Abraham Lake is a reservoir in the front ranges of the Rockies in Alberta, and in winter it keeps its own gas where you can see it. The valley floor drowned in 1972, when the Bighorn dam closed off the North Saskatchewan, and the plants that went under are still rotting, sending methane up in steady threads. In winter the gas never reaches the air. The lake freezes from the top down, so each batch of bubbles is caught on its way up and set in place as the ice thickens. By January the ice holds them in tiers: a big disc near the surface, smaller ones fading into the dark below, each column one stream of methane frozen a layer at a time. Any other lake would be under snow. This valley is a wind tunnel, and days of gales scour the surface down to something like dark glass.
From mid-January the ice is thick enough to walk on in cleats, and Preacher's Point freezes weeks before the rest of the lake. Where the sheet expands and buckles it throws up pressure ridges of broken slabs that curve for hundreds of metres. If you stand still out there you hear the ice working, deep cracks and booms travelling under your feet. The wind that keeps the surface clear will also knock you over, and drives the cold past minus twenty. The lake is named for Silas Abraham, a Stoney Nakoda hunter and guide who took some of the first Europeans through this valley. He died in 1964, eight years before the water covered the plains he had crossed. For most of the year there is no ice at all, just a long reservoir under the peaks, its shoreline bare where the water has been drawn down. It goes blue-green in July, when glacier melt loads it with rock flour. Every white disc is a pocket of methane, which traps roughly thirty times as much heat as carbon dioxide over a century. When the lake breaks up in spring, all of it goes straight into the air.