Earth Day postcards from space GeoEye satellite image This half-meter resolution image shows icefields near Adelaide Island (on the west), lying at the north side of Marguerite Bay off the west coast of the Antarctic Peninsula. GeoEye tasked its GeoEye-1 satellite to collect this image on April 18. For commercial imaging satellites, every day is Earth Day: In honor of today's eco-conscious holiday, Colorado-based GeoEye is releasing four recent snapshots of the planet, taken by the company's GeoEye-1 satellite as it orbited 423 miles (681 kilometers) above. Earth Day isn't just a day for pretty pictures. It's also an occasion to reflect on the state of the planet. This picture of broken-up icefields near Adelaide Island, off the coast of the Antarctic Peninsula, is a reminder that our planet's changing climate is a continuing cause of concern. The Antarctic Peninsula is considered one of the world's fastest-warming "hotspots," as documented by imagery from Europe's Envisat satellite. "Ice shelves are sensitive to atmospheric warming and to changes in ocean currents and temperatures," Helmut Rott, a professor from the University of Innsbruck in Austria, explained in a statement issued earlier this month. The northern Antarctic Peninsula has been subject to atmospheric warming of about 2.5 degrees Celsius [4.5 degrees Fahrenheit] over the last 50 years - a much stronger warming trend than on global average, causing retreat and disintegration of ice shelves. Antarctica's situation serves as a "canary in the coal mine" for the effects of global climate change and the greenhouse-gas effect, to which industrial activity is an increasing contributor. But this isn't just an issue for penguins around the South Pole, or polar bears around the North Pole. Opinion surveys indicate that the public is increasingly seeing a connection between global changes in climate and the way weather works in their own region. For more about the Antarctic Peninsula in particular, check out this report about the effect of climate change on penguin breeding patterns, this one about concerns for seal pups, this one about the encroachment of invasive species, and this video from 2007 about the continent's shrinking "cathedral of ice." Msnbc.com's Environment section has complete coverage of today's Earth Day goings-on. Where in the Cosmos GeoEye's picture of the Antarctic Peninsula was the subject of our latest "Where in the Cosmos" picture puzzle, posted to the Cosmic Log Facebook page. Stacy Thompson Layman was the Cosmic Log correspondent who first came up with the location shown in the picture (after a few hints), and to reward her late-night effort, I'm sending her a pair of 3-D glasses and a copy of "The World in 2050: Four Forces Shaping Civilization's Northern Future," which makes for relevant reading on Earth Day. To get in on future "Where in the Cosmos" puzzle contests, be sure to click the "like" button for Cosmic Log. Here are the three other GeoEye-1 snapshots: A curl of land at the tip of Australia's Towra Point Nature Reserve, located on the southern shores of Botany Bay, looks a bit like an elephant and its trunk. A boat speeds through the bay at upper left. Situated on an ancient river delta deposit, the Towra Point reserve is designated as a wetland of international importance because it is a breeding ground and home to many vulnerable, protected or endangered species with diverse habitats. There is also a Towra Point Aquatic Nature Reserve in the surrounding waterways. GeoEye tasked its GeoEye-1 satellite to collect this image on Feb. 19. This GeoEye satellite image shows a portion of the D. Ering Wildlife Sanctuary off the Siang River, directly above the Dibru-Saikhowa National Park, located about 7.5 miles (12 kilometers) north of Tinsukia, Assam, India. The sanctuary is named after the late legendary social reformer Daying Ering. The sanctuary consists of a series of islands in the Siang River that are home to endangered animals and many migratory birds. GeoEye tasked its GeoEye-1 satellite to collect this image on March 17. This half-meter resolution image shows the Okavango Delta (or Okavango Swamp), located in Botswana in central southern Africa. The Okavango is the world's largest inland delta and formed where the Okavango River empties onto a swamp and into a basin in the Kalahari Desert. Most of the water is lost to evaporation and transpiration instead of draining into the sea. Botswana is one of the world's most ecologically sensitive areas. The Moremi Game Reserve spreads across the eastern side of the delta. GeoEye tasked its GeoEye-1 satellite to collect this image on April 12. More views of Earth from space: