Alaska scientist and adventurer Kenji Yoshikawa studies permafrost, ground that has been frozen for more than two years. The warmth of the Earth's core keeps most places free of icy soil that doesn't thaw in the summer, but Fairbanks is a cold enough place that there's a bunch of it here.

Kenji and his partner Tohru Saito were close to my home the other day drilling a permafrost-monitoring hole on university land. I tagged along with my baby and we watched as Kenji drove a drill about 30 feet into the frozen silt beneath a black spruce forest. I held the frozen soil in my hand and formed it into a ball. The ball got smaller as it thawed, which is why thawing permafrost is bad for buildings on top of it.

Kenji's an interesting guy, and a great scientist. He's in Mongolia now, two days after I saw him, doing more permafrost drilling. Here's an article I wrote about him a few weeks ago: http://www.gi.alaska.edu/ScienceForum/ASF18/1842.html