increasingly alone — on their own shrinking island.”

As he traverses Alaska this week, Obama will become the first sitting president to visit the Alaska Arctic. Amid concerns that the U.S. has ceded influence to Russia in strategic Arctic waters, the White House announced Tuesday that it would ask Congress to speed up construction of new icebreakers. The U.S. currently has two working icebreakers, compared to Russia’s 40.