The loss of frozen ground in Arctic regions is a striking result of climate change and a cause of more warming to come.

YUKON DELTA NATIONAL WILDLIFE REFUGE, Alaska — The Arctic is warming about twice as fast as other parts of the planet, and even here in sub-Arctic Alaska the rate of warming is high. Sea ice and wildlife habitat are disappearing; higher sea levels threaten coastal native villages.

The main road in Bethel, where average temperatures have risen about 4 degrees Fahrenheit since the mid-20th century, is more of a washboard than a thoroughfare because of shifting ground. Building foundations in Bethel move and crack as well. Some roads, airport runways and parking areas have to be reinforced with liquid-filled pipes that transfer heat out of the permafrost to keep the ground from slumping.