DENALI NATIONAL PARK — When I was 12 years old, I didn’t know permafrost was like frozen lasagna. I didn’t know what permafrost was. I grew up in a small town on the Hudson River in New York.

Leaving cloven hoofprints from the Yukon-Kuskokwim Delta to the Arctic National Wildlife Refuge, more than 3,500 muskoxen live in Alaska. All of those shaggy, curly-horned beasts came from one group of muskoxen that survived a most remarkable journey in the 1930s.

Maybe she has the right idea, the arctic ground squirrel. Sniffing the chilly air, looking up to see the first stars of the season, she has decided to check out. A few weeks shy of fall equinox, the squirrel is now bunkered up for winter, three feet beneath the tundra of the North Slope.

On a November morning long ago, Jeff and Annette Freymueller were feeling the effects of the 1 a.m. flight that had carried them home, to end-of-the-line Fairbanks. There was no rush to get up on that Saturday 16 years ago. They slept in.

DENALI NATIONAL PARK — When I was 12 years old, I didn’t know permafrost was like frozen lasagna. I didn’t know what permafrost was. I grew up in a small town on the Hudson River in New York.

Leaving cloven hoofprints from the Yukon-Kuskokwim Delta to the Arctic National Wildlife Refuge, more than 3,500 muskoxen live in Alaska. All of those shaggy, curly-horned beasts came from one group of muskoxen that survived a most remarkable journey in the 1930s.

Maybe she has the right idea, the arctic ground squirrel. Sniffing the chilly air, looking up to see the first stars of the season, she has decided to check out. A few weeks shy of fall equinox, the squirrel is now bunkered up for winter, three feet beneath the tundra of the North Slope.

Floating down the Fortymile River, we saw a cut in the green hills that hinted of a creek. My canoeing partner and neighbor, Ian Carlson, 13, wanted to see a ghost town. The map told us one should be dead ahead.

The evidence is in: Snowshoe hares near Wiseman eat lots of dirt.“I have thousands and thousands of photos of hares eating soil in this one little spot,” said Donna DiFolco, a biologist and cartographer with the National Park Service. DiFolco has studied hares in the eastern portion of Gates of the Arctic National Park since 1997. That’s when she started counting hare tracks near Wiseman as part of a lynx study. 

About 160 years ago, U.S. Secretary of State William Seward was taking some heat for his significant role in the purchase of Alaska. On the day the Russians received the $7.2 million check, a group of white travelers were at Nulato, getting ready for an upriver trip to Fort Yukon to explore this strange land. Among them was Frederick Whymper, an adventurous English artist who had signed on to help document a telegraph project across North America. In his book “Travel and Adventure in the Territory of Alaska,” he left behind some insights into what America was getting itself into.

Just beneath the owl box, hung 20 feet up the stem of a balsam poplar, the backyard barbeque continued late into the evening. Despite the thwap of badminton birdies and the chirp of human voices, the boreal owl had work to do.

Just outside my window here at the University of Alaska Fairbanks, workers are drilling into the asphalt of a parking lot using a truck-mounted rig. They twist a hollow bit 25 feet into the ground and pull up hard, clear evidence of why the blacktop is sinking.

Of the five species of salmon that swim Alaska waters, the pink is by far the most plentiful. Some scientists think the fish is an overabundant predator that outcompetes other salmon and some seabirds.

In Alan Weisman’s book, “The World Without Us,” the author ponders “a world from which we all suddenly vanished. Tomorrow.”

For the past century, official thermometers scattered around Alaska have shown a warming trend. Most of the trusted weather stations are in river valleys; Gulkana, at 1,300 feet, is the high point of Alaska’s 21 “first order” weather stations, some of which have been running for a century.

A Fairbanks scientist recently made an intricate new map of Denali while crisscrossing its summit a few times in a single-engine airplane. His top-of-the-continent measurement was within a few feet of a GPS reading done a few years ago, using a system he calls fodar.

When I left my sister’s house in Brooklyn yesterday afternoon, I was 4,200 miles from my home. That’s a long way, but I slept in my Fairbanks bed before the next sunrise. 

Millions of Alaska birds nest on rocky emerald islands seen by few people other than ship captains. One of the funkiest of these creatures is the crested auklet, which looks like a bassist in a punk band and smells like a tangerine.

KANUTI HOT SPRINGS — After a few hours of skiing through deep snow, Forest Wagner and I smelled a tuna sandwich. We knew we were closing in on warm pools of water.