Permafrost is ground that stays frozen year round; the permafrost in interior Alaska also has massive wedges of actual ice locked within the frozen ground. When that ice melts, the ground surface collapses and forms a sinkhole that can fill with water. Thus, a thermokarst lake is born. At first glance, Big Trail looks like any lake. But look closer and there's something disturbing the surface: bubbles.

A growing number of people are visiting Norway’s protected areas. This poses new challenges for national park management. Excrement and rubbish left behind by thousands of tourists degrades Lofotodden National Park’s idyllic nature. What can be done about this problem?

The Kostanai Region declared a state of emergency on Sept. 4 after forest fires burned a record 43,000 hectares (the size of Сarribean Barbados island) and forced an evacuation of 1,841 people.